Zigroid

http://www.ls1tech.com/forums/showthread.php?t=568797

^^^ mimic that setup.
433rwhp & 409rwtq through a stalled automatic. probably be around 450 rwhp through a 6 speed. thats through an LS6 intake too. with a fast 90/90 setup it'd probably make another 10-15 rwhp. thats another $1000+ though!

PRC cnc ported LS6 heads w/ PRC dual valve spring upgrade and competition valve job - $1250
TSP Torquer V.3 231/234 .643"/.598" 111 LSA - $390
TSP chromemoly pushrods - $110
Cometic .040" thick head gaskets - $150

total: $1900 + shipping.

AL SS590 M6

A LOT of us speed freaks like to wrench and often decide to try a different combo or step up our game. I'm even thinking of trying a bigger set of heads and a 90/90. Does that mean that there's something wrong with my smaller heads and 78/ported tb combo? Check my sig and get back to me on that.

Kraest

Do it once and never do it again.

AFR 225cc and a nice 23x/23x cam.

I made 471 rwhp with the Dart 225cc and a 236/239 cam, but the car smoked because of the stupid heads. Dart 225cc if you want to change the valve seals and a Futral Motorsports F-14 would be my choice.

Mike

Trevor98ramair

You really have to choose which direction you're looking to go. You could set the car up for boost down the road, but you're going to sacrifice some power N/A. Our Precision Race Components cylinder heads are some of the best on the market. Besides AFR, we are the only other cylinder head company to use a full CNC valve job machine! This ensures incredible consistency with every set. Beware of advertised flow numbers. The Trick Flow heads/TEA heads always advertise higher flow numbers, particularly on the exhaust. We flow-tested a set of their 5.3L cylinder heads that a customer sent us to flow for him, and they were reported to flow 315 and 255 on the intake and exhaust, respectively. The heads flowed 298 and 201 on our bench. Their exhaust numbers in particular are always super inflated. We do not use a pipe to flow our exhaust on our SuperFlow 600 bench, which would normally add 15 cfm or so to the numbers. How they end up 50+ cfm high I don't know. The AFR 205cc heads will flow 293 cfm @ .600" lift on the intake on our bench, but it starts backing up really quick (by .625" lift). AFR's certainly aren't a bad head, but the thicker deck is the only real benefit vs. a ported LS6 or 5.3L head. In comparison, our stage 1.0 LS6 cylinder heads using the stock 2.00"/1.55" valves with our competition valve job will flow 306 cfm @ .600" lift. Our new 5.3L port that will be ready to ship in the next 10-14 days is flowing 308-310 cfm consistently. They will retail for $1,199 using the 2.04"/1.575" stainless steel valves and PRC dual spring kit w/ titanium retainers rated for .660" lift.

As for picking a head to work with boost, it depends on how much boost you're looking to run. I ran 12 psi of boost with my D1SC ProCharger on my '99 C5 and 347 cid. It was a built engine with unported heads, and it would consistently make 630 RWHP. I ran 8.5 psi of boost on my 402 cid LS2 in my '05 Corvette with a D1SC ProCharger, and it would consistently make 660 RWHP. Thicker decks do help to avoid lifting heads, but if you're going to be running a stock bottom-end a thicker deck won't be needed. You're going to be limited to 8-9 psi safely on a stock bottom-end. Build the short-block up with good pistons and rods, and then you can raise it quite a bit! We have run up to 22 psi of boost on our black '05 Corvette with a 404 cid LS2 stroker and twin 67mm turbos. It made right at 1,000 RWHP on a Mustang dyno. It wouldn't make much more than 940 RWHP on our Dynojet 248 because we could not run it under load. We are currently running PRC-ported Darts on our twin turbo C6, but we've run into the smoking issues with those in the past, too. We actually met with Dart last week in regards to the smoking issues that we had with their heads. They are now using different guides and have also switched to a tighter valve seal. We'll see how it works out.

You have to choose which way you want to go before you purchase your heads/cam package. If you want it ideal for boost, we could set you up with a set of ported 6.0L heads. With the 72cc chamber size, it would lower your compression ratio on a stock bottom-end to right at 9.6:1. This wouldn't help power N/A but would give you more room for boost on pump gas. For a supercharged application, you ideally want a traditional split-pattern cam with a wide (i.e. high numerical) LSA. This won't necessarily hurt your N/A power if spec'ed out properly, but it could hurt your dynamic compression ratio some (depending on the other specs).

Feel free to give me a call, shoot me a PM, or e-mail me at trevor@texas-speed.com, and I'll be more than happy to discuss your options with you.

Trevor
Texas Speed & Performance

Zigroid

speak more of these! whats the unmilled chamber volume? can the heads be fit with 2.08"/1.6" valves for use on an LS2?

Trevor98ramair

The CNC work will include full porting of the intake and exhaust runners, but it will only have minor cleanup work on the chambers. So, you'll be looking right at a 63cc chamber size. On a stock bottom-end LS1 with factory thickness head gaskets and assuming that the piston comes out of the block .007", you'll be right at 10.75:1 CR without any milling. On a stock bottom-end LS2, the 63cc chamber and factory thickness head gasket will put you right at 11.23:1 CR. We do make a .003" cleanup pass on the decks before they ship to ensure an even sealing surface. If you were wanting them cut down beyond that, you would need to specify when ordering. The stage 2.5's will be setup with 2.04"/1.575" stainless steel valves using the factory seats. If you are wanting a stage 3 5.3L head setup with 2.08"/1.60" valves with the upgraded seats, it would be an additional $200. So, if you order a set of stage 3 5.3L heads from us, you'll be looking at $1,399 + shipping.

Let me know if you have any other questions or concerns.

Trevor
Texas Speed & Performance