Rob 02

Stock HP on an early C5 is usually ~285 so that makes since.

Roddy13

what kind of post is this? Did you read the thread?

it has nothing to do with what an early C5 usually dyno's.

He gained 13hp from long tubes, full exhaust and a custom dyno tune. He is asking if his gains from these mods is normal.

its not those are terrible gains for the money invested and he should have gained almost double what he did.

Also most 2000's routine dyno 300-305rwhp as they did come with the largest spec cam of all the years (excluding Z06). But we also discussed numbers are just numbers what we are looking at here is the gains alone over the benchmark regardless of what the benchmark is.

Smh

OP I would highly recommend checking your spark plugs and wires. I'm thinking with such low gains you may have a burned through spark plug wire that was touching the header, or one that is not seated properly. Also since the plugs had to come out to do the headers check that none of them are cracked. You might audibly hear a misfire. Outside of this check for any sounds like an exhaust leak as you could have a bad gasket affecting your numbers.

Also we klnow your baseline of 307rwhp was measuredon the same dyno as the after results of 320rwhp so there is no discrepancy between using a different dyno on a different day.

Rob 02

The stock exhaust flows pretty good. What kind of gain do you expect to see from headers and a tune on a stock LS1 with a restrictive air box?

Are you saying he was making over 300HP bone stock?

TommyTomlin

Still missing it guys....
with these mods-
-Texas speed long tubes
-Texas speed high flow catted mid pipe
-corsa cat back

His results are untuned vs. tuned
The gains seen are from the TUNE ONLY

Scotty2000SS

OP get in here! It's getting ugly

Rob 02

Rodny13.

Have you ever had experience with a misfire situation in either bank?

I would think that the OP has enough common since to not run a dyno run with in crawl home mode with a check engine light on.

Roddy13

Maybe I am misreading but it reads to me that OP has no mods before tune 307 whp, then after mods and tune 320whp.

Rob 02 yes experience with misfire. Not all misfires result in a CEL, there is a trend, threshold and trigger algorithm in the ECU which must be met, some people call that an occurance count or frequency of event. (I've built more than one low 10 second +138mph car and have written my own tune files in the past). 320whp with those mods is low on an LS1.

If OP made 307 with headers, exhaust before tune, with a 6MT that is low, and/or the dyno reads low and is not calibrated correctly and we are seeing measurement uncertainty.

Rob 02

The stock exhaust breaths better than most people think by conventional wisdom. The stock exhaust manifolds do quite well. Good for over Z06 power. In fact Long tube headers only help the High end, RPM's over 4,500.

I have dyno'd at 406Hp with the stock exhaust (Z06 ti). I love the drive-abity. I have been building engines a long time.

Antz97znj

Huh? Yea because that LS6 intake makes such a big difference lol

scottieg74

I have a 97 c5 A4 with 123k
im not at all impressed with the dyno numbers.

magnum stage II cold air induction
XS long rube headers
hi flow cata
xpipe
flowmaster force II axel back

bigger mass meter
bbk 80 throttle body
ls6 intake manifold

dyno'd 301 rwhp

Shirl

13hp / 16tq with tune. Sounds about right to me. Although I would think there would be a better gain with the tune. Conditions would play a part too and as someone else said, doesn't look like there is an intake on the car.. ? In extreme heat (95 degrees out) with similar mods years ago, my car only made around 312hp and I was a little upset about that. But on a cool day at the track, it was running 12.3's. So, really the track is the true test.