How do I find out my compression and what size gasket to use?
09-25-2004, 03:14 PM
#1
TECH Regular
Thread Starter
Join Date: Dec 2003
Posts: 441
Likes: 0
Received 0 Likes
on
0 Posts
How do I find out my compression and what size gasket to use? I am not exactly sure if this is my compression but I think it might be about 11.1?
I wanted to use a graphite gasket and I know how thick the gasket is plays a roll in compression. My block is o ringed and will spray 200-300 shot of nitrous so how thick of a gasket should I use? I am going to run 91 gas so I dont really want to go higher then 11.1
Heres some info
-6 cc piston
64cc LS6 heads
cam will be around high 240/250 range and lift about .620/.630
Let me know if theres anything else I need
thanks
I wanted to use a graphite gasket and I know how thick the gasket is plays a roll in compression. My block is o ringed and will spray 200-300 shot of nitrous so how thick of a gasket should I use? I am going to run 91 gas so I dont really want to go higher then 11.1
Heres some info
-6 cc piston
64cc LS6 heads
cam will be around high 240/250 range and lift about .620/.630
Let me know if theres anything else I need
thanks
Last edited by SStroked 410; 09-25-2004 at 03:47 PM.
09-25-2004, 04:11 PM
#2
I'm coming up with 11:1:1 assuming you are 4.040 bore/4.00 stroke/stock graphite gaskets/-6cc pistons/64cc heads/ and assuming your pistons are .007" out of the hole. You really want to get a max quench height of .035-.045", .040 being about average. If you use stock gaskets and your pistons are .007 out of the hole you will be around .046 quench assuming compressed gasket thickness of.053. I'd drop the gasket thickness some and go about 11:3:1 to obtain max quench.
09-25-2004, 07:17 PM
#3
TECH Regular
Thread Starter
Join Date: Dec 2003
Posts: 441
Likes: 0
Received 0 Likes
on
0 Posts
thanks
Yeah sorry, forgot to add 4.040 bore, 4.00 stroke, 6.125 rods
How do you find out if the pistons are out of the hole .007"?
What size gasket would put me at 11.1.1? I dont really want to go higher because the gas sucks in CA. On nitrous I will always use race gas but while driving through town I dont want to have to worry about getting race gas.
Yeah sorry, forgot to add 4.040 bore, 4.00 stroke, 6.125 rods
How do you find out if the pistons are out of the hole .007"?
What size gasket would put me at 11.1.1? I dont really want to go higher because the gas sucks in CA. On nitrous I will always use race gas but while driving through town I dont want to have to worry about getting race gas.
09-25-2004, 10:05 PM
#4
TECH Junkie
Join Date: Aug 2002
Location: Fort Collins, CO
Posts: 3,726
Likes: 0
Received 0 Likes
on
0 Posts
To find out how far your pistons are in/out of the bore, use this formula:
Deck Height = 1/2Stroke + Rod Length + Compression Height + Deck
You'll have to look at your piston specs to find out what the compression height is. I'm also not sure what the stock LS1 Deck Height is off of the top of my head. You'll need those two to get an accurate calculation.
As far as your compression, you need to tell us exactly how thick your headgasket is while it's compressed.
To figure out compression use this formula:
V1 + V2 + V3 + V4 + V5 / V2 + V3 + V4 + V5
V1 = Bore^2 x Stroke x .7854 x 16.39
V2 = Combustion Chamber volume in CC's
V3 = Headgasket bore^2 x Compressed Height x .7854 x 16.39
V4 = Distance piston is in/out of the bore in CC's. If piston is out of bore, subtract this number instead of adding it to the equation
V5 = Piston Dome/Dish in CC's. If piston is domed, subract from equation instead of adding.
Deck Height = 1/2Stroke + Rod Length + Compression Height + Deck
You'll have to look at your piston specs to find out what the compression height is. I'm also not sure what the stock LS1 Deck Height is off of the top of my head. You'll need those two to get an accurate calculation.
As far as your compression, you need to tell us exactly how thick your headgasket is while it's compressed.
To figure out compression use this formula:
V1 + V2 + V3 + V4 + V5 / V2 + V3 + V4 + V5
V1 = Bore^2 x Stroke x .7854 x 16.39
V2 = Combustion Chamber volume in CC's
V3 = Headgasket bore^2 x Compressed Height x .7854 x 16.39
V4 = Distance piston is in/out of the bore in CC's. If piston is out of bore, subtract this number instead of adding it to the equation
V5 = Piston Dome/Dish in CC's. If piston is domed, subract from equation instead of adding.
09-26-2004, 12:32 AM
#5
Or you can go here:
http://www.rosspistons.com/calculator.php
You can also measure the piston height with a deck style caliper if you have access to one. May be easier just to use the formula with the info from your pistons. Most are usaully .007-.010" out of the hole.
As far as more compression goes, I don't think you will notice any diffrence between 11:1 to 11:3:1. Your tuner should easily be able to make up the diffrence in that and you will have the correct height/clearences.
http://www.rosspistons.com/calculator.php
You can also measure the piston height with a deck style caliper if you have access to one. May be easier just to use the formula with the info from your pistons. Most are usaully .007-.010" out of the hole.
As far as more compression goes, I don't think you will notice any diffrence between 11:1 to 11:3:1. Your tuner should easily be able to make up the diffrence in that and you will have the correct height/clearences.