No power gain from Underdrive Pulley?...

[Quadcammer]

Originally Posted by Boxtaboy

Any truth to some comments in the video that the stock pulley acts as a harmonic dampener, and that replacement risks engine damage? One comment even sites an article claiming so.

not on the 986. Its a simple aluminum pulley. It has not harmonic dampening whatsoever aside from its weight, which is not much different than the aftermarket ones.

On 987 cars, they have a true harmonic dampner which is why you have to buy a much more expensive underdrive.

Whats the word on this boxster making 273 wheel hp? Or is this one of those stupid dynos that converts to engine hp?

[Gilles]

Originally Posted by Quadcammer

not on the 986. Its a simple aluminum pulley. It has not harmonic dampening whatsoever aside from its weight, which is not much different than the aftermarket ones.

On 987 cars, they have a true harmonic dampner which is why you have to buy a much more expensive underdrive.

On my 987 the OEM pulley did Not have a balancer.., but I replace it with an UDP to reduce the speed of the accessories after frying three steering pumps on the track (thankfully replaced under warranty) and it's been installed on the engine for at least 20k without any issues with the water pump on the SoCal summer with heavy traffic..

I believe that the only 987's that came with the dampened pulley are the engines on tye GT3 and perhaps the 987 Turbo 911's

[Porsche9]

My UDP has been on my car for 20,000 plus miles with no ill effects. Only a little more power to the wheels and no issues at the track.

[Topless]

Wow, 273.8 RWHP sounds like a lot for any Boxster. That is about what my brother's 3.8L sleeper Cayman puts out.

Bottom line: Changing the underdrive pulley to preserve your PS pump might make sense for a track rat. Chasing a hp increase might not.

[Gilles]

Originally Posted by Gilles

I replace it with an UDP to reduce the speed of the accessories after frying three steering pumps on the track (thankfully replaced under warranty) and it's been installed on the engine for at least 20k without any issues with the water pump on the SoCal summer with heavy traffic..

I am sorry but forgot to mention that along with the UDP I also installed an oil cooler on the steering rack return line, by copying a design posted by Eric323 (Hergesheimer), but this story belongs on a "how to save your steering pump" …LOL

[jaykay]

-parasitic engine torque load reduced.
-p/s pump damage pontential at a sustained 4K+ rpm reduced.
-measured net BHp change as a result of reduced parasitic torque load will vary.