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The solid center is the one I used on my Boxster and will use on the 996. Making a part nobody will ever see this pretty - at the cost of reliability - is insane.
Originally Posted by Flat6 Innovations
We love the UD pulley, but the unit we use has a solid center.
We love the UD pulley, but the unit we use has a solid center. The CVheetah looks fine, just don't use this one! We've seen three fail this year alone that came in one customers engines. This one didn't have another track day left in it.
But it could have been worse. This is what happens when fashion is employed where it has no place.
I have engines with hundreds of track hours using our solid center UD pulley with zero issues and thousands of miles. The top one above has less than one track season under its belt. The factory isn't the ultimate authority on these sorts of things, hell they are the ones who created an engine with 23 documented modes of failure, most of which occur on the street and not on the track.
I installed the UD pulley Saturday. What was a 3-4 hour job on the 986 is a 30 minute job on the 996. There's even room for a RotoZip w/ grinding wheel attachment to take care of the TDC boss, much nicer than the mini-hacksaw I had to use on the Boxster.
Really old thread but to be meaningful, voltage measurement of the output of the alternator with a UDP will need to have full load on it. At some point the slower-turning alternator may not be able to keep up with the demands of the car. If you turn on headlights, rear defroster, AC at full blast, wait until the car is hot and radiator fans are on, and turn on the seat heaters, you need to be sure the alternator can produce enough voltage at the RPMs you will be running at.
Just saying that there is likely a spectrum of possibilities. Slower spinning accessories can be a plus or a minus depending on what you need from them.
Really old thread but to be meaningful, voltage measurement of the output of the alternator with a UDP will need to have full load on it. At some point the slower-turning alternator may not be able to keep up with the demands of the car. If you turn on headlights, rear defroster, AC at full blast, wait until the car is hot and radiator fans are on, and turn on the seat heaters, you need to be sure the alternator can produce enough voltage at the RPMs you will be running at.
Just saying that there is likely a spectrum of possibilities. Slower spinning accessories can be a plus or a minus depending on what you need from them.
This research has already been done on ours cars and the general data shows anything under 2k rpms, the aftermarket UD pulleys can't match factory output. Other than that, they are identical in output above 2k. So bottom line is unless you sit in traffic more than you drive or you like lugging the engine, you shouldn't notice any issues.
Here's mine and pretty much supports what I said above.
I've had BRRacing in Los Gatos do some work on my car lately. Those guys know how to set a car up for the track as well as anyone. I asked Bruce what he thought about the UD pulleys and he told me it's all good, nothing bad and almost a necessity on tracked Boxster/caymans. I'm going to have the one I got recently put on since I'm looking for all the cheap power I can get!
I've had BRRacing in Los Gatos do some work on my car lately. Those guys know how to set a car up for the track as well as anyone. I asked Bruce what he thought about the UD pulleys and he told me it's all good, nothing bad and almost a necessity on tracked Boxster/caymans. I'm going to have the one I got recently put on since I'm looking for all the cheap power I can get!
BRRacing set up my PSS9's. Great guys, and the car's working great now.
I wonder if GT3's had higher output alternators or smaller alternator pulleys? They came stock with a smaller crank pulley.
I need to get one b/c my power steering pump is starting to weep at track days after sustained high rpms.
I'm about to install one on my 986 boxster, and every instructional guide tells me that you must use a tool or some other sort of device to lock the crankshaft pulley to keep it from moving when loosening or tightening the crank bolt.
Now, with the car on the ground, with the transmission in gear and the parking brake engaged, the crank should not turn and the pulley is held relative to the crank with a keyway.
So, in light of that information, no tools should be needed to keep the crank from moving.
I'm about to install one on my 986 boxster, and every instructional guide tells me that you must use a tool or some other sort of device to lock the crankshaft pulley to keep it from moving when loosening or tightening the crank bolt.
Now, with the car on the ground, with the transmission in gear and the parking brake engaged, the crank should not turn and the pulley is held relative to the crank with a keyway.
So, in light of that information, no tools should be needed to keep the crank from moving.
Am I missing something here?
Thanks
What you are doing, by using the driveline to lock the assembly, is killing the dual mass flywheel.. the link that connects all these items to allow the crank to be locked. The load it is experiencing is also opposite of what it sees in operation. I use a strap wrench, and a second person to hold the crank pulley when removing it. I don;t even trust the locking pin boss on the crankcase, as I have seen them break when doing this job.
What you are doing, by using the driveline to lock the assembly, is killing the dual mass flywheel.. the link that connects all these items to allow the crank to be locked. The load it is experiencing is also opposite of what it sees in operation. I use a strap wrench, and a second person to hold the crank pulley when removing it. I don;t even trust the locking pin boss on the crankcase, as I have seen them break when doing this job.
Hadn't considered the dmf. Thanks for your excellent response
Anyone try the EBS Racing underdrive pulley? Im considering buying this one. Seams to be built well and the price is great. $165 and it comes with the belt. Sold on eBay.
Anyone try the EBS Racing underdrive pulley? Im considering buying this one. Seams to be built well and the price is great. $165 and it comes with the belt. Sold on eBay.
The advantage of machining out the center on this pulley to reduce weight, does not offset the weakness of the pulley.
Go to a brand with more material in the center.
I am not sure about this pictular brand, but the majority of the ones that have failed, from my research are the machined out centers.
Take a look at RSS, mine was made very well.
09-26-2012, 12:11 AM
