QSPres

iTrader: (15)

I was just reading the new HPP this month (April 07') and there is a feature on a 00' TA that has a 6L transplant. It has 10.5:1 compression, a LS6 intake, a cam (244/248 at .050 and .612/.615 lift) and a valve job and makes 450 hp at the rear wheels. Its street driven and has A/C, etc. Built by RPM.


I have a simliar motor (LQ9) and a 78mm FAST intake. Its all going into a 71' GTO. What would I need to make close to 500 RWHP and still have the engine streetable? My car will have A/C and all that as well. The motor right now is stock.


I was told by a local guy that's trying to break into the LS1 market with ported heads that there's no way to do it without huge heads and big compression, but I'm fairly sure he's full of it based on what I've been reading here.

ArrestMeRed99Z28

iTrader: (1)

Definately doable with a big cam and really good heads (Trick Flow) but I don't think that big cam would be much fun in a huge heavy old car like a 71 GTO, and you'd need a ported 90MM Fast, and an Electric Water Pump and an awesome tune. Is this gonna be a race car like the '70 in your sig or is this a street car?
AJ

QSPres

iTrader: (15)

Street car. But it will have a fiberglass hood, front and rear bumpers, and rear decklid. It won't be any heavier than the typical F-bodies.



Why is the 450hp car so mild? Does the extra 50hp really dictate all that?

ArrestMeRed99Z28

iTrader: (1)

244/248 is not mild. But the higher the power level the harder it is to acheive. I think it can be done with good heads meant for your 4 inch bore. You should take a look at the thread about the Vengence racing stock bottom end LS1 build up. they hit 521/46x with less cubes and a smaller bore. However the price of parts was $8500. For $5000 less you can have 450hp.

QSPres

iTrader: (15)

I believe with the right head work on my stock heads and cam I can get there. There's no way I can't get 50 hp on a port job and that better intake.


Thanks.

Ragtop 99

iTrader: (7)

a little higher compression like 11:1 would help too

QSPres

iTrader: (15)

That I can do. Will half a point make that much difference?

justin b

iTrader: (3)

6.0 is the right way to make power,more inches=more power ,i got one and love it

Ragtop 99

iTrader: (7)

Extra compression will add HP. The amount of actual gain will be in part determined by how it influences your cam selection. The extra CR also contributes to allowing a radial cam to be more streetable by boosting low end torque and helping with idle quality.

11:1 to 11.5:1 is a pretty common target for high performance street motors.

justin b

iTrader: (3)

11.5 is tricky on 93 sometimes,espically if your fuel injected

justin b

iTrader: (3)

i like 10.5 ,its easy to please but the motor is not slouchy,it also make tunning my nos easier

QSPres

iTrader: (15)

I honestly figured I'd leave the compression ratio mostly alone. With A/C and all the other power options, detonation will come fairly easy. Alot of that will have to do with the cam and the corresponding cylinder pressure it helps create too.



I was just wondering if anyone on the forums had achieved that HP level with a 6L motor. From the magazine article, RPM claims they've built alot of those 450hp combinations....

Chicago Crew UnderBoss

iTrader: (1)

There have been a lot of guys right around or at the 500rwhp range on a 408 iron stroker and it takes great heads, Trick Flows (are the best performer right now) or even AFR 225s, a ported fast 90, matched ported throttle body, properly selected fairly aggressive street/strip cam, bigger 1 7/8 headers (1 3/4 is not going to cut it), no cats, elec. water pump, underdrive pulley, 11 to 1 compression, and a DARN GOOD tune on a dyno who knows his **** in the LSx tuning world etc., etc.

Call LME and BRIAN usually answers and is is always willing to help out to get you where you want to go. As someone mentinoned, the perfect combo in a 346 N/A motor with VENGENANCE RACING just made 525rwhp and 479rwtq, and they have been duplicating this package now for a couple of months getting over 500rwhp with TRICK FLOW HEADS and a 240/244 camshaft.

So as long as you follow the winning forumla for sucess and just don't pick your parts here and there without port matching, etc., etc., and PERFECT cam selection for your heads and cubes, then the extra 62 cubes of a 408 vs. 346, should be a no brainer to make 500rwhp these days (but it won't be a budget build)!

QSPres

iTrader: (15)

It would be so much easier, and you would make yourself look much more intelligent, if you read the entire thread before posting.........


6L is 346ci now?



I REFUSE to believe that one can make 450rwhp with a stock 6L (cam, valve job, and LS6 intake) but it takes a stroker package, aftermarket heads, and increased compressio ratio to make 50 more hp at the rear wheels.



If that's the case, I'll call RPM and follow their formula. In fact, I'm sure with some head porting, the cam can be less radical. I'm not about to spend $6000 for 50 more hp....

Ragtop 99

iTrader: (7)

trickier, but doable. Depends on the cam and how much it bleeds off at lower rpms. I like the idea of being around 11.1 to 11.3 for a NA motor on the street. I can see that with nos that not pushing the CR is a safer bet.

DONAIMIAN

iTrader: (18)

Not by any means depending on where you live. In Texas, its done all day. If 93 is available I would deff go above 11.0