Wheel speed vs Engine RPM

[BRD-PREY]

I saw someone graph of Wheel speed vs Engine RPM, I think it came from HP tuners, do we have a similiar map? I'm guessing they are grabbing the ABS wheel speed sensors?
Ed

[joecar]

Hi Ed,

RPM and MPH are related by RPM / MPH = 336 * GR / TD where GR = overall gear ratio and TD = tire diameter inches.
you can rearrange to get MPH = RPM / 336 / GR * TD and make a calc pid for it.


Or if you want wheel speed in rpm, then engine / wheel = GR = axle * trans
rearranging: wheel = engine / GR = engine / (axle * trans)

If you have an A4, you can make a calc pid (using your axle ratio instead of 3.23): WHEEL = {SAE.RPM} / (3.23 * {GM.BOXRATIO})


There's nothing in the HPT scantool that EFILive scantool can't do... :hihi:

[BRD-PREY]

No It looked like he plotted front wheel speed, rear wheel speed and engine rpm. He was using it to show traction leaving the hole. It showed wheel spin vs front and engine rpm coming down to match rear wheel speed.
I saw it on LS1 Tech here it is.
http://www.ls1tech.com/forums/drag-racing-tech/1326837-6-speed-launch-help-wheelslip-graph.html

[WeathermanShawn]

That looks like a simple Excel program..

[joecar]

He's logging the pid GM.WHLSPD which relies on comms from the ABS/EBCM controller.