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Old 01-22-2002, 05:40 AM   #1
EneMy X
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Default So If Im going to push 350 WHP??

So Im getting ready to turbo My 2.5 RS, everything is in order, FYI I will be using a haltec EMS.

So Im wondering what to do with my tranni to make it hold say about 350 WHP?

I have tried and tried to find information on the tranni but have had almost no luck.

What are my options on making the tranni tuffer? I have clutch and flywheel already but im hearing the tranni isnt going to take much more then 280 WHP...

Any help would be great, thanx.
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Old 01-22-2002, 07:57 AM   #2
LUME
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Your transmission (if its a 5MT) will NOT handle 280 wheel horse power. At least, not if you plane to take advantage of that power in all gears....

--Roy
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Old 01-22-2002, 10:05 AM   #3
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Cheapest solution may be to remove the gears and have them cyro treated. This is rumoured to make them stronger but by how much, nobody knows.

-Michael
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Old 01-23-2002, 02:23 PM   #4
cRayZee
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If you want that much power.. from what i've read around i-club, you have at least these 2 choices: dog box or get an auto tranny.

I dunno e xactly how or why the auto trannies are able to handle the power, but they do...

If you like using the clutch and shifting, then there's a dog box. These things don't use helical gears and no synchros. You know the sound your car makes when you're on reverse? It'll be making this sound too going on all forward gears as well. And without synchros, you'd probably have to learn how to rev match well
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Old 01-23-2002, 02:28 PM   #5
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grrr... your tranny can and will hold 58gagillion WHP assuming you're making a peak of 100lb ft of torque and you rev the car to the moon.

HP doesn't break transmission gears, Torque does.

Now, with that out of the way, go half dog. 2nd gear is the big problem.
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Old 01-23-2002, 11:46 PM   #6
subyguy2
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Thank You Jewbaru, I was just about to post what you said until I saw you allready did. Well said. There needs to be a thread informing everyone on the forum who doesnt know, that horsepower does not make your clutch slip or your gears break, torque does!!!

Chris
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Old 01-24-2002, 01:45 AM   #7
EneMy X
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Default Thanx for the info

Yo thanx for the info guys so how much will run of these dog boxes run me? any links or info on pricing?


thanx all
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Old 01-24-2002, 08:50 AM   #8
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Jewbaru:

Relax. Personally, I know this. Now just try and assume that this engine will never make it over 7 or 8 grand.... (like any other subaru engine). In that case, a stock tranny will not handle 280 wheel horsepower. Sheesh.

--Roy (going to push my boxer to 20,000 RPM.....)
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Old 01-24-2002, 11:37 AM   #9
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Lume, you can't be that vague. A RS-T pushing 3psi can put down more than 280hp in first or second gear without a correction. You cannot mesure the tolerance of a gearbox by wheel horsepower, period.

And what do you mean "like any other Subaru engine?" The STi revs to ~8k, the standard WRX revs to 7k, and the 22b reved to ~8.5k.
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Old 01-24-2002, 04:01 PM   #10
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I would like to see a dyno chart showing 280 WHEEL horsepower at 3psi.

And yes "Any other subaru engine" refers to that engine..... like I said, 7 or 8 grand (last time I checked, 8500 wasn't that far off from 8000). My point is these engines wont make 10,12, or 20K RPM...

--Roy
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Old 01-24-2002, 04:27 PM   #11
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3psi is most likely a tad over 200hp at the crank, so with a 30% drivetrain loss, that's ~140hp to the floor at a 1:1 ratio. Put it thru the first and second gears (first IIRC is around 3.5 gear ratio) that multiplication would be over 300hp to the wheels after the tranny does it's job. However, the trans still only see's ~200 or so lb/ft of torque.

Flat out, you cannot use HP as a mesurement of a transmissions strength. If someone says "well, I wanna run 400hp, will my trans break?" don't say "yea", correct them and say "HP doesn't matter, it's the torque that counts".

8500 is quite a bit "off" of 8000 when you're talking RPMs. On the same token, 8500 isn't that much off of 9000rpms is it?

[EDIT] I know where you're coming from, but in the long run, it's better to correct him and let him know torque is what counts, and not HP.

Last edited by Jewbaru; 01-24-2002 at 04:35 PM.
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Old 01-25-2002, 07:56 AM   #12
LUME
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Default OH MY GOD!!!

Quote:
3psi is most likely a tad over 200hp at the crank, so with a 30% drivetrain loss, that's ~140hp to the floor at a 1:1 ratio. Put it thru the first and second gears (first IIRC is around 3.5 gear ratio) that multiplication would be over 300hp to the wheels after the tranny does it's job. However, the trans still only see's ~200 or so lb/ft of torque.
Jewbaru.... I'm sorry but now I get to make fun of you.

If you have 200 hp at the crank, you are correct that you will get (probably) around 140 hp to wheels. But horsepower cannot be multiplied through the transmission! Torque can be multiplied, and RPM can be multiplied, but the product of the two must always remain constant and thats power! Sorry to say, but you are sorely mis-informed about the mechanics of rotational speed, torque, and power.



--Roy
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Old 01-25-2002, 10:32 AM   #13
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oops, I screwed up my math. Oh well, it doesn't matter. Laugh it up.

My point stands, don't agree with someone when they start talking about HP breaking their gearbox, you're just helping the misinformed stay misinformed.
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Old 01-25-2002, 04:09 PM   #14
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True that.
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Old 01-26-2002, 03:20 PM   #15
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To answer the above's question about why the auto is stronger, it's because automatic transmissions use planetary gearsets. With this setup, the gears never come out of contact and are thus less likely to incurr shock. The shock applied between shifts is what generally takes out gears in a manual.
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Old 01-27-2002, 03:41 AM   #16
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i did not know that Brandon, thanx!

that's my "what did i learn today" for sunday jan. 27th

-Lou
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Old 01-27-2002, 07:10 AM   #17
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If you raise the redline of the engine then can might cause overheating problems within the tranny case (more friction=more heat), thus causing some parts of the tranny to expand in certain areas.

If that's the case then the gears may fall out of their proper orientation making them a lot more prone to the shearing effects of any torque applied to them.

Mind you one won't be running that hard all the time but this may introduce a window of opportunity for failure. Am I way off here?

Would this effect straight dog gears as much since the tooth profile is much beefier?
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Old 01-29-2002, 08:31 PM   #18
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To build a transmission with dog engagment gears will cost you $4000.00 if someone else puts it together, unless you use Chalak gears, or a half dog set up, which are less expensive and have people squabling over their reliability (lets not get into that here, if you are interested, search it). Add to the cost a 20kg center diff and a front lsd and it will cost you alot. This is the reason why I am selling my turbo parts. A bulletproof tranny puts me significantly over $10,000.00 and I don't have that much money to spend. Trying to find a used full dog transmission is an excercise in futility. I searched the entire globe, and everybody said that they have never had one, or that they are REALLY hard to come by.

Greg
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