zoasis

I'm willing to be that the wheels/tires are the culprit. They weigh around 58lbs! Thats roughly 12-14lbs heavier than the track wheels. Thats a helluva lot of unsprung weight. Not to mention the larger wheel size.

With all of the above factored in and a Dyno that reads low, I believe the numbers posted. Baseline may have been 10HP lower.

3rdpower

Where did you hear they weigh that much?? I don't think 19" wheels would that much of a difference... You are not going to lose 20+ HP through 1" taller and 2" wider wheels.


I'm thinkin' ECU is possibly the disconnect.

2003z

iTrader: (7)

I weighed my 19s with 275/35 S-03s on the bath scale at 60lbs!

slay2k

So? The non-track 18" with tires are around 54lbs, and the 17" are like 48lbs...

That wouldn't make such a huge dyno difference... I say the dyno's ****ed up.

arvin

iTrader: (2)

I don't think its the wheels. I have the Superleggera III 19x9.5 fronts and 19x11 rear. I don't know how much it exactly weighs but I know that it weighs much more than my stock track wheels. My baseline dyno is at 235 with the 19's and before Borla exhaust. I am just waiting for my headers to do another dyno run.

350zdanny

Nissan350ztt -

You're right about the Gtech not being accurate by any means, but it's precise in it's measurements usually (that's what users say). Meaning if the Gtech says he lost a half second, he probably did. I can't see how that's possible though.

Jeffh355 -

Headers are a good idea, but do you think that because he doesn't have them he is losing power? If that's the case I think I'm gonna need a set of Nismo's. They bolt right up to the cats, right, not the y-pipe?

Dan

Jeff@Performance

The headers bolt up to the cats, I don't feel that's why he's losing power, but headers will help move the air out of the heads more efficiently. Some one here I'm sure knows more about head flow caracteristics than I would, but if the exhaust can get out better, it seems to me the intake air would have an easier time getting in too??? Someone please fill me in if I'm on the right track here.

Brandon@Forged

Jeff, I think you are right. I believe the faster you can get the air in and out... the better.

Chebosto

iTrader: (43)

the wheels might be a factor--

even if the 19s are close to the same weights as stock, its the rotational energy that needs to overcome to spin more mass at the outter edges of the wheel.... it just sucks energy as its tries to spin it faster and faster.. but that would only realy matter off the line, when its already spinning the mass will accelerate, althought not as quickly, the power read outs shouldnt be that much lower....
i dunno about 10hp difference, is that possible? maybe it was just a fluke dyno.. if you're getting 5 hp spead throughout the runs, maybe its the dyno measurements.. how many pulls did you take?

3rdpower

I think I found the culprit hehe... and it's possibly a combination of a few things, however I totally forgot that Friday I put some poop fuel in my car... I think it was rated at 87 or 89. Total unconscious occurance... Just kinda drove up and grabbed the pump with mind on other things. In any case I went and picked up some Preston Octan booster and I figured out I had put poop gas in my car.

The real screwy part is today I had to go fill up and guess what? I did it again ... I'm pretty sure this combined with not resetting the ECU prior to the pull is really my weak point.

Thanks for not me up for doin' somethin' so stupid (in advance of course!)

ECU is going to be ordered anyway, I'm doing because well... it needs to be done anyway!

2003z

iTrader: (7)

Its definitely not the wheels. see my post in the wheel section, but I only lost 3 hp between the iforged and track wheels.