Are my calcs right? (compression ratio)
Thread Starter
Staging Lane
Joined: Jan 2004
Posts: 74
Likes: 0
From: East Hartford, CT
Are my calcs right? (compression ratio) OK, TEA S2 unmilled 5.3 L heads
63cc chambers
Lunati 382 stroker w/8cc dished pistons
I've been told the 5.3L heads w/out milling will bump my compression to 10.8:1 on a stock LS1
the Lunati Kit advertises bumping compression to 10.6:1 on a stock LS1
So I tried various formulas:
1: 10.8-10.1 = .7 + (10.6-10.1) = .5 , .7+.5 = 1.2 so 10.1+1.2 = 11.3:1 compression
Then I tried the static compression formulas listed in another thread (http://www.grapeaperacing.com/GrapeA...ccompratio.cfm)
(r2 × pi) × length
Stroke = 4.00
Bore = 3.898
(3.898/2)^2 * 3.14159 *4.00 = 47.73458766236
47.73458766236 * 16.387 = 782.22668802309332 CC cylinder volume
Chamber Volume:
63cc chamber
8cc reliefs
3.898" bore
.040" gasket
63+8+x (I assumed x is ~5cc ?) =76cc
Wasn't quite sure how to calculate the space the gasket takes up (also not sure if the gasket size is correct? stock size gasket)
so using:
Static Compression Ratio = (S+C) ÷ C
Where S = Total Swept Volume and C = Chamber Volume
so, (782.23 + 76)/76 = 11.2925 which also shows 11.3:1 compression
So am I right in assuming my 382 is running w/11.3:1 compression? (just wanna verify my math... )
63cc chambers
Lunati 382 stroker w/8cc dished pistons
I've been told the 5.3L heads w/out milling will bump my compression to 10.8:1 on a stock LS1
the Lunati Kit advertises bumping compression to 10.6:1 on a stock LS1
So I tried various formulas:
1: 10.8-10.1 = .7 + (10.6-10.1) = .5 , .7+.5 = 1.2 so 10.1+1.2 = 11.3:1 compression
Then I tried the static compression formulas listed in another thread (http://www.grapeaperacing.com/GrapeA...ccompratio.cfm)
(r2 × pi) × length
Stroke = 4.00
Bore = 3.898
(3.898/2)^2 * 3.14159 *4.00 = 47.73458766236
47.73458766236 * 16.387 = 782.22668802309332 CC cylinder volume
Chamber Volume:
63cc chamber
8cc reliefs
3.898" bore
.040" gasket
63+8+x (I assumed x is ~5cc ?) =76cc
Wasn't quite sure how to calculate the space the gasket takes up (also not sure if the gasket size is correct? stock size gasket)
so using:
Static Compression Ratio = (S+C) ÷ C
Where S = Total Swept Volume and C = Chamber Volume
so, (782.23 + 76)/76 = 11.2925 which also shows 11.3:1 compression
So am I right in assuming my 382 is running w/11.3:1 compression? (just wanna verify my math... )
Gasket volume is just like the Cyl Volume (but much thinner). 10.16 bore (for 4" gasket bore), 0.1016 thickness (at .040). Basically 8.24cc gasket. You still have one unknown in your formula - The piston sticks up out of the bore on a LS1, so subtract that from the gasket thickness for easier calculation. If it sticks up .08 then take it out of your .040 gasket for a total .032 thickness. That lowers your gasket volume to about 6.8ccs.
I'm coming out with 11.05 using metric numbers.
Are you going to have the cylinders honed?
I'm coming out with 11.05 using metric numbers.
Are you going to have the cylinders honed?
Thread Starter
Staging Lane
Joined: Jan 2004
Posts: 74
Likes: 0
From: East Hartford, CT
Originally Posted by BigTex
Gasket volume is just like the Cyl Volume (but much thinner). 10.16 bore (for 4" gasket bore), 0.1016 thickness (at .040). Basically 8.24cc gasket. You still have one unknown in your formula - The piston sticks up out of the bore on a LS1, so subtract that from the gasket thickness for easier calculation. If it sticks up .08 then take it out of your .040 gasket for a total .032 thickness. That lowers your gasket volume to about 6.8ccs.
I'm coming out with 11.05 using metric numbers.
Are you going to have the cylinders honed?
I'm coming out with 11.05 using metric numbers.
Are you going to have the cylinders honed?
Cool, i just wanted to make sure I didn't end up getting a crazy compression (read a post where a guy got like 12.7:1 compression w/a similar setup... but he musta had his heads milled)
The motor's already built... i got a killer deal on a stock bore 382 kit so I used that and just had the cylinders cleaned up (used a low mileage LS6 block)
