So another Cometic gasket needed - Performance Forum

Forum Post / Reply
You must log in before you can post or reply to messages.
So another Cometic gasket needed
Monday, February 25, 2013 8:48 AM
So I got 10,000kms on the car last summer. Took the motor out to inspect things this winter. Looks like I am needing a new head gasket and also crank bearings and potentially another oil pump. I have to get the motor to the shop so they can tear it down as were are only going on visual inspection. So I am trying to figure out what the stock thickness head gasket is (2000 LD9), I've read around 0.036" but not 100% sure. I have been running the 0.030" cometic mls and am wondering if I should try a thicker hg for my setup. Looking for a little insight from the boosted guys. If the 0.030" is what most are running I'll go ahead and order a new one. This time around the head and block are going to be confirmed they are true and flat. Head was done last time so hopefully its still ok. Anyways, any insight is appreciated.




Re: So another Cometic gasket needed
Monday, February 25, 2013 11:05 AM
stock is around .050. i dont kno where you read.036, dont recall that ever being talked about as stock thickness lol

since ur boosted id go with an .074 cometic.



It's nice to be injected but I love being blown.
Re: So another Cometic gasket needed
Monday, February 25, 2013 11:29 AM
I use the .074 on my 2200.
Re: So another Cometic gasket needed
Monday, February 25, 2013 4:21 PM
Looks like TTR has 0.030, 0.040, 0.051, 0.075 or 0.080.



Re: So another Cometic gasket needed
Monday, February 25, 2013 5:35 PM
Do some reading on quench height and compression and decide for yourself. Decking blocks and heads (especially) and running different thicknesses of head gaskets can mess with the quench areas of the head that help to dissipate combustion heat. If you go to short on the height you can run the risk of holding heat and detonation. Too thick and youre usually running too low on compression and have a weak slow fuel burn. If youre boosting or running nitrous you can benefit from running a little thicker to be safe and control detonation. Honestly its hard to just recommend one because we dont know how much your head and block have been decked if any and what kind of deck height youre running.

This opens up the whole low compression for boost vs high compression for boost thing. But thats another story.



Re: So another Cometic gasket needed
Tuesday, February 26, 2013 9:03 AM
I went with .051 running 12 psi boost (turbo). Didn't get to drive it too much before the trans went, but I'm happy with it so far. That's my .02 anyway.


2004 Cavalier Sedan
Re: So another Cometic gasket needed
Friday, March 01, 2013 10:54 PM
stock is .046 on the LD9 engine...



Re: So another Cometic gasket needed
Saturday, March 02, 2013 1:20 PM
sounds good, looking into ordering a 0.075" and seeing if I have better luck with a thicker one.



Re: So another Cometic gasket needed
Sunday, March 03, 2013 5:38 AM
Thought about doing the 2.3 oil pump swap while the motors apart?


2004 Cavalier Sedan
Re: So another Cometic gasket needed
Monday, March 04, 2013 11:09 AM
Something to remember is under high boost applications, a thicker headgasket is more likely to blowout on you. Personally I wouldn't take a .075" thick gasket over 17psi with a GT3076R (just for reference) as far as reliability goes.



Re: So another Cometic gasket needed
Monday, March 04, 2013 1:43 PM
I went with a thick head gasket since Im runnng an 086 head. I custom ordered a .090(I think, its been a while) but it has been a while, then again I am not worried about a blowout as I have an O-ringed block. I copper sprayed the thing and have head studs. I also plan on tearing down after the first heat cycle and retorquing the head as per cometic's instructions.






Re: So another Cometic gasket needed
Monday, March 04, 2013 6:20 PM
blowout on a cometic? what you runnin nitro methane and 60 psi of boost?



It's nice to be injected but I love being blown.
Re: So another Cometic gasket needed
Monday, March 04, 2013 7:16 PM
-Z Yaaaa- wrote:blowout on a cometic? what you runnin nitro methane and 60 psi of boost?

Lol you know what i meant Brad. With more layers, there's more of a chance of one of them to fail under high boost. Reasoning behind me going with a custom .030" with a 92mm bore head gasket, and 7.9:1 CR pistons for the 086 head swap.



Re: So another Cometic gasket needed
Tuesday, March 05, 2013 5:57 AM
as long as the clearance is there an .030 is ok but in the end, its still risky to use. its my opinion that it would work best on a stock engine with stock pistons.



It's nice to be injected but I love being blown.
Forum Post / Reply
You must log in before you can post or reply to messages.

 

Start New Topic Advanced Search