Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

Compression Ratio (Dynamic and static)

Thread Tools
 
Search this Thread
 
Old 06-23-2006, 10:33 AM
  #1  
TECH Fanatic
Thread Starter
iTrader: (8)
 
Xtnct00WS6's Avatar
 
Join Date: Jan 2005
Location: Sterling VA
Posts: 1,429
Likes: 0
Received 2 Likes on 2 Posts

Default Compression Ratio (Dynamic and static)

Could someone help me plug in the numbers for this calculator?

http://www.kb-silvolite.com/calc.php?action=comp

Here is what I have so far:

Cylinder head volume : 63 (243's milled .010)
Piston head volume: ??
Gasket thickness: .045
Gasket bore: 3.905?? (I have cometics)
Cylinder bore diameter: 3.898
Deck Clearance: .0001??
Stroke: 3.622??

Rod Length: ??
Intake closing Point: ?? It's a TR 224 on 114.

If you know the number for something that has a ??, please chime in

Also, what compression ratio's (dynamic and static) should I shoot for on a stock short block? It's a DD, but with occasional track times. I'm thinking of getting a new cam and milling the heads a bit more to attain the most desirable numbers.

Thanks!
Old 06-23-2006, 11:47 AM
  #2  
12 Second Club
iTrader: (5)
 
jinxedz's Avatar
 
Join Date: Jun 2004
Location: Toronto
Posts: 509
Likes: 0
Received 0 Likes on 0 Posts
Default

IIRC there was an Excel spreadsheet floating around that was able to calculate DCR/SCR

Ill post it if I can find it
Old 06-23-2006, 11:50 AM
  #3  
12 Second Club
iTrader: (5)
 
jinxedz's Avatar
 
Join Date: Jun 2004
Location: Toronto
Posts: 509
Likes: 0
Received 0 Likes on 0 Posts
Default

Here is a link to the post with the excel file ...

https://ls1tech.com/forums/showthrea...ighlight=excel

Hope that helps
Old 07-27-2006, 12:07 AM
  #4  
TECH Fanatic
iTrader: (2)
 
camarokid94's Avatar
 
Join Date: Dec 2004
Posts: 1,154
Likes: 0
Received 1 Like on 1 Post

Default

wow this cant be right can it? MY DCR is crazy high what did i do wrong?
if i add 15 to my cam ABDC like it says then my DCR is only 9.173 wow that is high!!
good luck to me to tune it LOL


ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc) Cylinder Head Vol
(cubic in.) 03.721
Piston Head Volume (cc) Piston Head Vol
(cubic in.) 00.000
Gasket Thickness (in.) Swept Volume
(cubic in.) 43.244
Gasket Bore (in.) T.D.C. Volume
(cubic in.) 04.164
Cylinder Bore Diameter (in.) Gasket Volume
(cubic in.) 00.539
Deck Clearance (in.)
Note: Neg. nubmer above deck, Pos. number below deck Deck Volume
(cubic in.) -0.096
Stroke (in.) STATIC COMPRESSION RATIO 11.385

OPTIONAL DATA
Rod Length (in.) Adjusted Stroke (in.) 03.171
Intake Closing Point (degrees)
ABDC @ 0.050 lift plus 15 degrees DYNAMIC EFFECTIVE COMPRESSION RATIO 10.097
Old 07-27-2006, 07:17 AM
  #5  
TECH Senior Member
 
PREDATOR-Z's Avatar
 
Join Date: Mar 2004
Location: BFE
Posts: 14,620
Likes: 0
Received 16 Likes on 16 Posts

Default

If your cam is advanced 114+4 then you are ~ 11.0:1 and 8.65 DCR
Right where you should be.
Old 07-27-2006, 07:52 AM
  #6  
TECH Senior Member
iTrader: (4)
 
GuitsBoy's Avatar
 
Join Date: Apr 2003
Location: Long Island, NY
Posts: 6,249
Received 3 Likes on 3 Posts

Default

rod length is 6.098 on a stock motor. Not sure about your IVC though. I do tend to use that compression calculator as opposed to the preadsheet, FWIW.
Old 07-27-2006, 08:33 AM
  #7  
Staging Lane
iTrader: (11)
 
98formulaMAH's Avatar
 
Join Date: Jan 2005
Location: Virginia Beach
Posts: 97
Likes: 0
Received 0 Likes on 0 Posts

Default

what is the stock LS1 piston head volume?
Old 07-27-2006, 08:35 AM
  #8  
TECH Senior Member
iTrader: (4)
 
GuitsBoy's Avatar
 
Join Date: Apr 2003
Location: Long Island, NY
Posts: 6,249
Received 3 Likes on 3 Posts

Default

Originally Posted by 98formulaMAH
what is the stock LS1 piston head volume?
0. Theyre flat top pistons with no valve reliefs. I have small flycuts so I estimate mine at 1cc.
Old 07-27-2006, 10:10 AM
  #9  
TECH Fanatic
iTrader: (2)
 
camarokid94's Avatar
 
Join Date: Dec 2004
Posts: 1,154
Likes: 0
Received 1 Like on 1 Post

Default

is mine right at 9.1 DCR
.045 gaskets milled to 61cc AFRs
ABDC @ 0.050 lift is 48 ???
Old 07-27-2006, 10:12 AM
  #10  
TECH Fanatic
Thread Starter
iTrader: (8)
 
Xtnct00WS6's Avatar
 
Join Date: Jan 2005
Location: Sterling VA
Posts: 1,429
Likes: 0
Received 2 Likes on 2 Posts

Default

Originally Posted by PREDATOR-Z
If your cam is advanced 114+4 then you are ~ 11.0:1 and 8.65 DCR
Right where you should be.
You're responding to camarokid correct? Because I figured mine to be about 10.7:1 and 8.04 DCR.

Thanks!
Old 07-27-2006, 10:32 AM
  #11  
On The Tree
iTrader: (6)
 
MISERICORDIA's Avatar
 
Join Date: Sep 2004
Posts: 132
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Xtnct00WS6
You're responding to camarokid correct? Because I figured mine to be about 10.7:1 and 8.04 DCR.

Thanks!
I get yours at 11.069 SCR 8.242 DCR using these values:
63
0
.045
3.9
3.9
-.007
3.622
(optional)
6.098
72.5

That is if your cam has no advance. If it is has advance of +4 then the last number should be 68.5 instead of 72.5 which gives a DCR of 8.539.
Old 07-27-2006, 10:46 AM
  #12  
TECH Senior Member
 
PREDATOR-Z's Avatar
 
Join Date: Mar 2004
Location: BFE
Posts: 14,620
Likes: 0
Received 16 Likes on 16 Posts

Default

Originally Posted by Xtnct00WS6
You're responding to camarokid correct? Because I figured mine to be about 10.7:1 and 8.04 DCR.

Thanks!
No talking to you
I do it on J-Rod calc. No matter how you look at it this is a guestimate.
You need to imput actual values but it is pretty close.
Like 10.9X SCR and 8.6X DCR
Old 07-27-2006, 11:08 AM
  #13  
TECH Fanatic
Thread Starter
iTrader: (8)
 
Xtnct00WS6's Avatar
 
Join Date: Jan 2005
Location: Sterling VA
Posts: 1,429
Likes: 0
Received 2 Likes on 2 Posts

Default

Ohh ok!

Do you have a link so I can download j-rod's calculator? I've been using the modified one by PianoProdigy.

I also just used this one (http://www.rbracing-rsr.com/compstaticcalc.html) and got 10.85 or 10.89 depending on if I use -.0007 or .0007. Which one should it be?

EDIT: it should have been either -.007 or .007 which is either 11.06 or 10.68. Is the negative number when it's out of the hole?
Old 07-27-2006, 11:31 AM
  #14  
TECH Senior Member
 
PREDATOR-Z's Avatar
 
Join Date: Mar 2004
Location: BFE
Posts: 14,620
Likes: 0
Received 16 Likes on 16 Posts

Default

It is -.007 and here is the link

http://users3.ev1.net/~black_ops/cam...calculator.xls
Old 07-27-2006, 03:09 PM
  #15  
TECH Fanatic
iTrader: (2)
 
camarokid94's Avatar
 
Join Date: Dec 2004
Posts: 1,154
Likes: 0
Received 1 Like on 1 Post

Default

Can Someone Help Me Figure Mine? Its A 113+1
Old 07-27-2006, 03:53 PM
  #16  
On The Tree
iTrader: (6)
 
MISERICORDIA's Avatar
 
Join Date: Sep 2004
Posts: 132
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by camarokid94
Can Someone Help Me Figure Mine? Its A 113+1
I get 11.364 SCR and 8.417 DCR. I think the last number using this calculator http://www.kb-silvolite.com/calc.php?action=comp should be 73. Same result with PianProdigy's calc.
Old 07-30-2006, 08:12 PM
  #17  
11 Second Club
iTrader: (17)
 
bad6as's Avatar
 
Join Date: Mar 2005
Location: Maryland
Posts: 4,796
Likes: 0
Received 0 Likes on 0 Posts

Default

can some one help me learn how to use that so i can optimize my cam choice?
Old 07-31-2006, 09:49 AM
  #18  
On The Tree
iTrader: (6)
 
98NBMZ's Avatar
 
Join Date: Jul 2004
Posts: 181
Likes: 0
Received 0 Likes on 0 Posts

Default

The cam I have is a Futral Custom grind but I input my numbers in the calculator as they should have been. How far off is the calculator going to be since it is using Comp grinds and not the CamMotion grinds?

Here is what I have:

Cam: 238/242 112
Bore: 3.898
Stroke: 3.622
Rod: 6.125
Heads: 60cc
Pistons: -4cc
Deck: standard
Head Gasket: stock

I got a DCR of 8.78 and SCR of 11.49 using this calculator. Can someone confirm this for me being that my cam is a CamMotion grind.

*EDIT - I used PianoProdigy's calculator*

Thanks,
John
Old 07-31-2006, 10:08 AM
  #19  
TECH Senior Member
 
PREDATOR-Z's Avatar
 
Join Date: Mar 2004
Location: BFE
Posts: 14,620
Likes: 0
Received 16 Likes on 16 Posts

Default

Give me the advertised durations at .006 and I'll let you know.
Old 07-31-2006, 10:09 AM
  #20  
11 Second Club
iTrader: (17)
 
bad6as's Avatar
 
Join Date: Mar 2005
Location: Maryland
Posts: 4,796
Likes: 0
Received 0 Likes on 0 Posts

Default

can some one give out the stock 98 ls1 info


Quick Reply: Compression Ratio (Dynamic and static)



All times are GMT -5. The time now is 10:06 AM.