Compression Ratio, Too High...Too Low ??? |
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Compression Ratio, Too High...Too Low ??? |
2-OH! |
Sep 6 2007, 05:44 PM
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#1
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Senior Member Group: Members Posts: 552 Joined: 17-October 03 From: Santa Clarita, Kalifornication Member No.: 1,253 |
Ok folks,
We just finished rebuilding the motor...94mm pistons and cylinders to match...71mm stroke...but old 1.7 case...CC'd the heads and come up with 44 cc's per cylinder... Do the calculations and we come out with 1971 cc's...Great !!! But, The problem is the compression ratio is now 10.64 to 1... The question of the day: Should I take the cylinders and heads back off and shim them to get a little relief...Probably not going to get much...Might knock it down to 10 or 9.75 (if I'm lucky)... DO NOT want this thing to clatter and diesel on me when I get it back together... OK, let me have it...What are your thoughts ??? 2-OH! |
Jake Raby |
Sep 12 2007, 12:05 AM
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#2
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Try it.. It tried it for almost 3 years off an on with nothing but ill results. The stock FI doesn't like more than 8.3:1 CR with a cam similar to my 9550 or 8:1 with the stock cam. Adding fuel pressure generally does very little except heat up the fuel and add to the possibility of pre-ignition.
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Heeltoe914 |
Sep 12 2007, 04:27 PM
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#3
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Senior Member Group: Members Posts: 1,135 Joined: 31-January 06 From: Tujunga Calif, Member No.: 5,506 |
Try it.. It tried it for almost 3 years off an on with nothing but ill results. The stock FI doesn't like more than 8.3:1 CR with a cam similar to my 9550 or 8:1 with the stock cam. Adding fuel pressure generally does very little except heat up the fuel and add to the possibility of pre-ignition. I am sure you have more knowledge than most on this and we will take every bit of info you provide to heart. But since the eng, in the beginning of its life ran well except for noise from the piston hitting the valve maybe and oil getting past the rings, Bad flycut on heads, I feel the injection mite work??????. The motor had some really hard runs on it like a 6-8 hr drive up and back to WCC 07 in high heat over 100 degrees, it never really had any heating problem. It also had a few good canyon drives that it pulled well on so it most not be to fare from working especially since the CR will be lowered to stock, one way or another. Please correct me if I am incorrect on this thinking. |
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