What is my compression ratio?
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
What is my compression ratio?
I know my engine is bored .030 over. I have stock length rods. The pistons are flat top with 4 small valve reliefs. I have TFS 23 Degree heads. Comp Cams XE 262.
If there is any other info I need here let me know and I will try to get it. The engine is installed and running nicely. I was just curious what CR I am running now.
Thanks for any help.
If there is any other info I need here let me know and I will try to get it. The engine is installed and running nicely. I was just curious what CR I am running now.
Thanks for any help.
Safety Car
Joined: Aug 2001
Posts: 3,686
Likes: 202
From: Waterford Mi
Re: What is my compression ratio? (Eddie 70)
Check out this site for your answer http://www.kb-silvolite.com/calc.phtml
Melting Slicks
Joined: Dec 2001
Posts: 2,025
Likes: 1
From: Billings MT
Re: What is my compression ratio? (Eddie 70)
Not sure on which gasket your using, but here is what i got with the following specs:
Bore: 4.030
Stroke: 3.48
Combustion Chamber cc: 64
Head Gasket thickness: .041 (common)
Head Gasket Bore: 4.166
Deck Height: .025
Piston Dish cc: 6cc (this may be 12 with 4 valve reliefs)
CR: 9.62
Bore: 4.030
Stroke: 3.48
Combustion Chamber cc: 64
Head Gasket thickness: .041 (common)
Head Gasket Bore: 4.166
Deck Height: .025
Piston Dish cc: 12cc
CR: 9.05
:cheers:
Bore: 4.030
Stroke: 3.48
Combustion Chamber cc: 64
Head Gasket thickness: .041 (common)
Head Gasket Bore: 4.166
Deck Height: .025
Piston Dish cc: 6cc (this may be 12 with 4 valve reliefs)
CR: 9.62
Bore: 4.030
Stroke: 3.48
Combustion Chamber cc: 64
Head Gasket thickness: .041 (common)
Head Gasket Bore: 4.166
Deck Height: .025
Piston Dish cc: 12cc
CR: 9.05
:cheers:
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
Re: What is my compression ratio? (VETDRMS)
Vetdrms, it does have 4 reliefs. Thanks for the info. I am somewhere near 9:1. Stock was 10.25:1, did the over bore drop it the one point?
Melting Slicks
Joined: Dec 2001
Posts: 2,025
Likes: 1
From: Billings MT
Re: What is my compression ratio? (Eddie 70)
No, a larger bore will actually increase the static compression ratio, as will a longer stroke. (As more air is effectively "pumped" into the cylinder).
I'm not sure how you would be at 10.25:1 stock, unless you were running a domed piston, or a flattop w/o valve reliefs and a thin metal head gasket.
What head gasket are you using? steel shim or fel-pro type?
Also, do you know your deck height? did you have the block decked?
I think stock is .025.
[edit] If you had a standard deck, with 64cc heads (originally) and they used something like a .020 steel shim head gasket you would be right at 10:1 You can pick up a half point or more by going with a steel shim head gasket, you just want to be sure your deck surface and heads are flat.
[Modified by VETDRMS, 1:11 PM 3/2/2003]
I'm not sure how you would be at 10.25:1 stock, unless you were running a domed piston, or a flattop w/o valve reliefs and a thin metal head gasket.
What head gasket are you using? steel shim or fel-pro type?
Also, do you know your deck height? did you have the block decked?
I think stock is .025.
[edit] If you had a standard deck, with 64cc heads (originally) and they used something like a .020 steel shim head gasket you would be right at 10:1 You can pick up a half point or more by going with a steel shim head gasket, you just want to be sure your deck surface and heads are flat.
[Modified by VETDRMS, 1:11 PM 3/2/2003]
