Xise

I always thought the NA ej25 blocks were bad for turbo apps due to the higher compression and tendency to detonate because of the high comp + boost.....does having the EJ22T heads somehow bump compression down to an acceptable level for turbo apps?? because that would just be awesome, as I know of a set o ej22t heads bolted sill to the exhaust mani,turbo and up pipe from a leggy turbo...if that bolts right up to an ej25 motor with the proper specs for "safe" boost on i'll slap that right on my RS lol.....just ECU would be the problem. If I am correct it is NOWHERE NEAR that easy to do reliably. anyone test the ej25 with the 22t heads?? i would love to see proof of this If I could find everything I needed the ideal setup I think of would be; EJ22T block EJ25 phase 2 crank EJ257 connecting rods and pistons EJ20 wrx heads usdm from what I understand and research I have done the heads bolt up with no drilling of any coolant passage and strokes the engine without any boring or using oversized pistons/rings/bearings to 2.3...I am sure there is a thread about it on bbs.legacycentral.org. I imagine this combo would be quite monstrous for boosting potential.

Hi, I don't know a ton about the difference between these cars aside from the obvious ones. I have an 04 RS and want to get sti coilovers/brembo brake rotors/calipers from the 04 sti. Does anyone know if these are simply bolt on or is the lug assembly different? I believe 04 RS is 5x100. This is going to be my first mod on the car before i really have to get into doing a motor swap so I want the chassis and suspension to be ready for a cosworth block. I am going to keep my 2.5 RS badges on the car so no one will be the wiser.....but if i need to gut my entire suspension and swap all of it for sti parts before i can get coilovers and brakes i might just sell the RS and buy an STi. Hopefully it will be nice and easy bolt on goodness...like buildinga snap-tite model lol. almost forgot, when doing an engine swap from an RS EJ25 to the sti ej257...can i keep my AC condensor or does it get in the way??

Thanks a bunch guys, ya i figured the RS had a slightly different block than the STi did, I can't thank you guys enough for your help...the first forum to actually give me a quick answer instead of simply dismissing me as a noob. fact is this is my first subaru and my first AWD, I am use to BMW motors so this is all new to me. And as far as the turbo is concerned i can't even afford to think about doing that now....I just want to get some new heads/cams/gears for the first actual mod....maybe if I am feeling fiesty...(and have the $$) I can get my block machined...or just buy a Sti long block and THEN get a turbo.....I will determine that after I see how fast some DOHC heads are on this car. Actually here is a good question how much HP do you think an RS motor could produce if I did stick w/ NA? AND! does anyone make performance differentials for under 1 grand...for just one...I mean damn. Oh ya almost forgot so oficially what motor code is mine? EJ2555, EJ255T, or EJ2557??

I tried posting at all except one of those boards and you are the first person that gave an actual answer. Thanks a lot man you helped me out a ton, now it is time to empty my savings account lol

Hi, this is my first post. I have been trying to find out how interchangeable subaru parts are. I know that my 2.5 RS has the EJ25 block as does the STi, i wanted to know if mine was a toned down version or the exact same block. Basically what I am trying to do is convert my SOHC heads to the DOHC heads/ cams that the STi uses, I just want to know if all the valves and stuff would line up....I looked at the head gaskets for both cars and they look identical. I am basically asking if STi parts would bolt directly on to my RS motor. Can anyone help me out???