Underdrive Pulleys - 986 Forum - The Community for Porsche Boxster & Cayman Owners

David N. · 10-13-2006, 04:27 PM

Has anyone tried one in their Boxster? Friends with other sports cars swear by them for easy hp, and they seem like they'll have less collateral issues than intakes and exhaust. If I'm changing out the belt anyway, maybe good for a few extra horses?

-David

Ocean Blue 2000S

CJ_Boxster · 10-13-2006, 04:52 PM

If you do go that route, DO NOT buy a cheap brand.

The reason we have the heavey underdrive pulley is for crank balance and i think to absorb engine vibration...Going lighter will reduce the effectiveness of this but you will gain...maybe 3 hp per pound lost in weight. Some manufactors claim to have very well balanced underdrive pulleys...If i were to risk it, i would go with those companies product.

MNBoxster · 10-14-2006, 02:53 AM

Quote:

Originally Posted by CJ_Boxster

...but you will gain...maybe 3 hp per pound lost in weight...

Hi,

Huh..?? 3HP?? Yea, right - more like 0.3HP and then, only maybe. It's the ancillaries driven off the drive belt which cause the greatest parasitic loss...

Happy Motoring!... Jim'99

David N. · 10-14-2006, 05:01 PM

Thanks for the response.

As I understand the Boxster uses a dual-mass flywheel instead of a spring-dampened clutchplate to help absorb that vibration. I didn't really want to mess with that dampening at all, just reduce the losses from the alternator and compressor. I guess an underdrive pulley isn't worth the trouble.

-David

ocean Blue 2000 S