 Help me determine my compression ratio |
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| Cevan |
 Apr 14 2010, 11:45 AM
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Senior Member  Group: Members Posts: 1,079 Joined: 11-December 06 From: Western Massachusetts Member No.: 7,351  |
So I've started my engine build and have the engine mocked up to measure the deck height. My preliminary measurements are around .030. I've got to do some juggling around of components to get them more equal to each other. Here's what I've got:
head volume: 58.2 CCs bore: 96mm stroke 71mm Based on the cam I'm using here's what I get for different deck heights: .040 static C/R 8.84:1 dynamic C/R 7.76:1 .050 8.63:1 7.57:1 .055 8.53:1 7.48:1 .060 8.43:1 7.4:1 The engine is going in a 914 (obviously) that will be used for spirited street driving. I have 93 octane gas available here. The car will be driven between sealevel and 1000'. I'm using webers with SSI H/Es and a Bursch muffler. |
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| Dave_Darling |
Apr 16 2010, 09:02 AM
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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 
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There is a formula that takes valve opening times into account for dynamic CR. It doesn't take into account chamber shape or any of a zillion other variables, but at least it's a number... (IMG:style_emoticons/default/wink.gif)
The conventional wisdom I've heard is to shoot for .040" clearance between the pistons and the heads. There are people who run less, but they really REALLY know what they're doing... The advice most of them have for the Rest Of Us seems to be .040". --DD |
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Posts in this topic
Cevan Help me determine my compression ratio Apr 14 2010, 11:45 AM
Cevan So after refining and practicing my deck height me... Apr 15 2010, 08:52 AM Racer Chris Stock rods, 6000 rpm max?
I'd do it. Apr 15 2010, 09:53 AM ME733 .............034ths inch is way too CLOSE as a dec... Apr 16 2010, 08:37 AM
Cevan
.............034ths inch is way too CLOSE as a de... Apr 16 2010, 10:07 AM Cevan
There is a formula that takes valve opening times... Apr 16 2010, 10:15 AM ME733
There is a formula that takes valve opening time... Apr 16 2010, 03:31 PM |
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