Lead me in the right direction
12-29-2002, 06:02 AM
#1
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Lead me in the right direction
Hey all I am a newbie and I drive a 2002 Impreza 2.5RS...I was running a 75 shot zex kit for awhile but was looking at getting a new car because of the lack of power...now that I feel like there is a little bit of potential in the EJ25, I was wondering if anyone could point me in the direction.
I was looking at running high 11's low 12's. Seriously what would I need to do this? I am already looking in to getting new rods and pistons lowering compression down to 9.5:1 and looking at a decent amount of boost...11-12 pounds. Just wondering what else I would need to do? HELP PLEASE!!!!
I was looking at running high 11's low 12's. Seriously what would I need to do this? I am already looking in to getting new rods and pistons lowering compression down to 9.5:1 and looking at a decent amount of boost...11-12 pounds. Just wondering what else I would need to do? HELP PLEASE!!!!
12-29-2002, 11:38 AM
#2
Registered User
Join Date: Nov 2002
Location: Lake Forest, Calfornia
Posts: 673
Car Info: 2004+ Two Tone Green
there are many things you could do. unfortunately they are all very costly. you may want to contact cobb tuning. they can direct you in the right direction. also they have turbo kits for your motor. if you want to take it a step further then have the motor built with the turbo kit.
12-29-2002, 02:52 PM
#3
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I am looking at dumping about 6-8 grand in to the motor in the next few months....I figure that should be enough to get me in hte 12's...breaking 11's...hmmm, not sure if that is going to happen. But I am shooting for that. Yes...I do plan on building the motor, at the very least I plan on new rods and pistons. To go with that I figure a nice little turbo kit would be real nice. I am just basicly looking to lay the smack down on some supras...maybe a few corvettes and all of these so called budget super cars. Hopefully things work out ok. Thanks for the lead with Cobb.
12-30-2002, 04:45 PM
#4
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cobb is a great place to look as was mentioned. www.cobbtuning.com
also check out www.vishnutuning.com and www.i-speedusa.com
-PJ
also check out www.vishnutuning.com and www.i-speedusa.com
-PJ
12-31-2002, 03:24 PM
#7
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An MY2002 RS should be a Phase II EJ25 engine, which if memory serves is a 16 valve SOHC head, and internals running 52mm big ends with the thrust face on No. 5 main. There's loads that you can do with that, it's just a question how much money you wanna spend 
The stock crank is a good quality forged item so there's no need to change that (unless you want to run over 450 lb/ft). Rods will want to be filed under "b" for bin, replace with a good set of billet steel rods. I've always liked JE pistons and would thoroughly recommend a set.... should be "off the shelf" from Cobb.
Head wise, I would suggest dumping the SOHC ones and fitting a set of EJ20G Type RA, EJ20K or EJ205/7 DOHC heads. The pick of the bunch is the EJ20G Type RA head, a Subaru / Prodrive homologation special casting with improved water ways, but very rare. An inexpensive option is the EJ20K head (I can get head pairs for as little as UKP 250), but you'll end up with shim-over-bucket follwers... it may make more sense to use EJ205 heads (again, about UKP 250 a pair), which have a 35mm rather than 33mm follower... 35mm is a common size (VW et al) so it's very easy and inexpensive to convert to top hat shim and become aquainted with an 8000 RPM redline.
Presumably you'll be wanting to fit a turbo of some description so the exhaust manifold will need to be changed anyway, so any incompatibility with your existing one and the new heads is irrelevant, just get a turbo manifold and down pipe... (as well as a turbo, of course
) intake manifold could be an issue, but they can be had relatively inexpensively too if needed. As luck would have it Phase II manifolfds come with 440cc injectors, with a decent fuel pressure reg running 4 bar differential they'll be good for 370 BHP before you need to change them... there's loads of options, with 850cc available "off the shelf", which will see you to well over 500 BHP.
Naturally you'll need an ECU to run the engine, and there loads of options. A "plug in" type is of no advantage because a lot of the control and sensor wires won't be in the car... choose one that can be mapped by a mapper you trust.; it's better to sacrifice a few bells & whistles and get a good map, rather than having the ECU that can do loads of stuff that you'll never need and then end up with a shoddy map and a poorly running car just because it was mapped by a chimpanzee rather than a real mapper.
You could try to rely on the factory ECU and add a "knock retard" box and a "funky fuel pressure regulator" and a whole manner of other band-aids ... IMVHO they're no substitute for doing the job properly... at best they'll stop the car from blowing up, but they'll never allow you to exploit the engine to its full potential.... it's one thing slapping a turbo on a stock engine and then having a little box of tricks to allow it to run, it's a very different thing if you've built an engine that is mechanically sound enough to run a good 450-500 BHP. As a wiser man than I once said "anything that's worth doing, is worth doing right".....
You'll also want to look at upgrading the fuel pump etc (all the "usual suspects") and perhaps look at the tranny. For what it's worth, a good ECU will keep your tranny alive unless you have zero mechanical sympathy, decent ones will allow you to drop the boost in the lower gears; ultimately this will slow your 1/4 mile times a bit, but it give you time to save up for a good tranny, and it allows you to drive home from the strip rather than having the car towed away... you can always disable the feature when you have a good tranny!
Hope this helps (I know it's only the tip of the iceberg, but it gives you some ideas),
Pat.
The stock crank is a good quality forged item so there's no need to change that (unless you want to run over 450 lb/ft). Rods will want to be filed under "b" for bin, replace with a good set of billet steel rods. I've always liked JE pistons and would thoroughly recommend a set.... should be "off the shelf" from Cobb.
Head wise, I would suggest dumping the SOHC ones and fitting a set of EJ20G Type RA, EJ20K or EJ205/7 DOHC heads. The pick of the bunch is the EJ20G Type RA head, a Subaru / Prodrive homologation special casting with improved water ways, but very rare. An inexpensive option is the EJ20K head (I can get head pairs for as little as UKP 250), but you'll end up with shim-over-bucket follwers... it may make more sense to use EJ205 heads (again, about UKP 250 a pair), which have a 35mm rather than 33mm follower... 35mm is a common size (VW et al) so it's very easy and inexpensive to convert to top hat shim and become aquainted with an 8000 RPM redline.
Presumably you'll be wanting to fit a turbo of some description so the exhaust manifold will need to be changed anyway, so any incompatibility with your existing one and the new heads is irrelevant, just get a turbo manifold and down pipe... (as well as a turbo, of course
) intake manifold could be an issue, but they can be had relatively inexpensively too if needed. As luck would have it Phase II manifolfds come with 440cc injectors, with a decent fuel pressure reg running 4 bar differential they'll be good for 370 BHP before you need to change them... there's loads of options, with 850cc available "off the shelf", which will see you to well over 500 BHP.Naturally you'll need an ECU to run the engine, and there loads of options. A "plug in" type is of no advantage because a lot of the control and sensor wires won't be in the car... choose one that can be mapped by a mapper you trust.; it's better to sacrifice a few bells & whistles and get a good map, rather than having the ECU that can do loads of stuff that you'll never need and then end up with a shoddy map and a poorly running car just because it was mapped by a chimpanzee rather than a real mapper.
You could try to rely on the factory ECU and add a "knock retard" box and a "funky fuel pressure regulator" and a whole manner of other band-aids ... IMVHO they're no substitute for doing the job properly... at best they'll stop the car from blowing up, but they'll never allow you to exploit the engine to its full potential.... it's one thing slapping a turbo on a stock engine and then having a little box of tricks to allow it to run, it's a very different thing if you've built an engine that is mechanically sound enough to run a good 450-500 BHP. As a wiser man than I once said "anything that's worth doing, is worth doing right".....
You'll also want to look at upgrading the fuel pump etc (all the "usual suspects") and perhaps look at the tranny. For what it's worth, a good ECU will keep your tranny alive unless you have zero mechanical sympathy, decent ones will allow you to drop the boost in the lower gears; ultimately this will slow your 1/4 mile times a bit, but it give you time to save up for a good tranny, and it allows you to drive home from the strip rather than having the car towed away... you can always disable the feature when you have a good tranny!
Hope this helps (I know it's only the tip of the iceberg, but it gives you some ideas),
Pat.
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