winters97gt

Sorry, was off .7 hp on a very old dyno.

haljensen

GM has to certify ALL LS3's at 430/436 HP with no more than 1% variation so the 10HP break in is BS. Our way of only posting the best of 3 or 4 runs isn't really fair, maybe we should average the runs instead? Total the 4 runs and divide by 4 for a truer final figure?

Some shops advertise high HP for every vehicle they test, those of us that have been on the Forum for awhile know who the culprits are. I'm not going to name a shop since I don't want to get banned but one shop was notorious for always posting the highest HP numbers, stock or modified. A good Dyno operator can "adjust" almost any numbers he wants and some Dynos seem to give high numbers regardless of the car being tested.

Most Dynojets will give similar numbers if they are handled and reported properly. I had my '05 on 4 different Dynojets and all were close. My '08 has only been on 2 but they both agreed within a few HP of 375RWHP stock.

9157

rico750sxi

GMHTP's 2012 test car laid down 415rwhp.

JUIC3D

Yep, and then went 12.8@112 mph. . . that sure sounds like a 415whp machine

taken19

I agree that GM will certify their NEW motors within 1% of each other. And again, I have no data to confirm this, but I have heard of some cars gaining 10-15 rwhp more after the rings have seated.

So what if the 385 rwhp motors generally have 0-1000 miles on them and the 400 rwhp motors had 1000-10,000 miles on the motor. Does that make more sense?

I'm just shooting in the dark here, but it makes sense to me.

JUIC3D

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

FWIW, my LS3 made 421/398 with intake, headers, ported throttle body, and no tune.

Detoxx03

Any smart person know that motors make more power as miles go up. I had a fresh motor built last year and the initial dyno was at 452 and after proper break in it put down 457. I'm sure if I would have threw it on the dyno again after a good 10-15K miles it would have made more.

And as for the grand sport making 415 and then running a 12.8, that is more of an indictment on the driver than the car itself. Let's be real here. Look at the ZL1 that was running bad times until they put a competent driver behind the wheel. Doesn't mean the car doesn't make the power it just means its not being used properly.

JUIC3D

I'll take track numbers over dyno numbers all day long.

Detoxx03

Not arguing which one means more

JUIC3D

What did the ZL1 run with a competent driver? I can't imagine it being much better than low 12s given its curb weight.

Detoxx03

11.9@119 if I recall correctly. Some people kept running 12's. It should run low 11's with DR's.

FNBADAZ06

Agreed. Even if there was a "competent driver" at the wheel, the dyno numbers they got were from a happy dyno or operator.

HOXXOH

Dyno numbers are only good as a tool to determine the differences in changes, especially for tuning.

Just to show that the numbers simply by themselves don't mean much, here's what my '08 A6 did.

I dynoed 382HP on a Dynojet and yet had a best ET of 11.89 on DRs. This was with a Vararam CAI, ported TB, Z06 exhaust manifolds, Z06 mufflers, and a tune.

Now you'd think all those cars who are getting 375-390 that are bone stock, should be cranking ETs in the elevens without problems. And the ones who get 415-425 after headers, CAI, tune, DR,s, etc. must most certainly be running mid-elevens. So check the performance list, because it's a better indicator of power.

I'd guess somewhere there's a website to create a dyno sheet to what ever number you'd like. Maybe www.fakedynosheet.com or www.dynobragingrights.net

JUIC3D

Nice websites Tom.

For comparison, my intake, headers, throttle body car that put down 421/398 went 11.6@119 on a warm October night.

Conversely, when I first had the cam in the car, it still went 11.5@122 and after some seat time and better tires, its a consistent 10 sec car with a best of 10.6@129

mowe

421 and 398. Why the diff in tq? My numbers arent really relevant for total but with I/h/e and tune made 436 and 432 tq.

JUIC3D

I have 1 7/8 headers. I put them on, knowing I would be adding a cam and probably another 150hp down the road. 1 3/4 would have been better if I was staying bolt-ons, but I knew I'd be needing more flow at some point. The 1 3/4 likely would still be ok, but given how the car performs, I think I made the right choice.

mowe

Yeah I've got the same headers. 1 7/8

JUIC3D

Those numbers were also untuned so its likely that the fueling was WAY off and could have benefited from fatter fueling in the midband.

skeezer

Why do you say the 1 3/4 would have been better with just bolt ons? Are you saying this with keeping in mind a cam wouldn't be brought into the picture at any point?