Low pressure turbo system?

[jg09]

I've been looking around at ways to gain around 50-65 horsepower in my Outback and I think I've settled on a low boost pressure turbo setup (8 or 9 psi or so?). After doing some research, here's what it looks like I'll need to do:

Buy an ej25t exhaust manifold
get appropriate sized turbo
rig up oil feed system
get top mount intercooler (from WRX STi)
bend and fit appropriate tubing
get higher flowing fuel pump and fuel injectors
ECU tune

I'd like to be able to use stock motor internals and I'd like to be able to use the stock auto transmission for now. The way I figure it, I'll be setting myself up for a larger turbo in the future when I get the infamous boost bug and need more.

So my questions are: The ECU will have to get reflashed for this, right? Will the ej25's stock compression level be right for this application? NA compression level is 10:1 whereas turbo Subaru models were 8.2, IIRC (at least the STi is for sure).

[Huffer]

You will need piggyback engine management. Your ECU is not capable of being reflashed in the manner that you think. This is not a WRX ECU.

The Perfect Power 6 is you best choice for EM besides a Greddy Emanage which may or may not be able to deal with the self-learning that the Subaru ECU does.

[liquidracing]

nope

[Grafton]

you'd also need a turbo crossmember
my .02

[rougeben83]

You will need piggyback engine management. Your ECU is not capable of being reflashed in the manner that you think. This is not a WRX ECU.

The Perfect Power 6 is you best choice for EM besides a Greddy Emanage which may or may not be able to deal with the self-learning that the Subaru ECU does.

PP6 has issues with adjusting fuel trim for part-throttle. That is why Rallitek offers a 5th injector setup that you would have to tune to give the additional fuel. PP6, just like the emanage will occasionally be learned by the ECU regardless and you'll have to reset it.

No one has bothered to hack the first generation of the Phase 2 ECU's like openecu and the like. Even the Ispeed reflashes that works on 2.5RS' do not work for the Legacy ECU's afaik. Someone tried working with Ispeed, sending their unit back and forth several times, but they just couldn't get a drivable tune from the flashes.

Either piggyback will need to be custom tuned. DO NOT believe what rallitek says and go with one of their "off the shelf" maps, it may be enough to get you to the tuner, but you're not going to run as fast or as safe as with a custom tune.

You can notch your crossmember. That's the cheap alternative to a turbo xmember (you'll need to get a Legacy turbo or WRX wagon xmember, as the WRX sedan uses a different set of control arms).

[anothernord]

With the stock compression, 5-6 psi seems like a safer number as far as boost; this is the boost that the AVO turbo kit uses on N/A subarus.

[xXGTBspecXx]

you might want to follow my build to prep your motor for things close to 10psi. just tested my setup today and im safe all the way up to 18psi...hehehehe i love _______ blocks

[decke48]

yes but with 9.5:1 compression you will never get to 18psi without some meth and c16

[grayguy]

Meh, put a Rising rate fuel pressure regulator on it, Keep it to 5-6 psi and have fun

[liquidracing]

nope

[anothernord]

I second the 5-6 PSI max, that's what the AVO turbo kit uses for our motors.

[sexystover]

the knock is what kills our engine, the internals arent strong enough to handle preignition, so you either need forged internals, lower compression pistons, or run no more than 6 psi


its not the timing that causes knock but lower octane fuel can ignite easier, and when you add forced induction to a car it raises the in cylinder temperatures to the point that it will ignite the fuel before the park plug does

[liquidracing]

nope

[sexystover]

i meant on a STOCK ecu that has no TIMING adjustment, the timing is correct and cannot be retarted or advanced like you said so there for the timing does not affect the knock but the increase in cylinder temperature causes pre ignition, read before you go on a rant or try to call me out....

and the higher octane fuel isnt to allow for more PSI, but to allow for the higher cylinder temperatures... :wink:

[xXGTBspecXx]

i think you guys just like saying retard.

[sexystover]

i think you guys just like saying retard.

this is true... lol

[liquidracing]

nope

[liquidracing]

nope

[sexystover]

so, we're both right.....and.......RETARDED! :grin:

very true lol

[liquidracing]

l

[sexystover]

wonder if we can talk timing......since that is a HUGE factor in aftermarket boost? is the pp6, MSII, emanage, etc. the ONLY answer? is there a piggyback controller that changes ONLY timing AND fuel curve? i don't like the safcII or the neo for the very reason that it ONLY affects air/fuel ratio. anyone use the vafc for vtec? does it controll timing? or, what does?

exactly my feelings... anyone know?

[liquidracing]

i

[rougeben83]

wat? Tha'ts exactly what the emanage and pp6 does. I don't understand what you're asking for.

There's a bunch of separate items you can use to substitute for the full on piggyback. RS owners have been turbocharging their n/a ej25 for years using any combination of RRFR, voltage clamps, knock sensors, etc.

If you really want to get into it, go over to rs25.com's aftermarket F/I section and you can find all the combinations people have tried over the years.

[liquidracing]

o

[liquidracing]

o

[sexystover]

i have a boost control/timer and a 12v output if you wanted nitrous or something.... its like 400 new, i dont need ti anymore its brandy new someone give me 250 and ill ship it

[liquidracing]

o