Hybrid Build Questions

[WRCsubeRS]

Hey guys... I just wanted to get some Local feedback as to Hybrid builds...

I'm thinking about doing a EJ257 bottom end (getting one for $1700, good price?) with my 2.0L heads, I'm having a hard time finding more info on the build. Could you guys point me in a direction or give me some more info on what I need to be concerned about? Here is what I'm concerned/confussed about right now:

-Overall Drivability/Performance, I'm looking for reliable>power
-Wiring
-Tuning/ECU mods needed
-What parts are a MUST(eg. Lower compression head gaskets, oil pump etc)
-Intake Manifold/Accessories Bolt on compatibility

Anything else I should know?

Thanks in Advance!

[100_Percent_Juice]

I don't know if you have looked yet but I am pretty sure there is an entire section on NASIOC about it.

[sperry]

Originally Posted by WRCsubeRS

Hey guys... I just wanted to get some Local feedback as to Hybrid builds...

I'm thinking about doing a EJ257 bottom end (getting one for $1700, good price?) with my 2.0L heads, I'm having a hard time finding more info on the build. Could you guys point me in a direction or give me some more info on what I need to be concerned about? Here is what I'm concerned/confussed about right now:

-Overall Drivability/Performance, I'm looking for reliable>power
-Wiring
-Tuning/ECU mods needed
-What parts are a MUST(eg. Lower compression head gaskets, oil pump etc)
-Intake Manifold/Accessories Bolt on compatibility

Anything else I should know?

Thanks in Advance!

I raced my WRX for a while with a hybrid build: STi bottom end, WRX heads (ported/polished/stock cams).

Performance will be a good 20-30hp/tq lower than the same setup w/ the STi heads. The AVCS heads (even w/o working AVCS) flow a ton better and the stock STi cams & valvetrain are much better than the WRX heads. My porting/polishing couldn't come close to the stock flow of the STi heads.

Reliability should be on-par with a non-hybrid motor... unless you're racing it. The WRX heads do not have the dual valve-cover breathers that the STi heads have. So if you're tracking it, it's easy to pressurize the heads with all the blow-by from the bigger block/turbo and pump oil out the breathers under high lateral G's. A catch can on the valve breathers will be a *must* on a hybrid block IMO. You have to keep the oil out of the intake or you'll end up detonating and blowing ring-lands.

Wiring is a no-brainer. You can use your OEM WRX ECU and wiring harness w/o modification.

I'd suggest an AccessPort and a professional dyno tune for the car. But you can certainly get equivalent results with an open source tune on the stock ECU. The nice thing about an open source tune on the older 16-bit WRX ECU is that it's possible to directly set all the emissions flags so you'll never have to worry about smogging the car. The AP will cost more, but I'd feel better with a professional tune on the car as far as reliability is concerned. I'd recommend Mike Warfield at GST in Hayward or Paul Debecker at DBTuned in Sacramento for a great dyno tune... just make sure the car is mechanically sound before bringing it to them... nothing sucks more than trying to tune a pile of parts that aren't working.

You should be fine to run OEM headgaskets IMO. You'll only run a little higher base compression, but that's not necessarily a bad thing unless you're one of the folks that lives/dies by the PSI number they're tuned for. Running higher base compression and less overall boost can make just as much power as the other way around, plus you should have better low-end and quicker spool... you'll just be giving up the high end a little... but you're doing that anyway with the WRX heads.

If you've got the motor apart, you may want to shim the oil pump, or go with a larger pump. Talk to Matt (kuncklesplitter on the forums), he can get 12mm oil pumps, gaskets, etc for your build. I'm not up on the best oil pump for a hybrid block... you're likely to be just fine w/ the stock pump as long as it's in good shape... I'd ask around NASIOC or send a PM to GST Mike, he knows his shit.

The stock WRX intake manifold and all accessories will bolt on just fine. The only difference between the WRX's intake manifold and the STi is the throttle-by-wire throttle body... and the red powdercoat.

[WRCsubeRS]

Exactly the Info/Advice I was looking for... Thank You so much Scott, I really appreciate it!

If anyone else has anything to add, please do...