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Old 05-31-2000, 11:04 AM   #1
Kyle Paton
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Lightbulb Question for Shiv

Shiv,

What is your thought on higher comression pistons for my EJ25 engine. I want to stay all motor and currently have:Borla Headers, stromung int. pipe and dual tip exhaust, UR pulley and am waiting for the Cobb tuning intake.
Please let me know if this is a wise or worthwile mod.
Thanks
Kyle

Good job on the mag
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Old 05-31-2000, 01:32 PM   #2
shiv
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Hi Kyle,

Thanks but I'm afraid I have very little firsthand experience on internal engine upgrades. All things equal, high CR will improve across the board power and throttle response, potentially requiring the use of premium gasoline. But high CR pistons, with labor, is quite pricey and may not give you as much bang for your buck as you'd like. Hope that helps (probably not).

shiv
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Old 05-31-2000, 01:35 PM   #3
8Complex

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Just a thought, I believe you can shave the surface of the heads and achieve higher compression as well, just not as much as changing internal components (unless you're nuts and take a lot off).
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Old 05-31-2000, 03:02 PM   #4
Wreckleford
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.

[This message has been edited by Wreckleford (edited May 31, 2000).]
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Old 05-31-2000, 03:05 PM   #5
Wreckleford
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I am not familiar with Subaru head gaskets, but with Hondas, the gaskets are made of three layers. You can separate them and use just the center layer for an easy way of increasing compression. It sounds a bit risky, but apparently it works without any side effects.
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Old 05-31-2000, 03:55 PM   #6
ColinL
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It would be wiser and less time consuming to use brass gaskets. PeteH (a legacy turbo guy) was attempting to hawk some a few months back in various compressed thicknesses.

I doubt any RS owners bought a set.
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Old 05-31-2000, 08:16 PM   #7
Aspen
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Wreckleford,

You've been hanging around too much on the Hybrid board. B16a gasket trick, been there, done that. Quasi-Spoon head gasket at half the price.

Now I wish that HKS or JUN would make a thin metal head gasket for the EJ25.
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Old 05-31-2000, 08:20 PM   #8
The_extreme
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I beleive a company called Payen do a thinner head gasket for just such a purpose - not sure if U can get them in the US though.

cheers

Jeff
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Old 06-01-2000, 06:33 AM   #9
svxtrem
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Subaru's have a negative deck height. The piston actually sits above the head surface. The head gasket is especially designed to give about .040 of clearance so as to provide a good 'squish' area. A thinner gasket will not appreciably raise the compression and may cause the pistons to contact the head.
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