Destructive Torsional Harmonics or How to keep your cam bolts from backing out...
05-12-2014, 10:00 PM
#106
OK, change in plans for the .2 damper. We've found a way to get the mass where it needs to be and make it smaller. We'll get these started! I don't think many people will want to machine the stock parts on their cars...
05-13-2014, 07:45 AM
#107
06-22-2014, 01:33 PM
#109
Jamie - thank you for sharing info. Here is a list of questions for you.
1. Can you please provide a current update re status of the 3.8 version, thank you?
2. Did you post the technical results of the testing with either your original test equipment or the Porsche factory test equipment? I read where the testing was in progress, but didn't see the actual results posted and am interested in reviewing them.
3. Porsche engineers are pretty smart, and any time aftermarket products claim improvement/gains I am initially skeptical, whether from the perspective of a single component or a system of systems. In this case, what is the effect of adding 5-6 pounds to a balanced crank?
4. I understand the benefits being sought, but after witnessing the benefits of reducing the flywheel weight the thought of adding 5-6 pounds to the crank is not attractive, especially for a track oriented car with the stock dual mass flywheel. In addition to the harmonic testing results it would be interesting to see dyno runs before and after to see how much performance was being sapped; do you have comparative dyno run results to share? For a track oriented car that still sees some low RPM use going to the shop or in the paddock, perhaps this only makes sense when paired with the LWFW?
5. I had a LWFW on my RSA and really liked how it transformed the throttle response; however, I'm not convinced it is needed on the GT3 as it already revs very quickly. More importantly, from those I know it seems that the 3.8 RS's appear to have incurred more engine reliability issues on track than the base 3.8 GT3, often resulting in either cam adjuster bolts backing out or broken pressure plate. One significant difference between the two engines is the RS LWFW, so it is natural to associate the LWFW with the problems and want to stay away from it. There may be other problems besides harmonic balancing that are inherent/created when using the LWFW; what is the likelihood that the harmonic balancer is the silver bullet that cures the RS LWFW reliability issues?
6. While the emphasis has been on the benefits at lower RPM vice track RPM, how would this come into play when the inevitable "oops" happens and one has an over-rev? Crank pulley and cam adjustor bolts backing out seem to be a consequence often witnessed in the event of an over-rev; would this harmonic balancer help or hurt in he case of engine over-revs? Obviously a tad more difficult to gather actual test data on this, and more difficult to find a loaner for testing... ;-)
Thank you!
1. Can you please provide a current update re status of the 3.8 version, thank you?
2. Did you post the technical results of the testing with either your original test equipment or the Porsche factory test equipment? I read where the testing was in progress, but didn't see the actual results posted and am interested in reviewing them.
3. Porsche engineers are pretty smart, and any time aftermarket products claim improvement/gains I am initially skeptical, whether from the perspective of a single component or a system of systems. In this case, what is the effect of adding 5-6 pounds to a balanced crank?
4. I understand the benefits being sought, but after witnessing the benefits of reducing the flywheel weight the thought of adding 5-6 pounds to the crank is not attractive, especially for a track oriented car with the stock dual mass flywheel. In addition to the harmonic testing results it would be interesting to see dyno runs before and after to see how much performance was being sapped; do you have comparative dyno run results to share? For a track oriented car that still sees some low RPM use going to the shop or in the paddock, perhaps this only makes sense when paired with the LWFW?
5. I had a LWFW on my RSA and really liked how it transformed the throttle response; however, I'm not convinced it is needed on the GT3 as it already revs very quickly. More importantly, from those I know it seems that the 3.8 RS's appear to have incurred more engine reliability issues on track than the base 3.8 GT3, often resulting in either cam adjuster bolts backing out or broken pressure plate. One significant difference between the two engines is the RS LWFW, so it is natural to associate the LWFW with the problems and want to stay away from it. There may be other problems besides harmonic balancing that are inherent/created when using the LWFW; what is the likelihood that the harmonic balancer is the silver bullet that cures the RS LWFW reliability issues?
6. While the emphasis has been on the benefits at lower RPM vice track RPM, how would this come into play when the inevitable "oops" happens and one has an over-rev? Crank pulley and cam adjustor bolts backing out seem to be a consequence often witnessed in the event of an over-rev; would this harmonic balancer help or hurt in he case of engine over-revs? Obviously a tad more difficult to gather actual test data on this, and more difficult to find a loaner for testing... ;-)
Thank you!
Last edited by RedRSA; 06-22-2014 at 02:04 PM.
06-22-2014, 02:57 PM
#110
OK, let me see if I can get to all of them!
We're still working in out, has been slow with vacations, races, engine builds, etc... I'll update this week with more details for timing.
We didn't post the data from the porsche factory equipment, as we wanted to test the 997.2 3.8L version as it is likely the one we will move forward with for all of the Mezgers.
3. Porsche engineers are pretty smart, and any time aftermarket products claim improvement/gains I am initially skeptical, whether from the perspective of a single component or a system of systems. In this case, what is the effect of adding 5-6 pounds to a balanced crank?
I agree the porsche engineers are smart, but sometimes they get caught with things that surprise them (996/997 coolant fittings, 991 rod bolts, etc...). On the 4.0L we know of some cars that are on their 3rd engine due to oil pump failures. In our own work we have seen bored and stroked engines last 1500 street miles before eating the oil pump spur gear, backing out cam bolts, etc...
We're offering the damper up to others as we needed it/wanted it for our larger engine builds.
Crank shafts are balanced rotationally, so not much changes balance wise as the damper is also balanced rotationally. There are more issues with bolting on a flywheel/clutch to the crank shaft that isn't balanced...
We don't have the dyno runs, but I can tell you from customers that have already installed, they felt no difference in acceleration (these are track cars) and the comment that around town, the car felt "smoother"... We will back this up with data.
The difference from a stock flywheel to a LWFW is two fold, the mass and the distance to the center of rotation the mass is rotating around. The flywheel is about 2x the size of the damper and far heavier as well. Since the damper is about the same size as the crankshaft, the moment is limited around the center of rotation and why you don't see much difference in rev speed.
The RS does indeed have the LWFW, and the GT3 has a dual mass flywheel. The Dual Mass flywheel acts as a harmonic damper, just on the wrong side of the crank shaft to be truly effective. So if you're happy with where your GT3 is rev wise, clutch wise, etc... I too would leave it alone. We know our damper is keeping big engines with more bore and more stroke than the 3.8L so I suspect strongly that the damper will help alleviate some of the "mysterious" cam bolt loosening, etc...
Any over rev needs to be checked by taking the engine down. Lots of stuff can happen. I would say that the damper will help a little for small overrevs, but frankly would never sign up for something like that. I've seen GT3 engines that have rev'd to over 10k without issues, and others that grenade at 9200, so it's a crap shoot. Bottom line:
Be cautious and slow with your shifting!
3. Porsche engineers are pretty smart, and any time aftermarket products claim improvement/gains I am initially skeptical, whether from the perspective of a single component or a system of systems. In this case, what is the effect of adding 5-6 pounds to a balanced crank?
We're offering the damper up to others as we needed it/wanted it for our larger engine builds.
Crank shafts are balanced rotationally, so not much changes balance wise as the damper is also balanced rotationally. There are more issues with bolting on a flywheel/clutch to the crank shaft that isn't balanced...
4. I understand the benefits being sought, but after witnessing the benefits of reducing the flywheel weight the thought of adding 5-6 pounds to the crank is not attractive, especially for a track oriented car with the stock dual mass flywheel. In addition to the harmonic testing results it would be interesting to see dyno runs before and after to see how much performance was being sapped; do you have comparative dyno run results to share? For a track oriented car that still sees some low RPM use going to the shop or in the paddock, perhaps this only makes sense when paired with the LWFW?
The difference from a stock flywheel to a LWFW is two fold, the mass and the distance to the center of rotation the mass is rotating around. The flywheel is about 2x the size of the damper and far heavier as well. Since the damper is about the same size as the crankshaft, the moment is limited around the center of rotation and why you don't see much difference in rev speed.
5. I had a LWFW on my RSA and really liked how it transformed the throttle response; however, I'm not convinced it is needed on the GT3 as it already revs very quickly. More importantly, from those I know it seems that the 3.8 RS's appear to have incurred more engine reliability issues on track than the base 3.8 GT3, often resulting in either cam adjuster bolts backing out or broken pressure plate. One significant difference between the two engines is the RS LWFW, so it is natural to associate the LWFW with the problems and want to stay away from it. There may be other problems besides harmonic balancing that are inherent/created when using the LWFW; what is the likelihood that the harmonic balancer is the silver bullet that cures the RS LWFW reliability issues?
6. While the emphasis has been on the benefits at lower RPM vice track RPM, how would this come into play when the inevitable "oops" happens and one has an over-rev? Crank pulley and cam adjustor bolts backing out seem to be a consequence often witnessed in the event of an over-rev; would this harmonic balancer help or hurt in he case of engine over-revs? Obviously a tad more difficult to gather actual test data on this, and more difficult to find a loaner for testing... ;-)
Be cautious and slow with your shifting!
08-09-2014, 02:33 PM
#113
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10-09-2014, 04:00 PM
#116
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First 997.2 damper is here!
Sending to RedRSA as he has his engine out for a quick test fit...
It measures 5.1875" in diameter, this is the same diameter as the RS pulley. Want to confirm before we release them.
Sending to RedRSA as he has his engine out for a quick test fit...
It measures 5.1875" in diameter, this is the same diameter as the RS pulley. Want to confirm before we release them.
10-09-2014, 06:31 PM
#117
Thanks, Jamie! Looking forward to receiving it and doing the test fit!
10-16-2014, 01:56 AM
#119
Update from the test fit...
The damper fits without any issue. Due to the thickness of the damper the belt can't go on without removing the damper. Obviously this isn't ideal. We're going back to see if we can shave 3mm off to make room to get the belt on without any issues.
Will update as soon as we discuss...
The damper fits without any issue. Due to the thickness of the damper the belt can't go on without removing the damper. Obviously this isn't ideal. We're going back to see if we can shave 3mm off to make room to get the belt on without any issues.
Will update as soon as we discuss...
