March 28 prc cylinder heads results

[blake-b]

Originally Posted by Camper

did someone recommend this for your blower setup? seems like someone gave you a bad recommendation based on what little I know. you should have went with a 68-70 CC to keep CR around 8.5-9 and also a stronger valve is ideal . maybe someone can chime in with more knowledge than I.

Yep, I asked the guy who spec'ed my cam what CC to go with and he said 64.5-65cc would raise my compression from 9.2:1 to 9.9something (I cannot remember). I went with the hollow valves because IF I decide to change cams again, I can go with a more aggressive lobe because the lighter weight valves aren't as prone to valve float.

There have been a few threads on here that say a higher compression ratio (~10:1 if I recall) was better for a centrifugal. I even remember reading the same thing on LS1tech. I don't remember the specifics, but the consensus was you can get away with more CR with a centrifugal than with other types of FI.

I am pairing these heads with this cam:
235/260@050, .610"/.575" 115+6 LSA and meth.

The only reason I am changing heads is because of the thicker deck on the PRC's. Oh, and the 6 bolt feature. I won't need another head regardless of what I build in the future. The WCCH's made plenty of power and they and the PRC's have similar flow but the PRCs are thicker decked and that gives me some peace of mind.

[villan2]

What kind of hp you get out of the heads alone just curious?

[blake-b]

Originally Posted by villan2

What kind of hp you get out of the heads alone just curious?

It will depend on your combination. I do not expect any more power from the new heads, I got them for peace of mind and longevity (I hope). I expect the cam to pick up maybe 10-20hp and the meth to pick up quite a bit of hp and a smaller blower pulley to pick up 50+ (from 15psi to 20psi).

As a generality, heads can be worth 25+ but that depends on the supporting mods (cam, intake, etc). Perhaps someone with more knowledge will be along soon. The only way you will know is to get it dynoed (which you did already so you have a baseline for the new mods), swap parts, retune, dyno it again on the same dyno in similar temperature conditions to see what YOU gained.

[Pro Stock John]

Well most veteran LS shops will tell you that 10:1 is okay for a super charger at basic boost levels.

LS engines are the best small block engines ever made by GM, so the rule of thumb that folks would use for older style small block Chevy engines really don't apply. Our heads are amazing when compared to old style castings, and take much less timing to make killer power. They are also aluminum and dissipate heat much better.

So the stronger your engine HP, the less boost you would need to hit to make the same power as an older style small block. A cammed LS3 and blower combo could make over 600rwhp and with older small blocks, well, that's hard to do with out more boost.

I've lived the LS scene since the beginning (I co-founded LS1Tech), but I'm also an example of someone who's made mistakes along the way. I build an 8:1 346 CID back in 2004/2005 that had a blower and then a turbo. I had to make 2 more lbs of boost to make the same power as a 9.5:1 engine, and that engine didn't drive as well down low.

So try keeping the compression in the 9.5:1 - 10.1:1 range and have fun.

[Jason 98 TA]

We can do some extra milling for you no problem if you decide you want to bump the compression before your install. It doesn't take much time at all

[MikeOD]

Originally Posted by Camper

I have my doubts you'll hit 500+ with that cam, especially if you arent upping the CR.

I agree...more lift will help.

Originally Posted by Pro Stock John

Well most veteran LS shops will tell you that 10:1 is okay for a super charger at basic boost levels.

LS engines are the best small block engines ever made by GM, so the rule of thumb that folks would use for older style small block Chevy engines really don't apply. Our heads are amazing when compared to old style castings, and take much less timing to make killer power. They are also aluminum and dissipate heat much better.

So the stronger your engine HP, the less boost you would need to hit to make the same power as an older style small block. A cammed LS3 and blower combo could make over 600rwhp and with older small blocks, well, that's hard to do with out more boost.

I've lived the LS scene since the beginning (I co-founded LS1Tech), but I'm also an example of someone who's made mistakes along the way. I build an 8:1 346 CID back in 2004/2005 that had a blower and then a turbo. I had to make 2 more lbs of boost to make the same power as a 9.5:1 engine, and that engine didn't drive as well down low.

So try keeping the compression in the 9.5:1 - 10.1:1 range and have fun.

I agree again...to be honest, if it's strong enough to take it, and you've got a good intercooler, even up to 10.5:1 will work well...anything lower than 9.5:1 and you'll really start to feel that it's a dog for throttle response (though good tuning can help), and will need more boost to make the same power.

[villan2]

Well texas speed shipped my heads out today i will get them Tuesday ill take some pictures and post them.... I'll keep you updated on results.

[SPCBA]

buying heads that you expect no gain from seems wierd

[villan2]

Weird??? The 250cc and 255cc aren't a big difference from 260cc and plus I am going with a stroker kit..... And I will get hp from them.

[blake-b]

I think he was referring to my post about not expecting gains from them. My current heads have bigger runners but the PRC heads flow the same so I should pick up low end. I did not get them for gains overall. I got them for the thicker deck, smaller chambers, and 6 bolts. When I upgrade to a larger engine in the future that has 6 bolts, I wont need new heads. Plus, selling my old ones offset the cost substantially.

[villan2]

I will post pictures of the cylinder heads today they will arrive today.... Also installing them Mach 18

[villan2]

here is few pictures

[Jason 98 TA]

Don't forget to use the billet rocker pedestals we sent with the heads!!

[villan2]

Thank you guys great service and the heads look great and i will be buying a engine or sending mine to you guys... My local speed shop speed inc in IL uses u guys..... Thanks!