Compression, Not your average Engine |
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Compression, Not your average Engine |
Mblizzard |
Oct 16 2018, 06:44 AM
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#1
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Advanced Member Group: Members Posts: 3,033 Joined: 28-January 13 From: Knoxville Tn Member No.: 15,438 Region Association: South East States |
Ok so as many know, I an building my dream engine. With lots of Type 4 Store goodies including Nickies, 78 mm crank, and 102mm P/Cs, LE-200 heads and a decent cam, I am looking at where I want my compression to be.
With a normal engine and quality components it seems that 8.5 to 9.5 is about the limit before heat and detonation become issues. Don't have any measurements yet but playing around with some calculations and assuming a low deck height because I have a slight dish and or valve pockets in the pistons I could easily get to over 11 to 1. But I am think that might not be a long lasting engine. Looking at going for 10 to 10.5. Thoughts? (IMG:style_emoticons/default/blowup.gif) |
Dave_Darling |
Oct 16 2018, 03:20 PM
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#2
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914 Idiot Group: Members Posts: 14,991 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
Remember that the cam makes a difference to how much compression the engine can tolerate. More aggressive cam grinds generally allow you to (and require you to!) run more compression, in part because of the overlap where both intake and exhaust valves are open at the same time.
Things like bore size also play a significant role. (I think that has to do with the propagation speed of the combustion flame front, but I'm on very shaky ground with that memory!!!) Lots of variables, is what I'm trying to say. --DD |
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