Questions about Frankenstein EJ25.........i did search BTW

[ballitch]

Im new to this board but have been around nabisco and USMB for about a year or so. seen alot of info and threads about the EJ25 block/EJ22 heads frankenstein motor, but first background info.



i have a 98' legacy sedan with the super-reliable EJ22, been wanting more power for quite some time. i know ill have to run premium gas and all that jazz, the 11.5:1 CR is awesome and with some cams i think it will be even better. im aware of the HG issue with the phase I EJ25, and frankly, i dont care, if i can drive the car for 50k and replace one set of HG's, fine by me. i know Matt Monson has done this, and probably by now many more have too. i heard about a 4-layer HG, and to make sure to use the EJ25 one, but i want better high RPM power, EJ22 falls on its ass around 5k, only revs to 6k, trying to go 120 mph, on a long road takes way too long. my goal is 190 crank HP, seeing as the EJ25 comes with 165, and the 11.5:1 CR will raise that about 8-10%, throw in some cams, and i see it becoming possible. any advice or flaming is fine by me, need to know what im in for and if you know something about this, please say your piece. i would like to use the delta re-grinds, because they're so damn cheap. one more question, do i have the phase II EJ22 heads, pretty sure i do. forsee any problems/conflicts?


~Josh~

[douglas vincent]

From the many posts I have read, (no personal knowledge), raising rpm range is hard and exspensive.

190 chp is a lowly number. Not saying that mean, but if you are going to do all that work, I suggest shooting a little higher.

And to push the Forced Induction belief. 3 psi will get you to or over 190 chp. And 3 psi doesnt require anything BUT a turbo/SC.

[ballitch]

thanks for your input, i thought about turbo, but i would need a reliable block/head combo to fully appreciate it, is the phase I EJ25 a semi reliable candidate for turbo? maybe like 6 psi max. but 6 psi would get me like 40% more power, but im thinking along the lines of hp per dollar. how about i do the frankenstein motor, and 2-3 pounds of boost, i have a TD04 off a wrx laying around, just need up-pipe, downpipe, exhaust manifold, engine crossmember, and some sort of way to make the thing run off of EJ22 ecu. and i dont want to throw away $4000 for 6 psi from the avo turbo kit....so options anyone?




~Josh~

[ballitch]

and BTW what does SC stand for.........acronym im not aware of.





~Josh~

[douglas vincent]

Sorry, I thought you had the 2.5 to start with, therefore 3-4 psi = 190 chp. I was able to get 200-220 chp with 7 psi but havenet spent the money on engine management. Boo hiss.

SC = Supercharger.

[BAC5.2]

And on the turbo front, I made roughly 214whp and 251lb-ft on 16psi (with a cat, no oxygen sensor, and a horrible excuse for an intercooler). I should be closer to 225whp, and 265lb-ft at the same boost now.

[Matt Monson]

Okay. A couple of things to clarify. If you go with a phase I Ej25 bottom end, you will be at around 10.8:1 CR. This is the only engine that I have built (a couple of them at this point) and have only done them with EJ22E phase I heads. I know a guy on NASIOC who did a phase II EJ25 bottom end with phase II EJ22 heads. He's pretty happy with it. Running the phase II botom end should put you right around 11.4:1 CR on stock head gaskets.

The phase II heads do flow marginally better than the phase I heads. With the hybrid engine w/cams, and all the standard bolt ons (headers, high flow cat, cat back, intake) you'll hit that 190chp number. We never got Bohdi's car on the dyno before we tore it down, but I am pretty confident he was right around 200 at the crank.

On that kind of compression, you wouldn't want to boost it (neither turbo nor supercharger) on top of it. It would require really good engine management to keep from blowing it up. If you are thinking of boost, just boost the car as is. FAT makes a kit that is about a $1000 less than the AVO kit. The price difference is really EM. But for a 5psi turbo, you can go without electronic EM...

[greg donovan]

i too have been told that if you keep the boost in the 7 psi range on a ej22 you have no need for engine management.

[ballitch]

so youre saying that there would be no real threat of leaning out, with 50% more manifold pressure and air volume going into each cylinder? i find that hard to believe, but ive been told by a few people before that less than 7 psi would not cause TOO much more damage. what is the difference that makes the phase II EJ25 block have 11.5:1 CR? is it in the pistons or do the pistons come out of the block slighty or what? thanks for all your input guys. hate to say it, but might juist have to go turbo. But im not giving up yet.




~Josh~

[douglas vincent]

Without EM, or ignition timeing control of some sort, DO NOT go over 5 psi. It may not knock....But....I have two shot motors to prove otherwise. 7 PSI and no EM and 9.5-1 compression is great. Until it detonates.

[douglas vincent]

On the plus side of high compression.

IF you can get EM, then you can get HIGH hp per boost psi up to 12 psi. Technically.

I am at 200-220 chp for 7 psi. The stock 7 psi turbo motor is 160 chp. BIG DIFFERENCE. I have dyno proof of 152 whp on a Mustang dyno for 7 psi and thats with a bad plug wire AND a shot fuel tank sock.

But, since I have at least one warped head now, and the motor finally needs to have its cylinders honed out, and bearing replaced, I am swapping to a "gently used" turbo block and dropping down to 8-1 compression. I think I will live with this low power (in comparison) motor and rebuild the NA block, but machine the NA pistons to 9-1 compression, and then, with the PP installed, reinstall that block and see what happens.

Bench top racing at its best.

[Matt Monson]

ballitch,
The 11.5:1 CR comes from your heads having a smaller combustion chamber volume than the Ej25 heads.

Also, since you have phase II Ej22 heads, you CR would probably be more like 11.2:1 (guess without actually doing the math. Your heads have a 41cc chamber volume. The phase I Ej22E heads are 40cc's

[greg donovan]

this is a site you should familiarize yourself with:

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

[Matt Monson]

But always do your own math when referencing Ejcalcs. There are some calculation errors there...

[irishsetter]

I would say your best bet hp wise is ej22 block with 2.5 head and bottom end. I know a lot of wrx guys that run this setup and push the upper 200s. Depending on the turbo. I think you can run all stock 2.5 crank heads( ported is better) and some decent pistons and rods with the TD04 and run a 2.5 ecu. That might put you in the 200 range. Please correct me if I am wrong because this is the plan for my car.

[ballitch]

Okay. A couple of things to clarify. If you go with a phase I Ej25 bottom end, you will be at around 10.8:1 CR. This is the only engine that I have built (a couple of them at this point) and have only done them with EJ22E phase I heads. I know a guy on NASIOC who did a phase II EJ25 bottom end with phase II EJ22 heads. He's pretty happy with it. Running the phase II botom end should put you right around 11.4:1 CR on stock head gaskets.

wait a second.......you're saying i can throw the EJ25 crank, con rods, and pistons into the EJ22 block, but the bore on the EJ25 block is bigger than the EJ22, so do i use the EJ22 pistons instead? i also noticed that the EJ25 conrod or crank has more leverage than the EJ22 crank, kinda like putting 400 smallblock checy internals into a 350 block and getting a 383 C.I. with a longer stroke. But, the final word is EJ25 phase I block, EJ22 phase II heads = 11.2:1 CR? but before you said 10.8:1 CR......is it because of the 1 cc increase in head volume that makes the difference, if someone could please do the math for me, sure some one has it worked out already, that would be very helpful. once again, thanks for all the info. oh one more thing, i cant use the thinner EJ25 HG for this application can I? i woiuld like to keep the CR to a more "plus grade" fuel level if possible, 11.2:1 seems a little lofty to run just "medium" grade fuel.



~Josh~

[Matt Monson]

re-read it. You are confusing phase I and phase II bottom ends. The phase I bottom end is the 10.8:1 and phase II is 11.2:1 The piston dish is smaller on the phase II.

As for the other about using an EJ25 crank in an EJ22? It has been done, but I don't recommend it. Only a phase I EJ25 crank will work in the EJ22 bottom end. You would use your stock rods and pistons. Displacement is 2.35l. That's a lot of work for .15l gain when just using the Ej25 block complete gains you .3l

[ballitch]

sounds like a done deal to me.........ill be getting the shortblock in 9-10 days......so i have that long to fix my 86' GL wagon........the wagon with a EJ22 under the hood........






~Josh~