Compression ratio question
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Posting Guru
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From: where the deer and antelo
Compression ratio question
I just bought a short block (D1VE-6015-A2B)with 40 over dish top pistons. I plan to rebuild my C9VE heads and put on this engine. Any Idea what the compression ratio would be, and will I be able to use regular gasoline?
Laughing Gas
Joined: Jun 2003
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From: Chino, California
I can't decipher the numbers you posted, so I don't know what cc your heads are, or what engine we are discussing here.
Going .40 over will increase the c/r, but not significantly. C/R is determined by the number of CC's displaced (or compressed) compared to the volume leftover at TDC, then reduce to lowest denominator. 50 cubic inches compressed to 5 cubic inches would be a C/R of 10:1
Going .40 over will increase the c/r, but not significantly. C/R is determined by the number of CC's displaced (or compressed) compared to the volume leftover at TDC, then reduce to lowest denominator. 50 cubic inches compressed to 5 cubic inches would be a C/R of 10:1
Mountain Pass
Joined: Aug 2004
Posts: 143
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From: Tacoma, WA.
With out more information...
...it is not possible to answer your question accurately.
I would need the dish volume in cc's, amount the pistons are below deck at TDC, and actual chamber volume in CC's.
Assuming a standard cheap builder piston with a 25 cc dish which is typical, lightly decked heads with 75 cc chambers and the piston .020" below deck which is again typical for the builder pistons, your final C/R would be about 9.1 to 1. At "0" deck the C/R would be closer to 9.5 to 1.
This combo will not run on regular gas with a near stock camshaft. 89 should work though.
Scott J. / RHP
http://reincarnation-automotive.com
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I would need the dish volume in cc's, amount the pistons are below deck at TDC, and actual chamber volume in CC's.
Assuming a standard cheap builder piston with a 25 cc dish which is typical, lightly decked heads with 75 cc chambers and the piston .020" below deck which is again typical for the builder pistons, your final C/R would be about 9.1 to 1. At "0" deck the C/R would be closer to 9.5 to 1.
This combo will not run on regular gas with a near stock camshaft. 89 should work though.
Scott J. / RHP
http://reincarnation-automotive.com
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.
.
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Posting Guru
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From: where the deer and antelo
Thanks guys.
How do you determine the cc's of the dish in the top of the piston? In my mind I can see me filling the dish with water and measuring that volume but I'm shure that is not the correct way. I assume that you measure the top of the piston with streight edge and feeler guage to determine the clearance to deck at TDC? Does altitude play into this? I live at 6,900'.
How do you determine the cc's of the dish in the top of the piston? In my mind I can see me filling the dish with water and measuring that volume but I'm shure that is not the correct way. I assume that you measure the top of the piston with streight edge and feeler guage to determine the clearance to deck at TDC? Does altitude play into this? I live at 6,900'.
Mountain Pass
Joined: Aug 2004
Posts: 143
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From: Tacoma, WA.
You use a clear plexiglass plate with a small hole in it. Take some grease or vaseline and cover the dish with the plate using the vaseline to seal it. Use a syringe to fill the dish with water and record the amount. It can vary from 15 to 27 cc's depending on brand.
At your high altitude you can run an extra point of compression and still be fine on regular 87 octane fuel.
SMJ/RHP
http://reincarnation-automotive.com
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At your high altitude you can run an extra point of compression and still be fine on regular 87 octane fuel.
SMJ/RHP
http://reincarnation-automotive.com
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