Anyone a member of this site that drives a 2.5i or 2.5RS? Looking to learn a few things on how to turbo my non-turbo impreza 2.5i. Any suggestions would be appreciated. Or any sites you could refer me to review so I can build my na to turbo knowledge base from the ground up.
Well, i m not sure but ive heard more than once.. that it would be cheaper to trade in for a wrx.. than to turbo a RS.
it is alot cheaper and easier to just sell the rs and buy a wrx. the rs/i engine isnt made for a turbo and they will not play nice together, you would need to do an engine swap and anything else that goes along with that
See my posy in you other thread. Then check out rs25.com and nasioc.com (be prepared to sift through a lot of useless posts/threads on nasioc)
How will they not play nice together though? I mean how is turboing a 2.5i any different than turboing a honda civic or a Jeep Cherokee (anything non-turbo)? Is the engine in the 2.5i not the same as the wrx or STi? I thought the only difference was tuning, turbo, intercooler, exhaust, etc.
The engine in the 2.5i is NOTHING like the engine in the wrx and sti. EVERYTHING is different, block, crank, rods, pistons, heads, engine management, wiring... hence the "easier to sell the rs and buy a wrx" thing... Siegel
Gotcha. Thank you! I may have more questions though...like what else can I do to make a substantial increase in NA power? The only mods thus far have been an STi catback exhaust and cold air intake. I've heard of installing a new underdrive pulley but will that throw off my timing? I guess what I'm asking is what can I do next to my daily driver? It's gotta last me at least a couple of more years before I decide to sell this car and buy an STi.
The crank is the same. Thats it. In order to SUCCESSFULLY turbocharge a non-turbo 2.5RS/2.5i...you'll need: Turbo kit for it ($3000+) Header Turbo back uppipe (if not included in the header) engine management (stock ECU reflash, standalone, or piggy back) injectors intercooler lots of other misc pieces Tuning Built engine* *Engine: You will need to upgrade the pistons at an absolute minimum. Alone that is usually $2000 in just labor. Depending on what pistons you choose, it'll cost anywhere between $50 and $1500 for pistons. Then your weak link are rods. You can drop in EJ257 rods, then you have a larger choice of drop in pistons. But still, you'll need to budget atleast another $3500~$4000 for the engine just to make it reliable to 15psi of boost on a 'small' turbo. So you are looking at about $6000 to $12000 just to make it reliable and make only about 280 at the wheels. If you are creative you can go it cheaper...but, again...it will be easier to do: 1. Trade in for a WRX or STi. 2. Leave it N/A.
Pulleys alone are nearly useless...however...if you do underdrive-lightweight pullyes, along with a Fidanza 9.5lb flywheel will make the engine rev like magic. Borla header, Random Tech high flow cat and a high flow 2.5 inch cat back. The STi muffler is more than enough, but you need a larger diameter center pipe (either modified WRX/STi center pipe to fit the car, a custom one made from scratch, or a Stromung one), and then a tune will yield you at least 15hp/20tq at the wheels over stock.
Yep. However, they are MUCH shorter than the EJ251/253 rods. You will need to spec a custom piston for N/A use w/257 rods, or use drop in 257 pistons for turbo application. At that point you might as well use a 257 shortblock assy.
You can. If you are mechanically inclined and have cheap parts sources...you can either upgrade the stock block...or depending on if you can find a used sti block, use that....so...you can do it either way.
Unchanged. The 255 and 257 share the exact same internals except for pistons. 8.2:1 for STi-257 2004~2007, 255 is 8.4:1 in 2004~2007.
i have an RS. if you are interested in power you're in the wrong subaru, as others have said. however, WJM laid out some pretty solid mods that will net you a definite increase (plus the exhaust work will make it sound pretty sweet). after that though, you are going to pay out the butt for any real gains, and it's not worth it. one thing you can definitely take advantage of is the fact that the RS's are the lightest imprezas and have very good low-down torque. concentrate on handling and braking, and keep up with the big boys when things get twisty. if you have a chance, autocross! you will learn that your car can keep up with some pretty impressive stuff.
I just installed a stromung High flow cat which is 2.25" to a custom2.25" mid pipe to a sti muffler yes it is noticabley faster But it sounds like a ricer now:wtc: From what I've read the sti muffler is fine on stock cats but you should get something else or a long resonator if you get a high flow cat.