Small CC comp. ratio question on 427
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From: Atlanta
Small CC comp. ratio question on 427 Let's say you have a 30cc CC C5R head that is designed to be ported and polished and you just don't do it. You take no material out of the CC. How much would the dish (CCs) have to be in the piston to get the comp. ratio suitable for forced induction? 427, LS7, C5R, or whatever. Normal head gasket. More than 20ccs?
You may wanna go lower than that for boost, like under 10:1, it all depends.
You should be able to find the formula for calculating the Compression Ratio on your own pretty easily, just google. Need to know several other variable, like head gasket dimensions, etc.
You should be able to find the formula for calculating the Compression Ratio on your own pretty easily, just google. Need to know several other variable, like head gasket dimensions, etc.
11.5:1 on pump gas and no meth would be very difficult. i am building a boosted 347 and i am going with 8.5:1 CR, because i plan on running big boost on pump gas. i suggest you do not go over 9.5:1 if you are planning on using pump gas on an FI motor.
good luck
good luck
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You will have problems with detonation on an un-ported C5R head. The combustion chamber is rough cast and meant to be finished. That will make for horrible flame propogation and hot spots.
Shane
Shane
Most builders don't "overlook" porting castings such as the C5R heads . These heads are cast with the intention of a builder working the heads for the desired engine . That would be like not working a set of DRCE 3 heads .
It will run. Just not well. As stated above, those heads are designed to be worked. The combustion chambers are NOT remotely ready for an FI build. It would be worthwhile to take the heads and have them finished if you are planning on spending money on a FI system.
Just my $.02...
Shane
Just my $.02...
Shane
PM me. I can either get the heads done for you or put you in contact with our porter to have them finished. It won't be cheap but in my experience, Craig Gallant can make the heads perform to whatever level you require.
Thanks,
Shane
Thanks,
Shane
Thread Starter
TECH Fanatic
Joined: Dec 2001
Posts: 1,451
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From: Atlanta
Did I post these pictures? I'll have to figure out how to resize them.
Crap, it may be too small to see the details! This CC is as it came out of the box!
Crap, it may be too small to see the details! This CC is as it came out of the box!
Last edited by grb; May 22, 2009 at 09:30 PM. Reason: ADD PIC
