WRX heads vs. JDM ej20g

Do It Sidewayz · Post by **Do It Sidewayz** » Mon Jun 12, 2006 10:58 pm

i am planning to build a EJ22T with new rods and pistons, then top it all off with JDM EJ20G heads (i think they are ej20G heads).

I have been talking with a guy who is selling CP pistons, and Cometic gaskets, which i believe to be thinner in order to bring the compression ratio back to liveable numbers.

Are the CC's of both heads similar?? would i be able to use these head gaskets??

Matt Monson · Post by **Matt Monson** » Tue Jun 13, 2006 4:39 pm

Ej20G heads= 57cc
Ej205 heads= 45cc

tris91ricer · Post by **tris91ricer** » Tue Jun 13, 2006 8:46 pm

Question:

Does the cc of the heads count toward the total cc?

For instance, 2212 is the cc of the ej22t, but are the ccs of the heads counted in that?

I'm sure the cr could be calculated from these numbers/variables -- How?

I guess I don't quite understand how the heads work (on a physical level). . .

206er · Post by **206er** » Tue Jun 13, 2006 11:09 pm

displacement is how much air the pistons displace as they move, so this does not include the piston volume, head volume, or head gasket volume.
CR=total volume inside the cylinder with the piston at BDC devided by the total volume with the piston at TDC.

thehookeup · Post by **thehookeup** » Wed Jun 14, 2006 12:59 am

with the stock internals on the 2.2t short block with the 20g heads. its a great match. i know a lot of people say that the CR drops a lot . and it drops a lot of low end power.. but it with my TD04 it only lags to 3 grand and then i have power all the way. and even 1000-3000 it still is kinda of torquey. and if i ran a better turbo it would kick ass even more. 22t short block, 20g heads and a new vf34 or 39 and it will be awesome...

as far as the cc's go i agree, they are 57cc. , and the 20g heads are different, from the 22t sohc heads. but you can use the stock 22t head gaskets.

i also agree with 206er

tris91ricer · Post by **tris91ricer** » Wed Jun 14, 2006 10:27 am

Haha, your build is opposite mine! I have the ej20g sb and stock turbo heads!

I got most of my questions answered with a nice 2.35 stroker block as an example while I was kickin' it at Frantic Four today.
Thanks Eric!

Matt Monson · Post by **Matt Monson** » Wed Jun 14, 2006 3:47 pm

tris91ricer wrote:Haha, your build is opposite mine! I have the ej20g sb and stock turbo heads!

That's a great combo. I built one of those for a customer. It's right about 9:1 and with a teeny little VF-11 it's got a nice solid flat torque curve. My only regret is the bonehead I built it for blew it up with a stupid mechanic's error. It would have been the perfect auto-x car...

I also favour the Ej20G heads on an Ej22T with a big fat turbo. I too think all this talk of CR's is overrated.

One last thing to add, is that any set of WRX heads from '00+ will be a challenge to make work on an old Legacy. This is because of changes to the cam gears and timing marks. A couple of members have tried to make it work, and I have yet to see a documented success. If someone works the bugs out, I hope they post a blow by blow so others can see how to make it fly...

Also, I think that the "original" high power formula is being overlooked. DOHC Ej25 heads on the Ej22T. It's a great option and an easy conversion. Search for napphappy's recent thread on the subject to get the details of how to modify the heads for the oil and coolant to feed the turbo. They are basically the same castings as 97-98 EJ20K/EJ20H heads, and do have the smaller combustion chambers for those concerned about CR...

thehookeup · Post by **thehookeup** » Wed Jun 14, 2006 9:45 pm

One last thing to add, is that any set of WRX heads from '00+ will be a challenge to make work on an old Legacy. This is because of changes to the cam gears and timing marks. A couple of members have tried to make it work, and I have yet to see a documented success. If someone works the bugs out, I hope they post a blow by blow so others can see how to make it fly...

what do you mean?, i thought all you had to do with the 00+ wrx heads was drill out a couple of coolant passages? and then what did they do different to the cam gears so that it wouldnt work?

Do It Sidewayz · Post by **Do It Sidewayz** » Thu Jun 15, 2006 4:19 am

well. the guy is selling custom made CP pistons, with a set of Cometics that from what i can gather are thinner, in order to bring up the c/r for WRX heads. He tells me the C/r with the WRX heads will be around 8.5:1.

heads are coming off the ej20 i had in the car which threw a rod bearing. I don't know forsure that it's an ej20G, as i don't have it apart yet. But...the motor came from a JDM legacy..and came with a computer that said 1996 Legacy... The motor had a black WTA i/c on it, coil on plug ignition, and grey 440CC injectors

this motor is going to be used as a rally motor. so bottom end grunt is a nessessity.

Turbo will be a completely monsterized wrx TD04 turbo.

thehookeup · Post by **thehookeup** » Thu Jun 15, 2006 5:17 am

haha monsterized? i like that. but with all my expeirence with rally motors. is constant high rpm. never do i drop low into the power band. i stay around 5 grand to 7 grand. i guess its all preference

napphappy · Post by **napphappy** » Thu Jun 15, 2006 7:17 am

If it has a single turbo and a AWIC it is from a Pre 94' JDM(or almost anywhere besides the US) Legacy.
If the ECU has 4 yeallow plugs, the "1996" is a typo

tris91ricer · Post by **tris91ricer** » Thu Jun 15, 2006 8:59 am

Matt, you were a good part of the reason I got this setup. I'm muey impressed. I love it.

Its a great drive and very punchy when its not throwing codes. I'm still fighting my vss and iac valve.

Do It Sidewayz · Post by **Do It Sidewayz** » Fri Jun 16, 2006 3:57 am

thehookeup wrote:haha monsterized? i like that. but with all my expeirence with rally motors. is constant high rpm. never do i drop low into the power band. i stay around 5 grand to 7 grand. i guess its all preference

that holds true for the roads you guys have out in Oregon...but here we've got some nice twisty stuff.

PLus with the 34MM restrictor...top end grunt is basically thrown out the window.

Monsterized is right...it's getting a 19G compressor wheel, ported and oversized wastegate, plus a pile of other tricks.

In regards to the EJ20...the computer we got with it must have been a mistake as it did not have the 4 Yellow connectors, instead it had a big "terminal block" with a 6 mm bolt holding the connector to the computer

Arctic Assassian · Post by **Arctic Assassian** » Sat Jun 14, 2008 2:34 am

ok so. My tech friend is telling me I can put ej205 heads on my 2.2 and run it with my 2.2 ecu... I know this to be untrue, but I don't know why. Could someone, like matt, explain in detail why I cant just bolt em on.

PhyrraM · Post by **PhyrraM** » Sat Jun 14, 2008 6:58 am

Matt Monson wrote:
One last thing to add, is that any set of WRX heads from '00+ will be a challenge to make work on an old Legacy. This is because of changes to the cam gears and timing marks.

Arctic Assassian · Post by **Arctic Assassian** » Sat Jun 14, 2008 10:59 pm

Yeah, I can read too. But that doesn't show me the differences. Yesterday, I put the two setups side by side, and I think I figured out how to run ej205 heads on my computer.

BXSS · Post by **BXSS** » Sat Jun 14, 2008 11:16 pm

Funny thing about the EJ20G heads + ej22t shortblock - if the CR is about 7.8ish:1 (not sure that it is 7.8:1) that would put it @ the same CR as the 6 bolt (non crank walking) 4g63s from the GVR4 & Eclipse.

Although the CR is a little low by todays standards you should be able to push alot of boost through the motor...

PhyrraM · Post by **PhyrraM** » Sat Jun 14, 2008 11:27 pm

Arctic Assassian wrote:Yeah, I can read too. But that doesn't show me the differences. Yesterday, I put the two setups side by side, and I think I figured out how to run ej205 heads on my computer.

I *think* the number and location of the pulses on the cam sprockets changed on EJ205s. I *know* they did for the crank position sensor.

Arctic Assassian · Post by **Arctic Assassian** » Sun Jun 15, 2008 12:19 am

I wish i had ej20g heads.

93forestpearl · Post by **93forestpearl** » Mon Jun 16, 2008 7:45 am

Ya the crank and cam position sensors are different on the new stuff. You need the newer ECU and wiring for it. One benefit would be the ability to do some open-source tuning, ie RomRaider.

Don't forget that the EJ22T's pistons protrude by, I wanna say .020. At the moment I don't have a 22T shortblock that is together for me to measure. If you go too thin on the head gasket things will touch each other that shouldn't. When I put the EJ25D heads on that I picked up, I'm gonna use the .051 Cometics. The stock gasket is .059. With the the smaller dish of the Wiseco's I have, I should be at or a hair above 8.0:1. I'll miss the off boost luggability of 8.5:1 and the torquey 22T heads, but meh, I'll get over it.

ciper · Post by **ciper** » Mon Jun 16, 2008 7:50 am

Anyone know the resulting compression ratio from an EJ25 with EJ22NA dual port exhaust heads?
Is there a difference between phase 1 and phase 2

93forestpearl · Post by **93forestpearl** » Mon Jun 16, 2008 8:04 am

I've heard you end up with a higher compression ratio, like maybe into the 11's. I don't know for sure. My buddy is supposed to be working on this. Maybe check RS25?

ciper · Post by **ciper** » Mon Jun 16, 2008 3:46 pm

I used the specs from http://wac.addr.com/auto/obs/turbo/ejcalcs.html with the calculator http://www.bgsoflex.com/cr.html -
* Cylinder head Volume (CC) = 40.00
* Piston Top Volume (CC) = 14.00
* Cylinder Bore (Inches) = 3.9
* Cylinder Stroke (Inches) = 3.11
* Deck Height (Inches) = 0.000
* Head Gasket Thickness (Inches) = 0.060
# Computed Compression Ratio is 10.3 to 1

If I use the SOHC gasket thickness of 0.023 # Computed Compression Ratio is 11.5 to 1

For fun I entered the stock EJ22 specs -
* Cylinder head Volume (CC) = 40.00
* Piston Top Volume (CC) = 14.50
* Cylinder Bore (Inches) = 3.8
* Cylinder Stroke (Inches) = 2.95
* Deck Height (Inches) = 0.000
* Head Gasket Thickness (Inches) = 0.060
Computation Results:
# Computed Compression Ratio is 9.4 to 1

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

WRX heads vs. JDM ej20g

WRX heads vs. JDM ej20g