It's the same tank of gasoline that was in there when we datalogged it a week ago and it had no detonation. And that was in hot weather just like when I did the dyno run. Same as Mishri, he also had his datalogged and dyno'd on the same day(s) I did.

If it comes down to selling the frickin car I will spend the money to dyno it one more time with a set of stock tires/wheels on it.

Just pisses me off that's all. Grrrr... Frustrating.

Oh, and yeah I drove the car both runs. And the first run I had a little better torque, a little less horsepower. But it was pretty close.

 

i think the tall tires are playing a fairly big role in the rwhp loss.. I'll bet its more like 10-15rwhp.. if tall rims/tires are enough to slow people down by .1-.3 at the track then that could translate to up to a 30rwhp loss.. and then i had a disapointing day at the track running M&H DRs 275/45/17s or whatever they are.. 275/17 forgot height.. 27" tire.. lowest 60ft was 2.2 vs 2.0 on stockers..

 

Like what everyone else said. Swap your tires with Mishri and see what your outcome is. I can deffinalty see how having heavier wheels could effect your power numbers. Dynos can give different readings at different times too, even in the same hour on the same car from what I've been told.

 

Wheels will lose some power, though not much.

I lost exactly 8rwhp/4rwtq from stock 17s to 20x10s.

 

Your numbers are way low.

Get in touch with Brenspeed. He may want you to datalog some points and email the pull to him. Have your dyno guy include the A/F in the pull file.

 

So only 8rwhp/4rwtq going to 20x10's eh? That's kinda what I thought. With the 20's what was your overall diameter? With the 295/45/R18 I'm at 28.5".

I've been considering emailing brenspeed about this as well and I might do that next week just to see what they have to say about it.

Especially if brenspeed pushes for it I might spend the $100 and schedule a dyno next week with stock tires on the car.

 

The numbers do seem lower than I'd have expected, but from personal experience on the butt dyno I am actually not really surprised. The first S197 I had was an 07 GT Premium with an automatic. It had a JLT CAI and was running a Brenspeed 91 tune, then a BamaChips 91 Race tune later. The transformation in that car from stock to CAI/tune was ridiculous, and it had 3.31s too. Then I decided that I wanted a manual car instead to do the whole supercharger deal, so I traded the '07 (which I regret btw, I liked that car better). When I got the '09 (with 3.31s also), I put the same JLT CAI on it shortly after purchase, and had Brenspeed and BamaChips both send me 91 octane tunes. I was seriously disappointed in both. I expected about the same performance, but I KNOW that automatic had more power by a good margin (based on what I could "feel", it had to have been about 25rwhp). I'm not sure why this is, but when you listed your result, I just had to nod. I should have kept that '07...

 

without that little spike in power that I have and you don't our numbers aren't far off at all.. maybe 275rwhp for me.. too bad I couldn't start earlier in the rpm range on the dyno..so we could se a good comparison..

 

The auto's have shorter 1st, 2nd, and 3rd gears, right?

 

My basic expectations were that my manual transmission should make up for most of Mishri's gains from the pulleys and plates. I expected numbers at or close to his.

Right now I have a 20whp differential between Mishri's car and mine. Assuming I put the stock tires back on the car and do another dyno run, and gain approximately 5-10whp out of it, then the overall deficit gets knocked down to 10-15whp instead of 20.

While annoying that the car seems to have this unexplained deficit in power, is it really worth hundreds of dollars in dyno testing and the associated time to try to do anything about this?

How far do I go to try and fix this before it becomes overreacting on my part? Honest question.