Compression options on LS2 build

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Jun 27, 2014 | 10:46 AM

turboost

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Compression options on LS2 build

I'm finishing up a stock bottom end rebuild on an LS2. I have a pair of used TEA 243s that I had CC'd and came to 68cc. These heads matched up with stock gaskets come to ~10.5 CR. This will be a DD on 91 octane but I want to maximize its efficiency/torque. How much more compression can I go for, if any, and what would be the best way to go about it? This will be paired with an EPS 226/230 cam and the piston at TDC is above the deck .010.

Jun 27, 2014 | 12:02 PM

redtan

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Well definitely get back to at least the stock compression ratio if not slightly more.

No reason to go below that and even lower SCR due to the cam.

Shoot for 11.2-11.3 and get some thinner headgaskets for better quench.

Jun 27, 2014 | 04:10 PM

yonerhottlt1

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I thought 243 heads were 64cc stock which would produce 10.9:1 compression on a stock LS2. Does TEA open up the combustion chamber that much?!

Jun 28, 2014 | 12:09 AM

turboost

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Appearently so. Their website says 67cc, my builder measured 68cc. What is a comfortable compression to be at with this cam and 91 octane? And is milling the head a better route than thinner head gaskets? Are the thinner head gaskets reliable? Would I be better off with a head that flows a little less but has a smaller CC?

Jun 28, 2014 | 06:18 AM

redtan

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Mill a bit and use thinner headgaskets. The thinner headgaskets have more benefits than just lowering compression. Like I said before, shoot for low 11s with that cam.

Jun 28, 2014 | 04:15 PM

turboost

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Any problems with installing cometic .040 gaskets? Are they the only ones who make a thinner gasket?

Jun 28, 2014 | 07:15 PM

RezinTexas

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Measure your piston-to-deck height and shoot for 0.035-0.040" quench. That will tell you what head gasket to use

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Jun 30, 2014 | 03:12 AM

turboost

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I have some PRC 5.3s that I could use but I like the idea of the extra flow of the TEA 243s. Would the extra compression from the 5.3s be more beneficial than the flow of the TEAs?

Jun 30, 2014 | 05:48 AM

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redtan

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From: Belmont, MA

Quote:

Would the extra compression from the 5.3s be more beneficial than the flow of the TEAs?

No because you can get that compression from the TEAs also, just need to mill em' down.

Jun 30, 2014 | 09:54 AM

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KCS

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Quote:

Originally Posted by redtan

No because you can get that compression from the TEAs also, just need to mill em' down.

At 68cc, that's going to be a lot of milling, which will eat into PTV clearances and run the risk of causing a port mismatch with the manifold.

It's not like you can't mill the 5.3L heads either.

IMO, the compression will do more good for overall power.

Jun 30, 2014 | 03:20 PM

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turboost

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According to the calculations if I can get the heads to 64cc I'll have 11:1. Would this be a enough compression? How much milling would it take to get 4 cc off?