im doing the 2.5 NA(RS/LGT) DOHC engine swap into my 98 OBS. i was sourcing a DOHC intake manifold/rails/injectors for it since supposedly the SOHC mani won't bolt to the DOHC heads. well...

scubaru on lersoc is indeed running DOHC RS heads(what i will be) with a SOHC intake on his EJ257. what gives?.... i saw it the other day and wondered WTF?

i already have a DOHC mani(still on a complete JDM G engine) but would prefer to use what in the car already. please give a clue as to what's truly possible. thanks!

--keith

Make totally sure those aren't WRX heads.....that would be the difference. Visually, they're very similar.....

Laying a SOHC manifold onto a EJ25D longblock reveals the fitment issues. It doesn't fit.


Jay Storm

did you build scotts 257 jay?

iirc it was his stock RS running gear(heads/intake mani) minus the 257 block. not sure why i would remember him saying different. unless he misspoke, but he mentioned you multiple times having built stuff for friends etc. and seems knowledgeable. he a service tech at mike pruitt honda as well. he didn't seem confused, but anything is possible.

i dunno, i PM'd him the other day as he's giving me WRX valve cover gaskets for free. so i'll ask again when he responds.

if i can keep the G intact fully i would love to do that instead of having a "parts engine" laying around while i strip it randomly.

--keith

I haven't seen his motor firsthand....but I remember his RS being SOHC, as he sold some parts to DJ. I have personally compared the RS manifolds in SOHC/DOHC side by side after testfitting the SOHC manifold to our 98RS motor. The SOHC ports sit further away from the crank centerline, making the manifold wider as viewed in the car. Then the bolt pattern at the base is offset instead of inline like the DOHC.

I'll have to get with Scott to see what he's got. BTW...I haven't forgotten about you....I'm making progress on the EJ25 in the garage for you.

Jay

thanks man! im leaking oil out the backside of the engine currently. im going to put it on my lift tonight and see whats up. as long as i keep it topped off it's like a fresh oil change constantly. lol. it does use some, but the leak is more severe me thinks. i'll fix it first since gasket and seals are dirt cheap(the time to do it is hard to come up with).

does the 257 block make any diference with scott's build? i don't believe it would matter personally, but figured i'd ask.

--keith

Make totally sure those aren't WRX heads.....that would be the difference. Visually, they're very similar.....

Laying a SOHC manifold onto a EJ25D longblock reveals the fitment issues. It doesn't fit.


Jay Storm

scott is running 2002 wrx intake mani on his 99RS SOHC heads with the 257 block.

you say the D longblock. he may be ok since its the 257(hence the WRX mani)not a D block. and i have to run the DOHC intake manifold since its a EJ25D block with DOHC heads needing DOHC manifold?!?

right?

Not because of the block....only because of the heads. You're going to be using 98RS heads, which are DOHC, which have virtually the same casting as the older wrx heads. Your G manifold will work fine with my heads. Not an issue.

Jay Storm