Ej25 dohc,or ej25 sohc.

[Tireman28]

I’m building a round track motor for my legacy. i have both of these motors but don’t know what one to choose to build. I’m needing to make 300 to 350 hp without a turbo. The help would be great.

[GeneralDisorder]

Not going to happen with either of those motors. You would be hard pressed to make that much power NA with a Subaru 6 cylinder. 

 

Remember you are working with half of a 305 SBC. Even one of those has a tough time making 1 HP per cube. And the Subaru motor is already higher than that at 165 HP. That's the equivalent of a 305 making 330 HP. They are already maxed out. Making another 10 to 20 HP is possible but typically not worth the effort. 

 

The only way you will get even close to 300 HP is with a turbo. 

 

GD

[Tireman28]

Realistically I’m problay only needing around 200 or more. Is that possible with one of these motors naturally aspirated? i don’t have a budget i want to get all i can, even if being fully built is required.

[idosubaru]

You can frankemotor them which increases compression and folks have said they start approaching 190hp.

 

EJ22 heads on those blocks will bump power.

 

GD says to install the sohc pistons in the sohc block with the sohc heads.

 

Then add delta cams.

 

Lightweight pulleys are readily available.

[matt167]

If you do not need AWD. I would shoehorn a Toyota/ Lexus 1UZ-FE 4.0L V8 in there. They weigh 364 lbs, make 250hp with room to grow ( cams ) and are among the most compact V8 you can get. Also, being 32v DOHC they are pretty far advanced. They are also dirt cheap. You could couple it to an R154, or W58 trans, or even a Toyota truck transmission

 

If you need AWD, then a Subaru H6 is about where it is at for N/A. They all make 230-250hp but actually weigh more than the Toyota V8

Edited November 27, 2017 by matt167

[Tireman28]

I called delta cams told them I wanted to Frankenstein my motor. There setting me up with a 230 grind cam