JUIC3D

1 3/4 has been shown to provide more than enough flow for a bolt-on LS3 meaning that there is no restriction in the exhaust track that could be a source of more power.
There is no need for the larger 1 7/8 unless you really start pushing out some exhaust with forced induction of some kind.

I expected to have a cam and possibly either a blower, turbo, or nitrous setup in the future so I planned accordingly and went with the 1 7/8 knowing that I would be giving up a little bit until the extra flow was needed.

My cam is installed and nitrous should be on the car soon

KB9GKC

I've read lots of reports of motors getting stronger as they age.



Yes if they are broken in according to GM recommendations, if not your engine will have slightly less power.

Douglas in Green Bay

djbrun

I have dyno'd my car on three different dyno jets all with SEA correcton and smoothing set to 5.
With a little ove 1K on the clock I got 391/389.

Then after about 3500 miles at the same shop and dmn close to the same conditions. 399 and I think 392.

Then at another shop before the tune and exhaust. I got 401/394.

With LS7 complete exhaust 410/404.

DJ

oldmansan

You mean SAE and all dynos (even the same model) are different. Not to mention different temperature/humidity on different days.

I'm not saying new cars don't gain some power after breakin. I'm just saying without back-to-back dynos on the same dyno (not the same model) with like conditions it's a crapshoot.

San

taken19

Regardless of the discussions about back to back dyno runs and temp/humidity runs, this is exactly the data that supports an increase in Hp with engine breakin.

Thanks for posting

haljensen

Three DIFFERENT Dynojets.

Over how much time and how many miles? And only a 10 RWHP difference? Regardless of miles or time that's not much difference. 2-3% variation is possible with 3 different dyno runs on the same Dyno on the same day.

djbrun

Excuse for the mistype. I said very damn close to the same conditions. I know what your what your saying though. The results from the last two were within 2hp + tq which I found to be closer than I expect to see.
Back to back on one dyno jet would be the best way, just didn't work out that way.

DJ

djbrun

We are talking one year, I don't get to drive my car much. Summer time that year was pretty stable conditions, all around 96 degree's and the same humidity during my dyno pulls.

DJ

BADASSBU

My bone stock 09 a6 put down 403hp 399tq on dyno jet. Best et 11.79. Swapped in bone stock new LS7 over 18 months ago,have never dynoed new engine but did go 11.091@126 3 weeks ago.

firewallx

I don't understand why GM installed wet-sump on LS-3s.

bosco 08

What does a lower rear gear do to dyno numbers? i.e. 2.56 vs 2.73 identical cars.

Dendk

Stock 2008 LS3 A6 non NPP, axle back only Dyno results..typical.

taken19

What's the difference between the 3 runs, axle back only? I can't buy an axle back giving you 30 rwhp...

JUIC3D

Most people dont use STD correction. My car put down 528whp STD corrected with my current setup but SAE put it at 517.

And no, , axle back wouldn't give that much hp. Given that the best run was the first one, I'd assume the other 2 were back to back pulls and the signs of heat soak are present.

Toilets

I had my stock 12 centennial gs dynoed on Thursday so I can have a baseline. It had 850 plus miles on it. It did 399.43 rwhp. Ain't no GM high tech numbers but was close.

Dendk

That is what I understand...SAE is generally what is used not STD, axle back will not give you appreciable power gains. Runs we're back to back heat soak is present..I don't read anything into it other then just an LS3 run, your numbers vary depending on many factors but these motors are within A very narrow percentage stock and the hp is within this realm, was cool to watch some of the runs of other cars.

MarkRx

wonder how the 2 extra cats in the x-pipe plays out on the 2012's

bosco 08

Kerrdogg

Sounds like my bucket, think I'll trade for one of those fast 08's.

Kerrdogg

My 2011 didn't but the 2012's have two extra resonators, doesn't seem to effect stock power.