Tranny+Engine Question

[Bohemian_Funk]

So I'm considering building an STi/DOHC 2.5 hybrid (you know, STi block, DOHC 2.5L heads, etc., etc.) with a T04E turbo (my friend accidentally bought a second one, and he's selling it to me for 170 bucks :cool:), and I'm wondering if my stock '95 L AWD 5mt tranny can take the pressure. I'm almost certain a goodly portion of you guys know more than I do on such a regard... and the internet, as expansive as it may be, seems to be of little/no help, though I'd almost bet I didn't search hard enough somehow...

Either way, I'm looking at trying for about 300-350 hp (maybe 400? It's a wagon, though surely it doesn't weigh much more than your average STi) out of such an engine (as well as of course an upgraded fuel system and various management tools).

If this question has already come up, perhaps you guys could pm me a link? I tried searching to no avail, though I have come darned close.

[decke48]

the tranny wont last long with 300+hp but will last temporary if you can afford a tranny for a while. just be easy on the clutch. but i would get a jdm v1-4 sti or wrx tranny and diff cost around 1,500 to 2500 depending on which one(not installed). as for a clutch turbo trannys use pull type clutchs and non-turbo dont. but no the 2.2 tranny wont last long and youll probally break some teeth if you use it hard

[rougeben83]

ok, I'm really not buying this "lol NA transmission wont last long @ x hp".

The push style transmission found in all NA subarus is the same design that was used in ALL GC WRX'S AND STI'S. All that changed was the gearing and clutch. The only big deal with the pull-style transmissions on all the newer turbo cars is that it distributes the force on the clutch and flywheel more evenly.

Now if you want to go into specific YEARS of cars, that's a different story (FXT, LGT transmissions are probably your best bet in terms of 5spd transmissions, getting the widest 1st and 2nd gears vs. the "glass transmission" 02-03 WRX transmissions).

That being said, it REALLY depends on the driver. An aggressive driver can break a PPG-geared transmission if he's so inclined. Conversely, a driver that is gentle in his driving style (note that doesnt mean he DRIVES like a grandma), can drive a 300+whp turbo car on a stock NA transmission and still get his jollies.

[Sarra]

The heads won't handle that much boost, either. You'll need to upgrade the valvesprings to prevent float.

[Bohemian_Funk]

Well yeah I don't buy into the idea of the ENTIRE transmission just up and turning into a pile of ferro fluid with one quick slip of the right foot either, I'm just thinking that since this transmission has already seen 226k miles, some internal parts may or may not hold up to the task in the end. T'would be a terrible shame if my daily driver were to suddenly drop a transmission on a particularly fast jog down the highway or up a windy road. I'm nowhere NEAR ready to start the engine build yet, so I have plenty of time to make decisions (still the matter of replacing a goodly amount of my suspension and interior... daddy needs a new pair of STi seats and harnesses :twisted:), I just like to have all basses covered before any amount of [censored by user] hits the fan, y'know?

[edit]
Thanks for the quick responses, by the way.