Calculating CR after LE2 install
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Calculating CR after LE2 install
I'm trying to figure out what compression ratio I will be running once I have these new heads on.
I found a formula (below) an I wanted to double check my math and numbers.
Based on the stock numbers provided, I came up with 10.44 : 1 for a stock Lt1.
When I decreased deck height by .005 and used .026 gaskets I got 11.25:1
When I decreased deck height by .010 and used .026 gaskets I got 11.40:1
That assumes Lloyd
decks less than 0.010"
and the combustion chmabers remain 58cc.
Can anyone verify either of those numbers?
And can I safely run that on a stock bottom end with pump gas (92 octane)?
For giggles, I also checked CR with 54cc chambers.
When I decreased deck height by .005 and used .026 gaskets I got 11.87:1
When I decreased deck height by .010 and used .026 gaskets I got 12.04:1
I found a formula (below) an I wanted to double check my math and numbers.
Based on the stock numbers provided, I came up with 10.44 : 1 for a stock Lt1.
When I decreased deck height by .005 and used .026 gaskets I got 11.25:1
When I decreased deck height by .010 and used .026 gaskets I got 11.40:1
That assumes Lloyd
decks less than 0.010"
and the combustion chmabers remain 58cc.
Can anyone verify either of those numbers?
And can I safely run that on a stock bottom end with pump gas (92 octane)?
For giggles, I also checked CR with 54cc chambers.
When I decreased deck height by .005 and used .026 gaskets I got 11.87:1
When I decreased deck height by .010 and used .026 gaskets I got 12.04:1
Originally Posted by LS1Tech
CR = (Vbdc/Vtdc)
CR = [{(B/2)^2 * S*Pi}+Vcc+Vp+{(B/2)^2*Pi*(DH+TG)}]
Where:
CR= Compression Ratio
B = Cylinder bore (Stock LT1 = 4.00in)
S = Stroke (Stock LT1 = 3.48in)
Vcc= Combustion Chamber Volume (Stock LT1 = 58cc = 3.539 in3)
Vp= Piston Volume (Stock LT1 = 4.5cc = 0.274606 in3)
DH = Deck Height (Stock LT1 = 0.015 in)
TG = Head Gasket Crush Thickness (Stock LT1 = 0.05 in)
Pi = 3.1415
CR = [{(B/2)^2 * S*Pi}+Vcc+Vp+{(B/2)^2*Pi*(DH+TG)}]
[{(B/2)^2*Pi*(DH+TG)}+Vcc+Vp]
Where:
CR= Compression Ratio
B = Cylinder bore (Stock LT1 = 4.00in)
S = Stroke (Stock LT1 = 3.48in)
Vcc= Combustion Chamber Volume (Stock LT1 = 58cc = 3.539 in3)
Vp= Piston Volume (Stock LT1 = 4.5cc = 0.274606 in3)
DH = Deck Height (Stock LT1 = 0.015 in)
TG = Head Gasket Crush Thickness (Stock LT1 = 0.05 in)
Pi = 3.1415
Last edited by user 647483; May 31, 2006 at 09:48 AM.
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Posts: 2,182
From: Moore OK
Re: Calculating CR after LE2 install
Need to CC the combustion chambers, I don't think they are 58 unless he takes a lot of meat out of them.
Think they are closer to 52ish.
But on a stock bottom end I don't think I would worry too much about it. Ask Loyd where your Quench needs to be, thats prob more important.
Are you building a new motor? Deck height is your pistons to deck, doesn't matter how much is milled off the heads.
Think they are closer to 52ish.
But on a stock bottom end I don't think I would worry too much about it. Ask Loyd where your Quench needs to be, thats prob more important.
Are you building a new motor? Deck height is your pistons to deck, doesn't matter how much is milled off the heads.
Thread Starter
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Joined: Apr 2000
Posts: 1,444
Re: Calculating CR after LE2 install
Originally Posted by jsetzer
Need to CC the combustion chambers, I don't think they are 58 unless he takes a lot of meat out of them.
Think they are closer to 52ish.
But on a stock bottom end I don't think I would worry too much about it. Ask Loyd where your Quench needs to be, thats prob more important.
Are you building a new motor? Deck height is your pistons to deck, doesn't matter how much is milled off the heads.
Think they are closer to 52ish.
But on a stock bottom end I don't think I would worry too much about it. Ask Loyd where your Quench needs to be, thats prob more important.
Are you building a new motor? Deck height is your pistons to deck, doesn't matter how much is milled off the heads.
Anything milled off of the heads would effect the chamber, not the deck height.
Using stock engine bottom end, no milling on the block.
I talked to Lloyd about using .026 gaskets and he didn't seem to think that would be an issue.
(At least not as far as valve to piston clearance goes). I'm trying to ask more questions on the
board so others will find it in a search rather than fill Lloyd's inbox.
Originally Posted by Lloyd's Email
If you are using a stock bottom end, you wanna use an Impala head gasket
as opposed to the stock GM gasket. This difference alone can effect pushrod
length and intake fitment. The higher compression and improved quench is worth
5 HP and 8-10 RWTQ across the board so it is worth doing.
Just use a dremel to slot the intake bolt holes inward if needed.
as opposed to the stock GM gasket. This difference alone can effect pushrod
length and intake fitment. The higher compression and improved quench is worth
5 HP and 8-10 RWTQ across the board so it is worth doing.
Just use a dremel to slot the intake bolt holes inward if needed.
Using .026 gaskets and assuming 58cc chambers; 11.10:1
Using .026 gaskets and assuming 54cc chambers; 11.70:1
Using .026 gaskets and assuming 52cc chambers; 12.03:1
Last edited by user 647483; May 31, 2006 at 10:12 AM.
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Posts: 1,444
Re: Calculating CR after LE2 install
Hey, I did a search and found an answer LOL
Imagine that
Imagine that
Originally Posted by Javier97Z28
From Lloyd:
"A stock bottom end 350 with my LE2 heads and cam will be right at 11.1 to 11.2 to 1 with the .026 Mr Gasket # 5716 head gaskets."
"A stock bottom end 350 with my LE2 heads and cam will be right at 11.1 to 11.2 to 1 with the .026 Mr Gasket # 5716 head gaskets."
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