Z28SORR

Been a lot or talk about the LT4's. But I can only find a few hp numbers. If you have a real LT4 or upgraded LT1 to 4 specs. please list you hp.

MEAN LT1

Unless you havea real Camaro SS, Firehawk, or vette with an LT4, its not worth convering. You can make more hp from a aftermarket heads and cam then converting to a LT4.

Injuneer

The reason you don't see much in the way of LT4 HP is because the LT4 engine was only installed in less than 130 97 SS's and Firehawks. While others may have done "LT4 conversions", few, if any are TRUE LT4 conversions. Most are limited to the LT4 intake, LT4 heads and LT4 HOTcam, which is not even the cam used in the stock LT4's. They aren't making all the other changes like the cambered piston rings, undercut and rolled crankshaft, higher compression pistons, dual-mass torsional damper, etc that are included in TRUE LT4 engines.

A magazine article by More Performance claimed 429HP for an LT4 conversion, but that was on an engine dyno, all accessories stripped, numerous additional tweeks, including a multi-1000 dollar aftermarket ECU, etc.

96capricemgr

To put Fred's comments into perspective it is becomming almost routine for shops like Advanced Induction and Lloyd Elliot to do ported LT1 head and cam packages that deliver 400+RWhp through automatics which is way over 429 crankshaft.

BIG SHAFE

Are you sure about dual-mass dampers? I was almost sure they wer never in the F-body's. I know for sure the LT5 Vette's had dual masses.

Injuneer

The Corvette documentation claims they had the dual-mass damper. I doubt they would nave made a new one specifically for the F-Body with such limited production, so its possible the F-Body LT4's used the LT1 damper.

Denny McLain

My LT4 bone stock made 301 rwhp. With long tube headers, handmade dual 3" exhaust, K&N filter, adjustable fuel pressure regulator and a programmer to raise the red line to 6600 rpm we made 331 after tuning the fuel pressure from a 100 stock internal engine. Set of ported GTP LT4 heads and was able to get it up to 363rwhp and that was with the basically stock everything including cam.

Should have left it alone.

Ray86IROC

The grandsport registry has a dyno page w/ a lot of LT4s w/ various mods. Good source for numbers.

http://grandsportregistry.com/dyno.htm

Z28SORR

Sorry for the late response, been out of state all last week.
Ray86IROC & Denny McLain, thanks this is exactly what I was looking for.
Injuneer, even though I am aware of all this, I still appreciate the input.
For all of you, all out HP freaks, it may be hard to understand why anyone would want to do this specific upgrade. So I thought I'd list a couple reasons.
1. I already have an all out performance car, in my 84.
2. I think of this 97 SS as more of a grand touring car then an all out sports car.
3. As, some what, of a collector car I'd like to keep it mostly chevy parts.
4. The stock LT4's are getting around 300rwhp. Which is 50hp more then my stock LT1. With the addition of good headers and maybe the Hot Cam they're in the 325 to 350rwhp range.
5. So this could be 100+ hp in a nice streetable emission friendly package, without a lot of exotic tuning.
6. And finally I already have the LT4 heads, so why not?
Thanks again for all the responses.

kgkern01

Not to hijack this old thread, but you gained 32 rwhp just by upgrading heads on an otherwise bolt on engine with stock cam? How was the torque? Happen to have the dyno graph, I would love to see what the curves look like. I may have a head gasket going out, and figured might as well get the heads ported while they're off, and was curious as to potential gain on LT1 with roller rockers, since the stock Lt4 cam is almost the same as LT1 but with 1.6 rockers.

Denny McLain

e-mail me @ d48mclain@tx.rr.com, I'll scan the dyno sheet and e-mail it to you. The torque under 4500 rpm had a minimal effect with most of the gains were over 4500 both in hp and torque. Just pulled an old dyno sheet where the car made 337.3rwhp/351.7rwt with headers/bolt on mods and 363.5rwhp/363rwt compared to stock. Got so many fricken old dyno sheets it's hard to keep track of them all.

Your best buzz for the buck will be to bump up the cam along with redoing the heads as I went straight to a 396 instead of just doing a cam. If I had bumped up the cam I'm very confident it would have made around 400rwhp or even a little more.

maro z28

375 rwhp.......LT4 conversion, mods in sig.