I'm starting buy parts to build a LSX to put into my 07 coupe. I found a site that sell ls7 heads for just under $2300. I want to build a lsx with 500ci and the final goal is greater than 600 rwhp. So my question is A) can the heads support this in completely stock form, B) is this any less expensive then buying a set of aftermarket heads.

 

your kidding right

 

With 500 cubic inches to feed the stock LS7 heads would probably be challenged only a little at 600 flywheel HP (i.e., 20% more than a LS7). This strikes me as do-able with stock LS7 heads because you will have 17% more displacement: a big cam, headers, and you're there.
600 RWHP (670 or so flywheel HP) would be a push.

But I'd advise having the heads worked over to open them up a bit. The cost in minimal for what you get.

A big part of the equation will be the intake manifold you select.The big-inch LSX blocks are decked to get the extra cubic inches, so they heads are farther apart. No doubt various folks will make spacer plates so you can use standard LSx and LS7 intake manifolds, but someone will probably come out with manifolds that take advantage of the extra space for improved flow.

 

Not kidding, www.crateenginedepot.com sells the ls7 head for just under $2300. They are also know selling the lsx block. I've heard of guys making 560rwhp with long tubes and a cam on the ls7. Thats why I'm thinking of building the LSX. It's nore expensive than a blower, but the engine will be alot less strained and I wont add 150lb to the front end of my car.

 

" . . . and I wont add 150lb to the front end of my car."

Close to it . . . the LSX is a cast iron block. I'm not sure of the differences from the stock LS engine castings, but a standard cast iron LS6 block (its the standard block for the Silverado --I have one in the Camaro) weighs 90 lbs more than the aluminum version: very same casting just iron instead of aluminum. We used it in the Camaro because the iron is much stronger.
GM advertises that the LSX has a much thicker deck and heavier cylinder walls and webs than standard LS engines, etc., so the LSX probably has significantly more iron (and weight) than that 90-lbs-heavier iron LS block I have in the Camaro. Also, my understanding is that the LSX is a decked block in order to get some of the added displacement - if so that is even more weight.See . . .

http://www.google.com/search?hl=en&q...=Google+Search

Not to change you from your planned course, but the complete Procharger kit I have on my vette now weights about 55-60 lbs including all induction runners, intercooolers, brackets, etc.

 

That's really good info actually. I was under the impresion the whole time that it was an aluminum block. That changes things. I really didn't want to add that much wieght to the car. well i guess I have some figuring out to do. I did have a procharger on my 96 mustang gt. 1psc with the curved billet impeller and the three core intercooler. That kit was way more than 55-60lbs. The blower alone is 30lbs and the intercooler is at least 45lbs. Th kit was awesome as far as power and the sound of the blower and blow-off valve, but honestly I didn't like the quality of the kit. the clamps were ****ty and the piping didn't fit well. I use the car only on the weekend and have done a couple of autocrosses. I really want to do open track days so maybe I will stick to head cam intake.

 

If you go with a Procharger on a 'vette get the A&A Crovettes idler-tension pulley front bracket upgrade for the Procharger P or D1 models, or goe with the F -- more $$ and more capacity but it won't have to work as hard which will pay off if you use it alot.