sti trans rebuilt for more power

origionally i didnt use bracket, but made a small one as soon as i could, as it didnt quite fit right how it was on their.
however i just put my solenioids on the fire wall :\
phil

I haven't gotten into looking at it yet but i understand the newer cars have a different bolt pattern where the bell housing bolts to the car...can you use an old imprezza bell housing with a new sti transmission..maybe I don't know

More importantly remember the wrx's are very light cars. Their transmissions, flywheels, clutches, etc aren't really up to both high hp and high weight...it's a real stretch..kind of a down grade from the svx tranny

What I've been thinking; however, is when the production model of the b11s hits the streets we aught to be able to make a bell housing to use that transmission. It's already designed to support high hp on a heavier car.

I'm sure after the need arises the guys who are doing the 5 speed swaps now will come up with something to meet the demand.

Subaru manual transmissions, unlike their automatics, do not use a separate bellhousing like most doemstic RWD cars. The area used for the bell-housing (ineither a manual trans or an auto trans) is actually reserved for the front differential. You gotta take the entire trans and bolt it to the engine using fewer bolts than the factory intended and hope for the best.

Todd

Man its hard to keep track of this post.

Did you say that the stage 2 would actually lay down more power than the supercharged stage 3?

They will be about equal peek hp but remember nitrous is a flat amount of horse power accross the entire load and rpm range. So the stage 2 nitrous system will be faster in the 1/4 mile which is about the only use you get out of it. Where with the stage 3 blower you have 24/7 around town power.

there are a couple of people running the new 6 speeds from stis already

Only Alex (alex_umn) has an STi 6 speed... as far as I know. I'll also add that it drives pretty nice, in my opinion.:)

Hmm... aren't you worried about the roots style running a bit hot (compared to centrifugal or turbo)? Will it work very well without an intercooler? You're saying it provides higher performance due to the low end torque provided comes on earlier, right? I would think a centrifugal type supercharger would be better just due to it being more efficient.

People can argue the merits of one type of forced induction over another forever. A supercharger runs cooler than a turbo in general due to not having the soak from the hot gasses running the turbo. AT 6 lbs of boost we should be fine without the intercooler. Just from general experience and their track record I think roots blowers offer more performance but centrifugals are good too.

I can chime in here as my 2000 SVT Lightning uses a Roots type blower. Yes it is intercooled, but as a supercharger compresses intake air (as oposed to exhaust gases as in a turbo) several people have been able to run a roots type blower w/out an intercooler with no ill-effects. The best thing about a Roots blower is that it makes most of it power in the low rpms (<4000 rpms) and this gives drag racers that edge at the starting line. Screw type (centrifugal) superchargers are more efficient, but way more expensive and make the most power in the higher rev band (>4000rpms).

he's right, the roots style blower will take advantage of our motors w/ their low end power as opposed to a turbo or centrifical because they all run to make better high end and our powerband takes a dump at like 5600 so a roots is the most efficient and most powerful w/ out major engine rebuild

if it takes a dump at 5600 why is the rev limiter being raised higher?

and yes i am dumb so if that is a really stupid question be easy:D

Intercoolers
 

I agree. Even at about 8 psi with a turbo, it is questionable whether an intercooler helps. Definitly not needed for a supercharger at 6 psi. There is a certain amount of work required to get through an intercooler. This added backpressure causes the intercooler or turbo to run at a higher pressure. Say 2 psi loss through the intercooler. This means the turbo/super needs to run 10 psi to make 8 at the mainfold. The compressor actually runs hotter air in this case reducing the effectivness of the system. I'm sure the break is a little different for every applicaton. An A/W might be good with low losses. Also water injection.

The STi trans could handle all the power that our engine could ever produce... Ya wouldn't have to rebuild it... Get this, it isn't even built by Subaru...

It's built by some company in Germany from what I hear... However the old STi 5 speed from the version 6 and below are built by Subaru... They are still Very strong tranny's... Also the WRX 5 speed has recieved alot of crap... In most of the cars that I have seen, the tranny's have blown 2nd gear simply because of Abuse... Yes If I wanted to I'm pretty sure that I could go out to my car right now and do a few 6500 rpm clutch drops and maybe blow 1st gear out with the estimated 250hp (flywheel) that I'm making outta my SVX... It is all about how you drive it, really... I have also seen a WRX run a 11.9 1/4 mile on the Stock tranny... It is all about how you shift... Now, sometimes with the way that I drive I would feel a little more comfortable if I had the Forester XT 5 MT in it but hey that just makes me not drive quite so hard, and probably has saved me from a few tickets...