Bad calculations?
Thread Starter
TECH Apprentice
Joined: Jul 2008
Posts: 309
Likes: 1
Bad calculations? I'm calculating the stock compression ratio on a 2002 LS1 with the below stock specifications and getting a static CR of 10.36:1 instead of the expected 10.1:1
Is my math wrong? I apologize is this is a noob post, trying to understand where I'm going wrong. I have the negative values in there for Deck clearance volume. I noticed when I take those out it goes back to 10.17:1
5.7 LS1
Bore 3.898
Stroke 3.622
Number of Cylinders 8
Displacement 345.7896451
Chamber Volume 4.068453019
Swept/Cylinder Volume 43.22370564
Gasket Thickness 0.054
Gasket Volume 0.644417478
Rod Length 6.098
Compression Height 1.339
Deck Clearance -0.008
Deck Clearance Volume -0.095469256
Deck Height 9.24
Piston Volume 0
Compression Ratio 10.36104605 (cylinder volume + clearance volume + piston volume + gasket volume + chamber volume divided by clearance volume + piston volume + gasket volume + chamber volume)
Is my math wrong? I apologize is this is a noob post, trying to understand where I'm going wrong. I have the negative values in there for Deck clearance volume. I noticed when I take those out it goes back to 10.17:1
5.7 LS1
Bore 3.898
Stroke 3.622
Number of Cylinders 8
Displacement 345.7896451
Chamber Volume 4.068453019
Swept/Cylinder Volume 43.22370564
Gasket Thickness 0.054
Gasket Volume 0.644417478
Rod Length 6.098
Compression Height 1.339
Deck Clearance -0.008
Deck Clearance Volume -0.095469256
Deck Height 9.24
Piston Volume 0
Compression Ratio 10.36104605 (cylinder volume + clearance volume + piston volume + gasket volume + chamber volume divided by clearance volume + piston volume + gasket volume + chamber volume)
Thread Starter
TECH Apprentice
Joined: Jul 2008
Posts: 309
Likes: 1
So, I redid all my math including the below added variables...still getting 10.36:1 for a stock LS1. Can someone point out what I'm missing?
5.7 LS1
Bore 3.898
Stroke 3.622
Corrected Stroke (minus deck) 3.63
Number of Cylinders 8
Displacement 345.7896451
Chamber Volume 4.068453019
Swept/Cylinder Volume 43.22370564
Gasket Bore 3.905
Gasket Thickness 0.054
Gasket Volume 0.646734036
Piston to Head Volume 0.550921587
Rod Length 6.098
Compression Height 1.339
Deck Clearance -0.008
Deck Clearance Volume -0.095469256
Deck Height 9.24
Piston Volume 0
Ring Height 0.3
Piston to Bore Clearance 0.0021
Crevice/Clearance Volume 0.003856428
Piston to Headgasket Volume 0.003863356
BDC Volume 47.94274912
TDC Volume 4.623237961
Compression Ratio 10.36995057
5.7 LS1
Bore 3.898
Stroke 3.622
Corrected Stroke (minus deck) 3.63
Number of Cylinders 8
Displacement 345.7896451
Chamber Volume 4.068453019
Swept/Cylinder Volume 43.22370564
Gasket Bore 3.905
Gasket Thickness 0.054
Gasket Volume 0.646734036
Piston to Head Volume 0.550921587
Rod Length 6.098
Compression Height 1.339
Deck Clearance -0.008
Deck Clearance Volume -0.095469256
Deck Height 9.24
Piston Volume 0
Ring Height 0.3
Piston to Bore Clearance 0.0021
Crevice/Clearance Volume 0.003856428
Piston to Headgasket Volume 0.003863356
BDC Volume 47.94274912
TDC Volume 4.623237961
Compression Ratio 10.36995057
Thread Starter
TECH Apprentice
Joined: Jul 2008
Posts: 309
Likes: 1
I still don't understand why I'm getting 10.36 as my compression ratio instead of 10.1:1, Does anyone see where I'm going wrong? A second look by someone would be appreciated.
Static Values below
Bore 3.898
Stroke 3.622
Number of Cylinders 8
Displacement 345.7896451
Gasket Bore 3.905
Gasket Thickness 0.052
Rod Length 6.098
Compression Height 1.337
Deck Clearance -0.006
Deck Clearance Volume -0.071601942
Deck Height 9.24
Ring Height 0.3
Piston to Bore Clearance 0.0014
Piston Volume 0
Calculated Values
Chamber Volume 4.068453019
Swept/Cylinder Volume 43.22370564
Gasket Volume 0.622780924
Piston to Head Volume 0.550921587
Crevice/Clearance Volume 0.002571183
Piston to Headgasket Volume 0.002575801
Below added for BDC Volume
Chamber Volume 4.068453019
Swept/Cylinder Volume 43.22370564
Gasket Volume 0.622780924
Piston Volume 0
Crevice/Clearance Volume 0.002571183
BDC Volume 47.91751076
Below added for TDC Volume
Chamber Volume 4.068453019
Piston to Head Volume 0.550921587
Piston Volume 0
Piston to Headgasket Volume 0.002575801
TDC Volume 4.621950407
Compression Ratio 10.36737882
Static Values below
Bore 3.898
Stroke 3.622
Number of Cylinders 8
Displacement 345.7896451
Gasket Bore 3.905
Gasket Thickness 0.052
Rod Length 6.098
Compression Height 1.337
Deck Clearance -0.006
Deck Clearance Volume -0.071601942
Deck Height 9.24
Ring Height 0.3
Piston to Bore Clearance 0.0014
Piston Volume 0
Calculated Values
Chamber Volume 4.068453019
Swept/Cylinder Volume 43.22370564
Gasket Volume 0.622780924
Piston to Head Volume 0.550921587
Crevice/Clearance Volume 0.002571183
Piston to Headgasket Volume 0.002575801
Below added for BDC Volume
Chamber Volume 4.068453019
Swept/Cylinder Volume 43.22370564
Gasket Volume 0.622780924
Piston Volume 0
Crevice/Clearance Volume 0.002571183
BDC Volume 47.91751076
Below added for TDC Volume
Chamber Volume 4.068453019
Piston to Head Volume 0.550921587
Piston Volume 0
Piston to Headgasket Volume 0.002575801
TDC Volume 4.621950407
Compression Ratio 10.36737882
TECH Enthusiast
Joined: Apr 2010
Posts: 651
Likes: 10
From: North Carolina
Try using this Compression Calculator . . .
Be sure to enter all of your values as POSITIVE numbers ( i.e.- "3cc" for -3cc Flat-Top pistons ), same for Deck Height.
http://www.diamondracing.net/tools/
Be sure to enter all of your values as POSITIVE numbers ( i.e.- "3cc" for -3cc Flat-Top pistons ), same for Deck Height.
http://www.diamondracing.net/tools/
Thread Starter
TECH Apprentice
Joined: Jul 2008
Posts: 309
Likes: 1
Try using this Compression Calculator . . .
Be sure to enter all of your values as POSITIVE numbers ( i.e.- "3cc" for -3cc Flat-Top pistons ), same for Deck Height.
http://www.diamondracing.net/tools/
Be sure to enter all of your values as POSITIVE numbers ( i.e.- "3cc" for -3cc Flat-Top pistons ), same for Deck Height.
http://www.diamondracing.net/tools/
Well, that's not quite the point. That calculator comes up with 10.17
Which is great, but I don't have the formulas on how it did it. So how do I really trust it?
TECH Enthusiast
Joined: Apr 2010
Posts: 651
Likes: 10
From: North Carolina
If I can, I'm going to send you an attachment in a PM, if I can . . . If not, we'll use e-mail .
