Need Advice on ej253 to replace my ej251

[WESTcoast]

Hey everyone,

Right now I'm in need of an engine and I found a 2005 impreza engine (ej253 Sohc) that I want to pick up for a really good price. I have a 1999 Legacy gt (ej251 Dohc) which is misfiring and needs a another engine. I have a burnt piston which makes it so there is low compression in that chamber, having it fixed is basicly saying to have the motor rebuilt but i'd rather have another put in and this is a perfect oppertunity

Will I be able to do this swap?? yes they are both N/A 2.5 engines but the versions(what I am guessing the numbers of the end of ej25 stands for). I know that the ecu will be a problem as that will need to be replaced with one that knows about the Sohc engine or flash it (from what a friend suggested) What other complications will I run to if any.

Thanks in advance

Jon

[jey]

You can swap just the shortblock. Then you don't have to worry about any of the electronics variations between the motors.

[httrdd]

what is the HP difference? Is it worth an impreza engine or if you are going to do a swap why not go for more power?

[Huffer]

what is the HP difference? Is it worth an impreza engine or if you are going to do a swap why not go for more power?

There's isn't any real HP difference between the SOHC and the DOHC block. They're both around 165hp.

The issue is that you can't swap a SOHC long block into a car with DOHC equipped electronics/ECU.

But if you take the SOHC shortblock (just the pistons/cylinder/oil pan section) and mate that up with the DOHC heads, you will end up with a higher compression engine, maybe around 11.1:1. You might need to run 89 to avoid detonation, but you'll get a few ponies in return.

[BKiller]

I assume the Ej253 doesn't have the headgasket issue that the EJ251 has?

[WESTcoast]

what is the HP difference? Is it worth an impreza engine or if you are going to do a swap why not go for more power?

There's isn't any real HP difference between the SOHC and the DOHC block. They're both around 165hp.

The issue is that you can't swap a SOHC long block into a car with DOHC equipped electronics/ECU.

But if you take the SOHC shortblock (just the pistons/cylinder/oil pan section) and mate that up with the DOHC heads, you will end up with a higher compression engine, maybe around 11.1:1. You might need to run 89 to avoid detonation, but you'll get a few ponies in return.

thanks Huffer I appreciate that, sounds like a plan but yet sounds like I will be driving with a bomb hahahaha

But what about If i change the ecu or get it flashed to recognize the sohc part and all that good stuff or just get a sohc ecu will that work as well or is there more than meets the eye (haha transformers)

[WESTcoast]

I assume the Ej253 doesn't have the headgasket issue that the EJ251 has?


From what I heard no it doesnt have that problem, it was just our ej251 dohc that had this problem

[phi11]

it goes like this,
external leaks on SOHCs.
interal failure on DOHC.


different problems.

[WESTcoast]

ok I come back with the question I can get my hands on a sochc ecu will that help any towards wiring at all??

[1996Battlewagon]

Sort of... you will still have to cut and splice the SOHC ECU. I'm pretty sure (I could be wrong) that the wiring harness plugs are different between the SOHC and DOHC. Also, make sure that the engine you get IS a EJ253 because the EJ251 (SOHC) is MAP instead of MAF.

Good luck man. I went down this same road before I swapped my engine. I wanted SOHC before I abandoned it for a DOHC.

[Huffer]

ok I come back with the question I can get my hands on a sochc ecu will that help any towards wiring at all??

Not if you are running DOHC heads. DOHC heads need a DOHC ecu.