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Discussion Starter #1
I've heard alot of talk about the engine, so lets hear something on the STi tranny, as in, how much more HP it will be able to handle than the 5SPD? I've read that its better, but how much better????Lets hear some est. on how much HP it should be able to safely handle.
 

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Some confusion with terminology here - buy N/A do you mean naturally aspirated? Rumors of the new STi coming with a new 2.5L engine involves a turbo-charged engine - any reference in these rumors to the term NA points at the market it is going to be offered in (North America), not the type of aspiration. I doubt Subaru would put out a non-turbo motor in the STi after its mean years of success with the turbos. I have always heard that the 2.5L rumor involved a turbo - at least that is what my source has said.
 

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Discussion Starter #3
Official Numbers

If you read my topic before I edited it(something about 2.5n/a) that was my bust!!! :oops: :oops: :oops: :oops:
I read an earlier topic to way too fast and ended up reading it wrong. Hope I didn't offend anyone with my ignorance. I was just used to hearing NA=normaly asspirated, and US=north american market. THX for setting me straight MYSTi.
 

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Soopafly said:
I've heard alot of talk about the engine, so lets hear something on the STi tranny, as in, how much more HP it will be able to handle than the 5SPD? I've read that its better, but how much better????Lets hear some est. on how much HP it should be able to safely handle.
The STi tranny is capable of withstanding much more power thant the WRX tranny. Im sure the tranny was engineered to withstand additional HP and torque. Look how much extra HP the WRX tranny's can withstand - like an additional 100HP over stock :eek: . I think if you want to squeeze more power out of the STi you would first have to worry about engine detonation with the STi running 17.5 PSI on U.S. 93 octane, rather than worrying about the tranny going.
 

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Discussion Starter #6
I also agree, with DVTURK....but what I'm trying to get at more, is putting aside all engine probs what would the STi 6SPD be able to handle with out breaking under heavy load, IE: medium to hard launch. I seems to be the general concensus that the standard WRX 5SPD shouldn't be trusted much over 320 HP.
 

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Well, when you say medium to hard launches, what do you mean? Taking the STi and going from a stand-still and accelerating hard is about as aggressive as you want to go. A hard launch such as a clutch drop is not good for it at all. Even with the 6spd you're gonna break something if you do that...
 

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Soopafly,

If you want hard numbers, I don't know if anyone can give them, but I have heard that the stock STi 6-speed is used extensively in SCCA ProRally, at up to 30 psi (or higher) under heavy rally use.

A properly tuned EJ20 running at 30 psi should be good for well over 400 hp, so I think we can safely say the tranny is up to just about any task you want to throw at it. The exception, as has been noted many times on this site, is hard drag-launches. High-RPM clutch-drops aren't good for ANY transmission, much less AWD.

I read that the R33 Skyline in SCC's Ultimate Street Car Challenge (Feb. 2003 issue) has a HKS "Drag Launch Adapter" that lets the AWD car do RWD burnouts with the twist of a knob. If something like this can be fitted to the WRX like an aftermarket version of the DCCD with the ability to go full-rear, that might be your best bet.
 

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Soopafly this is where I've noticed all of the EVO's have their main problem. Their gearbox and transfer case is weak. Now, I launched my car between 6500 and 7000 RPM's twice. The launch was incredibly unbelievable. The front tires chirped and the g's were unreal. Anyways, I think that was tremendous load on the gearbox, using the stock clutch. (By the way, did anyone have problems with their stock STi clutch yet?) I monitored the feel and operation of the clutch closely afterward. It seemed unharmed. The car worked as if it was never launched hard. A couple weeks after though, I tried the same launch and messed it up. It was around the same rpm's but I came off the clutch too slow. Instead of almost popping it off, I sort of rode it off, if you guys know what i mean. I smelt the clutch for a while after. Now I feel a difference when I'm engaging the clutch. It doesn't have that crisp, rugged, solid feel when the gear goes in and I reaise my foot off the pedal. I may have done some permanent damage. (I may have strayed from the topic a bit but this is good info. anyway). Now I do not do this often at all and no one should. The car really wasn't designed to be launched that hard. (incredible feeling though). I want to talk about what we discovered when upgraded clutch discs are used in a later post
 

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Discussion Starter #10
This all sounds good to me. Not looking for nothing solid, just something approximate. When I said medium to hard launch I was thinking 3500 to 5500 RPM's not sure if there are any set numbers as to what a hard launch is, though I know I would not go over 5500 RPM's, unless my car was pretty well modded, and something like a Diablo SV pulled up next to me at the stoplight and I thought that I actually had a chance of beating it to the next stoplight. At that point I'm sure my ego would kick in. :)
 

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I've heard of JDM STi's running near 30 pounds of boost with the six-speed and not breaking anything. I doubt they are doing 7500 RPM clutch dumps, though. I don't think even a all out dog-box could take that type of abuse for long.

As for me, a 3,500 to 4,000RPM quick slip seems to do well in my current car, although I don't do it all the time, most of the time I baby it (launch below 1700). My friend who has a RS-T does 6000RPM clutch dumps all day in his RS, but he has a semi-dog box and he has gone through a stock RS trans, in fact I think two of them...

I'd rather wear the clutch than the tranny...
 
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