Batass

I love my car, but I'm just not too happy with it on the street. The stall is a little higher than I like, the auto is boring, and the power is, I can't believe I'm saying this but, more than I need. At the track its great, but I just don't hit the track as much as I thought I would. Not to mention the gas mileage is horrible, so I rarely take it out.

Its currently a forged 383, 200cc heads, xr288hr cam, and a vortech supercharger, with a 3000 stall ATI converter and built manual th350.

I'm thinking about throwing in either a 5.3 or a 6.0 with a T56. I want good low end grunt and just decent mileage. Maybe a small turbo later. I just dumped a lot of money into this motor/trans so it really sucks.

I could pick up a 6.0 just for the funds I get from the supercharger. My goal is to put me in the seat without having to push the pedal too far.

Here's why I'm posting though, I know the gen III motors aren't low end tq machines. What do you guys think?

five7kid

iTrader: (14)

There's a reason the T56 has two overdrive gears.

The LSx series is a fundamental step up in engine design. Better efficiency means more power for the displacement and fuel used.

It is a completely different animal than a SC'd 383, but wouldn't take long to learn to love it.

Batass

What do you think about the low end tq? Like around 2000 rpms. I might even keep the truck intake on it and run a small cam. Just big enough to keep the rev range under 6000. I would just add a turbo if I needed more top.

I think I could sell this motor, drop in a 6.0, and still have money in my pocket, sans new pistons and rods.

Atilla the Fun

Tonight or tomorrow morning I'll post engine-dyno test results of a stock LQ9's low-rpm torque, below 2000 rpm, then with headers, then with some tuning.

Batass

That would absolutely fantastic, thanks!!!

Atilla the Fun

A pure stock LQ9, with truck exhaust manifolds, cats, y-pipe and muffler, but standard correction instead of SAE, starts at 353.6 ft-lbs at 1600 rpm. By 2000 rpm it's up to361.1, and 2400 is 370.1. Peak torque is 396.3 at 4000, peak HP is 355.2 at 5300, and the test ended with 351.4 hp at 5700. The next test was with Dynatech 1.75" equal-length long-tubes for an '04-'05 GTO, with 3" collectors, into dual 2.5", into Flowmaster Super 40 mufflers, but still stock fuel and spark programming. 1600 rpm saw 360.0 ft-lbs, then 373.6 at 2000, then 385.7 at 2400. Peak was 421.7 at 3900, then HP peaked with 379.2 at 5700. Tuning made no difference until after 2000, with 359.1 at 1600, 372.5 at 2000, and 383.1 at 2400. Peak was440.3 at4400. Then HP was 408.0 at 5300, and 400.1 at 5700. Then they added illegal high-flow cats. 359.6 at 1600, 370.3 at 2000, 380.7 at 2400, 433.2 at 4400, Hp=408.3 at 5400, 401.9 at 5700. Then WASTING $900!!! on the FAST LSX 90mm, and the cats still on, gave 355.3 at 1600, 365.2 at 2000, 377.7 at 2400, 440.1 at 4600, HP=419.8 at 5400 and 414.7 at 5700. Lastly, WASTING $700!!! on Crane 1.8:1 rocker arms, 1600=356.9, 2000=369.2, 2400=381.3, 4700=448.9, HP was 428.9 at 5400 and 427.2 at 5700, all with untouched LQ9 cam and heads.

Batass

Wow, thats golden info. Just with a cam, that would have no problem matching my 383 N/A. It makes about 460-475hp.

Did the fast intake swap out the truck intake or was it an ls1/6? Rockers didn't net as much as I thought they would.

I think that engine would be a blast with a t56. I'm not sure what headers fit in our cars, but I would hope to run some factory ls1/6 manifolds, and just a small cam and tune. I don't see why I couldn't do it for around $2k+trans. Then a small turbo to bump up the power to around 650. Should be cake. I think I could sell everything I have and not have to spend any extra. But I'll be taking a nice hit considering I've spent 3k just on the shortblock. Oh well. I'll probably only get half my money back, but it should cover a lq4/9.

Atilla the Fun

The numbers given were for truck intake in all tests except the last 2, which both used the FAST LSX. for headers, hawksthirdgen sells the ones made by kooks, that's the only choice. for boost, skip the LQ9 with it's 10.2:1 compression and run an LQ4 with 9.4:1. The '02 LS6 cam is worth 40 HP, and works very well with turbocharging.

Batass

Obviously I have some research to do, but no factory headers will fit? I don't want to buy some nice headers, only to have to ditch them when I go turbo later.

Sounds like the truck intake will stay on. I've heard it distibutes air under boost better than the ls1/6 intake also.

Atilla the Fun

The truck intake won't fit under your stock hood. Alot of the guys on ls1tech.com turn the truck exhaust manifolds around and stick the turbo between the crank pulley and the radiator.

Batass

I've got a 4" cowl, do you think the front would be the problem? I'll have to research the possible manifolds, I guess worst case scenario, I'll face them front until I install the turbo.....or maybe I'll do it right away.