making a n/a ej25 into a sti ej25 (hybrid)

[tecnica technician]

alight I have been going over this in my mind for a couple of weeks now.

I have a 99 bd gt with the dohc heads I have been looking around and it seems that the sti intake manifold will fit the heads and there is a couple of place that make a turbo kit using the stock manifold?

the only ?s I have are about the ecu and what I have heard about the block only being able to handle 5-6lbs of boost I just wanted to know why that is, as for the ecu would a sti ecu work in the car or would I have to make a converter to make it work

Edited by Huffer for reading comprehension.

[ooberdoob]

hybrid you mean.

get the STi block, rebuild your heads. get a walbro 255. get em. get an STi turbo. upgrade head gaskets. get intercooler and STi injectors. STi oil pump.

couple other things, and have fun.

[sheepdog]

don't bother. swap the whole engine and ecu for an sti set. The wiring is a bitch but you are going to spend way more trying to swap bottom ends, find turbo setup, port those heads, get a decent fuel delivery system in, and wire up an ecu that will run it (dont bother with an STi ecu if for some reason you dont want to swap motors, youd have to splice that in too, go standalone, AEM or perfectpower).

it would be cool, but not worth the trouble imo. If you want to go FI without swapping engines, go perfectpower EM, avo turbo kit, and sti shortblock, fuel pump, and call it a day

[slip]

If you want to go FI without swapping engines, go perfectpower EM, avo turbo kit, and sti shortblock, fuel pump, and call it a day


So true

[Huffer]

If you're going to go to all that kind of trouble, you better fit better pistons for boost. Might as well have the rods balanced too.

[tecnica technician]

so no one has told me still why the reason the block can't take more then 5-6lbs of boost ? I get that the ecu might be hard a stand alone sounds like a good idea I have also thought of geting a reflash on the stock one

[Wiscon_Mark]

so no one has told me still why the reason the block can't take more then 5-6lbs of boost ? I get that the ecu might be hard a stand alone sounds like a good idea I have also thought of geting a reflash on the stock one

1. Fuel system will crap out, and you will run lean
2. Coolant sleeves aren't as strong as a closed or semi-closed deck engine
3. Pistons, rods, etc cannot take the boost. Get forged if you want to simulate that.

Overall, converting your EJ25 to something resembling an EJ257 would be more expensive than buying a brand new EJ257 shortblock.

[slip]

Overall, converting your EJ25 to something resembling an EJ257 would be more expensive than buying a brand new EJ257 shortblock.

It would damn near cost as much as a complete EJ257

[Wiscon_Mark]

yep

[sheepdog]

Yea. The block was never designed to handle any kind of forced induction, and to build it to a level where it could hold as much as a stock 257 block would not even be close to monetarily advantageous. Everything will swap right over to the new shortblock, so that is definitely the way to go.

[lgt2000]

The headgasket is about to go on my 00 Legacy GT, and I was wondering since I was planning to turbo the engine anyway, can I get an EJ257 block and bolt it up to my heads and use the emanage piggyback that I was planning to use?

[Huffer]

The headgasket is about to go on my 00 Legacy GT, and I was wondering since I was planning to turbo the engine anyway, can I get an EJ257 block and bolt it up to my heads and use the emanage piggyback that I was planning to use?

Yes, and No.

You can get the shortblock, hook it up to your heads.
You might be able to use an Emanage piggyback, but you'll have a tough time tuning.

Why? You'll be running MUCH lower compression on the new engine - the EJ257 shortblock is setup for boost. If you don't mind running around with no power until you can buy a turbo setup and ECU, go for it.

Waste of money IMHO.

[lgt2000]

I already have a trubo setup:
-WRX TD04 Turbo
-WRX Uppipe
-WRX Downpipe
-WRX Heatshields
-WRX Crossmember
-WRX Fuel Rail
-WRX Injectors
-WRX TMIC
-WRX Fuel Pump
-STI Exhaust Manifold
-STI Exhaust
-HKS BOV
-Vortech RRFPR
-eManage Blue
-WRX/STI Water Pump
-WRX Oil Pan

I am just missing an xmember, any other issues that could come up?

[Huffer]

You might as well buy a WRX block then...
Not sure you'd want to bother with a tiny TD04 turbo on an STi longblock.

[lgt2000]

i am going to run that turbo for now, it should give it enough power for it to not be a slug, Once I get everything figured out I will upgrade to a bigger turbo

[jackoctober]

If you want to go FI without swapping engines, go perfectpower EM, avo turbo kit, and sti shortblock, fuel pump, and call it a day


So true

This is exactly what my plan was, my only honest question is this:
how much of a bitch is it to do?