Head gaskets and Calculating compression
02-22-2013, 05:44 PM
#1
9 Second Club
Thread Starter
iTrader: (3)
Join Date: Sep 2010
Location: Mesa, AZ
Posts: 411
Likes: 0
Received 0 Likes
on
0 Posts
Head gaskets and Calculating compression I'm trying to figure the compression on the LS1 I'm building right now. I found the stock LS1 has Piston Deck Height in Operation: 0.203mm / 0.008"
(Above Deck Surface) so would I enter that number in the deck clearance box as -.008?
My engine has Wiseco +3.2cc flat top pistons with bore size of 3.905, the 243 heads are milled to 60cc I'm shooting for 11.1cr, I'm trying to decide on getting Cometic .040 mls, Cometic .045 mls or GM .054 mls head gaskets.
Depending on how I enter the deck clearance either positive to negative there is about .4 difference in the CR.
(Above Deck Surface) so would I enter that number in the deck clearance box as -.008?
My engine has Wiseco +3.2cc flat top pistons with bore size of 3.905, the 243 heads are milled to 60cc I'm shooting for 11.1cr, I'm trying to decide on getting Cometic .040 mls, Cometic .045 mls or GM .054 mls head gaskets.
Depending on how I enter the deck clearance either positive to negative there is about .4 difference in the CR.
02-22-2013, 06:17 PM
#2
11 Second Club
iTrader: (6)
Join Date: Feb 2005
Location: middle of nowhere, Kansas
Posts: 1,309
Likes: 0
Received 2 Likes
on
2 Posts
Most calculator enter piston out of the hole as negative. You say flattop pistons but then list a 3.2cc dome piston. Which is it? If you really have +3.2, then CR is going to be something like 11.8 with GM gaskets.
02-22-2013, 06:23 PM
#3
9 Second Club
Thread Starter
iTrader: (3)
Join Date: Sep 2010
Location: Mesa, AZ
Posts: 411
Likes: 0
Received 0 Likes
on
0 Posts
The piston are flat top with 2 valve reliefs, the valve relief are added cc so they get added as +3.2 and dome would be -3.2 because it takes away cc.
02-22-2013, 06:29 PM
#4
11 Second Club
iTrader: (6)
Join Date: Feb 2005
Location: middle of nowhere, Kansas
Posts: 1,309
Likes: 0
Received 2 Likes
on
2 Posts
Not with the calculator I use. Valve reliefs use a negative number because they decrease volume. In that case, use the Cometic .045" gaskets for 11 CR.
http://www.csgnetwork.com/compcalc.html
http://www.csgnetwork.com/compcalc.html
02-23-2013, 05:12 AM
#5
TECH Fanatic
valve reliefs will increase clearance volume in all cases. The piston manufacturer will take that into account when specifying the net volume (+/-) that the piston contributes to the equation.
02-23-2013, 05:19 AM
#6
TECH Fanatic
I'm trying to figure the compression on the LS1 I'm building right now. I found the stock LS1 has Piston Deck Height in Operation: 0.203mm / 0.008"
(Above Deck Surface) so would I enter that number in the deck clearance box as -.008?
My engine has Wiseco +3.2cc flat top pistons with bore size of 3.905, the 243 heads are milled to 60cc I'm shooting for 11.1cr, I'm trying to decide on getting Cometic .040 mls, Cometic .045 mls or GM .054 mls head gaskets.
Depending on how I enter the deck clearance either positive to negative there is about .4 difference in the CR.
(Above Deck Surface) so would I enter that number in the deck clearance box as -.008?
My engine has Wiseco +3.2cc flat top pistons with bore size of 3.905, the 243 heads are milled to 60cc I'm shooting for 11.1cr, I'm trying to decide on getting Cometic .040 mls, Cometic .045 mls or GM .054 mls head gaskets.
Depending on how I enter the deck clearance either positive to negative there is about .4 difference in the CR.
