Page 1: Table Of Contents
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.
Page 2: Computer Program Capabilities
COMPUTER PROGRAMS OPERATION Page 16 COMPUTER PROGRAM CAPABILITIES This list is indented to show access menu levels. See Program Access and Use on page 9. TUNE-UP key Page 16 1 Jetting Menu 1 Holley Page 17 This program will calculate the proper Holley carburetor jet to use based on a change in weather conditions.
Page 3 This program will calculate a bypass flow jet change for a continuous flow mechanical fuel injection high speed lean out system. See Important program information on page 21. 8 Square Area Page 22 This program will easily calculate the area of several nozzles or jets and provide a single orifice diameter equivalent.
Page 4 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...
Page 5 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.
Page 6 This program will 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).
Page 7 2 C.I.D. 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.
Page 8 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=).
Page 9: General Information
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.
Page 10: Communication Port
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.
Page 11: Competition Weather Analyzer
COMPETITION WEATHER ANALYZER Overview The 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.
Page 12 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 elevation (0 feet).
Page 13 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.
Page 14: Good Air / Bad Air
Summer to Fall at the same track. The typical change in air quality from the heat of the day to 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.
Page 15: Calibration
Also, keep your body heat away from the intake vents on the front. Use the RaceAir Pro the same way each time an air sample is taken. When in use, keep the RaceAir Pro in an environment similar to that being sampled. For example, don’t pull the RaceAir Pro directly out of a hot trailer and immediately take a sample.
Page 16: Computer Programs Operation
Press Alt= (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.
Page 17 (pressure altitude ft) Tune-Up Information. In 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.
Page 18: Holley
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.
Page 19: Mikuni Jets
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 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.
Page 20: Injection
Use the following chart as an aid in determining nozzle diameter for various nozzle types. Important: If the fuel system has a fuel pump loop with Approx Crower/ a bypass jet or a second fixed main bypass jet circuit, Diameter Kinsler Hilborn Enderle...
Page 21 == 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 ADR from baseline tune up) New ADR? 99.2 (Press IMPORT WEATHER DATA to import ADR )
Page 22 page 21.) 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 equipped with a high speed bypass circuit. This circuit is often used to alter the engine high RPM fuel curve to compensate for the loss in volumetric efficiency when operating above peak torque RPM.
Page 23: High Speed
Area= 0.004926 (Total nozzle area in square inches, RECORD this) Orifices= (Number of nozzles) Equiv Dia= 0.079 (Single orifice diameter equivalent in inches) (Setup complete, press ENTER to continue) 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)
Page 24: Meth. Spec
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.
Page 25: Egt Correct'n
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 standard 60 degree Fahrenheit day.
Page 26 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 run (no database of runs is used or required).
Page 27 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.
Page 28 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= (ET change for density altitude change ratio) (Setup complete) Press the SAMPLE key and allow the weather analyzer to stabilize on the = Sampled Wthr =...
Page 29 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.
Page 30: Gear Ratio
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...
Page 31: Standard
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.
Page 32 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.
Page 33 Corr? 0.9784 (Enter recorded correction factor from run to standardize) 60' ET? 1.083 (Enter ET from run to standardize) Std ET= 1.088 (Standardized ET for selected run) 330' ET? 2.928 (Enter ET from run to standardize) Std ET= 2.940 (Standardized ET for selected run) 660' ET? 4.445 (Enter ET from run to standardize)
Page 34 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.
Page 35 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: == Tire Size Old RPM?
Page 36 Wgt LR= (Calculated left rear scale indication in pounds) Wgt RF= (Calculated right front scale indication in pounds) Wgt RR= (Calculated right rear scale indication in pounds) 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.
Page 37 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.. (Press ENTER to continue) ..lap= (Laps since last stop, 0 for first stop, ENTER to continue) This Stop is...
Page 38 Gas= 6.01lb (Gasoline weight pounds for US gallons) MPH. This program is designed to calculate the actual vehicle speed in MPH using a 1:1 transmission ratio. The calculations are based on the tire circumference, the engine RPM, and the final gear ratio.
Page 39 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...
Page 40 Dome Vol= -25.70 (Calculated piston dome popup volume CC, negative number indicates dished piston) 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.
Page 41 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)
Page 42 C.I.D.? 358.0 (Enter desired engine cubic inch displacement) Bore? 4.035 (Enter cylinder bore diameter inches) No. Cyl? (Enter number of cylinders) Stroke= 3.500 (Calculated crankshaft stroke inches) Page 42...
Page 43 INDEX Subject Page Subject Page Air Correction Help, Additional Air Density Ratio High Speed Bypass Air Good/Bad Holley Jets Air Sample HP Correction, Dyno Bad Air HP, 1/4 Mile Barometric Pressure, Absolute HP, 1/8 Mile Blower Overdrive Keihin Jets Bypass, High Speed KeyBoard Functions Calibration Liquid Weights...

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