STI frankenmotor

[Aluxes]

Hey need some advice.....so I found a local wrecked 04 sti. Engine has 140,000. Owner sold the intake and turbo. Wondering if I can drop my 2.2 heads and intake on there and drop it right in place of my 2.2 block and just keep it n/a for now? My car is a 97 obs. Would the ecu and atock wiring work? Also the car was in a front end collision and the driver's side timing cover was crushed. Will the head be ok, or is there some type of other damage I should look for? Thanks!

[fishy]

I'm sure I'll be corrected if wrong but I think the STi would be built with a lower compression ratio than a regular 2.5L. So you probably wouldn't gain any power from frankenmotoring it up with 2.2 heads.

I suppose if you were going to make your own frankenmotor turbo setup that might be a good block to start with though.

 

 

Hey need some advice.....so I found a local wrecked 04 sti. Engine has 140,000. Owner sold the intake and turbo. Wondering if I can drop my 2.2 heads and intake on there and drop it right in place of my 2.2 block and just keep it n/a for now? My car is a 97 obs. Would the ecu and atock wiring work? Also the car was in a front end collision and the driver's side timing cover was crushed. Will the head be ok, or is there some type of other damage I should look for? Thanks!

Edited November 15, 2014 by fishy

[Bushwick]

The 2.2L heads on the 2.5L block raise the compression. The STi has a 2.0L, correct? You'd probably go backwards with lower compression to a lazy 8 something to 1, which isn't good. Although, if the 2.2L heads had larger valves and flowed more, top-end might be better. But low-end would probably suffer from lowered velocity. If you could get the 2.0L pistons to around a still street-friendly 10:1, it'd probably make decent NA power. Hopefully someone more knowledgeable will pipe up as you might have intake or EGR issues. A 2.5L block most definitely still be better as the extra .5 L  will make more torque, which is a must for the AWD cars.

[86BRATMAN]

The STi is the ej257,you would raise the compression ratio to about 10:1 with ej22e heads. But that would be a giant step in the wrong direction, the ej22e heads are not good flowing. Your best bet would be to grab up the engine and save it for a later date when you have the time and money to swap the car properly.

[fishy]

Bratman's comment about saving the motor for another project made me also think: if you can get it for filthy-cheap you could 'invest' in it and sell it on to some hotrod kid who blew up his motor or to someone else wanting to build a turbo project later on. 

You could also get the front bucket seats out of the wreck and put them in your car for a nice upgrade.

[Bushwick]

The STi is the ej257,you would raise the compression ratio to about 10:1 with ej22e heads. But that would be a giant step in the wrong direction, the ej22e heads are not good flowing. Your best bet would be to grab up the engine and save it for a later date when you have the time and money to swap the car properly.

 

STi is a 2.5L? Didn't realize. Why would it not work like any other Frankenmotor with EJ22 heads? Other than cam profiles, what's exactly wrong here? It'd be bullet-proof with the STi internals.

 

You could try and NA that engine then. I was forced to NA my Saab's 2.0L one summer when the factory turbo went and I sold my other car and was rebuilding and uprating the factory unit. Without boost, they act like a normal NA engine IF you run an NA exhaust and air filter. Timing might be a little low with the stock ECM in the higher revs. That's if it's in the STi. In yours, it'd probably make HP somewhere between what an EJ22 and a typical EJ25 makes, figure the low 130's to the upper 150's NA. Cam profile will favor the turbo; probably a little boring for NA.

 

If you can make your sensors work with the EJ257, mount your exhaust and intake, run a coolant bypass hose to the old turbo coolant inlet/outlets, and block off the old turbo's oil inlet (it's very high pressure, a rubber hose with a bolt won't work. Needs truly blocked off at the plate), and either run an NA oil pan OR find a way to seal the drain-back tube (assuming the pan clears your exhaust), the engine will run OK if it's anything like other "turbo" engines. Don't expect to win any drag races. Bypassing ALL boost in a turbo engine is sorta the same thing, though exhaust still gets held up in the turbine housing which can parasite 15-25hp minimum and a bunch of torque, not too mention top-end hp loses and overly retarded timing.

Edited November 17, 2014 by Bushwick

[86BRATMAN]

The STi pistons are pretty weak in stock form, they crack ringlands with small amounts of detonation, not something I'd call bullet proof. The biggest problem here is the ej22e heads, not the bottom end. But people love the heads so I'm not getting into that discussion.

 

You will not be able to run the ej22e heads off the STi ecu, that would require more work than it would be worth. Full wiring harness merge, change out the gas pedal to throttle by wire sensor and wiring, ecu, all related sensors must be used.

[Bushwick]

The STi pistons are pretty weak in stock form, they crack ringlands with small amounts of detonation, not something I'd call bullet proof. The biggest problem here is the ej22e heads, not the bottom end. But people love the heads so I'm not getting into that discussion.

 

You will not be able to run the ej22e heads off the STi ecu, that would require more work than it would be worth. Full wiring harness merge, change out the gas pedal to throttle by wire sensor and wiring, ecu, all related sensors must be used.

 

STi are weak? I just assumed they put forged internal in being the premium version.

 

 

I wasn't suggesting he use the STi ECM. If he can get the EJ257 to fit up with his sensors, he could run the engine NA after blocking looping the turbo coolant lines and block off the oil. If it was cheap enough, it might be worth the effort.

[86BRATMAN]

I'd put more faith in an ej22e block with ej25d heads than I would an unbuilt ej257, my buddy has a '14 model that had its engine replaced under warranty a few months ago at 9k miles completely stock because of ringland failure.

 

The running the complete motor off an ej22 ecu won't happen. Timing triggers are different, injectors flow roughly double the amount of fuel, throttle body is motorized not cable actuated, no place to bolt up a phase 1 idle air control valve, etc.

[Bushwick]

I'd put more faith in an ej22e block with ej25d heads than I would an unbuilt ej257, my buddy has a '14 model that had its engine replaced under warranty a few months ago at 9k miles completely stock because of ringland failure.

 

The running the complete motor off an ej22 ecu won't happen. Timing triggers are different, injectors flow roughly double the amount of fuel, throttle body is motorized not cable actuated, no place to bolt up a phase 1 idle air control valve, etc.

 

So you are saying an EJ257 shortblock with just the heads and block can't be adapted? Are the mechanicals of these engines the same i.e. same general bolt hole locations for intake manifold, headers, etc.? (just want to know)