Tech Tips - To Finish First, You Must First Finish ..... or Voltage Targets
Voltage targets can help you start and finish races so use the following rules of thumb to spot a pending problem or trouble shoot an existing problem.
Reference Voltage: If you are using a common lead acid battery, when the car is powered down via the master switch, the battery's voltage should be 12.6 to 12.8 when fully charged.
Charging Voltage: With the engine running (above an idle and assuming you have an alternator), the battery voltage should be a minimum of 1 volt above the reference voltage with all electrical items (rain light, brake fans, etc.) turned on and up to 2 volts above reference with the accessories turned off.If your voltage is outside this range, you most likely have an issue somewhere in the charging system.
Starting Voltage: Use your handy little multi-meter to check the battery voltage when cranking the engine to start. The voltage should not drop from the reference voltage more than about 2.5 volts during crank up assuming the starter draws the proper amperage. If the voltage drops to near zero and your cables are fine, it just might be time to replace the battery.
Bonus tip: Use the techniques covered in our Data Acquisition Webinars and it literally takes 3 seconds to keep track of your voltage targets.
News - Advanced Data Acq Classes
Starting in June we will have a brand new series of webinars for advanced data acquisition.
Attend the webinars and learn how using a modest data system with only speed, lat & long G, steering, throttle, brake and 4 suspension sensors to evaluate engine HP, gear sets, oil tank and fuel tank pickup issues, brake hysteresis, caliper flex, brake pedal issues, dynamic weight on all 4 tires, suspension frequencies, chassis roll gradients, roll hysteresis, and more...can make you faster!
Drop me an email (John@auto-ware.com) for more info and signup requirements. Don't forget we also have Off Site Data Analysis services available during race season. Call 800-647-2392 ext 201 for details.
|Equation of the Month - Drive Thrust|
Drive thrust is the force at the tires pushing the car forward. With this handy formula to follow you can use a spreadsheet or a math channel in your data system and make better choices in gear ratio selection.
TQ*DLF*GR*RPR/RR TQ is the engine torque at each RPM. DLF is the driveline friction loss factor - usually .85 to .90. GR is the gear ratio. RPR is the ring & pinion ratio, and RR is the rolling radius of the driven wheels (in feet, not inches).
Use your spreadsheet or data acq to plot your drive thrust for each gear vs speed and it will be obvious if you need a different gear set.
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