Engine swap JDM EJ25 STI engine

[1086]

That was my assumption when Crawford described their (vague) test results with their brz. EJ runs at its cr because that is where it is optimal - likewise with the FA - it has a high cr because that is where it is arguably optimal.

[TeamZleep]

More torque and no direct injection... Sounds like a winner to me.

[xwd]

So first of all the JDM STi doesn't use a 2.5L engine, it still uses the EJ207 2.0L engine it always has.

Second if you ran the EJ257 at 12.5:1 CR on anything but E85 or low boost it would detonate itself to death in about 15 minutes. It has a hard time not detonating at 8.5:1. DI goes a long way...

The FA20 is superior to the EJ257 in pretty much every way. The only reason those guys used the engine is because they were known setups which were in previous cars. There is no way I would put one in my car. You don't think Subaru has made any advancements in engines since they came out with the EJ257 in 2003?

[xwd]

Originally Posted by lickitysplit

I'm no expert, but I'm certain that the 12.5:1 compression ratio compared to the 8.5:1 in the EJ is to blame for the extra bump in power. Find an EJ25 at 12.5:1 and im sure you'll see more power in that engine than the FA20

No, you won't.

[boxer 2.5]

Originally Posted by SmsAlSuwaidi

Oh so his putting an ej25 and going na with it ?

This isnt some small block vs big block debate, but with alot of import motors displacement isn't everything.

There's no replacement for displacement. Except Forced Induction. N/A vs. N/A? Never a replacement.
C'mon man! Reads whats I's wrotes!

[SmsAlSuwaidi]

Originally Posted by boxer 2.5

There's no replacement for displacement. Except Forced Induction. N/A vs. N/A? Never a replacement.
C'mon man! Reads whats I's wrotes!

I did and hence I said it's not a small block vs big block debate.


Sent from my IBrick

[xwd]

Originally Posted by boxer 2.5

There's no replacement for displacement. Except Forced Induction. N/A vs. N/A? Never a replacement.
C'mon man! Reads whats I's wrotes!

Couldn't be more wrong.

[boxer 2.5]

Originally Posted by dwx

Couldn't be more wrong.

Explain =) Compression and or tuning may play a small role. But consider:
Honda:
3.2L v-6 ~ J32A1 225hp
3.5L v-6 ~ J35Z2 272hp

Basically the same drivetrain, just a higher displacement. Even the compression ratio's are close.

[lickitysplit]

Originally Posted by boxer 2.5

Explain =) Compression and or tuning may play a small role. But consider:
Honda:
3.2L v-6 ~ J32A1 225hp
3.5L v-6 ~ J35Z2 272hp

Basically the same drivetrain, just a higher displacement. Even the compression ratio's are close.

lol

[Dephective]

Originally Posted by boxer 2.5

Explain =) Compression and or tuning may play a small role. But consider:
Honda:
3.2L v-6 ~ J32A1 225hp
3.5L v-6 ~ J35Z2 272hp

Basically the same drivetrain, just a higher displacement. Even the compression ratio's are close.

You can literally take the same EXACT motor, change the runner length on the header and make more power.

Same thing could be said of changing exhaust port sizing for torque, etc.

It is NEVER just displacement.

Have you ever heard of variable valve timing? What about cams? what about piston speeds? What about number of cylinders with same displacement?

You clearly hadn't thought this through.

[Dephective]

Also, for those that want to get rid of DI..

There's a reason Audi, BMW, Merc and now virtually every other car manufacturer are going that route. Consider for the last decade that they have had pretty much flat torque curves (and gobs of it too) on shitty pump gas on tiny 4 cyl turbo applications. That doesn't happen without DI. DI does not only atomize the fuel better, it cools piston heads and the combustion chamber immensely. There's no way Subaru would have even considered running a 12.5 CR on shitty pump gas if it weren't for DI. Just because you guys can't figure it out, doesn't make it bad.



Edit: OP, if you want to throw boost at your car, change the pistons to a slightly lower CR like 10:1. Stock rods should be plenty enough for you unless you are going to be beating on her like she owed you money. Our rods are the same that go into the FA20DIT that will be in the new WRX as well as already in the Forester. If they are good enough for 295/295 factory, I'm sure they will be just fine for a little more than that.

[boxer 2.5]

Originally Posted by Dephective

You can literally take the same EXACT motor, change the runner length on the header and make more power.

Same thing could be said of changing exhaust port sizing for torque, etc.

It is NEVER just displacement.

Have you ever heard of variable valve timing? What about cams? what about piston speeds? What about number of cylinders with same displacement?

You clearly hadn't thought this through.