ls2 402 piston
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Teching In
Joined: Apr 2007
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From: South Florida
ls2 402 piston I am getting read to order my bottom end and I just need help deciding on pistons. It will have a comp star crank and rod combo. Stock 243 heads stage 1 from frankenstein. The car will be a daily and may see the track here and there with a little spray maybe.
Would the flat tops be the best? I was looking a diamond -2cc flat tops or -10cc dish.
Would the flat tops be the best? I was looking a diamond -2cc flat tops or -10cc dish.
Would the flat tops be the best? I was looking a diamond -2cc flat tops or -10cc dish.
It is not that simple!
In a 402 with a 64cc chamber, a 2cc flat top could end up with 11.9:1. That's REALLY pushing it with pump gasoline. If I ran flat tops in my 440 with 59cc chambers, I would need race fuel or ethanol with 13.5:1 compression.
OP, use a online calculator to figure out what compression you will end up with for you combination. I like to use This one.
In a 402 with a 64cc chamber, a 2cc flat top could end up with 11.9:1. That's REALLY pushing it with pump gasoline. If I ran flat tops in my 440 with 59cc chambers, I would need race fuel or ethanol with 13.5:1 compression.
OP, use a online calculator to figure out what compression you will end up with for you combination. I like to use This one.
Thread Starter
Teching In
Joined: Apr 2007
Posts: 28
Likes: 0
From: South Florida
It is not that simple!
In a 402 with a 64cc chamber, a 2cc flat top could end up with 11.9:1. That's REALLY pushing it with pump gasoline. If I ran flat tops in my 440 with 59cc chambers, I would need race fuel or ethanol with 13.5:1 compression.
OP, use a online calculator to figure out what compression you will end up with for you combination. I like to use This one.
In a 402 with a 64cc chamber, a 2cc flat top could end up with 11.9:1. That's REALLY pushing it with pump gasoline. If I ran flat tops in my 440 with 59cc chambers, I would need race fuel or ethanol with 13.5:1 compression.
OP, use a online calculator to figure out what compression you will end up with for you combination. I like to use This one.
Please excuse my ignorance first motor build trying to get it all worked out right
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Approx. 11:1 compression is plenty safe for 91 or 93 octane. A 4" stroke 402ci LS2 with 64cc combustion chambers will need a 8cc to 10cc dished piston to keep compression close to 11.0-11.2:1 using a 0.040 thick head gasket.
Last edited by R6cowboy; May 2, 2016 at 12:48 PM.
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Verdad Gallardo There are guys that will tell you you can go higher, and you can, but it's usually not worth the trouble. When you get close to 12:1, the potential gains from the increased compression are often negated by how much ignition timing you have to take out of it to keep it from detonating.
Thread Starter
Teching In
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From: South Florida
What would the bore size for the gasket be?
4.040?
4.02?
4.03?
Thread Starter
Teching In
Joined: Apr 2007
Posts: 28
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From: South Florida
Yeah, 11:1 to 11.5:1 is pretty safe. If you plan on doing some long runs, like at a Mile event or similar top speed type racing, I would suggest closer to 11:1.
There are guys that will tell you you can go higher, and you can, but it's usually not worth the trouble. When you get close to 12:1, the potential gains from the increased compression are often negated by how much ignition timing you have to take out of it to keep it from detonating.
There are guys that will tell you you can go higher, and you can, but it's usually not worth the trouble. When you get close to 12:1, the potential gains from the increased compression are often negated by how much ignition timing you have to take out of it to keep it from detonating.
Thread Starter
Teching In
Joined: Apr 2007
Posts: 28
Likes: 0
From: South Florida