Tranzor

Hey guys,

I'm looking at picking up some Patriot LS6-style stage 2 heads, and I'm debating on whether or not to get the 59cc or 64cc combustion chambers... so I thought I'd bounce it off the Internals section and see what everybody thinks.

Now, I do know the smaller combustion chamber is usually more desirable for the rise in compression. But there are a couple of factors for my decision:

Will it clear with my F13 cam (230/232 .595/.585 112+4 lsa)? The valves will be the standard 2.02/1.57, not upgraded or anything. I know I should always check PtV clearance, and we will... however, I don't want to check the clearance only to find that it'll be way too close for comfort and have to get a new cam.

Second consideration, the highest octane we have up here is 92. So, will the 11:1 compression of the 59cc heads be ok? Or will the 10.6:1 of the 64cc be better?

Last consideration... which one will work better with a dry shot of N2O? I've got a kit waiting to go on, and it'll have jets up to 150 hp. And I don't really know if higher compression is better for nitrous, or lower... I do know that lower is better for superchargers, don't know if it's the same for nitrous.

Thanks for your time, everybody!

Tranzor

After thinking about it more, I'm starting to lean toward the 64cc heads to be safe... anyone have any different thoughts on it?

jrp

iTrader: (16)

the PP ls6 style heads dont remove any material from the deck. the chambers are welded up. n2o likes the higher compression.

Tranzor

Ah ok.. so in that case, 59cc and 64cc would have the same clearance since no material has been taken off. Well then 59cc might be the way to go in that case... thanks JRP!

Only other hesitation is the 92 octane factor... I always use the best available to me (Chevron, Shell, etc), but I keep reading how that compression really likes 93. I don't want to get any detonation because the octane around here sucks.

JakeFusion

iTrader: (7)

The F13 on a 112+4 already raises DCR up pretty well. The DCR is what limits you on a certain compression. With 92, I'd say you'd be good at around 8.2-8.3:1 DCR.

59cc chambers are going to be more like 11.3:1 with a .060" MLS gasket, and with the F13, that puts your DCR up over 8.5:1.

Go with the 64cc chambers and a pair of Cometic .045" gaskets (for a tighter quench to fight off detonation). The thinner gaskets will raise the compression up to about 10.9:1 SCR and give you a DCR around 8.3:1. I'd rather run DCR up near max with a tight quench (.037" assuming the pistons protrude above the block .008") than a lower overall DCR and a much lazier quench. The tighter quench and better DCR will give far better performance and snappier throttle response.

Tranzor

That's another way to look at it, thanks Jake! Decisions decisions... I definitely want to be on the safer side, so with the gas around here, the 64cc and .045 gaskets sound like it might be the ticket.

I just want to make sure I do this thing as best as I can... don't want to have to spend the money twice because I didn't get as much of the facts as possible before purchasing and installing.