HELP

[BIG NASST]

About to get cam ,oil pump,hardened rods, timing chain,etc,are there significant gains to switching heads also?,i was lookin at ts 235 239 or 231 246 ,i see prc ls3 aftermarket heads ,6 bolt, one pair is 255cc the other pair is 260cc. The car has less than 4000 miles, so are the heads on there good enough,or would the addition of these add significant power,or rather what are the benefits?

[07-SRT]

I had my stock heads ported and milled.I gained 25 on tq and through the area under the curve.Peak HP was only 11 but gained 20 under the curve...Had a local tuner adjust after I installed heads but Im heading to Redline in south Florida in 2 weeks for tuning and hope to pick up more hp..I can definitely feel the tq increase at low rpms...Pre heads 479/424 post was 490/449

[christianchevell]

The flow is already great on the stock versus in ported heads, you will not net enough for most as the money spent is better spent elsewhere. And it is a case of performance is increased when making more radical additions such as stroking , at a very high lift long duration cam and such rather like getting a Fast intake and not netting much because its best on larger displacement and the stock is so good MSD even gave up making a airforce intake for the ls3 as they could not gain enough to make it worth people buying. You would go from flowing like 300 cfm to 310 cfm if needed ;both above the level of ported BBC heads.... and proving the difference in other than the stock heads ported being worth the money for the extra cash for custom heads with their design such as trick flow or some PRC, Mast, etc etc can get really expensive compared to the 1400$ for a pair of fully out fitted CNC ported GMPP heads with hollow intake valves and some springs to trash for the cams needed springs.
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Some places you would spend the price for a pair to buy one head for aftermarket and not gain much IMO Its all in what you plan to do with the car and how much you have to spend. And if you can find cheap porting just local not like,( not like your sending it out to improve on a great head already that much..... ), that can match the CNC job the factory does to the heads. Though for a little more that's pretty hard to beat from all I read, though a dealer dickey scoggins does up a factory CNC job for a little more and it does compare well to much more expensive porting jobs or such and beats a lot ....just as a factory CNC job can compared to lots of shops porting...and dickey scoggins does it to new factory cnc ported heads not send yours in ..... Lord knows I would never want to just use my heads as a core and wonder what your getting in return if I were you with only that low of mileage, and if not going FI stock leave the heads alone IMO is the best advice unless your into doing lots of work yourself , at your Mileage your lifters and baskets should be fine for a new cam and no need to pull the heads. Good Luck Most don't mill heads to bump the compression it screws the pooch on PTV clearance and you will have to swap out springs at intervals more like 25k due to the need to keep it together with no float and good closing pressure let alone if you over rev and stress the springs to make them weaker and then they need swapped out like asap if forcing a mechanical downshift and racing the rpms to the moon in a low gear....trans braking can be hard on a engine ....... too tight of a clearance for PTV can be dangerous and limit cam choices in lift, I know the TSP 235/239 clears stock clearance I used to run it. Great choppin hard charger. I had on a stock 13 ls3 with electric power steering and dual mode 491 hp and 448 tq with just CAI , SP long tubes and HFC with the 112 LSA tsp 235 239, on a MUSTANG DYNO.....

[BIG NASST]

What was build before heads to get to 479 424? So the above mentioned cams i might lose some low end hp or driveability,but new heads, or milling and porting the old ones, seems to bring significant hp and tq or driveability back to low end, since alot of the power(25 tq. 20hp) is under curve?

[BIG NASST]

sorry mr chevelle, i was typing i didnt see your answer already there.

[07-SRT]

Originally Posted by BIG NASST

What was build before heads to get to 479 424? So the above mentioned cams i might lose some low end hp or driveability,but new heads, or milling and porting the old ones, seems to bring significant hp and tq or driveability back to low end, since alot of the power(25 tq. 20hp) is under curve?

Before heads was cam, 226/236 629/629 111 lsa. LT headers and cai....25 was peak tq but actually had 30 under the curve....You can mill the heads and if you have a good porter that can cut and sink the valves you will be ok on ptv clearence (depending on cam selection) I only lost.009 on intake and actually gained .002 on exhaust..

[Gunmetal Speedster]

If you have the budget for heads I'd go for it.

[KonigWolf]

I run PRC 260cc heads, had them milled down to a 67cc chamber so when I put in the thinner cometic head gasket it would put me at about 11.1:1. Main reason I bought the PRC heads over going stock ported is they offer a better Piston-To-Valve clearance, so in theory, I wouldn't have to flycut my pistons as much for my VVT SS4 cam. Another reason I choose the 260s is I plan to go boosted When I grow bored with beating up on all the other NA cars. If(when) the boost pops the engine I'll probably pick up a 416 stroker kit, which the heads are already suited for.

Side Note:: My tuner thought that my heads were too big for my setup, he thought that the car would have made more power on a set of ported stock heads. I'm not arguing that and I also think his tune was also a bit conservative.