Pistons
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Posting Guru
Joined: Dec 2002
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From: chicago burbs
are you suggesting to remove the material from a set of stock pistons? i would say they definately don't have the meat in them to do it. if you are thinking of a set of aftermarket pistons, the answer is still prolly not. unless they are designed to be able to be dished, but then they would be un-necessarily heavy. KB pistons has a lot of dish pistons that are catalog listed, not sure if they list for M/400?
Laughing Gas
Joined: Nov 2002
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From: Fairmont
Keith Black and Badger says a minimum of .200" crown thickness and Keith Black says for dish size within .500" of the edge of the piston.
The Badger Hypereutectic pistons have a .500" thick crown. And a 30 over piston measure 4", so the dish diameter could be 3".
The Badger Hypereutectic pistons have a .500" thick crown. And a 30 over piston measure 4", so the dish diameter could be 3".
Posting Legend
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The edge of the dish has a radius, it is not a sharp edge. Check with your machinist.
Remember one other thing, When you calculate compression ratio make sure you have allowed for the buildup of combustion products on the surface of the piston and the head. Deposits will increase the compression and also form hot spots that can cause preignition.
Remember one other thing, When you calculate compression ratio make sure you have allowed for the buildup of combustion products on the surface of the piston and the head. Deposits will increase the compression and also form hot spots that can cause preignition.
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Joined: Aug 2004
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Ok thanks Torque1st.
Is there any ways to prevent deposits in the combustion chambers?
64cc combustion chambers and the 12cc dished pistons should give between 10.5:1 and 11.0:1, what would be the dynamic compression?
Should I shave the deck of the block to zero or less? what is your opinion?
Is there any ways to prevent deposits in the combustion chambers?
64cc combustion chambers and the 12cc dished pistons should give between 10.5:1 and 11.0:1, what would be the dynamic compression?
Should I shave the deck of the block to zero or less? what is your opinion?
Last edited by ReGGaTarT; Sep 17, 2004 at 08:09 AM.
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Posting Legend
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You will need to post your engine specs and what you are trying to do with the engine along with what it is going in. In other words ALL of the vehicle specs etc. Your cam will determine your dynamic compression. You will need a big one with that much static compression unless you are running race gas or propane etc.
Engine deposits will build up unless you take the engine apart to clean it monthly...
Engine deposits will build up unless you take the engine apart to clean it monthly...
Postmaster
Joined: Aug 2001
Posts: 4,270
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From: Delaware
A +0.030 piston with a 12cc dish and 3cc valve relief and a 64cc head will give 10.5:1 Static Compression Ratio if the piston has Zero Deck Clearance. A cam with an IVC angle of 66 degrees will produce a Dynamic Compression Ratio of 8.3:1. Normally I would say that this was marginal for detonation, but if the pistons are zero deck and the heads are CHI-3V Aluminum closed chamber heads, it will be OK.
I am running those heads with flattop pistons (3cc valve relief and 0.0665 deck clearance). My Static CR is 10.3:1. My DCR is 8.17:1. I have no detonation problems.
Do not shave the deck. Either use flattops like I am or use the Tim Myers pistons with a dish.
I am running those heads with flattop pistons (3cc valve relief and 0.0665 deck clearance). My Static CR is 10.3:1. My DCR is 8.17:1. I have no detonation problems.
Do not shave the deck. Either use flattops like I am or use the Tim Myers pistons with a dish.
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