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Crusin worlds most isolated city
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4by4,
Can you comment on the difference from Gen1 to Gen2? Why the switch? Was it because they realized it DID need to serve that purpose in Gen 1, so they made that revision in Gen 2? Or was there some other design factor that changed the need?
No idea. I can only guess that it was part of the refinement process or readying for the upcoming electro-hydrolic steering.
 

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No idea. I can only guess that it was part of the refinement process or readying for the upcoming electro-hydrolic steering.
Let's not forget its a quite different engine, with no IMS.

All this stuff about timing being thrown off with UDP's in general is just not correct, and only can apply in the case of a proper crank balancer pulley. If that were really the case then my LWFW would be a hell of a lot worse than a poxy pulley!! The stock flywheel is a dual mass unit with built in dampers so if a flywheel that weighs half as much and has zero dampening built in doesn't cause a fault it's safe to say the UDP won't.

With engine electronics these days any minor imbalance due to harmonics would be dealt with and the driver would have no clue about it.

Now if we talk about component lifetime now that is where harmonic balancer pullies come into their own and then you can easily argue for them.
 

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I'd have to agree I don't any way this plays into the harmonic balance. I've had mine changed for about 10K miles and can't detect any difference in mis-fires or other engine control feature.

As far a performance boost, I would have to disagree with the comments about no performance improvement. I had mine changed and at the same time I was installing a new flash in the ECU. However, when I picked the car up the shop apologized because they could not do the flash due to not getting the latest version downloaded in time, so I had to bring it back:( So I take it home and not expecting any difference in the car...wow, what a shock...with just the UDP, it felt like a new car! You know, when you make a change that you expect big things from, you can always "feel" it, but honestly I wasn't expecting much here, so a nice surprise. Quicker revs and much snapper feel. So maybe no HP but the effect was the same...later, after the flash it just got better. I think for this engine the UDP is a good mod and well worth it, with no downsides at all.
 

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Not that impressive on my side, but yes I notice improvement on higher RPM...
 

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I'd have to agree I don't any way this plays into the harmonic balance. I've had mine changed for about 10K miles and can't detect any difference in mis-fires or other engine control feature.

As far a performance boost, I would have to disagree with the comments about no performance improvement. I had mine changed and at the same time I was installing a new flash in the ECU. However, when I picked the car up the shop apologized because they could not do the flash due to not getting the latest version downloaded in time, so I had to bring it back:( So I take it home and not expecting any difference in the car...wow, what a shock...with just the UDP, it felt like a new car! You know, when you make a change that you expect big things from, you can always "feel" it, but honestly I wasn't expecting much here, so a nice surprise. Quicker revs and much snapper feel. So maybe no HP but the effect was the same...later, after the flash it just got better. I think for this engine the UDP is a good mod and well worth it, with no downsides at all.
I think "feel" is really important, in fact I know it is, as a driver. I know it has saved both me and my car. I won't regale everybody with the story, but I believe "feel", feeling for the car is an athletic gift. Like you, I could tell right away. And there is an improvement in performance. And if I were to pick one adjective with regard to the lightweight underdrive pulley? It would be smooottthhh!
 

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Revive old Thread.

So, with any aftermarket pulleys for 987.1 It increases power and decreases stress/temp issues with PS pump. Not worried about AC. But more importantly: How about Alternator and especially Water Pump esp. for us guys tracking our cars. Any issues with temperature?
 

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I have about 115 track days on a 987.1 CaymanS. Added the underdrive pulley years ago while "I was in there". I can't say I felt any additional power but do believe turning the P/S pump, water pump, and alternator slower can't hurt. No ill effects from the change. I don't think the pulley will solve the P/S issue and am using a P/S cooler.
 

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Has anyone been able to get a new under drive pulley bolt torqued to 50 NM and then 90 degrees??
I'm a pretty strong guy but there is no way I can turn this bolt 90 additional degrees.
 

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When I installed the UDP I used a jack handle on a 1/2" drive breaker bar for added leverage. Made it easy.


Dan
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Ok. Done. Had to put jack handle on the 'tool' to hold the pulley in place, and a long torque wrench on the bolt. Then prepare to flex your muscles. BTW: I had the torque wrench set to 220 ft/lb and it never 'clicked'.
 

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Underdrive pulles have been the cause of many enthusiast forum squabbles for decades. There is some credence to the theory that the stock pulley serves to absorb harmonics from the firing order (hence why it is sometimes referred to as a harmonic dampener.) This also lends itself to the issue that the poster above was having with a cold engine misfire or what the knock sensor assumed was a misfire.

To what extend does an engine receive damage by removing this part is up for debate. I know in the BMW world those long I6 motors do not respond well to changing the stock part. Would a compact boxer engine with a shorter crank suffer any affects? It seems like the anecdotal evidence suggests not.

For me it isn't worth the risk for a couple of HP.
The Pulley for a gen 1 car does NOT have or form part of a harmonic balancer. The mass is also insignificant.

For gen 2 its the opposite.

A UDP for a gen 1 works good.

Any updated feedback on UD pulleys given the above feedback and for the 987.2S in particular?

There is some youtube review that says it adds absolutely nothing power wise and then of course feedback that dynos have shown it does.
 

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I'd save my money for another project.

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