+1

Whenever you remove the dual mass flywheel and swap it for a single mass you're removing an external part of the equation when it comes to crank harmonics and its always a good idea to match that up with the other end and that's whether the engine is considered internally balanced or not. If the other end is a harmonic balancer then I'd never replace it with a solid piece but in this case that doesn't seem to be the case. Having said that, I do like the ATI damper Emre's posted about above. Is this an off the shelf unit from ATI Emre?

Wondering if there have been reports of failures of oil pump gears with higher power levels and single mass flywheel clutches?

Porsche has documented failures regarding the swap of dual mass flywheels for single mass types. It introduces a low speed harmonic where the pulley bolts come loose and failures were being reported at low speed driving. Further research there uncovered a slew of cam actuators coming loose which pointed to a harmonic problem.

Boxer engines are well balanced but they're certainly not void of any balance or harmonic issues. With BMWs inline 6 for instance the crank is considerably longer and sees quite a bit more vibration/harmonics. Part of the reason boxer style motors aren't as affected by it is the "shorter" crank.

Dzenno@PTF

 

+1 - same issue with a bent pin. I replaced with proto pulley that has much more contact area. Also used correct washer and locktite

 

Are there any cons with switching to a lighter pulley?

-Jose

 

@jjuroz, one can only go by the feedback gathered from those that have pushed their motors hard and ran the lighter crank pulley with enough beating/mileage on them considering proper tuning.

Its hard to say with any degree of certainty given no factual evidence whether there are pros/cons. Personally I wouldn't lighten it and would rather gather my power gains elsewhere. I think I like ATI's multiplate damper option as it theoretically should take some torsional vibration harmonics out of the picture just due to the nature of its design but even in that case its hard to know anything for sure unless ATI had the 996/997 motor on an engine dyno with torsional vibration equipment/software hooked up to measure the pre/post damper situation.

It'd definitely be nice to see some data on it with dual as well as single mass flywheels in place with and without a lightweight pulley.

Things like this can also easily be beaten to death for no reason if there are motors running fine without any issues with enough power/mileage on them. They don't tend to last too long if there are any significant/damaging crank harmonics being introduced.

@prodigymb, when the OEM pulley fails at the pin/bolt, what does it look like? Does it look like something backed out due to vibration possibly?

Dzenno@PTF

 

i can only comment as to what i have seen and neither one had the bolt backing out. on my yellow car the pin key was bending and deforming the pulley and on the 68mm 997 i was talking about the pin was snapped but the bolt was still tight. so we replaced that with en EvoMS pulley. i like theirs because it has more contact area and fairly strong spoke design. i have seen a bunch of older threads with broken BBi pulleys so i would def stay away from those.

ATi dampener looks good but i'm not sure its necessary here.

 

Neil from Performance Developments and myself designed the ATI dampener in conjunction with ATI. The purpose being to reduce the harmonic torsional vibrations that occur in the Porsche crank. These vibrations normally show up as bolts "mysteriously" backing themselves out of flywheels, oil pump gears being destroyed etc... We see these effects particularly on the 4.0L and up GT3/RS engines driving at highway speeds. Turbo's will be no different...

Most that are using them learned the hard way by replacing bits of an engine or oil pump gears that failed...

Anyone interested can contact me or Neil...

 

I wonder if a lot of these cases of "mysterious" backing out of bolts is caused by guys that run the hell out of these motors but don't rev match properly on downshifts along with the occasional misshift. Of course no one will admit to that. Running a lwfw and pulley would only aggravate the situation obviously. I have a built turbo 3.8 race motor with an RSR crank, RS LWFW, and an RS lightweight pulley. The engine has a 7500 redline but I have seen as high as 7800 on Motec. Average on track Rpms are 5600. Granted that's a lot lower than a GT3 motor but I have not encountered any issues at all and the engine is exclusively used on track and run very hard.

 

Nope wasn't overrevs, the harmonic is actually between ~2500-5000rpms. Guys that don't track their 4.0LRS have been through multiple engine failures due to oil pump gears breaking... We know it works and will help, but not trying to scare or push something on someone who's not wanting it...

Everyone has their own path and not looking to start a battle about the efficacy of it or not, I use it, and sell to our clients and the builds we're apart of.

 

Surprised 4.0L owners aren't suing Porsche for what would seem to be an obvious design flaw, if it can be proved. Especially on cars that are fetching close to half a million on the used market.

 

If it can....

 

You guys hit on it, the issue is easier for porsche to keep replacing engines for those customers. Also gotta keep in mind, very few 4.0RS are driven...

All crankshafts have torsional harmonics, the issue is when there is very little to dampen it out. The dual mass flywheel does an OK job, but it's on the wrong side of the crank shaft to be more effective. It's better than nothing. 997.2 GT3's for example, don't have issues with variocam actuator bolts backing out. 997.2RS does, difference, the GT3 has a dual mass flywheel, the RS has a single mass flywheel.

If you don't want the dampener, completely understood, but keep your dual mass flywheel at least...

 

would the erp clutch be considered a single mass flywheel? if so then would the anti balancer be advised on a 3.6 to 3.8 build? ati doesn't show a porsche application on their website. has anyone ever looked at the fluiddamper pulley?

 

Yes - it's single mass. Jamie has a great write up over on Neil's site - lots of great information. He really knows his stuff. Billet oil pump that he has is amazing.

I've spun a pulley off - and it was clear that it was vibration that caused it. I was running a lwfw. Pulley had never been touched.

Luckily - crank nose wasn't too damaged.

 

Jamie,
Pleasure chatting with you today. We're more than happy to run this harmonic balancer on our 997.1 Turbo rather than just a pulley. We have always felt that this is a the right way of doing things when switching to a single mass flywheel and we're happy to see that someone's really done their homework here.

Dzenno@PTF

 

Flat 6 even fire motor does not need a harmonic balancer, it is the most organically balanced configuration possible.