Glyn M Ruck

At the request of TruTaing I am moving this post to a new thread. He is interested in this discussion but does not want it poluting his thread. As a good friend I duly respect this.

Now posted here:

Quote:
Originally Posted by splinter
Interested to hear your long-term feedback on not only the UDPS, but also the new crank pulley. When my dampened evosport ODPS was installed, throttle response was definitely quickened - akin to a lightened flywheel. Its increased supercharger boost was merely another favorable happenstance.

The tasteful and intelligent modifications you’ve installed have resulted in one of the sharpest and most desirable rides on our forum, IMHO. Exceptionally well done.

I may get up to Mercer Island this summer. Perhaps we’ll have a chance to catch up.

My comments & questions

+1 on the tasteful & intelligent modifications. Tru's car is very pretty (tasteful) especially after installation of the BiX - A really nice car that doesn't look like a Xmas tree & looks all Benz.

I don't want to throw a cat among the pigeons & would like to keep this simple - I'm merely interested in your comments. V6 engines are inherently unbalanced & suffer from static, dynamic, torsional & harmonic imbalance unlike their inherently balanced inline 6 counterparts. Benz has gone to huge lengths to mitigate against the products of this imbalance with crank balance technologies, balancing shaft, dampers etc. Their own pulley is designed to mainly mitigate secondary torsional & harmonic imbalance. Weight of this pulley, amongst other things, being part of it's design to keep vibration & its frequency out of the critical area for this engine. Engine mounting design also plays its part.

Now we come along and put an aftermarket pulley on the engine of unknown integrity in these areas. So my question is - How well designed is this pulley when it comes to Benz' holistic approach to vibration mitigation.

The reason I ask this is that I was involved with MBs debacle with the 2 litre SOHC engine that saw a few people loose their jobs. These engines would wear out camshafts at an alarming rate & Benz had the oil industry running around trying to cure the symptom which we partially did but led them to discovery of the true failure mode. The camshaft produced an unusual harmonic at a critical frequency that caused cavitation of the oil film at the cam lobe, follower interface. The fix was to go from a single to a duplex timing chain & put a heavy harmonic damper on the timing chain/camshaft pulley which moved the frequency of the harmonic out of the critical area.

I would like some assurances that messing with the MB pulley does not cause cavitation of the oil film in the crank bearing area or other long term problems. A problem suffered by another OEM who shall remain nameless.

Making sure that the pulley has no deleterious effects in the bearing area is as simple as taking a few oil samples & looking for upward movement in the lead, copper & tin wear metal areas.

Comments welcome.

AMS Performance

Well, its only appropriate AMS starts the thread off . First it is important to understand a few engine basics....

There are two types of engines, internally and externally balanced. Externally balanced engines require an outside weight / balancer of some kind to offset the rotational mass of the engines internal components. On these engines you cannot mess with the crank pulley because external balancing is usually done via the crank pulley.

On internally balanced engines this is not the case. The pulley merely serves the function of powering the accessory pulley systems via the serpentine belt. Mercedes benz engines (along with most other higher quality modern engines) are internally balanced. The M112 engine does not have a harmonic "balancer"... it does however have a harmonic "isolator". This is a VERY important distinction. Its purpose is to absorb any harmonics in order to reduce NVH (noise vibration harshness). This is important both for refinement purposes (makes the engine run quieter/smoother/etc) and also for engine longevity to ensure various nuts/bolts throughout the engine done become loose over time due to the constant vibrations an engine produces. This has nothing to do with balancing (keep this in mind)

There are numerous ways this can be done. Some use mechanical based weights and other various methods. The OEM MB pulley uses a rubber based harmonic isolator ring which helps absorb all of these vibrations (ours uses the same design as well, we just improved on the design and made it stronger since the OEM pulleys have been prone to failure). In fact, ours does a better job of it and customers even comment their engines run smoother/quieter after the installation of our pulleys than before with the OEM unit. In addition, many of our customers have had our pulleys on their car for many years now and over 20k miles put on them with zero issues whatsoever. AMS has gone to great lengths to not only meet OEM specifications and ensure the pulley is 100% safe over the life time of the vehicle.

The main reason the OEM pulleys weight is 6.7lbs has nothing to do with engine dynamics or with balancing at all (after all its internally balance, the weight of the pulley isn't significant like it is on an externally balanced engine). The main reasons, as with any manufacturer, is COSTS. It simply costs way too much to machine aluminum harmonic dampened pulleys. There is no way they are willing to spend that much money on aluminum machined pulleys when they can just make a cast-steel/iron pulley and coat it for 1/10-1/20th the price, it simply does not make financial sense for them to do so. Its much easier for them to extract power via displacement or software tuning or changes to intake & exhaust then have to machine super light weight pulleys.

Furthermore, if you actually look at numerous exotic & high end manufacturers (porsche, ferrari, etc), all their pulleys are extremely small and lightweight. Some even use aluminum directly from the factory.

This is a topic that is quite often over blown out of proportion by people that do not really understand what is involved and why the manufacturer makes certain choices. Most often decisions are made for their financial reasons and not for any technical purpose (after all, they are in the business of MAKING MONEY, that is the whole point) . The BMW community has been using them for over a decade without issues, its only in the MB community that it is so taboo. Whats even more funny is that many communities out there are even using non-harmonic dampened aluminum pulleys for years (although I HIGHLY DISCOURAGE non-harmonic dampened pulleys, big no no).

A well designed high-rpm balanced fully harmonic dampened crankshaft pulley is 100% safe and will provide a good performance for the life of the vehicle without any negative drawbacks. It really does not get any more simple than that. We have sold 50+ of our M112 & M113 pulleys and not had a single problem whatsoever over the long term and many of our customers are still using our pulleys many years later and they have been 100% reliable, they are quickly becoming a staple in the Mercedes community.

I trust this thread can stay clean and on point, but unfortunately they usually get out of hand haha, lets see if this one can at least remain on point. I hope that answers most of your questions.

TruTaing

Thanks for starting another thread Glyn. I am a bit out of my league in terms of the technical aspects of this thread, but I will use the pulley as long as I feel it is not harmful to my engine and will post regular updates.

Meanwhile, I hope to learn something from this thread.



Question: How would a light weight fly wheel be different from a light weight crank pulley in our case w/ the M112?

AMS Performance

Well,

For auto M112s, there is not typical flywheel, its essentially just the ring gear which is very light and does not behave like a typical flywheel (since the torque converter essentially replaces it on an auto).

In many ways, lightweight flywheel & lightweight crank pulleys do the same thing (reduce mass) except they differ in two main areas in our specific case.

First, Our lightweight crank pulley does not remove any harmonic dampening components from their OE versions, we still retain the harmonic damper/isolator. Lightweight flywheels (on manual transmission cars) are single mass flywheels machined aluminum (w/ steel face), but the stock OEM components are dual mass flywheels which have an intricate networks of springs attaching two different masses designed to smoothen out the pulses & vibrations coming out of the engine. For this reason, you are never supposed to use a non-harmonic dampened pulley and a lightweight flywheel together because there is no vibration/harmonic absorption devices of any kind. You must have one or the other. On automatics you can only do lightweight crank pulleys.

Here is a diagram comparing the insides of a dual mass flywheel (above) w/ a single mass (below):





The other main difference between lightweight flywheels and lightweight crank pulleys is the sensation of torque. Lightweight flywheels feel like they lose torque, lighweight crank pulleys increase the sensation of torque. In this regard thats why crank pulleys are more well suited for the street and lightweight flywheels are better suited for the track.

Hope that helps
~AMS~

Glyn M Ruck

[QUOTE=TruTaing;3293280]Thanks for starting another thread Glyn. I am a bit out of my league in terms of the technical aspects of this thread, but I will use the pulley as long as I feel it is not harmful to my engine and will post regular updates QUOTE]

Tru - I don't think this pulley is going to do any harm to your car. My questions revolve around the R & D that goes into these things - Generally very little. Please for piece of mind do an oil sample at 10,000Kms

AMS Performance

[QUOTE=Glyn M Ruck;3293417]A lot of R&D goes into manufacturing pulleys. Luckily we benefited from the OEM design quite a bit and utilized many of its design attributes but simply improved on the OEM design, but it still took us nearly 2 years of design & prototyping to get this pulley onto the market so it was definitely not rushed by any means, which is why they have been such a huge success for us. They have been torture tested all the way to 155mph and performed flawlessly. If anything, the pulleys are actually safer than than most of the earlier M112/M113 pulleys which had a recall on them due to manufacturing defects, so to assume the OEM pulley is perfect is also a an unrealistic expectation. The main reason the OEM pulley failed was due to a cheap/weak harmonic damper. Ours is much stronger & thicker and also is made from a tougher synthetic rubber material.

All good questions Glyn, thank you for bringing them up, this should help answer most peoples questions and calm their concerns. Thanks

timdf

The issue is torsional resonance of the crankshaft and only the crank shaft - internally or external balancing of the engine has nothing to do with the inherent resonance of the crank.

The resonance of the crank is set by it's length and mass attached at either end - ie pulley and fly wheel.

The resonance is more of a problem on engines with more than 4 cylinders. That's why small 4 cylinder engines don't have this issue to the same extent.

Reducing the mass of the crank pulley will cause accelerated engine wear and most likely premature crank failure.

This topic has been beat to death elsewhere and those of us who truly understand engineering and have the qualifications and experience all agree - it's a dangerous mod for the minimal power gains.

https://mbworld.org/forums/w211-amg/...torsports.html

Glyn M Ruck

You don't have to convince me. I'm the kind of person who would give it a go. A sale of 50 pulleys means no real statistically meaningful history.

I think your reply is fair. I think you are over defensive and a little patronizing.

You are cavalier with your semantics when it comes to engine balance - internal - external - harmonics etc. They are ALL issues of balance or lack thereof and it's by product, vibration. Benz engines, like all recent relatively high tech engines are mostly internally balanced but making a distinction in today's world is not valid. They are mostly internally balanced & partially externally balanced. If they used a cam belt instead of a chain would you consider the camshaft damper to be external?

This comment is misleading "The M112 engine does not have a harmonic "balancer"... it does however have a harmonic "isolator". This is a VERY important distinction." and then your comments regarding NVH that follow.

Imbalance of any form at any stage results in a vibration of a specific amplitude & frequency and its various harmonics and there is inherently no difference between a harmonic balancer & a harmonic isolator in the real world of modern engine design. The approach is holistic. One accepts that the combustion process and other components of the running engine introduce vibration & the pulley provides some isolation but one can't draw a hard line in reality. Yes Merc OEM pulleys have been a problem in the past.

Thank you for you reply - I might well try one of your pulleys - Mercedes people are Mercedes people - I don't think that we think these things are "taboo". A Ferrari owner does not expect half a million kilometres out of his/her engine. A Mercedes owner does. Let's see what others more erudite than I think on the forum - and yes let's keep it clean & objective. This is not an AMS bashing exercise In fact the thread applies to all aftermarket pulleys.

AMS Performance

correct, by you, stop hijacking our threads. You have made your point once, if people want to read it they can use the search function.

Moderators have been contacted....

AMS Performance

Hello Glyn,

No problem, we are trying to keep the response as simple as possible so most people will understand obviously. Certain group of car owners are more inclined to try products freely than others (such as BMW owners) where as Mercedes owners tend to be less willing to do so simply b/c it is a much more conservative crowd (and understandably so).

With that said, Performance crank pulleys have been around since the muscle car era and have become a staple of the aftermarket tuning industry so they obviously work and are safe otherwise they wouldn't have lasted so long and would have been eliminated decades ago. There is also alot of mis-information regarding them so its easy to get confused.

We are confident that once you try our pulley, you will see first hand it is a top quality product and delivers on performance. If not you can always return it within 30 days (but we are confident you won't) .

Thank you for keeping the thread clean, we do appreciate your input. have a nice day.

TruTaing

Lets not get all bent out of shape. I specifically read through that thread linked by timdf and still felt compelled to let the product speak for itself along w/ the experience of a few other w203 crank pulley users.

Lets not get into discussing the past. Instead, lets continue to discuss the science behind why this will or will not work safely.

Thanks.

timdf

it was not my intent to hijack any thread - only to inject sound engineering knowledge and provide useful links.

Isn't that what forums are for ?

Again apologies if that's how you or anyone else feel about my input.

Glyn M Ruck

I understand crank resonance. I also have a racing background but not at your rarified level. I have great respect for Cosworth. They are however not perfect & I'm sure that you are aware of some of their screw ups when we sponsored a certain F1 team. You were no doubt not there at the time because you are part of the bunch that "truly understand engineering and have the qualifications and experience"

Glyn M Ruck

Tru enjoy the popcorn - I see what you mean. I'm pleased I did not mess up your thread. But we can all learn from debate. No one knows it all. My years of interaction with OEMs - in running race teams both cars & bikes has tought me this.

timdf

to post a few calculations (actually provided by Bobterry99) which explains the science as to what performance increase can be expected from a lightweight pulley ?

I can also provide a few useful links which explain the dangers of crankshaft resonance and how to mitigate it.

Again - it's not my intent to hi-jack any thread or bash any vendor as this information applies to any such modification.

Of course google is a powerful tool if you wish to perform your own research.

AMS Performance

Tim & Glyn,

Please slug this out in PM, do not destroy this thread... it started off with such promise and then Tim had to come in as he usually does and ruin it. Talk about it in PM. Keep the thread open for others who always want to come in and talk.

Thanks

Moderators have been contacted, and the thread has been reported. Let others come in and discuss, if you want to discuss back and forth, do it in PM. Your opinions have been shared, now lets let others come in and discuss.

Glyn M Ruck

The forum has been quiet of late so let me post edited exerpts from papers that are in the public domain. We will keep this simple.

Crankshaft Resonance

The subject of crankshaft torsional vibration and its importance is an area in which the key F1 players are very reluctant to discuss specifics. However, based on discussions with several crankshaft design wizards, it appears that there is quite a wide divergence of opinion on the subject of how best to deal with crankshaft torsional vibration.
A crankshaft, like a plain torsion-bar, has mass and a torsional spring rate that causes the crankshaft system to have its own torsional resonant frequency. The torque peaks and valleys plus the inertia loads from the acceleration of the reciprocating components cause the engine crankshaft itself to deflect (rotationally) forward and backward while it is operating. When those pulses (excitations) are near the crankshaft resonant frequency, they can cause the crank to vibrate uncontrollably and eventually break.
The torsional resonant frequency of the crankshaft system is a function of :

1. crankshaft length;
2. crankshaft torsional stiffness;
3. crankshaft stroke;
4. counterweight mass;
5. moments of inertia of rotating items attached to or driven by the engine.

It is well known that excitation of any component at or near one of its resonant frequencies will, in the absence of either substantial damping or opposing oscillation, cause the amplitude of the oscillation to increase without bound until the component fails.

Next post will be methods of mitigation.

acr2001

You really need to stop making threats by saying that "moderators have been contacted". This is an online discussion forum. The topics being discussed ARE related to your product and to this thread, even if you don't like it.

SeaCoupe

I absolutely agree.

If you don't like it tough.

Have to say Glyn, I'm learning here. Thanks.

Ed

AMS Performance

ACR,

I have not problems people discussing it, Glyn is discussing it freely and we have not asked him to stop. Our problem is with Tim.

With Tim its personal and he and a few others have continually been hijacking & bashing us and flat out making stuff up for some time now and have been asked to stop so it has nothing to do with this. Thats why the moderators have been contacted, that is a separate issue.

Glyn you are free to continue.

AMS Performance

With that said most of this applies to non-harmonic dampened dampened pulleys which we agree are not safe (and there are a few vendors on the forum trying to sell non harmonic dampened pulleys which are a BIG BIG no no, JBSpeed/KevinGOfast and all his clone names).

We agree that the pulleys they make are unsafe and can over the long run cause problems (Or even short term). You should never run a non-harmonic dampened pulley. Even though you may be able to get away with it for 25,000 or even 50,000 miles, you never know when disaster will strike. However, with a balanced harmonic dampened pulley these fears are unwarranted and unnecessary, especially when dealing with forged crankshafts. They are 100% safe and do not hurt the vehicle in the short or long run, as have been proven by real world testing and long term customer use.

Moral of the story, DO NOT run non-harmonic dampened pulleys, (especially ones that are underdriven), you are just asking for trouble.

This is the perfect example of what NOT to buy:

https://mbworld.org/forums/engine-pe...v6-models.html

http://cgi.ebay.com/ebaymotors/Merce...#ht_1131wt_962

Not to mention that seller is on dangerously shaky ground trying to market them as Carlsson Pulleys which is obviously Trademark violation among other things. Those are the kinds of pulleys buyers NEED to stay away from, they are dangerous, and untested and who knows what will happen if you install them. I would be shocked if an engine lasted more than 20k with pulleys like those (especially ones that increase boost and have no harmonic damper).

splinter

Surprisingly, it seems our M112 crankshaft’s longevity is relatively unaffected by its torsional damper design.
Vadim, a respected and knowledgeable tuner IMO, has been tweaking these engines almost since their first fitment in the W203.



Couple of cherry-picked posts sharing his perspective:

https://mbworld.org/forums/2633668-post15.html
https://mbworld.org/forums/3015436-post17.html

Nonetheless, mine has a dampened evosport crank pulley installed which – perhaps not coincidentally - was designed by him during his tenure there. I’ve grenaded enough engines during my wasted youth – from a variety of causes – that I’d prefer not to do it once again. While I understand that the AMS pulley is a dampened design that replicates the elastomer technique (that has previously been the subject of a MB recall on the M112) utilized in the OE damper, significant issues have arisen merely from improper installation.

MB’s specification is 200 Nm/147 ft.-lbs., plus an additional ninety degrees. It’s imperative that its bolt (#006 990 70 04) is torqued properly, lest one subject himself to potentially catastrophic engine failure.

https://mbworld.org/forums/c32-amg-c...ing-video.html
https://mbworld.org/forums/w211-amg/...ity-check.html

timdf: I have learned much from your posts.
Your participation is welcomed here as it’s in full compliance with MBW’s TOU, on topic, and insightful.

AMS Performance

Hooleys situation was not our fault and even Mercedes Benz NA and the authorized MB Dealers found out that the pulley was installed incorrectly. Any product installed incorrectly will not perform properly which is why we ALWAYS suggest taking it to the dealership to be installed to insure hassle free installation. If you do not believe us, anyone can email/PM hooleyboy himself and ask first hand. So that has nothing to do with this post nor does it affect AMS in any way.

That is also why the video was removed b/c everybody realized it was not our fault. In addition, it also showed our dedication to our customers and our level of customers service because we replaced his pulley FREE OF CHARGE even though it was not our fault. Show one other manufacturer that would do that (I doubt you can even find one). We stand by our products and our customers 100% and Hooleyboy's situation is just a perfect example of that.

That does however bring up a good point: make sure you find someone who is QUALIFIED to install the pulley.

Splinter,

Yes obviously you do the extra 90* which is why in our instructions we specifically say follow the manufactures torque specs rating. (This is obvious 101 stuff).

On another note, Vadim and whoever is running non-harmonic dampened pulleys must have ***** of steel or titanium b/c I would never recommend that to anyone. But yet again this proves further that our pulleys are even safer since they have the harmonic damper still intact. I pray for their sakes that they do not blow up any engines, but not running a harmonic damper is not recommended by us.

TruTaing

Omey, lets not get into discussing other companies product's - You don't like people bad mouthing your products, so lets not go about bad mouthing other's. Lets Keep to discussing light weight crank pulleys and the science in general.

I'm just trying to see that this discussion doesnt go out on a tangent...

Im learning lots from reading through this mostly drama free thread - lets keep it drama free and on topic.

AMS Performance

Fair enough, but that is first implying that they even are companies and not just people selling pulleys on ebay. I had no intention of bad mouthing, just a very dire warning about running non-harmonic dampened pulleys. Just a public service announcement of sorts that its just not safe over the long run. Always retain the harmonic damper if you can, which is why ours is the safest option for performance crank pulleys (which I believe is what this whole discussion is about). If I am wrong correct me, but just trying to stay on point regarding pulley safety and why ours our unique and the most conservative & safe pulley option versus more aggressive kits out there.