let me start off by saying im considering buying an STI as my next car.

my last car, an A4 was recently totalled in an accident, it had an extensive list of mods including a 300hp built motor & all the susp, brake & related supporting mods...... the car was very sturdy & in all the time i had it, the car had no major problems & aside from tuning headaches the car was reliable & a blast to drive

for me, part of the fun in owning a vehicle is the customization that goes along with it, so needless to say, ill be modding the STi


i realize the motor in these cars is a newer motor & few have had time to fully explore its tuning options so some of these questions may be hard to awnser

whats the Max Hp someone has reliably had on a ej25t motor & for what length of time?

if you were to classify a "weak link" in this motor/drivetrain, what would it be? (aside from the boost creep)

i notice many Subie owners run around 1 bar/14psi max, is that because of detonation, fear of overworking the turbo? or heat (EGT/Oil) issues? the 1.8t's im used to would run 20 psi reguarly & they have a smaller turbo & higher comp ratio (9.5/9.3-1)

has anyone done any modifications such as changing fuel injectors, adding an AFC or modifying the MAF housing...... what were the results with the subaru DBW(Drive By Wire) system?

does the motor have a MAP sensor as well as a MAF sensor?

am i correct in thinking the max torque split is 35-65 or 50-50?

whats the expected life of the center diff clutch? or is it viscous?

 

If the EJ-20T used in the WRX was any indication the EJ-25T
will be able to take 450+ HP without any problem. Lots of WRX's
out there making 380+ HP at the crank without any failure of any kind. I ran 18-19 psi through my stock internal EJ-20T with never any type of problem, engine or drivetrain. The EJ-25T in the Sti has better pistons better rods and a better block. The Sti also has a much better trans., beefier rear diff and bigger axles. As far as the drive by wire system, seems to work great with no hesitation at all unlike the BMW system. Expect to see turbo, injector and ECU package upgrades by fall of this year. Most people so far running aftermarket turbo back exhaust and filter upgrade making about 330 crank HP or about 290-295 wheel HP
with the only issue being boost creep which can be eliminated by porting the wastegate ($195.) I am also working on an alternative
boost control device for the Sti.

 

good ol so cali 91 Craptane

 

I have to wonder how much "reserve" potential the the US market STI engine has designed into it? It may not have the big hp potential that some people think. For one thing, the crankshaft has a longer stroke than the EJ20 crank. This equates to a weaker crank, UNLESS the rod and/or main journal diameters have been increased. Does anyone know if this is the case? The lower redline on the US market STI would seem to bear this out.

 

The only thing that has been documented is the potential to damage the engine due to lack of proper engine management. Other conclusions are premature and unsound.

 

Hey charlie its one of your fellow Audiworlders (I post as lighweight on AW).. Sorry to hear about your car, I didn't see the post on AW.. I know you asked about the STis reliabilty, but I don't have any friends pushing major power with their sti (my buddy is still stock) but I have another friend who sold his RS2 turboed URS4 for an Evo, and DAMM.. He layed down 360whp with a bunch of mods (injectors, cams, FMIC, exhaust manifold, turbo back exhaust, IC piping, intake, xede, EBC, and some other stuff I probably forgot) and the car is a beast.. Im still debating if I should go Evo or Sti but now that the MR is suppose to come to the states, I think Im going to go that route simply because of the good experience that my friend is having with his evo and I don't want that damm 5 speed.. Of course we'll see how good hes doing after a year or so.. How much power you looking for? The fact that the 2.5L is a new motor kinda worries me, which is another reason why Im leaning towards the evo.. Its definitely a tough decesion because each car has its own great qualities, good luck.. I hope my post helps..

 

i thought the ej20 and ej251/257 had the same stroke with the bores being the only difference.

 

Hmmm. Where'd you get that info?
Everything I've seen says the EJ20T bore and stroke is 92mm x 75mm and the EJ25T is 99.5mm x 79mm
The WRX crank is also forged chromolly

 

I don't think the crank is going to be a problem either, in a stock engine. My concerns were, is there enough reserve strength in the crank to withstand really big power gains. As the stroke goes up, the strain on the crank increases significantly. By enlarging the bearing journal size, the crank can be made stronger to compensate. 4mm doesn't sound like much but it can make a big difference in what the crank has to endure at high rpm.
So, all I'd really like to know is if there were ever any engineering changes made to the 2.0 crank when the stroke was lengthened to increase displacement of the Legacy engine to 2.5 liters, or if any changes were made to the standard 2.5 Legacy crank when it went into the STI.