Pondering a EJ25 w/ EJ22 SOHC heads hybrid. Learn me a bit!

[MCarp22]

Problem: 80WHP 3100lb wagon sucks at going up hills. The 4EAT is constantly going for 3rd gear, so the car spends 2-3 minutes above 4000rpm when traveling on the interstate. I think a bit of torque would help keep the cruise control honest.

Solution: A local mechanic friend of mine has a '98 EJ25 block sitting behind his shop. The headgaskets were blown so they swapped the whole motor. I was considering swapping my EJ22 block with the EJ25, keeping the SOHC heads and stuff.

Considerations:

What's different about the EJ25 block itself?
EGR the same?

10% more displacement ought to want 10% more fuel, the MAF ought to see the extra airflow though, right?

I figure the compression is 10.2:1 (calculated figuring a 41cc head, 14cc dished pistons and the thick SOHC head gasket). That won't be the the end of the world running on 93 with the conservative factory timing/tune.

So we'll figure on a 10% power bump from the displacement, and another 3% or so from compression ratio.

Discuss.

[AJM]

Huge open deck+more compression=blown headgaskets.

Not only that, but sensor spilcing as well.

[MCarp22]

Huge open deck+more compression=blown headgaskets.

Meh, I'm not intimidated by headgaskets. The aftermarket has pretty decent solutions available.


Not only that, but sensor spilcing as well.

What sensors are we talking about? I'd assume only the crank sensor would be in the block.

[AJM]

Huge open deck+more compression=blown headgaskets.

Meh, I'm not intimidated by headgaskets. The aftermarket has pretty decent solutions available.


Not only that, but sensor spilcing as well.

What sensors are we talking about? I'd assume only the crank sensor would be in the block.

True about the headgaskets, i'm not saying don't do it, I'm saying just know. Best thing you could do it get that block's deck closed....

I was thinking SOHC engine in a DOHC car, but your just swaping blocks and keeping heads,...so never mind, it'd work fine.


The only thing I can think of right now that might be a problem...is timing sprockets on the block. although i'm not sure that really makes a difference. Basically besides that, I think an ej25 block is the same as an ej22 besides bigger.

You need a manual...bad, 4eat suck so much power...I supose you can't right? Wifes car? Commuter?

[MCarp22]

You need a manual...bad, 4eat suck so much power...I supose you can't right? Wifes car? Commuter?

Yeah, Legacy is her daily driver, but i drive it anytime we go somewhere together.

[StatGSR]

its pretty much a bolt in affair, no notable differances in the 2.5 block from my understanding, and no wireing problems either. and yes it should run fine on a 2.2 ecu with premo in it. the only little issue there is from the headgaskets, the coolant passages for a 2.5 head dont entirely match up with the 2.2 heads, some people have drilled extra holes, and i think others didnt do much of anything about it and it worked out fine. but there was one guy on nasioc that talked to cometic about getting a 2.5 bore head gasket with 2.2 coolant passages which is probably the option i will go with then i build mine later this fall.

[MCarp22]

That's interesting to note, it shouldn't be a problem to drop the gasket on the head and figure out where coolant needs to go and drill accordingly.

[StatGSR]

^ yea but drilling through thin layers of sheet metal is tricky buisness. so just gota be carfull i guess.

[Jedi Taxi]

Deck the head mabye .025". you should get a decent bump in compression kpa from that, that way, you can run the 93 octane and be good too. Then just put on a cheap FPR from autozone (spectre brand) and crank up the pressure a bit. keep the knocking down.

I would have to agree with hondaman, The 2.5 MLS headgasket would work good with the combo set up. but wiring could become an issue. I would just change out the sensors, sense they all have the same ports. and use the matching computer.

Differences, the 2.5 has a bigger crank and a bigger bore. problems, when under boost, or lots of compression, cylinder vibration can occur and cause an unhappy engine. however, this happens upwards 12:1 kpa. Other than that, you should be good mechanically. Expect more torque.

[SammyDaFish]

I wouldn't bother.... the slight increase in displacement won't yield you much, add the minute increase in compression and it might give you a little, but still not worth the effort. You'll do all that work and get what, 10 20 hp and have to run premium.... not worth it.

What I'd do is take the whole DOHC EJ25 engine (assuming it still has the intake and all the sensors, injectors and stuff on it) Do the head job and run phase II ej25 gaskets (thin metal ones) the thinner gasket will give you a big increase in compression plus the EJ25 heads are far superior to the EJ22 heads. If you have the block and heads decked and use the good gaskets you will be able to avoid the blow head gasket issue that dohc ej25s have. The phase I ej25 will run fine off your stock engine management, all the sensors are the same.

If that engine you're taking had a lot of water in the crank case you might want to change the bearings in it before you use it too.