HTX

iTrader: (1)

I have a 99 Z28 A4 w/
lid K&N filter, ported throtle body, descreened MAF, Headers, and Borla exhaust.

I just had my headers installed by HPE last week and they dynoed it afterwards. I only put down 313 hp 324 trq. Ive compared my #'s with other people's on this site and they usually put down 325+ hp and 340+ trq. So naturally Im a little pissed off with my results. My numbers really take a nose dive at 5000 rpm where I thought that LS1's peak around 6000 rpm. Am I wrong?

One tuner blames the stock tune, and he says that a tune should get me 10-15 hp. What I need is a second opinion (before I cough up $425) I would appreciate anyone's input. Thanks.

foff667

iTrader: (2)

stockish LS1's such as yours generally peak at 5200-5500 rpms usually. As far as your numbers go they seem to be on point with your mods. Don't get hung up on dyno numbers...go to the track thats where you win or loose, not on a dyno.

HTX

iTrader: (1)

Im not so much hung up on the numbers as I am hung up on the fact that my numbers die off at 5000 rpm.

foff667

iTrader: (2)

again...run it at the track then compare those numbers

Billf6531

Post your dyno sheet. If it shows max torque @ ~4400, and max HP @ ~ 5200, and ~ 13.0 - 12.8 afr, you're golden.

edcmat-l1

iTrader: (10)

How many miles on the motor? 313 thru an A4 aint too shabby for what ya got. Like foff said, dont get hung up on everybody elses #s. Too many variables. As far as falling off at 5000, see first question...

foff667

iTrader: (2)

yeah I was gonna ask that, just for maybe valvetrain issues ie springs going...

HTX

iTrader: (1)

My motor has 120K miles. I really wish I did a befroe and after dyno. The guy at HPE blames the Headers. I used Hedman only cause I paid $100 for them. But I really dont think that the headers, even Hedman headers, would cause a drop in the higher end.

txhorns281

iTrader: (12)

tuning always maximizes performance gains from modification. (Unless your tuner sucks or your build sucks). If you don't want to spend the $$$, like Foff suggested, go to the track, see what it traps. 110 or slightly over would be a reasonable mark.

edcmat-l1

iTrader: (10)

Weak valve springs will peter out on the top end. Most of the time, they do just what yours is doing. they make the motor stop pulling.

It aint the headers. It should pull that high or high with the manifolds.

And unless your fuel is right at 12.5:1, yeah, a tune should get you a few more. But even that is debatable, depending on alot of factors

Chuck@

iTrader: (1)

There's always power to be gained over the stock tune after installing headers because you can use a lot more timing since the heat is getting out of the cylinder head faster! Quite possibly the people you're comparing numbers to had tunes! But yes, the headers you got aren't that great, but hey, for 100 bucks, who could complain? Bring it in for a tune and I bet you'd make the 325-330 you're looking for!

Chuck @ HPE
281-448-1300

SSpdDmon

iTrader: (10)

My '99 M6 untuned put down the following with just a lid, GMAF, bellow, !CATS, and Borla @ 50K miles:



...just for reference...5400rpm=118mph & 5600rpm=122mph

Chuck@

iTrader: (1)

All cars are a little different. We've seen bone stock automatics put down 330 rwhp before. All that is relivent with all this is the fact that he will see a gain in hp by doing the tune. car vs. car one shops dyno vs. another shops dyno...

too hard to do real solid comparisons without everything being equal.

Chuck

HTX

iTrader: (1)

Thanks guys for info and input. Ill be giving you a call shortly Chuck.