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View Full Version : Boosting a n/a JDM 2.5..?



05-28-2010, 11:06 PM
so impreza_gc8 and anothernord got me considering boosting my semi-recently swapped 2.5l and im looking for some info on all aspects since i never thought id be crossing over into the FI world...i dont even know what an up-pipe is so dont leave any details out..

im looking to get maybe 6-8 psi, what will i need?

here's the list ive compiled so far: tell me if im missing anything

td04 (i know of no other options that wont blow up my motor)
turbo intake manifold - (what models? and MY?
$100 turbo cross member from 93/94 Turbo Legacy, 02'-07 WRX/Sti, JDM Turbo Imprezas/Legacys.
$50 ebay uppipe
$20-100 Stock/aftermarket turbo intake inlet.
anothernord's pp6 ecu
intercooler (top mount? front mount? pros/cons of both?)

also not knowing how to swap it all in.. will i need to splice into wiring and such? or will bolt ons be all?

will i need someone to install this for me? or could i figure it out myself and save a few hundred $$

aurelius
05-28-2010, 11:59 PM
Lowering the compression?

Reason
05-29-2010, 12:12 AM
Metal headgaskets
ARP head studs
EJ22T Crank and rods
New piston rings
Walbro 255 pump
bigger Injectors
Some sort of engine management

This is what I would do

05-29-2010, 12:38 AM
also should add that i dont want to spend alot so that a swap would end up costing just as much
ej22t crank and rods work in the 2.5?

anothernord
05-29-2010, 12:43 AM
You can run 5 psi on stock interals all day long if you tune it right and give it enough fuel. Ill send you a PM about the PP6 shortly. Installing it is easier than you would think. I have the exact wiring diagram for our cars too.

Read up on RS25.com on people's builds. There is tons of info on DIY turbo'ing there. Basically, you can use stock WRX turbo stuff, or get custom up and down pipes made to fit your N/A manifold. If you have the money, I would personally go with that route since you don't have to mess with crossmembers and stuff hitting the engine. You will also need an oil line to go from the oil pressure sensor to the turbo, and an oil drain line to the oil pan. Just drill a hole into it, tap dat, then screw in a fitting. Use the throttle body coolant lines for coolant.

I'd use a top mount to begin with, then upgrade as you wish. However, an 02-03 TMIC requires a bunch of cutting stuff to get it to clear the firewall, so use a Forester XT, or 06-07 intercooler like I used to have since they are longer and skinnier, and fit way better.

Finally, upgrade your fuel pump to a Walbro or STi fuel pump.

I will add more later since I'm typing this all on my phone.

05-29-2010, 01:56 AM
i am so lost on rs25.com.. what about a '04 wrx manifold? i found one for a reasonable price

Reason
05-29-2010, 08:50 AM
You don't need a intake manifold, yours is fine.

anothernord
05-29-2010, 10:32 AM
List of what you need for 5psi:

-td04 turbo
-custom up pipe
-custom down pipe
-oil feed line
-oil drain line
-fittings for the above
-coolant hoses
-FXT or 06 07 WRX intercooler
-sections of 2" aluminum pipe and couplers to plumb pressure side
-intake piping
-rest of the exhause
-some sort of EM, such as the PP6 or Emanage
-Walbro 255 or STi fuel pump
-manual boost controller
-boost gauge

05-29-2010, 02:51 PM
is there any brand names or sizes of the oil feed/drain lines?

what will i need to ask an exhaust shop to make a custom up and down pipe? what sizes for each?

what will become of my headers, since they come off (right?) what happens to the open exhaust ports?

also what ive been wondering is what kind of numbers i may be putting down with only 5psi, im obviously not expecting a massive change but i am ondering if it the tiny amount will be noticable

will i need to modify my current 2.5" setup to accommodate the dp?

anothernord
05-29-2010, 05:05 PM
5 psi will seriously kick you in the pants; you're lookin at having power compairable to a WRX. Its fun and totally worth it.

I'd go to an exhaust shop that is comfortable with doing custom work, because a lot of the big chains like Midas won't even do that kind of work.

The up-pipe is pretty simple; its just a 90 degree bend with two flanges, one the bolts to your stock header, and the other that bolts to the turbo. Then, you can have them modify a WRX downpipe, stock or aftermarket, to fit your exhaust.

Like I said earlier, all of the questions you have and 100,000 more can be found over at RS25.com. The 2.5RS guys have been doing DIY turbo setups for years and there is a ton of knowledge there.

05-29-2010, 11:20 PM
well i found a stock boost gauge for free, a td04 with 11,xxx miles on it, 95% positive on jareds pp6, i'll get the up+dp custom made...

would a wrx fuel pump be an upgrade? i see alot of like 02-06 wrx pumps

im also seeing ALOT of bugeye TMICs some with, some without the ypipe.. thses are a significant $200+ lower than any other tmic ive seen, although 99% have been sti ones

didnt really post a question... but anyone have any guidance?

impreza_GC8
05-30-2010, 12:50 AM
I'll have a WRX topmount with ypipe for sale soon.
FYI, 5 to 6 psi will NOT be comparable to a WRX in power, just throwing that out there because it was mentioned. I run 11psi and am comparable to a WRX, if not faster than a few.

05-30-2010, 12:58 AM
how about the wrx topmount? wont i need to cut up a bunch of stuff to get it to fit?

05-30-2010, 03:43 PM
im also seeing that i may need to get a wrx water pump or cut a notch into the Xmember, also a custom DP but the up pipe will need a 1.5" extension.

anothernord
05-30-2010, 03:46 PM
I suppose setups vary, but I know that Rallitek's AVO turbo kit with 6 psi clamed to give a 2.5RS similar performace to a WRX. That's where I got that figure from. The Legacy is several hundred pounds heavier than an Impreza too.

If you use stock WRX exhaust stuff, then you'll have to swap the water pump and crossmember.

05-30-2010, 11:41 PM
good deal? :


For $375 plus shipping costs I'll send you

94-98 jdm legacy turbo cross-member

02 wrx turbo 65k

04 FXT tmic with oem bpv, both brackets, hard lines, and cast elbows

New tmic silicone hose kit

turbo water pump with t-stat housing cover.

02 wrx oem headers with oem uppipe, and the bracket to hang the turbo off of your DOHC heads.

Reason
05-31-2010, 12:26 AM
Sounds like it

anothernord
05-31-2010, 01:05 AM
Eh, I would offer $375 with shipping.

Reason
05-31-2010, 08:50 AM
Eh, I would offer $375 with shipping.
Dude will laugh at him, you are better off agreeing on a flat rate because now that I think of it shipping is going to be exspensive.

jey
05-31-2010, 10:26 AM
FYI, 5 to 6 psi will NOT be comparable to a WRX in power, just throwing that out there because it was mentioned. I run 11psi and am comparable to a WRX, if not faster than a few.

6 psi on a high compression motor will be more of a kick than the 6psi we're running on our low compression EJ22T and EJ257. Plus there's more displacement - I drag raced an 02 WRX even back when I had my 2.25" exhaust and we were completely side by side all through 1st and 2nd gears.



im also seeing that i may need to get a wrx water pump or cut a notch into the Xmember, also a custom DP but the up pipe will need a 1.5" extension.

You don't need a custom DP necessarily, any WRX downpipe will do.

impreza_GC8
05-31-2010, 12:32 PM
Jey that is a good point, which I forgot about. My CR is much lower to make it safer for higher boost. For the record though, my displacement is about 2.4L. But even my RS feels more peppy from 2500 rpm to 3500 rpm over my turboLegacy because there is no turbo lag, even though it doesn't make a lot of power, its all more or less available when I want it. A higher compression motor on 6 psi would probably be a LOT of fun. But you wouldn't have much room to grow like me and you do. 15 psi or more is doable on our setups.

StatGSR
06-06-2010, 10:24 AM
You don't need a custom DP necessarily, any WRX downpipe will do.

that is only if you are using the oem turbo location, which if you are not using an oem turbo header and up pipe. it will most likely need to be custom.

rstimpreza
09-11-2010, 12:27 AM
Any update on this?

Reuben
09-20-2010, 07:44 PM
Metal headgaskets
ARP head studs
EJ22T Crank and rods

This. Also, the 22crank is just a 2L crank gents. This would also reduce the stroke and displacement nicely, allowing for higher revs! do it fag!

But yes, def stick some thick HG's in there to reduce the CR.