IcemanG17

Its really not as much as you think...custom cams and proper tuning is about it on top of a full race exhaust with headers.....I think Dennis's stock S4 engine was about 300whp....which is typical for stock S4's with race exhaust...all the internals were stock.....

pantera928

I usually approximate loss from flywheel to RWHP at about 20%. E.G. a 300HP motor will deliver about 240 RWHP. Do you think that loss is about right?

mark kibort

no, that is not right, but maybe in the case of the automatics.
remember, that number is worst case, generally found in the upper gears at top speed to 50% of that top speed where the rolling losses alone halve in value. 20hp loss at 150mph goind down to 10hp loss at 75mph. for example.

15 % is the max loss you will see.

mark kibort

I got 335 rwhp a few times, when the motor was fresh-er. only 15 years old at the time.

it was a true 335rwhp. dennis was 387rwhp on a spike at the end of the dyno, so really 375ish. his non tuned dyno run was 360rwhp if I remember. so, 15hp for tuning. (about right) 25 hp for cams with 1mm more lift, and some other small tweaks. sounds about right.
my car had a very vented air box as well. the same engine bone stock, with no modifications at all, but without a cat, was 290rwhp, so it was strong to begin with, unless that number was aided by the cat missing, plus remember, it had GT cams. (or something very GT like)

Dennis K

Sharktuning (lots of it) helped. We did a significant amount of tuning before we ever went to the dyno. I ran 3 different MAFs and all three read differently. They're supposed to be calibrated to a curve designated by Bosch, but we didn't find that to be true.

Prior to our dyno sessions, we did several runs with wide-open throttle acceleration in 3rd & 4th gear with the purpose of getting everything into a safe air:fuel ratio. I had Bill Ball in the passenger seat w/ a laptop making adjustments to the Sharktuner maps in realtime.

Then over the course of four sessions at the dyno, Jim was able to refine the tuning. We took data from the Sharktuner logs and from the Techedge wideband O2 logs to make decisions on the changes to make to the WOT and closed loop maps.

Below is the delta over the dyno tuning sessions. We gained over 50 lb-ft of torque at various rpm, but compared to completely untuned, I'm sure we gained even more. If we had installed cams and dyno'd without any Sharktuning at all, the difference would have been greater.

mark kibort

Its too bad we couldnt see the untuned versions. what was bill changing during the non-dyno tunine runs? were those changes hp gainers you think. then, on the dyno, what did you tune differently than what you did in the in-car driving runs? Im amazed of the changes on the dyno run. 25hp average and about the same at peak. not bad.
sorry, your at about 380rwhp, not 375, due to that noise as I said before. you are at 375 at 6k! pretty amazing, really!

Rob Edwards

Getting interested in Sharktuning, Mark?

mark kibort

as soon as anderson sends me hacked up tuning port connector with the wires hanging off it. mine are just in a bundle with tape around the. holbert car legacy issues.