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Discussion Starter #1
OK, here is the plan-

A set of KB forged aluminum pistons (+.030). +.150 dome that will yield 11.4 compression when used with a set of 62CC Dart heads, 11.7:1 compression when used with a set of Edelbrock 60cc heads, or 12.1:1 compression when used with a set of AFR 58cc heads.

I am going to go with the DART Pro 1 CNC heads

[ May 16, 2005, 01:02 PM: Message edited by: 2FAST4U ]
 

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That compression ratio seems a little high unless you plan on running race gas. You could have problems with detonation I think.

KB makes a nice piston though and it sounds like a good choice of head manufactures.

Good Luck
Dan
 

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Are you ordering all your parts at one time? It seems prudent to order the heads, pistons, rings, valves (if separate), springs, cam, lifters, rockers, and other parts that interact all at the same time so you know that they are all compatible. Ordering from the same vendor might also be a good idea so you have someone to talk to about recommending matching components and also somebody to complain to if something isn't right.

I also agree your CR seems a bit high. You'll probably have to run race gas or expensive additives and detonation will be a constant question unless the engine is put together VERY carefully. You should be able to make plenty of horsepower at 9.5-10/1 compression with the right components matched up.
 

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If it were my engine, and intended for street duty, either use the .150 dome pistons and have the Dart heads opended up to achieve a 63 or 64 cc volume. I wouldn't want to go over 10.5 max on the compression, unless you are planning on using a long duration cam that will bleed some of the compression off. A better plan would be to use a higher volume head, or a slightly shorter dome piston. Our gas is pretty bad lately, and I don't think it is going to get any better.
 

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I have had 10.5:1 pounded into my head by a couple different engine builders as the max you would want to go unless you plan on running the more expensive fuels. Premium is just barely "good enough" at this ratio.
 

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Discussion Starter #6
I have contacted KB (United Engine and Machine) and have asked them if they can machine down the current -6.803cc dome to -2cc. That will yield a static compression of 11.0:1 and a dynamic compression of 9.2:1. That should be livable on 91 octane in a light car like the GT40.

And I know, 11:1 is pushing it.
 

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Originally posted by 2FAST4U:
I have contacted KB (United Engine and Machine) and have asked them if they can machine down the current -6.803cc dome to -2cc. That will yield a static compression of 11.0:1 and a dynamic compression of 9.2:1. That should be livable on 91 octane in a light car like the GT40.

And I know, 11:1 is pushing it.
Hmmmmmmmmmmmmmm 2Fast, you have definately peaked my curiosity on this issue. I would really like to hear some argument, err...uhhh...err I mean discussion, on this static vs dynamic issue. This is new to me.
 

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Discussion Starter #8
Dynamic compression takes into account the rod length and the cam timing. Essentially, it's the actual compression the engine will experience.
 

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Bill,
You should be OK. At worst you may need to add some octane booster (like 104) if you do experience detonation.
Just my thoughts,
Joe
 

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2Fast, It sounds like your trying to outdo yourself. :D I think after looking at your picks of your other car that is not going to be easy!

Dan
 

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Discussion Starter #11
Actually Dan, I'm trying to be very careful and not go too high. I could easily go with some very trick Edelbrock/Glidden 18º heads, 13:1 compression and a solid roller that will buzz to 8500 RPM, plus an aluminum block with a dry sump oiling.
 
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