Destroked EJ25

Josh Long · Post by **Josh Long** » Sun Mar 12, 2006 5:23 am

Unless anyone can come up with a good reason not to..... I am building up a phase one EJ25 block with the crank and rods out of a EJ22t. This will effectively destroke the EJ25. This looked to, in the mock up to be a really cheap way for me to build a turbo motor for my outback. I will only need to pick up some rings and perhaps a set of main bearings. I will be using the dished EJ25 piston, and the thicker headgasket, as well as the DOHC heads.

The only detractors I can think of is oil squirters (easily fixed), and the open deck (I only plan on running around 14LBS).

Splinter · Post by **Splinter** » Sun Mar 12, 2006 5:27 am

Why not use the EJ22T block?

Josh Long · Post by **Josh Long** » Sun Mar 12, 2006 5:33 am

I do not have one that is free like the rest of the parts. I would gladly use one, you got an extra?

This is going into a 97 outback wagon.

206er · Post by **206er** » Sun Mar 12, 2006 6:26 am

should rev nicely

entirelyturbo · Post by **entirelyturbo** » Sun Mar 12, 2006 2:20 pm

Well, I was under the impression that all EJ engines thus far have had the same stroke, only different bores, but my Haynes manual seems to say otherwise.

Matt Monson hopefully will chime in and most likely suggest you use a different block.

BAC5.2 · Post by **BAC5.2** » Sun Mar 12, 2006 7:19 pm

Isn't crank throw the same, but rod length is different.

Running EJ22T rods will give you, roughly, the EJ22T setup but with open deck. 8.0:1, 14psi, open deck... The WRX does it. I don't see why it wouldn't work for you.

206er · Post by **206er** » Sun Mar 12, 2006 11:20 pm

if you can use a ej25 crank to stroke an ej22, than no, the cranks do not have the same throw.
the deck height is the same however, which is why the ej25 rods are shorter.

Josh Long · Post by **Josh Long** » Mon Mar 13, 2006 1:18 am

The cranks for the EJ 25 are 79mm and the EJ 22 is 75mm.

Josh Long · Post by **Josh Long** » Mon Mar 13, 2006 1:23 am

BAC5.2 wrote: Running EJ22T rods will give you, roughly, the EJ22T setup but with open deck. 8.0:1, 14psi, open deck... The WRX does it. I don't see why it wouldn't work for you.

Are you confident of this compression number? What heads / version of pistons NA dished phase 1, or NA flat top phase 2 / and headgaskets did you factor in to come to this compression ratio? This is pretty much what I was shooting for.

After the mock up it sure looks like it should work great.

206er · Post by **206er** » Mon Mar 13, 2006 2:16 am

you want this:
http://wac.addr.com/auto/obs/turbo/ejcalcs.html

Josh Long · Post by **Josh Long** » Mon Mar 13, 2006 2:26 am

Perfect, thanks 206er!!!!

Josh Long · Post by **Josh Long** » Mon Mar 13, 2006 3:06 am

This is awesome after juggling some numbers it looks like I can have my choice of 7.7 or 8.3 to one.

8.3:1 should be rocking!!

One last question can anyone make a case with there being a quench issue due to the piston being 2mm below the deck?

franticfour · Post by **franticfour** » Mon Mar 13, 2006 4:38 am

206er wrote:if you can use a ej25 crank to stroke an ej22, than no, the cranks do not have the same throw.
the deck height is the same however, which is why the ej25 rods are shorter.

In order to stroke the 2.2 w/2.5 crank you must use custom pistons to keep the deck height correct.
The stroke is 4mm longer or 2mm up in the bore and the 2.5 rods are only 1mm shorter.
Eric

Matt Monson · Post by **Matt Monson** » Mon Mar 13, 2006 5:14 pm

I've talked to a few guys who are looking at doing this, but can't claim to have any personal knowledge about how it would work...

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Destroked EJ25

Destroked EJ25