Blog Post: Traction off, Torque Management Continues

[Bruce Nunnally]

Scan D5B

Today’s scan was with traction control disabled, to determine if the Torque Management Advance (retard) (TMAR) was originating from TCS. I observe that we still have TMAR with us, so I conclude it is not, and further study will be required.

Comparing today’s D5SB with prior D5SA, today’s peak was 468.9 whp vs prior peak 476.8 whp, or 8 less. Prior was a warmer day with somewhat higher humidity and earned a larger dyno correction of 2.4% vs 1% today. I am looking for repeatability here, and under 2% may be par for this type of testing.

I have added relative humidity to my scan table, so that the resulting scans can be self-correcting for conditions via dyno correction factor. The car tracks barometric pressure, relative humidity, and ambient temperature. With those figures an SAE 1349 dyno correction can be applied, and is figured in prior to graphing. I am also using a 400/464 ratio here for crank to wheels; I find this matches precisely with stock results.

Stock vs GM Dyno

This graph takes the GM LF4 engine dyno, converts it to wheel torque/hp, and compares it (dotted lines) to a scan from a stock ATS-V also converted to wheel hp (solid lines). They appear to overlay nicely.

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