HP & Torque Limits On a 69 5-Speed?

[JuiceMan]

Ok I have a stock 5-Speed trans in my 1969. I think this is a 901? Not sure please correct me if wrong. Anyways I was wondering what are the real world limits on this trans? Around how much torque and HP can they handle on a daily driver basis?

[pwd72s]

Much past 200 on the horsepower? Start thinking the much maligned 915 trans. Roland? Your opinion?

[This message has been edited by pwd72s (edited 08-17-2001).]

[Early_S_Man]

Well, the factory engineers thought it was getting marginal with the 2.2 'S' and 2.4/2.5 racing engines based on the 2.2. Certainly, the 'outboard' 1st gear is the weakest link, and have been broken with 3.0 street engines. If dumping your clutch is a favorite activity, something between a 2.7 and a 3.0 could get expensive to keep running with a 901 under it!

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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

[JuiceMan]

Well what would be the best trans to use with around 375hp and 350 lb ft?

Are there upgrades I could due to my 901 trans? Or would I be better to get a 915?

Sorry for my stupidity!

[pwd72s]

Arond 375 horses? 350 foot pounds? Uh, maybe a muncie M22? How to fit it in a '69 912 may present problems though.

[This message has been edited by pwd72s (edited 08-17-2001).]

[J Richard]

I read some time ago that a good rule of thumb for porsche equipment was that each component was designed with a 100% factor of safety. So the bottom line is if you have a car that is rated at 160hp, you could expect the box to handle 320hp. Provided of course it was in prime shape and wasn't a chronic issue like 2.7 cases or DM flywheels. The killer on the early boxes is they were designed for decent HP, but the torque is what you need to watch. Early cars didn't have much. 375 Hp? You must be thinking turbo or supercharging, please tell me you're not going to shove a chevy in there, I couldn't take it. (and if you found out how to get 375 out of a unblown motor, send me some info on the magic dust you found...)

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93RSA

[RarlyL8]

Not majic dust, laughing gas. HA!

Sounds like a V8 conversion in the making.
The 915 handles that conversion well by all accounts. If in doubt go to a G50 or 930 tranny. The 915 will only live in a high torque environment if you take it easy on the clutch.
Lots of Porschev info out there. Try the e-list, Rod Simpson, or Renegaid Hybrids.

[BlueSkyJaunte]

A recent article in Excellence detailed how a fellow put a 3.6 in his 914 but kept the 901 tranny. He blocked off 1st gear entirely, so he effectively has a 4-speed. However I think he was generating somewhat less than 300 hp. Will have to look it up.

(PS: It was a NICE looking car!!!)

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blue
'81 SC Targa

[campbellcj]

FWIW lots of 914 guys are using essentially the same trans (901/914 5spd) in pretty powerful 250-350hp conversion cars: 3.2's, 3.6's, V6 and V8's etc. I guess the key is how much torque your engine will put down in the low rev range -- 1st gear is the fragile one in this box but can be locked out or just deliberately not used much for launches. Also, supposedly certain engines (V6 water pumpers IIRC) produce less favorable vibrations than others, and the power pulses help tear the tranny apart that much quicker.

Chris C.

[This message has been edited by campbellcj (edited 08-19-2001).]

[Bill Verburg]

The original 901 had a max input torque of 19mkg(138 lb-ft), this was increased on the B series in '69, due to a new die cast Al. case, to 20.5 mkg(148.5 lb-ft). The '69 2.2L was the first use of the 225mm pull type clutch disk, as used thru '86. As previously noted, all of these transmissions have a generous safty margin built in.

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Bill Verburg
My Home Page My Pelican Gallery page My Porsche Owners Gallery Page

[BlueSkyJaunte]

That article I mentioned was in the June '01 issue of Excellence.