57CC Head To 75CC Head Advice
Thread Starter
Launching!
Joined: Jul 2003
Posts: 258
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From: Rancho Cucamonga, CA
57CC Head To 75CC Head Advice Since I have the motor apart, I'm considering upgrading my fully ported AFR 195CC LT4 heads to fully ported AFR 210CC LT4's. My current setup was all built around the heads having 57CC (Builder wrote "TME," whatever that means) chambers, but I have the opportunity to get a good deal on some prepped 210's. However, they have 75CC chambers. How would this affect the rest of the setup? What would I have to do to compensate? I don't know how much it's possible to mill these heads down. Also, my current setup had .036" cometic head gaskets with JE -22 CC dished pistons and 9.08:1 CR. I'll have enough fuel and I'll be doing Torque Head for the PCM conversion.
More specs: It's a 357. With 20lbs of boost (was built around making around 15lbs of boost) with a 76mm PT76GTSH and with the fuel system upgrades I'm hoping to be in the 800-900RWHP through an automatic. Cam grind is a hydraulic roller 290/290-14NR(232/232 @ .050, .544" lift with 1.6RR's).
Do I even have enough engine where I'd see gains? My heads have 2.02 intake valves with the 210's have 2.08 valves.
More specs: It's a 357. With 20lbs of boost (was built around making around 15lbs of boost) with a 76mm PT76GTSH and with the fuel system upgrades I'm hoping to be in the 800-900RWHP through an automatic. Cam grind is a hydraulic roller 290/290-14NR(232/232 @ .050, .544" lift with 1.6RR's).
Do I even have enough engine where I'd see gains? My heads have 2.02 intake valves with the 210's have 2.08 valves.
TECH Enthusiast
Joined: Dec 2017
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With rough math you would end up around 7.5 to compression. There aint **** going to make that better gasket wise and i doubt it would be safe to cut the heads that far. On an ls you have to cut .007 per cc so you would have to cut .126 off the heads or a little over 1/8 of an inch. Id stick with your current heads and just turn the boost up if you want extra power.
Just so im clear you would see no gains. You would lose power and it would be miserable to drive out of boost. Im not teying to sound like a dick just dont want you to make a mistake here.
Just so im clear you would see no gains. You would lose power and it would be miserable to drive out of boost. Im not teying to sound like a dick just dont want you to make a mistake here.
Last edited by jordoza; Jan 8, 2020 at 10:35 PM.
Thread Starter
Launching!
Joined: Jul 2003
Posts: 258
Likes: 0
From: Rancho Cucamonga, CA
With rough math you would end up around 7.5 to compression. There aint **** going to make that better gasket wise and i doubt it would be safe to cut the heads that far. On an ls you have to cut .007 per cc so you would have to cut .126 off the heads or a little over 1/8 of an inch. Id stick with your current heads and just turn the boost up if you want extra power.
Just so im clear you would see no gains. You would lose power and it would be miserable to drive out of boost. Im not teying to sound like a dick just dont want you to make a mistake here.
Just so im clear you would see no gains. You would lose power and it would be miserable to drive out of boost. Im not teying to sound like a dick just dont want you to make a mistake here.
Lloyd Elliot said he can cram in a 2.05 valve in my current head for a couple hundred bucks. Maybe I'll just do that instead...
Thread Starter
Launching!
Joined: Jul 2003
Posts: 258
Likes: 0
From: Rancho Cucamonga, CA
Haha! Unfortunately, I already have the pistons and they've been coated, so no ability to do that. But hey, I guess on a future build I'll keep that logic in mind! I do see what you mean on the shrouding. I can see the difference.
I don't think you have enough turbo with those cubes for 900whp through a stalled auto. 57cc to 75cc is a HUGE difference. Better off leaving the heads alone and getting a larger turbo.
Thread Starter
Launching!
Joined: Jul 2003
Posts: 258
Likes: 0
From: Rancho Cucamonga, CA
I guess I'll have to try and work some magic to see how much I can squeeze out of this mouse. 😁
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