thebetguy

OK so i'm going to get flamed big time for this, but what ever.

Let me start off by saying the newer 2.5i has no aftermaket and i'm getting kind of tired of that. I WANT BOOST. And no i don't want to sell my 2.5i and save for a wrx.

I'm looking for information on what i should use to peice together a turbo kit. i may just need all new exhaust from an 05 rs but i need ur imput.

thanks

zavier

why would you need the exhaust from an RS? you'd need the exhaust mani/up/dp from a WRX and you might also want to lower the compression...so that means engine internals...

if you don't plan on running more then 4-5psi then you should be fine with just the parts from a WRX but if you want more...lower cr pistons and forged rods should do it...other then that you need to also tap the oilpan and such to run oil feed/return lines for the turbo.

also you'd need a better fuel pump (i think a lot of people go with the walbro or whatever it's called) and fuel injectors (either wrx or sti)...you can save some money by not buying the turbo cross member and just notch the one you already have to fit the UP. I'm probably forgetting something...obviously you'd have to get a fmic, i think they still sell replica/cheap ones on ebay (obx?)...pretty much everything needed to turbo an RS goes for the 2.5i...really the only difference with the '05rs and '06-'07 2.5i engine is the ecu and avls

n0cigar

im on the same page as you. if you look at the forum 'turbo kits' in this section, that has pretty much everything you need and you can run up to 8 psi boost according to the vendor, but that seems a little high, 6psi, no problems.

https://www.i-club.com/forums/aftermarket-forced-induction-turboed-factory-na-engines-62/turbo-kits-164612/

they say its about 100 hp extra. im on the same page as you.

zavier

trust me when i say the stock 2.5i block will not take more then 6psi without a tune...and gl getting one on these new ECUs...not many people work on them

Vizzionz

4 psi is the MAX for any N/A engine, unless you do a "hybrid" engine like i'm planing to do [STi short block with the 2.5i heads running about 12-14psi daily :P]

zavier

except there are plenty of people running 6-8psi stock block...but that's cool...also the thread below this one from vivid...that dude said with a tune he was running a lot more...so no the MAX is not 4psi...but close

also if you used the STi short block with your heads you could run a lot more then 12psi...the reason the NA motor is so limited is because of it's high compression 10:1 + 6psi is a lot...there was a thread on nasioc that showed how to calculated it's "effective" psi...also the pistons in the stock block are not as strong as in the STi...so if you had the forged rods, the stronger pistons, 8.2:1...you could run a lot more boost

Vizzionz

i know i could run more boost with a STi short block and my 2.5i heads. but for daily driving, 12psi will be plenty fast for me, and if i need to up the psi, a boost controller will fix that

Evil Empire

iTrader: (1)

all the 06-07 blocks from what I understand are the ej257 semi closed deck block but with high compresion pistens so they sould be alot beter than the 2.5 rs-turbo's

zavier

well it's not the EJ257 bottom end...the WRX has the EJ257 bottom end like the STi...but the 2.5i has an EJ253 bottom end...non-forged pistons or rods...also it's open deck...that much is known, and if it's open deck it isn't en EJ257 bottom...

the new 2008 WRX motor is open deck (weird...the 2.0L was open, then it was the STi semi-closed, and now it's back to being open) as well as the 2.5i...so the newer 2008 WRX and 2.5i might share the same bottom end

Mariano

NOT TRUE

Evil Empire

iTrader: (1)

I will have to look more into the 2.5i's sharing the same block the guys that told me that are prity reputable. not that I am doubting what you know but I just want to see for my self. if you could I would love you to point me to something that might show that info.

thanks man
Tristan

AWDimprezaL

this comment lacks horribly, i run, and have been running 9 psi on my n/a 2.2 for WELL over a year 40K miles, with no more management then a RRFPR and bigger injectors

AWDimprezaL

sorry but no, the 2008 wrx uses the 255 which is what the LGT used, its semi closed and still strong as an oxe and the n/a version is still the 253, i work at a suby dealer, same P# for 255 08 wrx, and lgt

Vizzionz

i said ANY [READ: ANY] N/A not just on subaru's!!! (on a cavalier, with stock block can only handle 4psi maxed) 4psi is safe on any N/A, anything OVER 4psi, you're playing with the car gods and the money gods!


05 Impreza engines are as followed, RS/2.5i = EJ253, WRX(06+) = EJ255, STi EJ257

02-05 WRX/04 STi had the EJ205/7.

zavier

hmmm interesting...it was believed that the cast/mold for the short 2006-2007 WRX motor was actually the same mold used in the short STi motor...which would make the bottom end an ej257 just with different internals...but i guess i must be wrong on that part

i wasn't claiming the WRX has an STi motor in it...i was saying the bottom ends were from the same mold...i also was not claiming the WRX has the same internals...cause the WRX runs a 8.4:1 cr and the STi runs an 8.2:1 cr...so right there the difference is shown.

i never said the WRX was not an ej255 nor did i said it was a complete ej257...i was referring to the bottom end...o also the heads on the WRX and STi are different. Running different cam profiles even though both now have AVCS...whatever though right? Also it was more so a comparison on the fact that both the WRX and STi are semi-closed where the old WRX was open...but forget it...

and Vizzionz thanks for the history lesson...im sure that was a useful waste of time on your part

also im not even sure why we are talking about this...turbo'ing a car has nothing to do with open, semi-closed, or closed design. The old WRX motor was open...the 2.5rs/i is open...but that is where the similarities end. putting a turbo on an open deck will not cause problems, yea sure people have said "it will warp the cyl walls" which is not the case, at least not with these motors. if you wanna turbo an rs/i you need to make sure you keep the boost low unless you get a good tune, i've seen rs's run 12psi on a good tune for over 2yrs and no problems but normal motor issues (**** i've already blown a 2007 2.5i and it wasn't turbo'd haha)