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View Full Version : Max HP on stock motor

T-minus
03-29-2006, 11:40 PM
Hey guys. getting a WRX and was wondering what the max HP and torque i can safely get on stock internals and tranny. A friend said around 300 hp due to the tranny, doesnt sound right, never heard of the tranny being the limiting thing on power.
subbykid
03-30-2006, 12:31 AM
yep trannies are. For some reason, they just like to give, that and diffs or axles too. Guess it matters on how the car was treated, but I would say about 350whp or so is where problems will start to occur on stock internals.
MF-DIF
03-31-2006, 12:51 PM
Drive it with mechanical sympathy and it might hold 400whp before meltdown...but that is on borrowed time. Since you asked safely, i suspect you want it to be a daily driver that will be marginally reliable. I would not exceed much past 300whp...

The tranny is fine as long as you don't shock it. Do not powershift, dump the clutch, etc.
Apexi wrx
03-31-2006, 01:05 PM
^^^^^ what he said and if u get a used wrx ull never know how the car was treated either the new 06 wrxs have a better tranny now
schoellnasty
03-31-2006, 01:41 PM
the new 06 wrxs have a better tranny now

The only difference between the 06 and 05 trannies is the double syncro on 1st gear. Theyre no stronger than before. Actually, if anything the 06 trannies are worse because the lower final drive puts even more stress on the gears.
Krash114
03-31-2006, 03:34 PM
Actually, from what I recall the 2006 WRX uses the transmission from the 2.5 Legacy, which is a bit stronger than the previous generation transmission. This doesn't mean one can go about abusing the 2006 WRX transmission and not break anything, it'll still break with enough wrongdoing, but it will safely hold more power and torque.
Apexi wrx
03-31-2006, 03:41 PM
the new drive line is out of the forester xt
schoellnasty
03-31-2006, 05:07 PM
the new drive line is out of the forester xt

No its not. The FXT has the 4.44 FD, and the new WRXs have a 3.7 FD. For those that dont believe that its the same tranny save for the first gear syncro, I point you here (http://forums.nasioc.com/forums/showthread.php?t=972135). Posts 9 and 10:

02-05 3.9 final drive, 06 3.7 final drive

They all have the same gears, but the 06 final drive puts more stress on the gears than the 02-05 trannys.

As for changes in the tranny I was told by the certified Subaru Mechanic who rebuilt mine that the trannies are the same as 04-05 except for the double syncro in first.
SnowMann
04-03-2006, 04:02 AM
FWIW: The new EJ255 is shared with the 2006 FXT/WRX

It is not the same EJ255 that was available in the 04-05 FXT. Its longblock is/was identical to that of the '04+ STi