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USER`S MANUAL for v2

1. compu TECH 29962 Killpeck Creek Ct 301 884 5712 gt a Charlotte Hall MD 20622 301 884 5763 fax PRO COMPETITION WEATHER ANALYZER AND COMPUTER USER S MANUAL for v2 COMPETITION WEATHER ANALYZER AND COMPUTER RACEAIR MPUTECH SYSTEMS INC POWER 9 cy WEATHER DATA TRK romen as ENTER SET UP A Sampling and Fan Contro itomat TUNE UP AIR CORR g UGHT __ DIAL IN 7 me DRAG PERF DRAG FORMULAS ENGINE FORMULAS COPYRIGHT 2002 COMPUTECH SYSTEMS INC 29962 KILLPECK CREEK COURT CHARLOTTE HALL MD 20622 email computech ameritel net 1 QUICK START GUIDE 1 Make sure batteries are installed 2 Press POWER ON OFF key 3 Press SAMPLE key to take weather sample 4 Use left side black and red keys to access programs Press ALT first for red programs 5 Use down arrow NO key or up arrow YES key to move the display left indicator arrow to navigate program menus 6 Press ENTER to use program 7 Answer program questions to calculate result CONTENTS COMPUTER PROGRAM CAPABILITIES Page 3 GENERAL INFORMATION Page 9 Power Requirements Page 9 Keyboard Functions Page 9 Program Access and Use Page 10 Communication Port Page 10 Program Updates Page 11 Additional Instructions Page 11 COMPETITION WEATHER ANALYZER Page 11 Overview Page 11 Weather Terms Page 11 Good A
2. Compression Ratio Dome Compression Ratio Pour Chamber Correction Factor Correction Factor Setup Cubic Inch Displacement Date Set Density Altitude Dew Point Dial In Density Altitude Dial In Standard Displacement Cubic Inch Dome Volume Piston Pour Dyno HP Correction EGT Correction EGT Prediction Engine RPM Drag RPM Drag ET amp MPH from HP Fuel Injection Area Fuel Injection French Grimes Fuel Injection HS Bypass Fuel Mileage Fuel Setup Gear Ratio Circle Gear Ratio Drag Good Air GCOMPUTECH SYSIEMS NC INDEX Page Subject 17 Help Additional 11 High Speed Bypass 14 Holley Jets 15 HP Correction Dyno 14 HP 1 4 Mile 12 HP 1 8 Mile 22 Keihin Jets 21 KeyBoard Functions 15 Liquid Weights 34 Mikuni Jets 34 Mileage Fuel 40 MPH 40 Nitro Percent 40 Orifice Square Area 8 Piston Dome Volume Pour 10 Power Requirements 37 Precision Jets 38 Pressure Altitude 38 Program Access and Use 39 Program Setup 12 Program Updates 8 Relative Humidity 40 Reset Factory 8 Reset Power Off 13 Run Completer 13 Sample Air 26 Setup by Percent 25 Setup by Weight 40 Specific Gravity Gasoline 39 Specific Gravity Methanol 9 Square Area 24 Standard Performance Full 24 Standard Performance Inter 29 Throttle Stop 29 Tire Size Circle 33 Tire Stagger 20 Torque Converter Slip 21 Tune Up Information 21 Vapor Pressure 35 Water Vapor 8 Weather Analyzer Operation 3
3. No Cyl 8 Enter number of cylinders C 1 D 425 6 Calculated engine cubic inch displacement Liters 6 97 Calculated engine displacement CC 1000 Cubic Inch Displacement Find Cylinder Bore This program computes the cylinder bore diameter required to obtain a desired engine displacement Press ALT ENGINE FORMULAS then select C I D Menu then select Calc Bore to start this program Display Example Calc Bore C 1 D 358 0 Enter desired engine cubic inch displacement Stroke 3 480 Enter crankshaft stroke inches No Cyl 8 Enter number of cylinders Bore 4 046 Calculated cylinder bore diameter inches Cubic Inch Displacement Find Crankshaft Stroke This program computes the crankshaft stroke length required to obtain a desired engine displacement Press ALT ENGINE FORMULAS then select C I D Menu then select Calc Stroke to start this program Display Example Calc Bore C 1 D 358 0 Enter desired engine cubic inch displacement Bore 4 035 Enter cylinder bore diameter inches No Cyl 8 Enter number of cylinders Stroke 3 500 Calculated crankshaft stroke inches 40 Subject Air Correction Air Density Ratio Air Good Bad Air Sample Bad Air Barometric Pressure Absolute Blower Overdrive Bypass High Speed Calibration Chassis Setup by Percent Chassis Setup by Weight CID CID Bore CID Stroke Clock Set Communication Port Compression Ratio Compression Ratio Chamber
4. 1 Car 0 to start this program Setup Display Example T Stop Setup Fuel Methanol Press down arrow to change fuel then ENTER Car 228 Enter car or combination ID number Run 1 ENTER to go to next line Corr 0 9875 Enter correction factor for run 1 8 861 Enter ET for 1 1 190 Enter timer setting seconds for 1 Run 2 ENTER to go to next line Corr 0 9882 Enter correction factor for run 2 9 109 Enter ET for run 2 1 770 Enter timer setting seconds for 2 28 COMPUTECH SYSIEMS NC a 4 01 ET 0 0234 ET change for timer change ratio Setup complete Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press T STOP then 1 Car 228 to start this program T Stop Display Example T Stop Car 228 Fuel Methanol Fuel selected Old Tmr 1 540 Enter timer setting for reference run Old Corr 0 9878 Enter correction factor for reference run Old ET 8 914 Enter ET for reference run New Corr 1 0004 Auto transferred new correction factor New ET 8 900 Enter desired new ET New Tmr 1 457 New timer setting to run desired ET Gear Ratio Drag This program will calculate the necessary gear ratio to obtain the desired finish line engine RPM while accounting for tire size and torque converter slip This program works for 1 8 mile as well as 1 4 mile drag racing Pres
5. Example Est ET MPH Tire Circum 106 0 Enter tire circumference inches not diameter Trap MPH 154 22 Enter finish line MPH Trap RPM 7825 Enter finish line engine RPM Gear Ratio 4 56 Enter rear end gear ratio Conv Slip 829 Calculated torque converter slip RPM Pct Slip 10 59 Calculated torque converter slip Run Completer Drag This program will predict what the elapsed time and MPH would have been on a run that was aborted prior to the finish line In break out classes it is common practice to lift off of the throttle or to brake the vehicle prior to the finish line in an effort to take only enough win light to get there first and to avoid the possibility of breaking out This program utilizes the 1000 ft elapsed time the 1 4 mile elapsed time the 1 4 mile MPH from a previous full run and the 1000 ft elapsed time from the aborted run To use this program for 1 8 mile racing substitute the 330 ft elapsed time for the 1000 ft elapsed time the 1 8 mile elapsed time for the 1 4 mile elapsed time and the 1 8 mile MPH for the 1 4 mile MPH Press ALT RUN COMP to start this program Display Example Run Completer Old Part ET 5 774 Enter 1000 ft ET from full run Full ET 6 918 Enter 1 4 mile ET from full run Full MPH 194 30 Enter 1 4 mile MPH from full run New Enter to continue Part ET 5 638 Enter 1000 ft ET from aborted run Est ET 6 755 Calculated 1 4 mile ET for aborted ru
6. Hg is the pressure that is present at the location of the sensor from the atmosphere The term barometric comes from the weather instrument the mercury barometer which is used as a laboratory precision measuring device The term absolute refers to absolute zero where without the earth s atmosphere the measured pressure would be 0 Inches Hg Normal pressure gages have a scale that sets the atmospheric pressure of 14 7 pounds per square inch 29 92 Inches Hg as the zero point This is referred to as gage pressure The RaceAir Pro provides the absolute barometric pressure that is used in the calculations for ADR Density Altitude and the Correction Factor It has the biggest influence on air quality Absolute barometric pressure normally varies between 25 and 31 Inches Hg depending on the elevation above sea level where the sensor is The atmospheric pressure defined as Standard Day at sea level is 29 92 Inches Hg and decreases about 1 Inch Hg per 1000 ft of elevation Altitude Altitude is the elevation above mean sea level MSL in feet Altitude Density See Density Altitude Altitude Pressure See Pressure Altitude Barometric Pressure Absolute See Absolute Barometric Pressure Barometric Pressure Corrected to Sea Level In order to provide a standard method of stating barometric pressure the National Weather Service NWS adjusts the absolute barometric pressure observations to sea level
7. observed number torque or horsepower and press ENTER to see the corrected value Pressing ALT ENTER again will send the computer back to the Sampled Wthr screen The process can be repeated again for the next value The same technique can be used for previously recorded weather conditions using the AIR CORR program GENERAL INFORMATION Power Requirements The RaceAir Pro uses 6 AA batteries Note the polarity markings on the battery tray when installing the batteries The unit will automatically turn off after 10 minutes of inactivity The highest current draw on the batteries is the fan that comes on when the air SAMPLE key is pressed Use the display LIGHT only as necessary to preserve battery life The computer will display a caution message when the battery voltage is too low for acceptable operation If the display stops responding to keystrokes including the POWER ON OFF key it may be necessary to remove and reinstall the batteries to restart the computer The computer may also be powered with a 12 V dc adapter through the upper connector provided on the left side of the case The 110 V ac to 12 V dc adapter is available from Computech Systems Inc The unit may be safely powered by the adapter while the batteries are installed Keyboard Functions The keyboard has several multifunction keys The YES key also functions as an up arrow key and a plus key The NO key functions as a down arrow key and a minus key The spli
8. subtracting 0 003 from prediction for Dial In of 8 80 25 GCOMPUTECH SYSIEMS NC Dial In Density Altitude Method This program is designed to help class and bracket racers predict an elapsed time ET for the next run based on changes in the density altitude This program requires that the Dens Alt Setup function be run for each vehicle so that the program can calculate an elapsed time versus density altitude ratio The program has memory for 3 different data sets The Dial In is predicted from 3 previous runs that are entered into the computer memory during the Dens Alt Setup program and a recent reference run The reference run on which the prediction is based is selected by the user The reference run should be the most recent good full run when the vehicle performed as expected Runs that had tire spin unusual 60 ft times or gusty wind conditions should not be used for the reference run Change the run used as the reference old run as the race day progresses It is important to use the most recent good full run as the reference The most recent run will best represent the current traction and weather conditions Since this program utilizes runs from memory it is compatible with whatever fuel being used This program works best when the engine fuel air mixture is slightly rich so the vehicle performance will change appropriately with the weather changes This may require periodic jet changes during the race season The bene
9. weather analyzer contained in the RaceAir Pro measures the air quality It is based on the air temperature in degrees Fahrenheit F the relative humidity in percent and the absolute barometric pressure in inches of mercury Inches Hg Subtle changes in any of these variables can have an impact on the performance of your vehicle This portion of the RaceAir Pro will provide you with the STD or SAE HP Correction Factor Density Altitude ft Air Density Ratio Dry Barometer pressure Inches Hg Dew Point temperature F Wet Bulb Temperature F water Vapor Pressure Inches Hg and Pressure Altitude ft Weather Terms This list is in alphabetical order Air Density Ratio Air density ratio ADR is the ratio produced by dividing the calculated density of the air being sampled by the Standard Day air density Standard Day air is defined as a temperature of 60 F a relative humidity of 0 and an absolute barometric pressure of 29 92 In Hg The ADR for those conditions is 1 00 The RaceAir Pro expresses this ratio as a percent Standard Day 100 as an aid to understanding the performance increases and decreases that air density causes Air Density Ratio is used to determine engine fuel tuning changes If the ADR goes down 2 then fuel must be reduced 2 to stay at the same air fuel ratio 11 GCOMPUTECH SYSIEMS NC Absolute Barometric Pressure Absolute barometric pressure measured in inches of mercury Inches
10. will speed up the computer operation 5 Clr User Mem This function is not normally used Clearing the user memory will reset all computer variables to 0 All set up functions will need to be reentered COMPUTECH SYSIEMS NC Battery This line indicates the measured voltage in the computer circuit When on battery power it can show when the batteries are getting weak 3 Calculator This program is a 4 function calculator i e add subtract multiply and divide The key YES and the key NO are used to add and subtract To multiply press ALT then or to divide press ALT then Press ENTER to see the answer Important The calculator can be accessed from within any program by pressing ALT then ENTER The calculator function will remember the number from the computer program line where the left indicator arrow is positioned The calculator functions can then be used with that number The computer will insert the new calculated value back in the program line by pressing ALT then ENTER again Dynamometer Horsepower Correction The Sampled Wthr screen can be used to quickly correct observed dyno torque and horsepower values Press the SAMPLE key and place the RaceAir Pro near the engine air intake Allow the unit to finish sampling Make sure the left side indicator arrow is on the STD Corr or SAE Corr Press ALT then ENTER to transfer the correction factor to the calculator Press ALT then to multiply Press in the
11. worse and 103 better Atmospheric changes can be experienced when going from track to track or from Spring to Summer to Fall at the same track The typical change in air quality from the heat of the day to 14 COMPUTECH SYSIEMS INC the cool of the night is usually not very large However the RaceAir Pro will compensate for changes in all of the weather variables no matter how small Remember as the Correction Factor and the Density Altitude increase larger numerically performance will decrease As the Correction Factor and Density Altitude decrease smaller numerically performance will increase The lower the Air Density Ratio smaller numerically the leaner the jetting needs to be and the higher the Air Density Ratio larger numerically the richer the jetting needs to be Sampling Information The top portion of the RaceAir Pro where the red stripe is contains the weather sensors During the sampling process air is drawn in through the diagonal slits in the faceplate by the internal fan The air is then exhausted through the vents on the upper left side of the case These air passages must remain clear for accurate measurements Also the temperature humidity and pressure readings may not be accurate when the fan is not operating When the SAMPLE key is pressed the RaceAir Pro automatically samples current weather conditions locks in a set of good sample readings and then displays those readings along
12. 020 Enter TDC piston to block deck clearance inches use negative number for piston above deck 0 020 Gskt Vol 12 600 Enter head gasket volume CC enter 0 if not known New C R 11 00 Enter desired engine compression ratio Chamber 78 200 Enter head combustion chamber volume CC Use FLAT TOP Use flat top piston and with 0 131 deck piston down in bore dimension inches or dome 25 70 Press ENTER to continue Dome Vol 25 70 Calculated piston dome popup volume CC negative number indicates dished piston 38 COMPUTECH SYSIEMS NC Compression Ratio by Pouring Combustion Chamber This program will calculate the compression ratio of an assembled engine by pouring the cylinder full of light oil or alcohol through the spark plug hole It assumes that the piston is at top dead center and the head gasket is installed Press ALT ENGINE FORMULAS then C R Menu then select Pour Chamber to start this program Display Example Pour Chamber Bore 4 250 Enter cylinder bore diameter inches Stroke 3 750 Enter crankshaft stroke inches Boost 0 000 Enter max manifold pressure PSI gage Deck Hgt 0 000 Enter 0 for this line Gskt Vol 0 001 Enter 0 001 for this line Pour Vol 87 4 Enter poured volume measured CC Ratio 10 97 1 Calculated engine compression ratio Compression Ratio Find Piston Dome Volume by Pouring Use this program to calculate the piston dome volume for a piston when the popup size i
13. 3 Weather Analyzer Overview 29 Weather Terms 14 Weights Liquid COPYRIGHT 2002 COMPUTECH SYSTEMS INC 29962 KILLPECK CREEK COURT CHARLOTTE HALL MD 20622 41
14. DR from baseline tune up New ADR 99 2 Press IMPORT WEATHER DATA fo import ADR BaseBoost 0 00 Enter old blower manifold pressure PS New Boost 0 00 Enter new blower pressure PSI Adjust 0 0 Enter tune up change if needed Rail Chg 5 2 High speed relief valve change or PSI New Pill 0 057 Calculated new main jet size The next time the program is used it is not necessary to repeat the setup portion Press TUNE UP then Jetting Menu then select Injection and Select Jet The setup can be repeated anytime by selecting Calc Area 20 COMPUTECH SYSIEMS NC Fuel Injection Jets French Method Read the Tune Up Information section before using this program This program has been designed by French Grimes a well known expert in continuous flow fuel injection systems It will work without knowing the injector nozzle sizes Use this program with the baseline tune up information to predict the proper jet to use as the ADR changes Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press TUNE UP then Jetting Menu then select F G Injection to start this program Display Example F G Inject Fuel Pressure O Help 65 Enter fuel rail pressure PSI Fuel Methanol Press down arrow to select fuel ENTER Eng CID 410 0 Enter engine displacement cubic inches Max RPM 7500 Enter peak engine RPM Base ADR 95 7 Enter ADR from baseline tune up Ne
15. GCOMPUTECH SYSIEMS NC 3 Converter Slip Page 30 This program will calculate the torque converter slip RPM and percentage based on tire size MPH engine RPM and gear ratio CIR TRK FORMULAS key 1 Gearing Tires 1 Engine RPM Page 33 This program will calculate the resulting engine RPM change with tire size and gear ratio changes 2 Gear Ratio Page 33 This program will calculate the proper gear ratio to compensate for changes in tire size and desired engine RPM 3 Tire Size Page 34 This program will calculate the proper tire size to compensate for changes in gear ratio and desired engine RPM 4 MPH Calc Page 37 This program will calculate the vehicle MPH based on engine RPM gear ratio and tire size 5 Tire Stagger Page 34 This program will suggest a tire stagger condition based on track measurements 2 Chassis 1 Setup by Pct Page 34 This program will calculate the scale weights for each wheel from total vehicle weight and requested front rear and diagonal weight distribution percentages 2 Setup by Wgt Page 35 This program will calculate the front rear and diagonal weight distribution percentages from actual scale weights for each wheel 3 Fuel Mileage Page 35 This program will calculate fuel mileage from pit stop measurements predict when the next fuel stop should be made and calculate the fuel required to finish the race 4 Liquid Wgts Page 36 This program will calculate the weight of water methanol an
16. NTER key will make the computer go to the item where the left indicator arrow is positioned An alternate quick program access method is to use the number shown to the left of a program For example to access the Holley carburetor jetting program press TUNE UP then 1 to access the Jetting Menu then 1 again to get to the Holley program When a program needs a user input a will appear at the end of a statement A number from the computer memory may appear after the Either accept this number by pressing ENTER or press in a new number on the keyboard then press ENTER When an answer is presented an will appear at the end of the statement A blinking cursor block will appear on the right side of a statement when the computer is expecting a user input Recalculate Function The up and down arrow keys may be used to reposition the left side indicator arrow to a program input line Pressing ENTER will open that input and show a blinking cursor block to accept a new entry It is not necessary to restart the program from the beginning to calculate a new answer Communication Port The lower of the 2 ports on the left side of the computer is for communication with a personal computer PC The optionally available Computech Weather Pro software will interface with the RaceAir Pro When the communications link is established the sensors in the RaceAir Pro send information to the PC that is running the Weather Pro program The Weather Pro calculat
17. RF 543 Calculated right front scale indication in pounds Wgt RR 397 Calculated right rear scale indication in pounds 34 COMPUTECH SYSIEMS NC Chassis Setup by Weight This program will calculate the total vehicle weight the percentage of left side weight distribution the percentage of rear weight distribution and the percentage of right front to left rear diagonal weight distribution for a given chassis setup based on the actual wheel scale indications Press CIR TRK FORMULAS then select Chassis then select Setup by Wgt to start this program Display Example Setup by Wgt Wgt LF 649 Enter left front scale indication in pounds Wgt LR 660 Enter left rear scale indication in pounds Wgt RF 543 Enter right front scale indication in pounds Wgt RR 397 Enter right rear scale indication in pounds Car Wgt 2249 Calculated total vehicle weight in pounds Left 58 2 Calculated left bias Rear 47 0 Calculated rear bias Diagonal 53 5 Calculated right front to left rear bias Fuel Mileage Circle This program is designed to compute fuel consumption during a race It calculates the number of laps to the next required fuel pit stop the current miles per gallon and the required number of gallons to complete the race A unique feature of this program takes into account the number of caution laps run between fuel stops and automatically compensates for the reduced fuel consumption during those caut
18. This program is designed to help super class racers predict the throttle stop timer settings for the next run based on changes in the correction factor The correction factor method used can be changed from STD to SAE in the program setup area The SAE method should produce more consistent results for large barometric pressure changes or different track elevations This program requires that the T Stop Setup function be run for each vehicle or combination so the program can calculate an elapsed time versus throttle stop timer setting ratio The program has memory for 3 different data sets The program works for all length tracks and is compatible for use with either gasoline or methanol fuel However a setup fuel choice must be made to get accurate timer predictions The program will automatically go to the fuel setup program during the first use The setup function must be redone if you change anything that affects vehicle performance The timer setting is predicted from 2 previous runs that are entered into the computer memory during the T Stop Setup program and a recent reference run The reference run on which the prediction is based is selected by the user The reference run should be the most recent good full run when the vehicle performed as expected Runs that had tire spin unusual 60 ft times or gusty wind conditions should not be used as the setup runs or the reference run Change the run used as the reference old run as the race day progr
19. age 24 This program will correct the indicated or observed engine exhaust gas temperature EGT for variations in engine air inlet temperature The corrected EGT value can be used as a tuning aid 7 EGT Predict n Page 24 This program will calculate the indicated or observed engine exhaust temperature EGT from a corrected EGT and the current engine air inlet temperature DIAL IN key 1 Standard Page 25 This program will predict an elapsed time ET dial in for 1 8 and 1 4 mile Drag Racing based on 1 previous good run and the change in horsepower correction factor due to a weather change Note This program requires changing the fuel selection in SET UP Program Setup Fuel Setup when using methanol 2 Density Altd Page 26 This program will predict an elapsed time ET dial in based on 3 previous good runs and the change in density altitude due to a weather change T STOP key Page 27 This program will calculate the throttle closed timer setting to produce a desired elapsed time ET based on 2 previous runs 1 faster than the index and 1 slower than the index The program capacity allows data storage for 3 different cars or 3 different indexes DRAG FORMULAS key 1 Gear Ratio Page 29 This program will calculate the vehicle gear ratio based on tire size MPH engine RPM and torque converter slip 2 Trap RPM Page 29 This program will calculate the trap engine RPM based on tire size MPH gear ratio and torque converter Slip 4
20. ard 60 degree Fahrenheit day Then the Exhaust Gas Temperature Prediction program can be used to predict an indicated or observed EGT for a different air temperature Many things affect EGT i e engine type and design fuel mixture ignition timing engine RPM thermocouple location etc Typically properly tuned methanol fueled engines will have a corrected EGT between 1050 and 1200 F The typical gasoline fueled engine EGT will be between 1250 and 1400 F These corrected EGT ranges are not necessarily ideal for your engine The only way to find the desired EGT for a particular engine combination is by dyno testing or track testing See the Tune Up Information section for information on establishing a baseline tune up Press TUNE UP then select EGT Correct rio start this program Display Example EGT Correction EGT 1217 Enter observed EGT F Inlet Temp 77 Enter measured air temp F Corr EGT 1164 Corrected EGT F RECORD this Exhaust Gas Temperature Prediction Use the Exhaust Gas Temperature Correction program fisrt to obtain a corrected exhaust gas temperature EGT This program will predict what the indicated or observed EGT should be based on a previously recorded corrected EGT and the current engine inlet air temperature Press TUNE UP then select EGT Predict rio start this program Display Example EGT Correction Corr EGT 1164 Enter recorded corrected EGT F Inlet Temp 77 Enter measured air t
21. arometric pressure or pressure altitude temperature and relative humidity to the aeronautical industry defined standard day atmosphere The density altitude for an absolute barometric pressure of 29 92 Inches Hg or a pressure altitude of 0 ft a temperature of 60 F and a humidity of 0 is 0 ft A good air day in the spring or fall might be below 0 ft i e 831 ft Conversely a hot summer day might have a density altitude of 4500 ft equivalent to 4500 ft of altitude on a standard day Dew Point The dew point temperature is the calculated temperature at which the measured partial saturation of water vapor in the air will turn to liquid and form dew Moisture can cause inconsistent traction and in certain circumstances effect engine performance The warmer the air is the more water vapor it can hold See Relative Humidity for more information An air sample has a specific amount of water vapor present As the temperature drops and reaches the dew point the air can no longer hold the water vapor suspended so it condenses and turns to water This condensation will occur on cooler surfaces first Computech research with methanol fuel and to a lesser extent with gasoline has shown that when the ambient temperature falls to within 5 to 10 F of the dew point temperature there will be an unexpected slight fall off in performance due primarily to fuel degradation in the intake manifold that is caused by water contamination By keeping accura
22. d gasoline when the quantity in gallons is entered GCOMPUTECH SYSIEMS NC ALT AIR CORR key Page 17 This program will calculate the horsepower correction factor density altitude air density ratio ADR dry barometer wet bulb temperature dew point partial vapor pressure water vapor grains and pressure altitude from an input of temperature relative humidity and absolute barometer Use this program to calculate weather data when taking an actual air sample is not desired i e from logbook entries of temperature relative humidity and barometric pressure or evaluating other than sampled conditions ALT RUN COMP key Page 30 This program will estimate the 1 8 or 1 4 mile elapsed time and MPH for a run where the throttle was closed before the finish line The program uses information from a previous full pass to predict performance ALT DRAG PERF key 1 Full Run Std Page 30 This program will correct observed finish line elapsed time ET and MPH performance to Standard Day weather conditions This information can be used to compare runs done on different days to evaluate vehicle changes or driving techniques 2 Intermed Run Page 31 This program will correct observed 60 330 660 1000 and 1320 elapsed times ETs to Standard Day weather conditions This information can be used to compare runs done on different days to evaluate vehicle changes or driving techniques 3 Est 1 8 HP Page 32 This program wil
23. e Vol 8 30 Enter piston dome popup volume CC Ratio 10 46 1 Calculated engine compression ratio 37 COMPUTECH SYSIEMS NC Compression Ratio Find Combustion Chamber Volume This program computes the combustion chamber volume in cubic centimeters CC required to achieve a desired compression ratio Press ALT ENGINE FORMULAS then C R Menu then select Calc Chamber to start this program Display Example Calc Chamber Bore 4 250 Enter cylinder bore diameter inches Stroke 3 750 Enter crankshaft stroke inches Boost 0 000 Enter max manifold pressure PSI gage Deck Hgt 0 020 Enter TDC piston to block deck clearance inches use negative number for piston above deck 0 020 Gskt Vol 12 600 Enter head gasket volume CC enter 0 if not known New C R 11 00 Enter desired engine compression ratio Dome Vol 8 30 Enter piston dome popup volume CC Chamber 78 20 Calculated head combustion chamber volume CC to achieve desired compression ratio Compression Ratio Find Piston Dome Volume This program computes the effective piston dome volume in cubic centimeters CC required to achieve a desired compression ratio Press ALT ENGINE FORMULAS then C R Menu then select Calc Dome to start this program Display Example Calc Dome Bore 4 250 Enter cylinder bore diameter inches Stroke 3 750 Enter crankshaft stroke inches Boost 7 500 Enter max manifold pressure PSI gage Deck Hgt 0
24. e desired engine fuel flow percent change plus for richer minus for leaner For example press 2 then ENTER for a 2 richer engine fuel flow or 2 then NO key then ENTER for a 2 2 leaner engine fuel flow This tuning function can also be used when compensating for changes in the engine or vehicle combination such as ignition timing camshaft carburetor headers fuel injection pump fuel etc Holley Jets Read the Tune Up Information section before using this program The Holley Jet change program is designed to work with Holley carburetor jets from 50 through 100 The program utilizes actual jet flows as opposed to drill sizes when making the computations Use this program with the baseline tune up information to predict the proper jet to use as the ADR changes Important Use only unmodified Holley flowed jets with this program The Holley Jet program will not make accurate predictions for methanol or nitromethane fuels The Precision Jet program can be used for carburetors with a single orifice main metering system using other than gasoline fuel Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press TUNE UP then Jetting Menu then Holley to start this program Display Example Holley Jet Base ADR 95 7 Enter ADR from baseline tune up New ADR 99 2 Press IMPORT WEATHER DATA to import ADR Base Jet 88 0 Press in baseline tune up jet number Adjust 0 0 Enter tune
25. e not lost during battery changes Under normal operating and storage conditions it is not necessary to have the unit periodically recalibrated 15 COMPUTECH SYSIEMS NC Specifications Display Resolution Temperature 0 1 degree F Relative Humidity 1 Absolute Barometric Pressure 0 01 Inches of Mercury Internal Resolution Temperature 0 01 degree F Relative Humidity 0 1 Absolute Barometric Pressure 0 003 Inches of Mercury Accuracy Temperature 1 2 degree F Relative Humidity 3 Absolute Barometric Pressure 0 05 Inches of Mercury Repeatability Approximately equal to display resolution Weather Analyzer Operation Press and momentarily hold the POWER ON OFF key The computer will power up show the firmware version and go to the Live Fan OFF screen When the fan is not operating the sensor readings will not be accurate Press the SAMPLE key The display will read Sampling until the sensor readings are stabilized this may take a couple of minutes Then the display will read Sampled Wthr when the sensors have correctly measured an air sample Display Example use down arrow key to reveal more data Sampled Wthr 72 3 32 29 40 temp F humidity barometric pressure Inches Hg 15 11 59 59 date and time STD Corr 1 0389 HP correction factor selected STD or SAE Dens Altd 1686 density altitude ft ADR 95 2 air density ratio DryBaro 29 139 bar
26. elect Est 1 4 HP to start this program Display Example Est 1 4 1 4mi ET 6 918 Enter 1 4 mile ET Weight 1677 Enter vehicle starting line weight in pounds Est HP 1001 Estimated flywheel HP Corr 0 9784 Enter correction factor at time of run Corr HP 979 Estimated corrected HP 32 COMPUTECH SYSIEMS NC Elapsed Time and MPH Estimate from HP This program calculates the estimated elapsed time and MPH for 1 8 and 1 4 mile drag runs It is based on engine flywheel horsepower and vehicle weight The program can be used to see what effect changes in the vehicle weight or available horsepower will have on elapsed time and MPH Press ALT DRAG PERF then select Est ET MPH to start this program Display Example Est ET MPH Est HP 405 Estimated flywheel HP Weight 3250 Enter vehicle starting line weight in pounds 1 8 ET 7 405 Estimated 1 8 mile ET 1 8mi MPH 95 84 Estimated 1 8 mile MPH 1 4mi ET 11 662 Estimated 1 4 mile ET 1 4mi MPH 116 88 Estimated 1 4 mile MPH Gear Ratio Circle This program will assist in selecting the proper final drive gear ratio based on the old engine RPM the old tire circumference the old gear ratio the new engine rpm and the new tire circumference Press CIR TRK FORMULAS then Gearing Tires then select Gear Ratio to start this program Display Example Gear Ratio Old RPM 7250 Engine RPM was Old Tire 89 00 Tire circum
27. elevation 0 feet Without this standard the barometer readings would be meaningless at different geographic elevations around the world The correction adds about 0 001 Inches Hg per foot of elevation to the absolute barometric pressure number Corrected barometric pressure cannot be used for performance calculations without subtracting the local elevation from the NWS value Even then it would be an approximation because the barometer is at another location Barometric Pressure Dry See Dry Barometric Pressure Correction Factor The correction factor is a Society of Automotive Engineers SAE equation that uses the calculated dry barometric pressure and the measured local temperature to compensate for changes in dynamometer observed horsepower readings due to air density differences This method allows performance comparison of observed readings taken on different days or in different parts of the world The correction factor can also be applied to track performance There are 2 correction factor equations in common use in the industry the current SAE and STD or the old SAE standard The STD and SAE methods also have different reference points where correction factor 1 000 occurs Therefore values corrected with one method cannot be compared to values corrected by the other 12 GCOMPUTECH SYSIEMS NC Density Altitude Density altitude is a value in feet that relates the local measured atmospheric conditions absolute b
28. emp F EGT 1217 Target observed EGT F 24 COMPUTECH SYSIEMS NC Dial In Standard Method This program is designed to help class and bracket racers predict an elapsed time ET for the next run based on changes in the horsepower correction factor The Standard Dial In method is Computech s easiest to use and more accurate ET prediction program The correction factor method used can be changed from STD to SAE in the program setup area The SAE method should produce more consistent results for large barometric pressure changes or different track elevations The program works for all length tracks and is compatible for use with either gasoline or methanol fuel However a setup fuel choice must be made to get accurate ET predictions The program will automatically go to the fuel setup program during the first use The Dial In is predicted from 1 previous reference no database of runs is used or required The reference run on which the prediction is based is selected by the user The reference run should be the most recent good full run when the vehicle performed as expected Runs that had tire spin unusual 60 ft times or gusty wind conditions should not be used for the reference run Change the run used as the reference old run as the race day progresses It is important to use the most recent good full run as the reference The most recent run will best represent the current traction and weather conditions This p
29. epeated The program also assumes that the more time put into the second timer the slower the car will run higher elapsed time The program needs data from 2 runs to calculate the relationship between the second timer setting and elapsed time The setup runs should be made on the same day preferably in the same lane so that the traction conditions will be similar Make sure the 60 foot times are within 0 01 seconds of each other Make 1 of these runs with a timer setting that will allow the vehicle to run approximately 0 1 seconds faster than the target index The other run should be made with a timer setting that will cause the vehicle to run approximately 0 1 seconds slower than the target index It is likely that several runs will need to made to get 2 good runs for the setup Record the run data for all the runs including the correction factor and the timer setting Then select the 2 runs that more closely represent the setup criteria The setup procedure may be run as often as desired or whenever the accuracy of the program is not up to par The entire setup routine must be repeated for each vehicle or combination Important When a change is made to the first timer setting or any change is made that might affect vehicle performance the setup procedure should be performed again to assure accuracy Remember the T Stop program predictions can only be as good as the information put into the setup Press T STOP select T Stop Setup then select
30. er fuel factor is automatically set into the programs when gasoline or methanol is selected To compensate for other fuels or to use another factor press the down arrow key until Special is displayed then press ENTER The display will show Factor Press in the desired multiplication factor and press ENTER For example a fuel factor that is 10 less than the standard would be 0 90 2 T Stop Setup This function is discussed in the Throttle Stop program It only needs to be done to predict throttle stop timer settings 3 D A Setup This function is discussed in the Density Altd Dial In program It is used to determine the slope of run data for that program 4 SAE HP vs STD This function changes the horsepower correction method from Standard to SAE The default setting is STD When the SAE line is displayed press ENTER to cause the cursor block to flash then YES to change to the new SAE correction factor 2 Factory Setup 1 Set Clock This program is used to set the date and time 2 Show Calib This screen is for factory use to show the weather sensors calibration file 3 Factory Reset This program will remove the weather sensor calibration file from the computer memory DO NOT use this program without specific instructions from Computech on how to save the calibration file 4 Empty Recycle This program can be used when the Loading User Memory Message remains on the screen for several seconds Emptying the recycle bin
31. es the various air conditions logs the information and presents a graphic view of what the weather is doing A weather file is saved for future reference The Weather Pro software with the required cables and power supply is available from Computech Systems Inc Additionally the Comm port is used to update the RaceAir Pro program firmware An interface kit is available from Computech Systems Inc to perform these updates The kit contains the PC 10 COMPUTECH SYSIEMS NC wW interface software the PC to RaceAir Pro interface cable with serial adapter and a power supply Program Updates The RaceAir Pro program firmware is user updateable with the optional PC interface kit The latest version of the program will be posted on the Computech Systems Inc web site www computechracing com The downloads are free for the life of the computer As changes or additions are made to the program new files will be posted on the web site The RaceAir Pro may be sent back to Computech Systems Inc for program updates if desired Additional Instructions Please take the time to read each program operation so that you can utilize the RaceAir Pro System to the fullest Should you need personal assistance contact the Computech technical department anytime between 9 00 a m to 5 00 p m eastern time Monday through Friday Tech Line 301 884 5712 Fax 301 884 5763 email computech ameritel net COMPETITION WEATHER ANALYZER Overview The
32. esses It is important to use the most recent good full run as the reference The most recent run will best represent the current traction and weather conditions 27 GCOMPUTECH SYSIEMS NC The throttle stop program works best when the engine fuel air mixture is slightly rich so the vehicle performance will change appropriately with the weather changes This may require periodic jet changes during the race season The benefits gained in consistency and predictability are well worth the effort If the vehicle runs quicker than the computer is predicting when the correction factor is improving number getting smaller then the fuel air mixture is probably too rich and should be leaned slightly Conversely if the vehicle will not run as quick as the computer is predicting when the correction factor is improving then the fuel air mixture is probably too lean and should be richened slightly Efforts spent on getting the fuel air mixture correct will be well worth the rewards in increased predictability See the Tune Up Information section for more details T STOP SETUP Most current throttle stop systems utilize two timers in the same unit Typically the first timer allows the throttle to remain wide open for some period of time and the second timer controls the throttle closed time This program assumes that once adjusted the first timer setting will remain constant Any time the first timer setting is changed this setup procedure must be r
33. ference was inches not diameter Old Gear 5 13 Final drive gear ratio was New RPM 7500 Desired engine RPM New Tire 89 00 Desired tire circumference inches not diameter New Gear 5 31 Calculated gear ratio to use Engine RPM Circle This program will calculate a new peak engine RPM based on the old engine rpm the old tire circumference the old gear ratio the new tire circumference and the new gear ratio Press CIR TRK FORMULAS then Gearing Tires then select Engine RPM to start this program Display Example Engine RPM Old RPM 7250 Engine RPM was Old Tire 89 00 Tire circumference was inches not diameter Old Gear 5 13 Final drive gear ratio was New Tire 89 00 Desired tire circumference inches not diameter New Gear 5 31 Desired gear ratio 33 COMPUTECH SYSTEMS INC New 7504 Calculated engine RPM for this combination Tire Size Circle This program will calculate the required tire circumference based on the old engine RPM the old tire circumference the old gear ratio the new engine RPM and the new gear ratio Press CIR TRK FORMULAS then Gearing Tires then select Tire Size to start this program Display Example TireSize Old RPM 7250 Engine RPM was Old Tire 89 00 Tire circumference was inches not diameter Old Gear 5 13 Final drive gear ratio was New RPM 7500 Desired engine RPM New Gear 5 31 Desired gear ratio New Tire 89 05 Ca
34. fits gained in consistency and predictability are well worth the effort If the vehicle runs quicker than the computer is predicting when the density altitude is improving getting lower then the fuel air mixture is probably too rich and should be leaned slightly Conversely if the vehicle will not run as quick as the computer is predicting when the density altitude is improving then the fuel air mixture is probably too lean and should be richened slightly Efforts spent on getting the fuel air mixture correct will be well worth the rewards in increased predictability See the Tune Up Information section for more details DA DIAL IN SETUP It is likely that several runs will need to made to get 3 good runs for the setup Record the run data for all the runs including the density altitude The runs you select should all be good full runs with at least 100 feet of difference in density altitude between any two runs This will allow the program to calculate the amount of elapsed time change the vehicle experiences in comparison to the respective change in the density altitude The setup runs should be made on the same day preferably in the same lane so that the traction conditions will be similar Make sure the 60 foot times are within 0 01 seconds of each other Also verify that as the density altitude gets higher the vehicle slows down Conversely as the density altitude gets lower the vehicle should go quicker The setup function may be run as ofte
35. ion laps The program is broken down into two sections the pre race setup program and the actual race program Press CIR TRK FORMULAS then select Fuel Mileage then New Race to start this program Setup Display Example New Race Fuel 1 G 2 M 2 Enter fuel type 1 for gasoline 2 for methanol Capacity 22 0 Enter fuel capacity gallons Miles 100 0 Enter miles for race Laps 160 Enter number of laps for race Caution Factor Press ENTER to continue O none 0 280 Enter fuel SAVED on caution lap 28 as decimal Miles Lap 0 625 Calculated miles per lap Setup Done Press ENTER to continue Press CLEAR to Press ENTER to continue Return Press CLEAR to continue 35 GCOMPUTECH SYSIEMS NC Press CIR TRK FORMULAS then select Fuel Mileage then select Next Stop to start this program Next Stop Display Example Fuel Stop Last Stop was lap 0 This Stop is lap 42 Laps Since 42 Caution Laps 5 Eff Laps 40 6 Empty catch can Into can 1 Fuel can wot Gross 80 5 2 Gross 78 3 1 Empty 22 8 2 Empty 42 1 Max laps till Nxt Stp 62 3 MPG 1 77 Gal Needed finish 41 7 Stop Done Press CLEAR to Return Press ENTER fo continue Laps since last stop for first stop ENTER to continue Press ENTER fo continue Enter lap number for this fuel stop Calculated laps since last fuel stop Enter yellow laps since last fue
36. ir Bad Air Page 14 Sampling Information Page 15 Calibration Page 15 Specifications Page 16 Weather Analyzer Operation Page 16 COMPUTER PROGRAMS OPERATION Page 17 GCOMPUTECH SYSIEMS NC COMPUTER PROGRAM CAPABILITIES This list is indented to show access menu levels Refer to Program Access and Use TUNE UP key Page 17 1 Jetting Menu 1 Holley Page 18 This program will calculate the proper Holley carburetor jet to use based on a change in weather conditions It also allows the user to adjust the air fuel ratio to achieve the proper engine tune 2 Prec Jets Page 19 This program will calculate the proper jet diameter in inches or millimeters to use based on a change in weather conditions for any carburetor It also allows the user to adjust the air fuel ratio to achieve the proper engine tune 3 Mikuni Jets Page 19 This program will calculate the proper Mikuni carburetor jet to use based on a change in weather conditions It also allows the user to adjust the air fuel ratio to achieve the proper engine tune 4 Keihin Jets Page 19 This program will calculate the proper Keihin carburetor jet to use based on a change in weather conditions It also allows the user to adjust the air fuel ratio to achieve the proper engine tune 5 Injection Page 20 This program will calculate the proper continuous flow mechanical fuel injection main jet pill to use based on a change in weather conditions using jet and nozzle areas It a
37. is not an indication of total air quality 13 GCOMPUTECH SYSIEMS NC Relative Humidity Relative humidity RH is a value to indicate how much water vapor is present in an air sample Air has the ability to hold more water vapor as the temperature increases This phenomenon makes comprehending water vapor content difficult By always relating the amount of water vapor present to the maximum amount that air could hold at that temperature the relationship is easier to understand i e 50 RH is always 50 of the possible saturated water vapor content for air at any temperature Temperature Temperature F is also referred to as dry bulb temperature In order to correctly calculate the effect of temperature on performance the measured temperature needs to be similar to the engine intake air temperature Vapor Pressure Vapor pressure Inches Hg is a value calculated from the sensed temperature and relative humidity The RaceAir Pro uses numbers derived from mechanical engineering steam tables to calculate the partial saturation vapor pressure of the moisture in the sampled air That value is displayed and used in the Dry Barometric Pressure computation The vapor pressure number indicates the portion of air pressure that is actually from water vapor and of course will not support combustion Water Vapor Water vapor grains Gr is the same information as Vapor Pressure expressed in different units Some race teams u
38. ize Std ET 6 931 Standardized ET for selected run Std MPH 193 93 Standardized MPH for selected run Standardized Performance Drag Intermediate Times This program corrects all of the intermediate times for any run to the correction factor reference standard conditions i e correction factor 1 0000 This allows comparison of runs even runs made on different days as if the weather conditions were the same for all the runs Performance modifications can be realistically evaluated by removing the amount of change caused by the weather differences The program uses the fuel selected in ALT SET UP Program Setup Fuel Setup for the calculations Important This program can be used with either the STD or SAE correction factor method However since the different methods have different reference standards runs corrected with one method cannot be compared to runs corrected with the other The AIR CORR program can be used to input the actual weather conditions for a run and convert the correction factor number to the desired method The SAE method should produce more consistent results for large changes in temperature or barometric pressure 31 COMPUTECH SYSIEMS NC Press ALT DRAG PERF then select Intermed Run to start this program Display Example Intermed Run Fuel Methanol Press ALT SET UP 1 1 to change fuel Corr 0 9784 Enter recorded correction factor from run to standardize 60 ET 1 083 Enter ET fr
39. l estimate the horsepower output required to move the vehicle to the 660 track marker based on vehicle weight and elapsed time ET It will also adjust horsepower corrected to Standard Day weather conditions 4 Est 1 4 HP Page 32 This program will estimate the horsepower output required to move the vehicle to the 1320 track marker based on vehicle weight and elapsed time ET It will also calculate horsepower corrected to Standard Day weather conditions 5 Est ET MPH Page 32 This program will estimate the 1 8 mile elapsed time and MPH plus the 1 4 mile ET and MPH from engine horsepower and vehicle weight ALT ENGINE FORMULAS key 1 C R Menu 1 Calc Ratio Page 37 This program will calculate engine compression ratio from cylinder bore crankshaft stroke combustion chamber volume and piston dome volume Piston deck height head gasket volume and supercharger boost pressure are included in the equation GCOMPUTECH SYSIEMS NC 2 Calc Chamber Page 38 This program will calculate the required combustion chamber volume from cylinder bore crankshaft stroke and piston dome volume when a compression ratio is specified Piston deck height head gasket volume and supercharger boost pressure are included in the equation 3 Calc Dome Page 38 This program will calculate the required piston dome volume from cylinder bore crankshaft stroke and combustion chamber volume when a compression ratio is specified Piston deck heigh
40. l stop Equivalent green laps for fuel consumption Press ENTER to continue Reminder put catch can fuel into can 1 before weighing Press ENTER fo continue Enter can 1 weight full of fuel Enter can 2 weight full of fuel Enter can 1 weight after fuel stop include catch can fuel Enter can 2 weight after fuel stop Press ENTER to continue Estimated green laps before next fuel stop Calculated fuel mileage miles per gallon Press ENTER fo continue Estimated fuel required to end of race Fuel stop completed press ENTER Press ENTER to continue Press CLEAR to continue The CIR TRK FORMULAS Fuel Mileage Same Stop program can be used to recalculate all the fuel mileage information if an error occurred during the process or if the calculated data is lost Important The New Race data must be entered before the first fuel pit stop for each race Liquid Weights This program will provide the weights of water gasoline and alcohol based on the number of gallons input Press CIR TRK FORMULAS then select Liquid Wgts to start this program Display Example Liquid Wgts Gallons 1 Enter number of gallons Water 8 4116 Water weight pounds for US gallons Alky 6 6116 Methanol weight pounds for US gallons Gas 6 0116 Gasoline weight pounds for US gallons 36 COMPUTECH SYSIEMS NC MPH This program is designed to calculate the actual vehicle speed in MPH using a 1 1 trans
41. lculated tire circumference inches to use Tire Stagger Circle This program computes the required tire circumference for the inside drive tire based on the race track turn diameter the circumference of the outside drive tire and the center to center spacing of the drive tires Press CIR TRK FORMULAS then Gearing Tires then select Tire Stagger to start this program Display Example Tire Stagger Turn Dia 950 Enter track turn diameter feet OutrCirc 89 00 Outside tire circumference inches not diameter Tire Spec 54 50 Center to center drive tire spacing inches InnrCirc 88 57 Calculated inside tire circumference inches Chassis Setup by Percent This program computes the static weight to expect at each wheel of a vehicle for a given chassis setup based on the total vehicle weight the desired left side weight distribution percentage the desired rear weight distribution percentage and the desired right front to left rear diagonal weight distribution percentage Press CIR TRK FORMULAS then select Chassis then Setup by Pct to start this program Display Example Setup by Pct Car Wgt 2250 Enter total vehicle weight in pounds Left 58 2 Enter desired left bias Rear 47 0 Enter desired rear bias Diagonal 53 5 Enter desired right front to left rear bias Wot 649 Calculated left front scale indication in pounds Wgt LR 660 Calculated left rear scale indication in pounds Wot
42. llows the user to adjust the air fuel ratio to achieve the proper engine tune Additionally a fuel rail pressure change is calculated for use in adjusting a high speed lean out system relief valve 6 F G Injection Page 21 This program will calculate the proper continuous flow mechanical fuel injection main jet pill to use based on a change in weather conditions without knowing the injector nozzle sizes It also allows the user to adjust the air fuel ratio to achieve the proper engine tune 7 High Speed Page 21 This program will calculate a bypass flow jet change for a continuous flow mechanical fuel injection high speed lean out system 8 Square Area Page 22 This program will easily calculate the area of several nozzles or jets and provide a single orifice diameter equivalent GCOMPUTECH SYSIEMS NC 2 Blower OD Page 22 This program will calculate blower drive speed in relation to crankshaft speed based on pulley tooth count or circumference 3 Meth Spec Page 23 This program is used in conjunction with a hydrometer and thermometer to correct the specific gravity of methanol when checking for moisture contamination 4 Gas Spec Page 23 This program is used in conjunction with a hydrometer and thermometer to correct the specific gravity of gasoline 5 Nitro Page 23 This program is used in conjunction with a hydrometer and thermometer to determine the corrected nitro percentage of a measured sample 6 EGT Correct n P
43. mission ratio The calculations are based on the tire circumference the engine RPM and the final gear ratio This program assumes no wheel spin and no clutch slippage Press CIR TRK FORMULAS then Gearing Tires then select MPH Calc to start this program Display Example MPH Calc RPM 7250 Engine RPM GearRtio 5 13 Final drive gear ratio TireCirc 89 00 Tire circumference inches not diameter MPH 118 84 Calculated MPH Compression Ratio Values Known This program computes the true compression ratio of an engine All important factors are considered including bore stroke boost pressure deck height gasket bore gasket thickness combustion chamber volume and effective piston dome volume Press ALT ENGINE FORMULAS then C R Menu then Calc Ratio to start this program Display Example Comp Ratio Bore 4 250 Enter cylinder bore diameter inches Stroke 3 750 Enter crankshaft stroke inches Boost 0 000 Enter max manifold pressure PSI gage Deck Hgt 0 020 Enter TDC piston to block deck clearance inches use negative number for piston above deck 0 020 Gskt Vol 0 000 Enter head gasket volume CC enter 0 if not known Calc Gskt Vol Press ENTER to continue Bore 4 275 Enter head gasket bore diameter inches Thek 0 080 Enter head gasket thickness inches Vol 18 80 Calculated head gasket volume cubic centimeters Chamb Vol 77 00 Enter head combustion chamber volume CC Dom
44. n Est MPH 198 99 Calculated 1 4 mile MPH for aborted run Standardized Performance Drag Full Run Times This program corrects the elapsed time and MPH for any run to the correction factor reference standard conditions i e correction factor 1 0000 This allows comparison of runs even runs made on different days as if the weather conditions were the same for all the runs Performance modifications can be realistically evaluated by removing the amount of change caused by the weather differences The program uses the fuel selected in ALT SET UP 30 COMPUTECH SYSIEMS NC Program Setup Fuel Setup for the calculations Important This program can be used with either the STD or SAE correction factor method However since the different methods have different reference standards runs corrected with one method cannot be compared to runs corrected with the other The AIR CORR program can be used to input the actual weather conditions for a run and convert the correction factor number to the desired method The SAE method should produce more consistent results for large changes in barometric pressure or temperature Press ALT DRAG PERF then Full Run Std to start this program Display Example Full Run Fuel Gasoline Press ALT SET UP 1 1 to change fuel Corr 0 9943 Enter recorded correction factor from run to standardize ET 6 918 Enter ET from run to standardize MPH 194 30 Enter MPH from run to standard
45. n as you desire or whenever the accuracy of the program is not up to par The entire setup routine must be repeated for each vehicle Important When any change is made that might affect vehicle performance the setup program should be run again to assure accuracy Remember the Density Altitude Dial In program predictions can only be as good as the information put into the setup 26 COMPUTECH SYSIEMS NC Press DIAL IN select Density Altd select D A Setup then select 1 Car 0 to start this program Setup Display Example Dens Alt Setup Car 228 Enter car or combination ID number Run 1 DA 862 Enter density altitude for run 1 Run 1 ET 8 921 Enter ET for run 1 Run 2 DA 1020 Enter density altitude for run 2 Run 2 ET 9 005 Enter ET for run 2 Run 3 DA 1184 Enter density altitude for run 3 Run 3 ET 9 109 Enter ET for run 3 01 SEC 17 ET change for density altitude change ratio Setup complete Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press DIAL IN select Density Altd then 1 Car 228 to start this program DA Dial In Display Example Dial In Car 228 Last DA 1291 Enter reference run density altitude Last ET 9 112 Enter reference run ET New DA 1220 Auto transferred new density altitude New ET 9 071 Predicted new ET recommend subtracting 0 003 from prediction for Dial In of 9 06 Throttle Stop Timer Settings
46. ogram is used all the engine fuel nozzle sizes must be entered in the setup When the setup is completed the computer will remember the total nozzle area for future calculations This program and the Fuel Injection High Speed Bypass Adjust program use the same total nozzle area number from computer memory Use this program with the baseline tune up information to predict the proper jet to use as the ADR changes Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press TUNE UP then Jetting Menu then select Injection to start this program Setup Display Example Calc Area Nozzle area setup routine Orifices 8 Enter number of nozzles of this size Diameter 0 052 Enter nozzle diameter in inches More Yes Press ENTER to input more nozzles NO to stop Orifices 2 Enter number of nozzles of this size Diameter 0 020 Enter nozzle diameter in inches More No Press NO to stop Total Area Total nozzle area screen Area 0 017618 Total nozzle area in square inches RECORD this Orifices 10 Number of nozzles Equiv Dia 0 150 Single orifice diameter equivalent in inches Setup complete press ENTER to continue Injection Display Example Select Jet Area 0 017618 Total nozzle area square inches from memory Base Pill 0 065 Enter baseline main bypass jet diameter in inches Bypass 15 85 Calculated of pump fuel being bypassed Base ADR 95 7 Enter A
47. om run to standardize Std ET 1 088 Standardized ET for selected run 330 ET 2 928 Enter ET from run to standardize StdET 2 940 Standardized ET for selected run 660 ET 4 445 Enter ET from run to standardize StdET 4 464 Standardized ET for selected run 1000 ET 5 774 Enter ET from run to standardize Std ET 5 798 Standardized ET for selected run 1320 ET 6 918 Enter ET from run to standardize StdET 6 947 Standardized ET for selected run 1 8 Mile Estimated HP This program computes the estimated engine flywheel horsepower based on 1 8 mile elapsed time and vehicle weight The HP corrected for the weather conditions is also shown Use both the 1 8 mile and the 1 4 mile HP estimates to show the effective HP at the different parts of the track Press ALT DRAG PERF then select Est 1 8 HP to start this program Display Example Est 1 8 HP 1 8 ET 4 445 Enter 1 8 mile ET Weight 1677 Enter vehicle starting line weight in pounds Est HP 966 Estimated flywheel HP Corr 0 9784 Enter correction factor at time of run Corr HP 945 Estimated corrected HP 1 4 Mile Estimated HP This program computes the estimated engine flywheel horsepower based on 1 4 mile elapsed time and vehicle weight The HP corrected for the weather conditions is also shown Use both the 1 8 mile and the 1 4 mile HP estimates to show the effective HP at the different parts of the track Press ALT DRAG PERF then s
48. ometric pressure Inches Hg Dew Point 40 7 dew point temp F Wet Bulb 56 wet bulb temp F Vpr Prs 0 257 water vapor pressure Inches Hg Wtr Vpr 38 47Gr water vapor grains Press Alt 489 pressure altitude ft The RaceAir Pro will put the current weather data in memory for automatic transfer into any of the programs that use weather information The air sample data will be lost if the unit is turned off The unit will also automatically turn off after 10 minutes of inactivity thereby loosing the air sample data Keeping a logbook record of run information and applicable weather information is recommended 16 COMPUTECH SYSIEMS NC COMPUTER PROGRAMS OPERATION Air Correction Program This program is used to calculate weather data from keyboard entries of temperature relative humidity and barometric pressure Press ALT then AIR CORR to start this program Display Example Air Corr Temp 71 0 Enter temp F Humidity 31 Enter humidity AbsBaro 30 24 Enter barometric pressure Inches Hg STD Corr 1 0079 HP correction factor selected STD or SAE Dens Altd 630 density altitude ft ADR 98 2 air density ratio DryBaro 30 000 dry barometric pressure Inches Hg Dew Point 39 1 dew point temp F Wet Bulb 54 wet bulb temp F Vpr Prs 0 241 water vapor pressure Inches Hg Wtr Vpr 36 03Gr water vapor grains Press Alt 294 pressure altitude ft Tune Up Information In
49. ondensation inside a fuel container or moisture from the air If moisture is present in a fuel sample the hydrometer reading will be higher than expected Knowing what the specific gravity reading should be at a given temperature will verify that the fuel is not degraded Press TUNE UP then select Meth Spec to start this program Display Example Meth Spec Grav Fuel Temp 85 0 Enter measured fuel temp F SpecGrav 0 7823 Specific gravity fuel should measure Nitromethane Percent This program corrects the measured nitromethane content of a fuel sample for temperature This program is designed to be used with special nitromethane hydrometers that are based on either a 60 or 68 degree Fahrenheit temperature standard These hydrometers read in percent of nitro as opposed to the actual specific gravity Press TUNE UP then select Nitro to start this program Display Example Nitro Percent Hydro 60 Enter hydrometer temperature standard Fuel Temp 78 0 Enter measured fuel temp F Nitro 85 0 Enter hydrometer measured nitro Corr Ntr 89 5 Corrected nitro 23 COMPUTECH SYSIEMS NC Exhaust Gas Temperature Correction Monitoring cylinder exhaust gas temperatures EGT can assist in maintaining a consistent and repeatable tuneup However changes in engine inlet air temperature affects the exhaust gas temperature readings Use this program to correct an observed exhaust gas temperature reading to a stand
50. order to use any of the RaceAir Pro jetting programs a baseline tune up which includes a baseline air density ratio ADR and a baseline jet must be established Once the baseline tune up is established for a particular engine combination the jet change programs will compute a change in the carburetor jets or the fuel injection bypass jet pill based on an air density change The lower the air density is the leaner the engine needs to be The higher the air density is the richer the engine needs to be CAUTION When making any jet change always monitor the engine exhaust gas temperature EGT indications oxygen sensor O2 readings air fuel ratio indication etc most importantly take spark plug readings to make sure the air fuel mixture ratio does not become too lean Severe engine damage can be caused by excessively lean mixtures Important All the Computech Tune Up Jetting programs require the use of flow tested jets Modified jets or jets that are not flow tested do not have adequate fuel metering control for use with these programs To establish a baseline tune up operate the engine at full throttle in typical racing conditions Record the jet size or sizes used the ADR and any pertinent time or speed information Now lean the jet or jets down one size make another full throttle run and repeat the process of recording the jet or jets size ADR plus time and or speed information Inspect the spark plugs exhaust ports e
51. rifices 1 Number of orifices Equiv Dia 0 028 Single orifice diameter equivalent in inches Press ENTER to continue Blower Overdrive This program calculates the percentage of overdrive between the blower and the crankshaft Press TUNE UP then select Blower OD to start this program Display Example Blower OD BtmPulley 65 0 Enter bottom pulley teeth TopPulley 51 0 Enter top pulley teeth Overdrv 27 5 Blower overdrive or 127 5 of crankshaft RPM 22 GCOMPUTECH SYSIEMS NC Gasoline Specific Gravity This program corrects the specific gravity readings of racing gasoline based on the temperature of the fuel Hydrometer readings of the same fuel will vary with the temperature The fuel supplier can provide the reference specific gravity and the reference temperature at which that specific gravity was taken Knowing what the specific gravity reading should be at a given temperature will verify that the fuel is not degraded Press TUNE UP then select Gas Spec to start this program Display Example Gas Spec Grav Ref SpGr 0 7265 Enter factory reference specific gravity Ref Temp 60 0 Enter factory reference temp F Fuel Temp 67 5 Enter measured fuel temp F SpecGrav 0 7231 Specific gravity fuel should measure Methanol Specific Gravity This program corrects the specific gravity readings of methanol alcohol racing fuel based on the temperature of the fuel Methanol will absorb c
52. rmation to predict the proper jet to use as the ADR changes Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press TUNE UP then Jetting Menu then select Mikuni Jets to start this program Display Example Mikuni Jet Base ADR 95 7 Enter ADR from baseline tune up New ADR 99 2 Press IMPORT WEATHER DATA import ADR Base Jet 150 Press in baseline tune up jet size Adjust 0 0 Enter tune up change if needed New Jet 155 3 Calculated new jet size Keihin Jets Read the Tune Up Information section before using this program This program is designed to accept Keihin carburetor jet numbers Use this program with the baseline tune up information to predict the proper jet to use as the ADR changes Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press TUNE UP then Jetting Menu then select Keihin Jets to start this program Display Example Keihin Jet Base ADR 95 7 Enter ADR from baseline tune up New ADR 99 2 Press IMPORT WEATHER DATA fo import ADR Base Jet 150 Press in baseline tune up jet size 19 COMPUTECH SYSIEMS NC Adjust 0 0 Enter tune up change if needed New Jet 152 6 Calculated new jet size Fuel Injection Jets Area Method Read the Tune Up Information section before using this program This program is designed to work with mechanical fuel injection systems The first time this pr
53. rogram works best when the engine fuel air mixture is slightly rich so the vehicle performance will change appropriately with the weather changes This may require periodic jet changes during the race season The benefits gained in consistency and predictability are well worth the effort If the vehicle runs quicker than the computer is predicting when the correction factor is improving number getting smaller then the fuel air mixture is probably too rich and should be leaned slightly Conversely if the vehicle will not run as quick as the computer is predicting when the correction factor is improving then the fuel air mixture is probably too lean and should be richened slightly Efforts spent on getting the fuel air mixture correct will be well worth the rewards in increased predictability See the Tune Up Information section for more details Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press DIAL IN then Standard to start this program Fuel Display Example Fuel Setup Fuel Methanol Press down arrow to change fuel then ENTER Done Press CLEAR to return to program Std Dial In Display Example Std Dial In Press ALT SET UP 1 1 to change fuel Fuel Methanol Fuel selected Old Corr 0 9887 Enter reference run correction factor Old ET 8 829 Enter reference run ET New Corr 0 9792 Auto transferred new correction factor New ET 8 812 Predicted new ET recommend
54. s DRAG FORMULAS then Gear Ratio to start this program Display Example Est ET MPH Tire Circum 106 0 Enter tire circumference inches not diameter Trap MPH 154 00 Enter desired finish line MPH Trap RPM 7800 Enter desired finish line engine RPM Conv Slip 800 Enter estimated torque converter slip RPM Gear Ratio 4 56 Calculated gear ratio Engine Trap RPM Drag This program calculates the estimated finish line engine RPM The variables considered are ring and pinion gear ratio tire circumference roll out finish line MPH and estimated torque converter or clutch slippage at the finish line This program works for both 1 8 mile and 1 4 mile tracks Press DRAG FORMULAS then Trap RPM to start this program Display Example Est ET MPH Tire Circum 106 0 Enter tire circumference inches not diameter Trap MPH 154 00 Enter desired finish line MPH Gear Ratio 4 56 Enter rear end gear ratio Conv Slip 800 Enter estimated torque converter slip RPM Trap RPM 7800 Calculated finish line engine RPM 29 COMPUTECH SYSIEMS NC Torque Converter Slip Drag This program estimates the actual finish line torque converter or clutch slippage in RPM The variables considered are gear ratio tire circumference roll out finish line MPH and finish line RPM This program works for both 1 8 mile and 1 4 mile tracks Press DRAG FORMULAS then ConverterSlip to start this program Display
55. s not known Install the piston with rings in the bore at a measured distance below the deck of the block Next attach a flat clear plastic plate over the cylinder The plate should have 1 or 2 holes over the bore to fill the area above the piston with light oil or alcohol Then measure the exact volume of fluid required to fill the entire void The program will also work with available compression ratio tools that have an area above the piston notched for dome clearance The tool will have a volume number marked on it to indicate the notched area volume Provide this information to the computer to calculate the dome volume Press ALT ENGINE FORMULAS then C R Menu then select Pour Dome to start this program Display Example Pour Dome Bore 4 250 Enter cylinder bore diameter inches Deck Hgt 0 400 Enter measured piston flat to block deck inches Plate Vol 0 000 Enter 0 for flat plate or marked volume CC for tool Pour Vol 86 700 Enter poured volume measured CC Dome Vol 6 3 Calculated piston dome volume CC 39 COMPUTECH SYSIEMS NC Cubic Inch Displacement Values Known This program computes the displacement of an engine Values considered are bore stroke and number of cylinders Press ALT ENGINE FORMULAS then select C I D Menu then Calc C I D to start this program Display Example Calc C I D Bore 4 250 Enter cylinder bore diameter inches Stroke 3 750 Enter crankshaft stroke inches
56. se 100 Gr as the threshold for making water vapor related tuning changes Engine fuel flow and ignition timing may need to be increased above the threshold Wet Bulb Temperature Wet bulb temperature refers to using an expanding liquid type thermometer with a water soaked cotton wick over the sensing bulb This technique produces a lower temperature indication for lower humidity conditions due to evaporation The wet bulb temperature and the dry bulb temperature can be used to calculate Relative Humidity Good Air Bad Air The atmospheric conditions that make air quality better for racing are lower temperature lower humidity and higher air pressure Conditions that make the air worse for racing purposes are higher temperature higher humidity and lower air pressure Lower Correction Factor numbers lower Density Altitude numbers and higher Air Density Ratio numbers all mean better air quality The variables that cause the Correction Factor and the Density Altitude to decrease smaller numerically as well as the Air Density Ratio to increase larger numerically are a lower temperature a lower relative humidity a higher barometric pressure as measured with a barometer or a lower pressure altitude as measured with an altimeter Typically the STD Correction Factor will be between 98 better and 1 15 worse the Density Altitude will be between 300 ft better and 8 000 ft worse the Air Density Ratio will be between 85
57. t black and red keys have 2 functions When a black and red key is pressed the computer will go to the function labeled in black When the red ALT key is pressed then a black and red key is pressed the computer will go to the function labeled in red COMPUTECH SYSIEMS NC The POWER ON OFF key must be pressed and momentarily held to turn on the computer The ENTER key is discussed in Program Access and Use below The CLEAR key may be used anytime to exit a menu or program CLEAR is also used to backspace an incorrect entry When the computer is powered pressing the red SAMPLE key will turn on the fan and take a weather sample The weather sampling process may be aborted by pressing SAMPLE again Several of the included programs use weather information in the calculations When a program asks for current weather information pressing the IMPORT WEATHER DATA key will automatically transfer that data The RaceAir Pro powers up in the Live Fan OFF mode The actual air data from the last sample may be viewed by pressing ALT then IMPORT WEATHER DATA Program Access and Use The COMPUTER PROGRAM CAPABILITIES list can be used to select a program The list is indented to show the access menu levels The indicator arrow on the left side of the display may be repositioned in a menu or in a program screen by pressing the up or down arrow keys The up and down arrow keys will repeat or continue to move the indicator arrow when held Pressing the E
58. t head gasket volume and supercharger boost pressure are included in the equation 4 Pour Chamber Page 39 This program will calculate the engine compression ratio using the cylinder bore crankshaft stroke and the measured liquid volume poured into the combustion chamber of an assembled engine with the piston on top dead center TDC 5 Pour Dome Page 39 This program will calculate the effective piston dome volume by measuring the piston deck height installing a clear plastic plate in place of the cylinder head then measuring the poured liquid volume in the void 2 Menu 1 Calc C I D Page 40 This program will calculate engine displacement in cubic inches and liters from cylinder bore crankshaft stroke and the number of cylinders 2 Calc Bore Page 40 This program will calculate the cylinder bore required for a specified engine displacement when crankshaft stroke and the number of cylinders are given 3 Calc Stroke Page 40 This program will calculate the crankshaft stroke required for a specified engine displacement when cylinder bore and the number of cylinders are given COMPUTECH SYSIEMS NC ALT SET UP key 1 Program Setup 1 Fuel Setup This program is used to set the fuel type gasoline methanol or special in the Std Dial In the Full Run Std and the Intermed Run programs The default setting is gasoline Press the down arrow key to view the other fuels then press ENTER to select that fuel The prop
59. tc carefully for signs of detonation or other indications that the air fuel mixture ratio may be too lean Assuming there are no signs of being too lean and the vehicle picked up performance on the last run repeat the entire procedure again with the jet or jets 17 COMPUTECH SYSIEMS NC wv one size leaner Continue testing until the time and or speed slows down or the engine shows signs of the air fuel mixture ratio being too lean At that point richen the jet or jets 1 size when tuning for peak performance or 2 sizes when tuning for ET classes bracket racing The jet or jets and the ADR that you have at that time is the baseline tune up Record the baseline tune up information for future reference All the Tune Up Jetting programs provide jet suggestions that are more accurate than the jet size increments available This is done so the user can easily see the exact fuel requirement for the measured ADR change from the baseline ADR Select the actual jet closest to the suggested jet size while being careful not to run the engine overly lean round the number up for carbureted applications or round the number down for fuel injection bypass systems Anytime the tune up is slightly rich or slightly lean the Adjust line can be used in any of the jetting programs to make adjustments to the tune up by changing engine fuel flow a few percent at a time When the Adjust cursor block is flashing press a number key corresponding to th
60. te records as to when the performance actually falls off in relation the outside temperature versus the dew point temperature performance degradation can be predicted Dry Barometric Pressure The dry barometric pressure Inches Hg is the absolute barometric pressure with the partial saturation water vapor pressure from humidity subtracted The measured absolute barometric pressure is from a combination of oxygen nitrogen argon and some other trace gases plus water vapor The portion of the air that is water vapor will not contribute to combustion of the fuel and therefore must be factored out Dry barometric pressure is used to calculate ADR Density Altitude and the Correction Factor Dry Bulb Temperature See Temperature Pressure Altitude Pressure altitude is the aircraft altimeter indicated value in feet that results from setting the pressure adjustment window to 29 92 Inches Hg This number relates to the aeronautical industry defined Standard Day altitude An indication of O ft is equal to an absolute barometric pressure of 29 92 Inches Hg Lower or negative values i e 180 ft indicate more air pressure Higher values i e 2500 ft show less air pressure An altimeter will also show absolute barometric pressure Inches Hg in the pressure window when the altitude pointer is rotated to indicate O ft Note that this number is pressure only Until it is adjusted for temperature and humidity via the density altitude process it
61. to continue 21 GCOMPUTECH SYSIEMS NC High Speed Display Example High Speed Area 0 004926 Total nozzle area in square inches Main Pill 0 060 Enter baseline main bypass jet diameter in inches Old HSDia 0 040 Enter baseline HS bypass jet diameter in inches Old HS 16 21 HS bypass of engine fuel flow New HS 18 00 Enter desired HS bypass New HSDia 0 042 New HS bypass jet diameter Suggested changes to the high speed relief valve poppet pressure setting are presented in both the Fuel Injection Jets programs on the Rail Chg program line That line suggests that an increase positive number or decrease negative number be made to the relief valve cracking pressure PSI setting to maintain the same engine RPM operating point This change is necessitated by the new main bypass jet and the resultant fuel rail pressure change Orifice Square Area This program will calculate the square area of round orifices such as jets pills or nozzles Varied quantities and diameters are easily handled An equivalent diameter for the total square area is also provided Press TUNE UP then Jetting Menu then select Square Area to start this program Display Example Calc Area Orifices 1 Enter number of orifices of this size Diameter 0 028 Enter orifice diameter in inches More No Press NO to stop Total Area Total area screen Area 0 000616 Total orifice area in square inches O
62. up change if needed New Jet 89 1 Calculated new jet number Different size primary and secondary jets or staggered jet sizes can be quickly checked by using the Recalculate Function See the Program Access and Use section for details 18 COMPUTECH SYSIEMS NC Precision Jets Read the Tune Up Information section before using this program The Precision Jet program is designed to work with precision drilled reamed and flowed jets Hand drilled jets are not accurate enough for precise fuel metering This program is designed to accept carburetor jet diameter in inches or millimeters Make sure to enter the decimal point and zeros to denote the diameter dimension It will work with any fuel Use this program with the baseline tune up information to predict the proper jet to use as the ADR changes Press the SAMPLE key and allow the weather analyzer to stabilize on the Sampled Wthr screen Press TUNE UP then Jetting Menu then select Prec Jets to start this program Display Example Prec Jet Base ADR 95 7 Enter ADR from baseline tune up New ADR 99 2 Press IMPORT WEATHER DATA to import ADR Base Dia 0 032 Press in baseline tune up jet size Adjust 0 0 Enter tune up change if needed New Dia 0 033 Calculated new jet size Mikuni Jets Read the Tune Up Information section before using this program This program is designed to accept Mikuni carburetor jet numbers Use this program with the baseline tune up info
63. w ADR 99 2 Press IMPORT WEATHER DATA to import ADR Base Jet 0 060 Enter baseline main bypass jet diameter in inches Adjust 0 0 Enter tune up change if needed Rail Chg 2 0 High speed relief valve change or PSI New Jet 0 057 Calculated new main jet size Fuel Injection High Speed Bypass Adjust This program will calculate a high speed bypass lean out orifice diameter change for mechanical fuel injection systems The program is based on a percentage of engine fuel being bypassed back to the fuel tank It will calculate the current bypass percent and then size an orifice for a desired bypass change The first time this program is used all the engine fuel nozzle sizes must be entered in the setup When the setup is completed the computer will remember the total nozzle area for future calculations This program and the Fuel Injection Jets Area Method program use the same total nozzle area number from computer memory Press TUNE UP then Jetting Menu then select High Speed to start this program Setup Display Example Calc Area Nozzle area setup routine Orifices 8 Enter number of nozzles of this size Diameter 0 028 Enter nozzle diameter in inches More No Press NO to stop Total Area Total nozzle area screen Area 0 004926 Total nozzle area in square inches RECORD this Orifices 8 Number of nozzles Equiv Dia 0 079 Single orifice diameter equivalent in inches Setup complete press ENTER
64. with a number of calculated weather values These values may be used independently or in conjunction with the programs contained within the RaceAir Pro computer for accurate performance prediction and tuning assistance Important Air samples should be taken at approximately engine air intake height above the same type of surface as the racetrack i e dirt asphalt or concrete Keep the unit out of direct sun and away from engine exhaust or other heat sources while sampling Also keep your body heat away from the intake vents the front Use the RaceAir Pro the same way each time air sample is taken When in use keep the RaceAir Pro an environment similar to that being sampled For example don t pull the RaceAir Pro directly out of a hot trailer and immediately take asample The amount of time required for such a sample to stabilize is significantly longer than normal and the result could be less accurate The sampling process will typically take between 15 seconds to 3 minutes Don t allow water to enter the vents in the front or on the left side If this happens onf the display appears confused remove the batteries and allow the RaceAir Pro to dry out Calibration Each RaceAir Pro goes through a rigorous calibration process to assure the highest accuracy of the readings The calibration data is unique to each unit The data is stored in the computer memory with an internal battery backup so the weather sensor corrections ar

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