evo462

iTrader: (27)

I recently installed PRC 225 heads and an MS3 cam into my 2003 Z06. I decided I want more power so I'm going to supercharge it. I know the MS3 cam is not ideal for boost so I'll most likely be pulling it out when I pin the crank for the blower, since it's only a little bit more work.

I wasn't sure what to do about the heads though. I believe I have the 62cc version, so I imagine the compression ratio is slightly higher than the 243 LS6 heads that came on the car. I plan to run methanol injection, but I wasn't sure if these heads are going to make life difficult.

Link to heads

I do not plan to change out the short block at this time so I will be limited as far as how much power I can make (650RWHP-ish is what I'd be shooting for) so I probably wouldn't need to run very high boost anyway to hit that.

Just wondering what everyone's thoughts were on these heads. Plan "B" will be to install a set of 317 casting heads and drop the compression some, but the PRC heads are nice and they have a thick head deck, compression issues aside. If I didn't "have" to swap the heads I probably wouldn't just so I didn't have to do all the labor associated with that. They've only been on the car a few hundred miles.

Thanks!

A.R. Shale Targa

iTrader: (2)

You could just convert it to E85 and keep the boost at a safe 10-12 lbs and then you wouldn't need to change the heads.

evo462

iTrader: (27)

Yeah I did e85 on my turbo camaro and want to stick with 93 octane this time so I am not constrained by e85 availability.

evo462

iTrader: (27)

I've never run a methanol setup but was hoping that could take the place of e85.

evo462

iTrader: (27)

So just doing some static compression calculations, assuming my numbers are correct, I am looking at a touch over 10.8:1 CR.

I really would prefer to not run e85 so it's either going to be meth injection or head swap. Not looking to set a horsepower record either, somewhere around the 650 RWHP mark. But at the same time I guess a head swap wouldn't be THAT much more work in the grand scheme of things. Would likely be 317's.

I have not decided what to do about the cam.

Ping King

iTrader: (20)

I would just run the cam as is. Just go for it. You may want to consider meth injection though, but i think if you set a reasonable limit on boost you should be able to have a tune that works.

evo462

iTrader: (27)

I still have to remove the crank pulley bolt and the Corvette steering rack to pin the crank so really it'd only be a few more hours of work to swap the cam out.

If I can make these heads work within the horsepower range the stock short block will tolerate, and swapping out the can would help that, I would be all about it.

If I have to change out the heads then so be it but in would prefer not to if reasonable.

A.R. Shale Targa

iTrader: (2)

No doubt the 317s and some .060" cometics would drop ya to 9.6-9.7 ish
range but those PRC 225s are such a nice piece...it'd suck to have them just
sittin' around or have to sell them. Now that I think about it; used to be a
fella on here (nitroused383) who documented a 35 hour fancy valvejob on un
ported 243s, milled .010", with .040 cometics,roughly 11-1comp,224cam. I
remember this because his F-body made 444rwhp SAE w/open cutout. IIRC
the car ran mid to low elevens and then he stuck a single turbo on it and now
runs 10.50s on low boost. Perhaps you could contact/search and see how he
did it and if it has lasted....haven't seen much of him in about a year.

evo462

iTrader: (27)

They are definitely nice heads but don't want to leave them on and sacrifice the short block. Considering I made 450rwhp I don't think it'd take much boost to hit my 625-650rwhp goal either.

A.R. Shale Targa

iTrader: (2)

For sure 7-8 pounds of boost would get it done...problem with boost is just
like nitrous...you have a volume **** (pill size/wastegate spring) and the
pipes out back are your favorite song..sooner or later your gonna wanna rock
out and turn that **** up !!!!!!

evo462

iTrader: (27)

I had a turbo Camaro before this, I can control myself (if for no other reason than I don't want to do an engine swap right now)

JakeFusion

iTrader: (7)

You have similar compression to an LS2 (which is 10.9:1). Corvette owners run superchargers and turbos in the 7-8lbs range without a problem on the LS2 and push 10-11 with the stock motor and that sort of compression. You'll just make more power and have more responsiveness vs a 9.5:1 motor with the same boost. Really, a 9.5:1 motor is useful for higher boost.

One thing that will help is the MS3. It will help with the compression as the valve events will lower your cranking compression a good bit vs a stock LS2.

evo462

iTrader: (27)

Yeah that's a good point about the LS2 being 10.9:1 CR.

I really don't think I am going to keep the MS3 in for a blower though...I realize it'd bleed off some boost and maybe offset the compression but I would prefer to have something a little less extreme and custom spec'd to my setup for boost.

I'll throw some methanol on top of 93 octane and not worry too much.

Thanks!