ej251 build reccomendations

[4doors4hp]

sooo.. i have a 2000 legacy wagon bh b4 GT.
this is the N/A year for the GT.
it has a ej251 motor. phase 2 single cam As far as i know and understand..
ive read many things,
swapping an ej22 head to it, for more compression and more power,
but isnt the ej22 a twin cam motor?
secondly, doing an intake, can i remove the small air box right off the intake manifold, or does it need to be left on? some say it helps with immediate airflow?
could i so to say, swap STi rods, pistons etc in this motor? i though the sti had shorter cams than this motor.
what im thinking of doing is:
delta cam shave,
cai (cobb or weapon R, ganzaflow)
uel headers,
hks or apexi exhaust.
light weight pully and flywheel.
i believe this would be a considerate enough of a bump for a few HP.
but help me out here.

[1996Battlewagon]

The mass-produced EJ22 is single cam. The swap is called the "frankenmotor" and is well documented and proven on this site. It isn't as cut-and-dry as you might think though as many have run into issues with ignition and spark when using the stock ECU alone.

You can put STI pistons and rods in the EJ251. What do you mean by "shorter" cams? Valve clearance issues?

Ditch that airbox. It's heavy and stupid.

Your build plan is legit. Contact Delta directly as they are more than likely the nicest and coolest guys I've ever spoken to on the phone.

[Garrison]

You definitely can swap sti pistons and rods but the flip side is, compression will drop--> so turbo it! Have delta regrind your single cam for better turbo usage, go el headers and definitely do the lightweight flywheel, but don't also do a pulley; you're more likely to get Misfire codes.
Good luck!

[4doors4hp]

thanks alot guys. would you rather going strictly motor vs a small boost?
id like the 200-225 hp area, nothing dramatic. just some decent power.
doing an ej22 head, with a cam shave id see compression bump up,
but will the head swap give a decent size power increase?
vs.
sure using sti pistons and rods will drop compression,
so boost would become available,
i believe the pistons would need to be machined to fit the block correctly too?
however rods and pistons alone are a $1000, would it be worth doing vs a factory turboed motor swap?
i know the ej251 is a open deck vs the ej20 is a semi-closed deck.
the ej20 swap would require the drive shaft, wireharness conversion, which would be a PITA, but do-able, but id need a crossmember too..

[Garrison]

$1000?
Da fuq you looking at?

Just grab a used set of nasioc, it shouldn't cost you more than $200-300. And no, they're drop in replacements.

I will probably always advocate turboing, vs na unless it's high horse application in which case the throttle response of the na would be superior, imo.

But low boost makes for an really fun street car. I ran 7lbs on my EJ25d, stock. My calculations using 90% volumetric efficiency put it in the 270hp at the crank. Stock pistons and rods. Yours is different because of the compression ratio (bumped from 9.5 to 10.1), as well as your porcelain pistons (not literally, figuratively) so you can't run much boost stock, but again, sti pistons would fix that.

[4doors4hp]

$1000?
Da fuq you looking at?

Just grab a used set of nasioc, it shouldn't cost you more than $200-300. And no, they're drop in replacements.

I will probably always advocate turboing, vs na unless it's high horse application in which case the throttle response of the na would be superior, imo.

But low boost makes for an really fun street car. I ran 7lbs on my EJ25d, stock. My calculations using 90% volumetric efficiency put it in the 270hp at the crank. Stock pistons and rods. Yours is different because of the compression ratio (bumped from 9.5 to 10.1), as well as your porcelain pistons (not literally, figuratively) so you can't run much boost stock, but again, sti pistons would fix that.

i was looking at rallyracing parts for new sti pistons and rods.
and good to hear. might go boost yet then.
well currently im looking to do the frankenmotor. the issue of mine is finding the build in my year motor. i have a phase 2 ej251, and alot i see are phase 1 motors.
if ive read correctly, id need a 95 ideally ej22.? so confused...
and the difference of single port vs dual port heads? .

[mycargoesvroom]

You can use phase 1 EJ22 Dual Port heads. You'll need the intake manifold, engine wiring, cam/crank gears, and ECU from the car you use the heads from though.

[4doors4hp]

You can use phase 1 EJ22 Dual Port heads. You'll need the intake manifold, engine wiring, cam/crank gears, and ECU from the car you use the heads from though.

thanks for the response, exactly what i needed.
as for wiring, the entire harness?
now the ej22 is a MAF and a ej251 II is a MAP correct, easy conversion or since im using a ej22 ecu i wont need to worry about that?

[02_Legacy]

not to thread jack, but anyone know what the C/R would be if STI rods and pistons were installed in an otherwise stock EJ251? Im curious and may end up doing this in the future.

[mycargoesvroom]

You can use phase 1 EJ22 Dual Port heads. You'll need the intake manifold, engine wiring, cam/crank gears, and ECU from the car you use the heads from though.

thanks for the response, exactly what i needed.
as for wiring, the entire harness?
now the ej22 is a MAF and a ej251 II is a MAP correct, easy conversion or since im using a ej22 ecu i wont need to worry about that?

Correct. Basically, the block doesn't care what heads are on it. As long as you're using the appropriate engine wiring, sensors (on the intake manifold) and cam/crank gears for timing you're set.

[4doors4hp]

Well after further research, the CR of sti pistons would be around 8.7:1. An easy turbo ready motor would be a ej22 block with ej251 heads
I wouldn't turbo a ej251 on anything over 8lbs due to its an open deck. The j253/2572/255 all are semi closed and brace the cylinder walls better. I think im not going to do the franken build. From what I've read it does as a lil power, but the top 5k plus rpms run flat an under 1500 it's boggy.
Running high comp pistons in an ej251 block with cam shave etc, increases power over the entire band better.
If I find a cheap 257/253 around then boost will be going

[1996Battlewagon]

Meh, if I were you, I'd just build the 251 heads you already have. Call up delta and they'll let you know what they can do in regards to cams and head work. These engines respond really well to exhaust and head work and to me, the work to get the frankenmotor running just right outweighs the actual fruit of the labor. With bolt-ons, head work and cams, you should net close to 150 horsepower at the wheels.

[4doors4hp]

Yeah I think ill just build it up.