G/B for Underdrive pulley on CaymanClub

[CJ_Boxster]

Isnt the Crank pulley on the boxster as far as function, the same as other vehicles?

What i mean is usually the Crank Pulley turns belts which we all know, HOWEVER it also is a harmonic balancer for the crank... with my experience with bolt on mods on other vehicles, removing your Crank pulley/Harmonic Balancer will throw off some balance that the crank needs in order to prevent premature bearing failure... and by removing the Stock pulley and installing a lightweight Crank Pulley (which commonly do not have harmonic balancer atributes) can reduce the life of the bearings.


I would recommend performing an oil analysis before and after installing the new lightweight Crank Pulley to check for increased wear in the Crankshaft bearings.

[cheetah]

On many cars the crank pulley is a harmonic balancer also, but not on the Boxster. The stock piece is a very lightweight item, and only used to turn the accessories. My custom-made one has been on my car without any problems, and can be seen here:

http://www.cheetahonline.com/products/n8039.html

This is a 20% reduction, has been tested, and it works great. A noticeable increase in power throughout the powerband. The voltage has been tested with all the accessories on during idle for extended time without any drop in voltage.

This also takes 2/3 the power to turn the pulley, as it was made as lightweight as possible. I have not been able to dyno it yet, but I hope to soon.

Paul

Originally Posted by CJ_Boxster

Isnt the Crank pulley on the boxster as far as function, the same as other vehicles?

What i mean is usually the Crank Pulley turns belts which we all know, HOWEVER it also is a harmonic balancer for the crank... with my experience with bolt on mods on other vehicles, removing your Crank pulley/Harmonic Balancer will throw off some balance that the crank needs in order to prevent premature bearing failure... and by removing the Stock pulley and installing a lightweight Crank Pulley (which commonly do not have harmonic balancer atributes) can reduce the life of the bearings.


I would recommend performing an oil analysis before and after installing the new lightweight Crank Pulley to check for increased wear in the Crankshaft bearings.

[insite]

10 - 15HP at the wheels is BS. Mantis (they race a Cayman S in PCA) has an underdrive pulley that fits all boxsters / caymans at mantissport.ca. they're good for 6HP, but the primary use is to slow the power steering pump slightly so the PS couplings don't melt (a problem on C7's and 987's in particular).

[easyc]

Common problem on 986S too!

[blinkwatt]

Originally Posted by cheetah

On many cars the crank pulley is a harmonic balancer also, but not on the Boxster. The stock piece is a very lightweight item, and only used to turn the accessories. My custom-made one has been on my car without any problems, and can be seen here:

http://www.cheetahonline.com/products/n8039.html

This is a 20% reduction, has been tested, and it works great. A noticeable increase in power throughout the powerband. The voltage has been tested with all the accessories on during idle for extended time without any drop in voltage.

This also takes 2/3 the power to turn the pulley, as it was made as lightweight as possible. I have not been able to dyno it yet, but I hope to soon.

Paul

How hard was the install? What tools were required? How many miles have you had it installed for now?

[blinkwatt]

http://www.caymanclub.net/reviews/showproduct.php?product=157

Should be the same concept on a 986.

[cheetah]

The installation was not hard at all. The Cayman directions are very close to that of the Boxster.

Socket set for the various bolts to get to the pulley. To take the pulley off there are a few ways:

1. Screw a bolt through the hole in the pulley and into the area that needs to be ground down. This will hold the pulley still to take the bolt off. (this is what the Porsche book recommends)

2. Use the Porsche tool or equivalent to hold the pulley still

3. Use a strap-wrench to hold the pulley still.

I actually prefer #3 as it won't leave any marks and can be used to mount the new pulley easily.

Once the pulley is held still, a 24mm (I believe) socket will need to be cut down shorter. I was able to get the racket in this tight spot to take the bolt off, but the torque wrench to put it back on just wouldn't fit.

Grind the ridge as shown in the other installation. Put new pulley on and reverse instructions. The new belt that I listed is used as the stock one will be way too long.

I don't drive the car everyday (third car), but I have put it through every conceivable test to watch voltage, coolant temperature, and steering response. The voltage is good even with full load, the temperature stays the same, and steering feels exactly the same. I also monitored these driving with the Durametric logging all the sensors.

As stated, this is a 20% underdrive.

Any other questions, feel free to ask...

Paul

Originally Posted by blinkwatt

How hard was the install? What tools were required? How many miles have you had it installed for now?

[Gary in BR]

Has anyone installed an underdrive pulley on their 986 yet?

[insite]

i just read the instructions for that install. FYI, that thing they grind off is actually kind of important during an engine rebuild. there's a pin that goes through the OEM pulley and that aluminum protrusion at six different positions required for proper reassembly of the motor.

[steve00s]

Thats pretty cheap HP compared to other things that we do. 5 HP is not much but neither is $200 and there is some benefit on the power steering issue too (not that I've ever worried about that). The reviews that I have read report no problems. I've had these on other cars I've owned and have kind of wondered why I didn't hear anything about them in the Porsche world. I'm buying one.