i have a 95 legacy with a bad head gasket. i thought it would a cool project to put my96-99 2.5 heads on it. has anyone put phase 2 ej25 heads on a phase 1 ej22 block. i know the intake manifold is different, but is there any other issues like exhaust, OBD-1/2 issues(like CPS) to worry about. should i even expect to see power gains without rebuilding anything in the block.

 

positive or negative, please post useful information only.

thanks

Well firsst off 96-99 2.5 is still a Phase I motor. (Thrust bearing on #3 main, DOHC)

 

Hmm......not sure what you will gain from that. Perhaps a bit more flow and HP on the very top end.....but my gut feeling is that you will not really notice anything signifigant and you may lose torque.

 

The more common hybrid is to do the opposite. 2.5 block (phase I or II) with you're original 2.2 heads and intake. this combo bumps the compression slightly, along with more displacement, and retains all the cars original sensors, ECU, wiring.

 

Others know more, may chime in. Check out NASIOC as well.

People have done this... to EJ22t engines to get more top end power. I haven't seen anyone do the swap on NA EJ22s. If you did it, you'd have to run a EJ25d ECU (or a piggyback or standalone) because your EJ22 ECU would get confused and you'd honestly not gain much power and you'd probably hurt your reliability.

 

Yeah, and phase I heads are DOHC and phase II are SOHC.

If you did it, you'd have to run a EJ25d ECU (or a piggyback or standalone) because your EJ22 ECU would get confused and you'd honestly not gain much power and you'd probably hurt your reliability.

 

 

 

I don't think ECU management would be an issue.

 

The displacement of the motor would still be the same.

 

Cam Sprocket may need swapped, but otherwise I am sure the 2.2 ECU could run the engine fine. Only thing that would change is the heads.

 

Still vote no for the idea......but the ECU wouldn't be any issue.

thanks guys, this info helps. if i dont attempt to put the 2.5 heads on, does anyone know of after market cams for a sohc, i can't seem to locate any. and/or is it worth porting the heads and intake mani. i know this isnt the best car to try and get massive HP gains but its a daily driver and i wouldnt mind at more power if i'm already going to do the work

Honestly, if you're pulling the motor out to do headgaskets, get a 2.5l that needs headgaskets. Do the headgasket job, drop it in instead of the 2.2 and you'll get a 30hp boost right there.

 

DOHC heads on a 2.2 will DROP the compression ratio... good for more boost if you're running a turbo, not good if you're not. So, if you're putting a homebuilt turbo setup on it, it's a good thing. If you're not, don't.

 

Putting 2.2l SOHC heads on a 2.5l block will raise the compression, to the point that you need to run premium all the time. But, it does pull way harder on the bottom end, which is where most motors spend their time. Your butt-dyno will be very pleased with this combo.

 

There are lots of 2.5l engines out there with blown headgaskets. I got my last shortblock for $20. The guy I bought it off of wanted to keep the heads so he could send them out to be machined. That way, the next blown 2.5 he gets he has a set of heads ready to go.