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Old 09-23-2008, 02:31 AM   #1
subyboy
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Default EJ22t with 2.5L DOHC heads question.

Hello all, I am working on putting DOHC rs heads on my 2.2l turbo block. Now I have a question, I was thinking of using the thin sohc head gaskets to reach a calculated compression ratio of 8.0:1, the thing is I read on another thread in this section is that the EJ22t's pistons are not flush with the deck of the block. I was wondering if what read was true and if I have a problem with the pistons contacting the head. Thanks in advance.
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Old 09-23-2008, 05:10 AM   #2
reddevil
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Once the heads are off, simply crank the motor over by hand and see how far the pistons emerge from the case.

I used standard NA 3ply metal head gaskets mysefl..
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Old 09-23-2008, 12:22 PM   #3
subyboy
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OK, with using the 3ply metal head gasket, what is the caculated comp ratio?
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Old 09-23-2008, 02:08 PM   #4
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I used the thin gasket but it's very minimal head clearance! something like .015 -.017?

I think I used the Phase 2 2.2gasket?

Ran on the rev limiter (6500rpm) for more than a year racing & playing and had no problems.

Check your piston positive deck and choose a gasket.
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Old 10-06-2008, 01:30 PM   #5
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I use the EJ25D head gaskets. If you by chance float a valve, you will want the extra few tenths of a millimeter. Especially important depending on which cams you are running. If you run the stock 25D cams, they have a very close piston to valve clearance, hence the reason for wanting a little extra room. Why are you so interested in the calculated compression? Just wondering?
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Old 10-10-2008, 12:41 AM   #6
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If you use the stock EJ22T block and the thick HG, you will be at 7.5:1 CR. That is a little bit low, IMO.

If you swap in N/A EJ22 pistons, you go up to 9.0:1 CR. But I would definately be wary of close piston to valve tolerance.

You really should match the gasket you use to the bore of the block you use. (EJ22X)


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Old 10-13-2008, 11:03 PM   #7
aznjoker604
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ok im going to be ordering wiseco pistons and k1 rods, which ones do i need to order to achieve 8.0:1 compression ratio? also which gasket would i need to use? Ill be mating the ej22t to ej20k heads which i believe are 47cc vs the 49cc usdm heads
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Old 10-14-2008, 09:12 PM   #8
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If you can tell us what the piston dish is on the wiseco's, and what head you are using (and how many cc's the comb. chamber is) I can get you the CR. Or you can do it, google compression ratio calc. and pick which one you want to use. I use the darn thing every week.

But if the heads are 47cc's, and if you use stock dished pistons (28cc's), along with the stock stroke (75mm), and stock bore (96.9mm), with the stock HG thickness (1.52mm), with no piston above the deck, and no rod length changes (stock is IIRC, 5.135'', 130.47mm) I calc. you get 7.4:1 CR, if you swap in pistons that have less dish or use a head with less comb. chamber volume your CR will go up.


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Old 10-15-2008, 12:17 PM   #9
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I am using stock '03 WRX heads 48cc? and STOCK EJ22T pistons with 97-98 EJ22E headgasket. I run just fine. I think my CR is 8.35:1 according to someone a while back. I have no problems really... car pushes 20psi daily on my EVO3-16G-8cm^2 and 285whp via Mustang Dyno. 20psi comes in at 3700rpms on a 4th gear pull; JDM STi DCCD 6spd.

The '97-'99 EJ25D heads have higher compression heads than the 95-'96 EJ25D; Legacy Lsi/2.5GT.
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Old 10-16-2008, 02:13 AM   #10
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so you can run the thinner ej22e head gasket without any problems? some people have been saying the pistons may hit the head on the thinner gaskets
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Old 10-16-2008, 03:44 AM   #11
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fuji k, if you were to buy aftermarket pistons, do you stay with 8.5 compression ratio design?
id like to purchase wiseco pistons, the ones designed for the ej22t are for 8.5 compression ratio, do i just purchase these?
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Old 10-16-2008, 10:15 AM   #12
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Quote:
Originally Posted by aznjoker604 View Post
fuji k, if you were to buy aftermarket pistons, do you stay with 8.5 compression ratio design?
id like to purchase wiseco pistons, the ones designed for the ej22t are for 8.5 compression ratio, do i just purchase these?
I've been wanting to go somewhere 8.5:1 or even 9.0:1 CR. Lower staying with 8.5:1 is a bit safer for pump gas. You can always tune it running 9.0:1, which I WANT to go with but we'll see if it'll go well with a GT3076R setup on pump gas...ekkk!! Don't want Detonation....

Yes, I'd stay with a 8.5:1. Hopefully that correct for the head setup you are going to run with. The '95-'96 2.5L DOHC heads have more cc in the cunbustion chamber than the 97-99 2.5L DOHC. My WRX heads have more cc as well. Pistons must be according to head setup.
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Old 10-16-2008, 06:31 PM   #13
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I just purchased ej20g heads, so I was wondering the head cc's were on those heads.
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Old 10-16-2008, 11:43 PM   #14
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Quote:
Originally Posted by subyboy View Post
I just purchased ej20g heads, so I was wondering the head cc's were on those heads.
You'd have to see if the combustion chamber is clovered or not.
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