CR Questions
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Originally posted by "Someone"
Originally posted by freak007
one way you can calculate existing compression ratiois to take a compression testand divide the results by 14.7it will be relatively close...
Originally posted by rb77413
How close? On my 383 I have a adv 277^ w/ .477 lift. My compression test was 160-170 That comes out to about 11:1 Is that right? I was trying to figure out the same thing. Trying to figure if I can use a bigger cam.
Bob
Originally posted by freak007
one way you can calculate existing compression ratiois to take a compression testand divide the results by 14.7it will be relatively close...
Originally posted by rb77413
How close? On my 383 I have a adv 277^ w/ .477 lift. My compression test was 160-170 That comes out to about 11:1 Is that right? I was trying to figure out the same thing. Trying to figure if I can use a bigger cam.
Bob
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Yep. My dad and I came up with that formula (divide by 14.7) also by using logic and just common sense. We ended up getting way high compression ratios for the engines. We asked many people and everyone said you cant do it that way.. no one had a reason why though. Just goes to show YET AGAIN how theory gets block out of the water when you bring it into reality.
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Well Jeff I just stated why you cant do it that way 100% VE.
Allow me to pose the question a different way Who has done a Compression check on their stock engines and knows the stock compression ratio/advertised compression ratio/measured compression ratio? You can post just the info Ill do the math.
Allow me to pose the question a different way Who has done a Compression check on their stock engines and knows the stock compression ratio/advertised compression ratio/measured compression ratio? You can post just the info Ill do the math.
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Im not sure how accurate they will be but the 173K mile 2.5 that I took out of my Spirit was about 135 on each cyl. That was dry and with 5 bumps. My 2.2 (before I pulled it) had about 130 dry and 180 wet.
Supposidly the 2.5 should have 7.8 CR and the 2.2 should have 8.2. But thats ass backwards from my compression findings. But then again we all know what blowby I was getting with the 2.2.
Have at it Lori
Supposidly the 2.5 should have 7.8 CR and the 2.2 should have 8.2. But thats ass backwards from my compression findings. But then again we all know what blowby I was getting with the 2.2.
Have at it Lori
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I could tell you the head CC and the piston dish CC as far as factory specs.. but I never have CCd any of my own parts. Lori does head gasket thickness work into the above equation anywhere?
And dont you also need the volume of the cyl at BDC and TDC?
And dont you also need the volume of the cyl at BDC and TDC?
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http://www.kb-silvolite.com/calc.phtml
that link will actually calculate th cr for you. Im lazy and dont feel like typing everything. The cylnider compression / 14.7 doesnot work using your 2.5L I came up with 9.18:1 no way is that it.
that link will actually calculate th cr for you. Im lazy and dont feel like typing everything. The cylnider compression / 14.7 doesnot work using your 2.5L I came up with 9.18:1 no way is that it.
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Yep thats why dad and I wanted an explaination of why not.
Also check this our Lori. Dennis made this kick ass spreadsheet that does all kinds of things. Towards the bottom is CR calculations. But you need to know head cc bore dish cc etc.
http://www.fwdmopar.com/sites/dennis/math.xls
Also check this our Lori. Dennis made this kick ass spreadsheet that does all kinds of things. Towards the bottom is CR calculations. But you need to know head cc bore dish cc etc.
http://www.fwdmopar.com/sites/dennis/math.xls
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Yeah I knew about that one but guess what Cant use it with WebTv on the bright side my printer came in for my computer so sometime next week I should get the rest Bob wont let me set it up until we move to our new apt. That will be 6 weeks 6 very long weeks on WebTv and dial up.
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