BaileyII

Does anyone have any experience with this for a 997.1S?

BF951

Great question. I've often wondered if there would be a benefit and tradeoffs between track and street.

Petza914

Unless you're going yo be tracking the car at frequent sustained high RPMs without high amperage demands (a/c, stereo, no lights, etc) its going to compromise the ability for the alternator to recharge the battery and not gain you very much. If you decide to do it, RSS makes a nice one.

BaileyII

Petza914

I'm sure there are plenty of people using them, but because it's a larger size than the stock pulley diameters, it slows down the rotation of everything on the motor that is turned by the crank pulley - water pump, A/C compressor, alternator, etc. Depending on how much reserve capacity is built into these subsystems, it may be just fine or it may not - output from the alternator may be lower, volume of coolant pumped through the motor will be lower (water pump impeller turning slower), efficiency of the A/C may be lower (compressor turning slower), etc. I don't realistically know how much power can be freed up, but it's likely not more than 3-5 and you probably won't even be able to tell the difference. I've never installed one on any of my cars, which are all street driven. Others may have some direct experience with these in a 997 and can chime in with their viewpoints.

Bruce In Philly

I want to ask a dopey question from the cheap seats.......

Why would anyone think they know more than Porsche engineers when it comes to these very important, foundational systems?

Look, I get suspension for example.... suspension is a massive trade off/battle between marketing to the poser and providing for the enthusiast. But engine internals that drive pumps? Really? Are there folks that really think the risk vs reward is ... well.. in their favour?

Peace
Bruce in Philly

kisik

I was considering RSS unit myself only to help my Power steering pump and fluids that would see high temperatures on the track. Caymans do convert for electric all the time. For 3.8L you would need a special balancing pulley and not a regular 3.6 or Boxer one. I don't need for extra engine power. A good driver will always outsmart extra horse power. Just like people are saying is that there are way too many variables here where water pump comes first to me.

nwGTS

yes if you track the car. otherwise you'll overdrive and overheat the power steering fluid pump. this is why cup cars use electric pumps not driven by the crank.

sober_owl

how about if u have the 3.6 can you upgrade to the 3.8 harmonic balanced pulley?

kisik

3.6 pulley is different from 3.8 and not back comparable. Not even sure what additional "upgrade" would be.

sober_owl

well the 3.8 pulley is harmonicaly balanced..it absorbs vibrations from the crank vs the regular pulley that doesnt..

what that means is bearing life should be increased and engine should run smoother..

porsche upgraded the 3.8 probably because thry wanted people paying the extra premium to feel a difference in drivability..

my question is if a stock 3.8 pulley would fit the 3.6?

halo777

I just had the RSS underdrive pulley installed on my 997.1 c4s (RWD converted.) Havent driven it yet, as the car is in semi-storage for the winter. Will have to provide a review in the Spring.

Jake Raby has an underdrive pulley for the Boxster/Cayman, and states:

Time and time again this install gives us the largest net power increase of any other bolt on.. I've installed a 3,000 dollar muffler and set of headers in the past and haven't gained as much power as this pulley provides.

...despite any actual values, this mod is one of the few that can be felt in the driver's seat.
I see 5-7 HP at the wheels and a torque increase of generally 5 lb/ft after the installation on my dyno. What should be more considered is this mod creates more power across the ENTIRE RPM range, so the average HP is increased and thats a much bigger gain on a stop watch or in the driver's seat than just a peak HP gain.

Full thread located here...
http://986forum.com/forums/performan...ve-pulley.html

Shred

Bruce, unfortunately Porsche didn't race the M96/97 and was being cheap so I guess they didn't know or pretended they didn't LOL!

For track use the underdrive pulley or power steering fluid cooler is essential.
I know because I had that failure on my 986S after being on the track like many other people.