Hey guys! I've been away for many many years but I'm back

My first car 13 years ago was my 1989 Trans Am GTA, drove it for a few years until something in the engine or transmission started vibrating on the highway and exploded to a metal grinding halt, and then put it in storage for 10 years. Well, the car is out of storage now, and I'm ready to build it into the car I always wanted it to be.

I've set my target for the engine to a 600hp aluminium LS build. I'm hoping to get some opinions for the most cost effective way to get a smooth, reliable, and nicely street-able 600rwhp with torque all the way through. Must not need anything higher than 91 octane to run.

I am leaning towards 6.0L - 6.2L VVT motors such as L76, L92 or L94. I really like the idea of keeping VVT even if I have to sacrifice a bit of top end HP for the awesome torque curve. Open to other suggestions though.

I'm interested what you guys think would be some of the most cost effective part combinations, both N/A and forced induction, to achieve the 600hp figure. I won't be looking to go higher than 600 on this particular build so "future proofing" for more HP later isn't necessary.

My initial thoughts were to go with lower compression pistons, new rods / lifters / springs / cam, and then supercharge one of the motors above with ~7PSI.

After adding up all the costs, particularly the ones associated with the supercharger, and given the relatively low HP target, I got wondering if maybe it would be better to go N/A for this build. Could you get 600hp of nicely streetable power out of one of these motors without forced induction?

 

i would say a turbo set up with a very good tune is gonna be the most cost effective way to get there imo now with that said lets break a couple other things down as well first off 600hp is not a mild build with all the street outlaws bs going on rigt now people have got confused on what a lot of power is and 600hp is a lot of power some thank 500 or so is low number not true you have to remember our cars only came out with around 200 or so if your slaming on it from a stop much like drag racing or burn outs your gonna need to beef up your rearend to hold a stock 7.5 wont hold forever with that much power ive ruined them with 350hp motors so 600 will deffenetly do it you also mention you want it to be 600hp to the wheels which means your gonna need more than that at motor due to you loose ruffly 15 to 20 percent of your power threw the drive train. so you really need to build a motor with around 650 to 670 to get 600 at the wheels but basically what im trying to say i guess is there is no cheap way to get 600hp to the wheels thats alot of power not a low hp target at all and will cost some big coin my brother got 308hp out of his 6.0 completly stock with a tune only and that truck was pretty fast for a stock dd so i see nothing wrong with the lq9 or wat ever it is

 

Oh I know it isn't a mild build at all. It's probably going to be a ~$15,000 motor with few stock parts left at the end of the day. And yes, new rear end for sure. 600 to the flywheel is a good goal, I don't need 600 to the wheels...that might be pushing it for my goals and budget. Did I say to the wheels somewhere? I didn't mean to.

My last car was an 06 GTO LS2 with cam, intake, full headers and exhaust and custom tune. Fast car, but not quite as fast as I wanted. Granted, it was quite a bit heavier than the Trans Am is going to be but still. Then I got a ride in my friend's 600hp M3 realized that was my sweet spot for power and streetability lol. When I say smooth and nicely streetable, I just mean that I don't want a cam that will kill all the low end torque on the motor. I don't think it will be a mild build though.

The more I research it, I think turbo or supercharger with low compression pistons is the way to go for a 91 pump gas 600hp build.

As far as I can tell, the stock crank should hold up to that power level - is that correct? I will be getting stronger rods and new valve-train obviously.

I would go with an LQ9 but I want one of the aluminium motors. I want that 80lb off the front end of the car, especially if I'm adding a supercharger. I'm doing everything I can on this car to make it handle better.

 

yes the stock bottom end will hold up to the power you want on a ls the weak part down there is going to be bearings the new ls stuff loves to throw crank bearings so i would take the extra time to but a very very good set in but the stock crank should hold no problem imo

some where in your post you had said 600rwhp so i assumed you ment rear wheel horse power my mistake on that

 

Iron 6.0 block. Bore it to ls3 bore

Find stock take out ls3 rotating assembly.

Do headers cam and ls3 heads/intake top end

It will dyno high 400's to 500 whp depending on the cam and fuel and obviously transmission. Thats a solid dirt cheap 550-600 hp crank


Or iron 6.0, stroker crank to 408-416" depending on bore. Stay with the ls3 take off heads. You can find them for 500-600$. Ls3 intake. I have seen these make 500-530 whp in 6spd car. Cant beat ls3 top ends for the money

 

If you can get an ls3 then start with that

 

> Iron 6.0 block bored to LS3 with LS3 rotating assembly and heads/intake

> Do headers and cam

What you're basically saying is that an LS3 with headers and cam can make 500rwhp? That seems a bit high to me. Maybe with a reaaaally aggressive cam, which will kill the street driveability though, no?

As I said, I'm fairly set on sticking with an aluminium block. If I find a cheaper 6.0 block, i.e. L76, can that be bored out to LS3 bore or is the aluminium block not strong enough?

Will a stroked LS3 setup vs normal stroke setup, all else being equal, make substantially more peak HP or mostly just more lower end torque?

Thanks for your help

 

Most cammed ls3's we see 460-470's whp for medium cams in a manual

Full bolt on ls3 camaros dyno 420's through the 6 spd. Autos dyno good bit less however

Not uncommon to see 50-80 whp gain with cam header and good tune

It will be much easier to get to 500 whp with a stroker 408-416". They will make a few extra hp all things equal but will do it at lower rpm and make a bunch more torque

Still very streetable with proper tuning.

My buddys 416 ls3 made 530 whp in a 6 spd and ran 10.9's all motor driven 5 hrs to the track and back, after 17 passes lol

 

i think cams headers and tune your looking at a solid 400-426hp to the wheels maybe a little more if the tune is good theres alot of shops that claim they tune but are not that good shop around and do research on the tuner tune will make the biggest difference you can throw all the parts in the world at it but with a bad tune it means nothing most ls3 stock make about 425hp or so to the flywheel so about 350 or so hp to the wheels stock so its not crazy at all to think you can get four hundred to to the wheels with a cam headers and tune just watch who dynos your car ive seen people that can fool the dyno no problem making stock cars show numbers like 5 or six hundred hp when there only puting 350 to the wheels in the real world

 

I agree 400 to the wheels would be no problem, but we're talking about getting 500 to the wheels. That extra 100hp is a big jump for an N/A motor haha.

 

yes agree there if your looking for a 600hp motor which would be ruffly around 500 maybe 525 to the wheels its gonna take a more then just cam and headers to put that to the wheels for sure imo

 

but them modes and a cheap nitrous system like the cheater or sniper kit would put you very close to the number your looking for

 

Nitrous would be a nice and cheap way way to get up to my magic number but there are no insurance companies here that will insure a nitrous enabled car. I'm not even allowed to put in a roll cage with any insurance company I talked to. It's considered racing modifications and is not allowed.

But bolt on a supercharger? No problem. Lol. Go figure.

 

dang that sucks here we can have nitrous the bottle just cant be on if you get pulled over

 

Well that's the same thing here, which to the insurance companies means that the only reason you would have it is to race since it isn't street legal, and so nobody will actually insure the car.

 

do your insurance companys inspect your cars or somthing cause the way i see it what they dont know dont hurt them

 

Yes they definitely do. Especially the classic car insurance companies, they do a rather thorough check of everything. That said, they are quite liberal with what they allow. Nitrous, roll cage, and engine mods that bring it to over 700hp are basically the only things they don't allow.

Even if they didn't do an inspection, isn't it a bit pointless to have car insurance if they will tell you to screw off when you get into an accident and see all those unauthorized mods you didn't declare that went against your contract terms isn't it? Haha. I rather have my $30,000 toy covered in the event of an unfortunate accident.

 

My buddy 1fas92 put down 505rwhp with a big cube LS3, cam in the 240 range @.500, through a 6 speed. Those LS3's flow 300+ cfm out of the box.

I had another buddy in a fourth gen, stock LS2 bottom, LS3 top end that put down 469 with a Night Fury cam and all the boltons.

Nitrous on a short block 6.0 would probably be the cheapest way there. More than one way to skin a cat.

 

Do they warranty factory Hellcats? That seems crazy to me