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Old 06-05-2004, 09:10 AM   #1
ChAi
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Default head gasget thickness

what is the thickness of the head gasget for 99RS SOHC? 1mm or 2mm
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Old 06-05-2004, 10:42 AM   #2
greg donovan
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i suggest you find one and measure it to be sure.

but thhis is what i found through some research.

99 ej25 HG is .058cm

this was from:
http://wac.addr.com/auto/obs/turbo/ejcalcs.html
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Old 06-05-2004, 12:31 PM   #3
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This doesn't really answer your question but they are making me one that is 0.027 http://www.cometic.com/
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Old 06-05-2004, 01:06 PM   #4
greg donovan
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Quote:
Originally posted by John*G
This doesn't really answer your question but they are making me one that is 0.027 http://www.cometic.com/
thats cm i hope
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Old 06-05-2004, 03:16 PM   #5
ChAi
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thank for the info

so if i have turbo in my car, can i use the 98 ej25 DOHC head gasket (0.152cm) on 99 EJ25 SOHC to lower the compression ratio?

and what is the STI 2.5L head gasket thickness

Last edited by ChAi; 06-05-2004 at 03:24 PM.
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Old 06-05-2004, 06:55 PM   #6
greg donovan
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Quote:
Originally posted by ChAi
thank for the info

so if i have turbo in my car, can i use the 98 ej25 DOHC head gasket (0.152cm) on 99 EJ25 SOHC to lower the compression ratio?

and what is the STI 2.5L head gasket thickness
yes you can use the dohc gasket on a sohc car. you may have to modify the gasket to make sure the oil and wat er passage hole line up. you dealership should have both in stock so you can compare. and yes it will lower the CR. about 1 point.
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Old 06-05-2004, 10:02 PM   #7
ChAi
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Quote:
Originally posted by greg donovan
yes you can use the dohc gasket on a sohc car. you may have to modify the gasket to make sure the oil and wat er passage hole line up. you dealership should have both in stock so you can compare. and yes it will lower the CR. about 1 point.
what do you mean by "1 point" is it from 8.5:1 to 7.5:1
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Old 06-05-2004, 11:02 PM   #8
greg donovan
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Quote:
Originally posted by ChAi
what do you mean by "1 point" is it from 8.5:1 to 7.5:1
yes 10.1:1 to 9.1:1 would be a change of 1 point from what i understand. those numbers are just for illustration purposes.

use this page to calculate CR:
http://www.kb-silvolite.com/calc.php...1441a39409fc71
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Old 03-10-2005, 01:21 AM   #9
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Quote:
Originally Posted by greg donovan
yes 10.1:1 to 9.1:1 would be a change of 1 point from what i understand. those numbers are just for illustration purposes.
Everywhere I've ever seen "1 point" used, it refers to 0.1, -> "point 1"

AKA 10.1 to 10.0

Not even talking about the gaskets here, just the wording. I have no idea how much the compression would change with the other gaskets, but a whole 1.0 drop seems like a LOT from just thicker gaskets...
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Old 06-06-2004, 12:05 AM   #10
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how do you make the intake manifold hook up right if you change the distance from head to head?
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Old 06-06-2004, 12:22 AM   #11
greg donovan
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Quote:
Originally posted by RS_to_WRX_swap
how do you make the intake manifold hook up right if you change the distance from head to head?
forgot about that. im not sure. maybe there is enough room to make it fit? like i said not sure.
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Old 06-06-2004, 03:01 AM   #12
ChAi
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Quote:
Originally posted by RS_to_WRX_swap
how do you make the intake manifold hook up right if you change the distance from head to head?

it only 2mm different not that much
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Old 06-08-2004, 03:01 PM   #13
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FWIW...I have a new set of Cometic gaskets that I will sell if anyone is interested. P/N C4264HP, Thickness is .043" with a compressed thickness of .040". I will let them go for $110shipped.

Reason for selling? They're making me a set of .027" gaskets to run around on......

If you're going turbo, they'll make you a set of .060" gaskets or even thicker if you want. Call Kevyn at 440-354-0777ext.120 and tell him Jay from Sourcemotorsports sent you!


Jay Storm


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Old 03-09-2005, 06:06 PM   #14
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back from the dead...

Jay, did they make these specially for you. how much? and what are they made of? thanks
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Old 03-09-2005, 11:52 PM   #15
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Quote:
Originally Posted by Lavery
back from the dead...

Jay, did they make these specially for you. how much? and what are they made of? thanks
They were special order at one time, but they have a stock number now even though it's not listed in their catalog.

The construction is 3 layers of full stainless steel. The outer surfaces are evenly coated with a nitrile coating as opposed to OEM gaskets only having beads run around the key areas and a layer of aluminum or some other soft material.

Buy Crash477's set. He got them from me and now doesn't need them. Help a brotha out!!!! You won't be disappointed.

As for manifold fitment with the thinner gaskets, it's a non-issue. There is more than enough room to fit the intake. If you've portmatched, it may require a little massaging to get the flush finish back. It may make the exhaust manifold a little more tricky to slide over the studs. A little more arm power is all that's needed to gently squeeze the header in while lifting it into place. Although, this allows the header to stay put when the nuts are loosened instead of falling on your head.....

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Old 04-08-2005, 04:28 AM   #16
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Quote:
Originally Posted by Storm
FWIW...I have a new set of Cometic gaskets that I will sell if anyone is interested. P/N C4264HP, Thickness is .043" with a compressed thickness of .040". I will let them go for $110shipped.

Reason for selling? They're making me a set of .027" gaskets to run around on......

If you're going turbo, they'll make you a set of .060" gaskets or even thicker if you want. Call Kevyn at 440-354-0777ext.120 and tell him Jay from Sourcemotorsports sent you!


Jay Storm


Jay Storm

HOW MUCH DOES THIS AFFECT THE COMPRESSION RATIO? ANY NOTICABLE GAINS OVER THE STOCK GASKET SIZE?
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Old 03-09-2005, 08:54 PM   #17
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I have a .027" cometic HG for sale too. its brand new.. $100 bucks shipped and its yours.
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Old 03-09-2005, 09:09 PM   #18
RS_to_WRX_swap
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Quote:
Originally Posted by Crash477
I have a .027" cometic HG for sale too. its brand new.. $100 bucks shipped and its yours.
tempting...
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Old 03-12-2005, 07:37 PM   #19
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Quote:
Originally Posted by RS_to_WRX_swap
tempting...
still thinking about it?
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Old 03-09-2005, 09:14 PM   #20
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its still in its original wraping, never opened.
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Old 03-12-2005, 07:48 PM   #21
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yeah, it would help to know what the compression will be after the head gasket swap however.
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Old 03-12-2005, 09:31 PM   #22
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so this would go on the 03 RS right? so it would be about 10.5:1 instead of 10:1
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Old 03-13-2005, 12:07 PM   #23
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yeah, ok thats what i thought...
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Old 04-08-2005, 08:19 AM   #24
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No need to yell.....You ever hear of the PM function??? I have 3 different thicknesses listed in that one post....which one are you talking about?

With the thinner ones, I think there are noticable gains over the stock thickness....but I don't have any dyno numbers. Many others have used these thinner gaskets.... maybe one of them will have concrete numbers. Cometic can tell you how much it will change, but I think the figure is about .3-.5....maybe a little more....

If you need a set, lemme know....I have one set of .027" left. Check with Crash477 first though, he wasn't going to need his anymore.


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Old 04-08-2005, 01:28 PM   #25
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Default I am interested.

Is 027" the thinnest head gasket available for the SOHC EJ25? I remember reading somewhere that the STI gaskets were even thinner.
Also, any issues with piston / valve interference using these thinner head gaskets with stage 2 cams?
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