Notices
GM Engine & Exhaust Performance EFI | GEN I/GEN II/GEN III/GEN IV Engines |Small Block | Big Block |
Sponsored by:
Sponsored by:

Comp. change, head gskt. thickness ??

Thread Tools
 
Search this Thread
 
Old 03-31-2005, 01:08 AM
  #1  
Staging Lane
Thread Starter
 
RGMEPP's Avatar
 
Join Date: Feb 2005
Location: ARNOLD MO. (ST. LOUIS)
Posts: 94
Likes: 0
Received 0 Likes on 0 Posts
Default Comp. change, head gskt. thickness ??

Soon to have the 6.0 LQ9 down for a cam. head gasket thickness is going down from .054 to .032. Before I go digging through my books, is anyone out there a wizard on this kind of stuff ?? How nuch increase in compression ??
Old 03-31-2005, 03:10 AM
  #2  
11 Second Club
iTrader: (1)
 
Grey Silver's Avatar
 
Join Date: Feb 2003
Location: Allen,Texas
Posts: 499
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by RGMEPP
Soon to have the 6.0 LQ9 down for a cam. head gasket thickness is going down from .054 to .032. Before I go digging through my books, is anyone out there a wizard on this kind of stuff ?? How nuch increase in compression ??
The pistons in a stock LS1 motor come out of the hole about .010. With a .032 head gasket the piston will hit the head. If you want more compression shave the heads or put some pistons in it.
Old 03-31-2005, 07:50 AM
  #3  
TECH Fanatic
iTrader: (11)
 
Green Thunder's Avatar
 
Join Date: Apr 2004
Posts: 1,532
Likes: 0
Received 0 Likes on 0 Posts
Default

Here is a compression calculator to help you with the math..
Compression Calculator
Old 03-31-2005, 07:54 AM
  #4  
TECH Addict
 
Yelo's Avatar
 
Join Date: Feb 2003
Location: Geneseo, NY
Posts: 2,864
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by Grey Silver
The pistons in a stock LS1 motor come out of the hole about .010. With a .032 head gasket the piston will hit the head. If you want more compression shave the heads or put some pistons in it.
????


If the piston comes out .010 and the gasket is .032 then he has .022 clearance between the piston and the head....I think this is a little close for comfort myself and that he will REALLY need to check p/v clearance VERY CAREFULLY but the piston won't hit the head itself
Old 03-31-2005, 12:07 PM
  #5  
11 Second Club
iTrader: (1)
 
Grey Silver's Avatar
 
Join Date: Feb 2003
Location: Allen,Texas
Posts: 499
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Yelo
????


If the piston comes out .010 and the gasket is .032 then he has .022 clearance between the piston and the head....I think this is a little close for comfort myself and that he will REALLY need to check p/v clearance VERY CAREFULLY but the piston won't hit the head itself
No it won't hit untill you start it up. The clearance you refer to is called quench. Do a search in the internal engine section and you'll figure it out.
Old 03-31-2005, 07:40 PM
  #6  
TECH Addict
 
Yelo's Avatar
 
Join Date: Feb 2003
Location: Geneseo, NY
Posts: 2,864
Likes: 0
Received 1 Like on 1 Post
Default

How can a motor with .022 clearance between the top of the piston and the bottom of the head have piston/head interference ???

Maybe I'm just dumb here but it seems to me that even when started that there will STILL be .022 clearance.....even with heat expansion there should still be room, WHY would ANYONE make a gasket that would CAUSE the piston to touch the head ????
Old 04-01-2005, 02:32 PM
  #7  
? ? ? ? ? ?
iTrader: (16)
 
BigTex's Avatar
 
Join Date: Nov 2001
Location: East of Dallas
Posts: 7,126
Likes: 0
Received 2 Likes on 2 Posts
Default

It all depends on the duration of the cam and valve timing. If the valves aren't open too far when the piston reaches the top, then there isn't an issue.

I do agree however that the .008 negative deck height with a .033 gasket thickness is a pretty tight quench.
Old 04-02-2005, 06:09 PM
  #8  
11 Second Club
iTrader: (1)
 
Grey Silver's Avatar
 
Join Date: Feb 2003
Location: Allen,Texas
Posts: 499
Likes: 0
Received 0 Likes on 0 Posts
Default

[QUOTE=BigTex]It all depends on the duration of the cam and valve timing. If the valves aren't open too far when the piston reaches the top, then there isn't an issue.

I do agree however that the .008 negative deck height with a .033 gasket thickness is a pretty tight quench.

Let's forget about the valves for now, we can always cure that problem.

Are you saying that the piston will not hit the head at .022 quench on an LS1 motor?
If anyone decides to try this please be sure to let me know because I would like to hear how it works out for ya.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Oobray
8-Lug Truck Performance
70
06-13-2022 03:38 AM
Noah Burns
GMT K2xx Trucks General Discussion
5
09-07-2015 05:50 PM
GrooveCityZ71
GM Engine & Exhaust Performance
7
08-31-2015 12:05 PM
BennyB
GM Parts Classifieds
15
08-01-2015 08:48 AM



Quick Reply: Comp. change, head gskt. thickness ??



All times are GMT -5. The time now is 05:34 PM.