LT1 $EE Speedometer Scalar - 8000 PPM

[dave w]

I'm posting hoping to better understand the LT1 $EE Speedometer Scalar.

Attached is my homework figuring out the speedometer scalar for a stock 1995 F-Body / EE_16209481 .bin file.

For my homework assignment I'm using the formula Speedometer Scalar =(40*3.23*806)/4000 Is my formula correct?

VSS = 40 pulses per driveshaft revolutions
Gear Ratio = 3.23:1 rear end gearing
Tire size = 245/50R16 = 806 rotations per mile

The answer I arrived at for Speedometer Scalar is 26.0338
The 1995 F-Body Auto 3.23 EE_16209481 Speedometer Scalar is 26.0 (see attached)

The question I have is if I wanted to substitute an 8K VSS the new formula, based on the example above, would be: Speedometer Scalar = (40*3.23*806)/8000?

Thanks in advance'
dave w

[steveo]

makes sense, right? precisely twice the pulses per revolution, so a 4k calibration divided by two.

let me know if it works, i do plan on making a better speedo calibration tool eventually.

[dave w]

Thank you for the reply Steveo.

There's a challenge I'm having to workout. I'm re-flashing the PCM for an engine swap / engine transplant. The project vehicle is nearly 300 miles from me. The challenge is ... will the re-flash be a smile or a frown? I will re-flash using the project vehicle tire size / gear ratio / 8k VSS formula posted above.

dave w