peavynation

There seems to be a potential (and possibly contested?) upside to tracking your M96. I trust LN Engineering / Flat6 in their opinions and experience, and here is a possible upside to (occasional) higher rpm usage on an M96 as it pertains to the dreaded IMS (quoted from the following http://www.lnengineering.com/ims.html). See the line I've highlighted below in red.
So, drive it like it was stolen, and keep your car happier! Now THAT'S Porsche engineering! Lol!! (I'm sort of kidding folks, I don't think if you beat the crap out of your car, you'll make it happier. But there is some truth to this I believe). But, in order for oil to get in the bearing seals must be removed. Still, interesting info. Happy tracking!


The engineer’s initial thoughts were that the ball-separator failure led to bearing collapse, but after analysis of said IMS bearings, it would appear that bearing wear/fatigue spalls lead to separator wear and outer race failure. Separator failure and bearing collapse causes catastrophic failure of the mounting bolt(s) and IMS/timing chain components. The first recommendation was to use a bearing without seals and secondly to use a higher viscosity oil (with greater film strength). More frequent changes will also improve lubrication quality. An oil with extreme pressure additives like Moly might also further assist in increasing bearing life. Higher rpms also increases bearing life as this lessens the viscosity requirements of the lubricant to maintain EHD lubrication, also providing a reasonable explanation of the lack of IMS failures in tracked cars or those driven "like they were stolen." Likewise, far more failures are found in engines with low mileage that are garage queens and never driven to their full potential. Further recommendations by the retired Timken engineer are evident in the design of LN Engineering’s IMS upgrade and retrofit kits.

Tippy

Hmmm.......interesting. Timken bearings must be good, we use them and *** in our jet engines. I guess I'd trust the Engineer on his assessment about revving the motors high.

Although, I'm struggling with the viscocity thing.

jyoteen

well, that explains why my IMS is intact

Macster

One has to be careful with the info... A car that is used daily, is driven long(er) distances, and as a result has less water and unburned gasoline build up in the oil could potentially tolerate harsher driving -- being driven like it was stolen -- without any harm other than the wear and tear the other engine internals would experience.

Whether the engine cases need splitting cause the IMS needs attention or the rings/pistons or main/rod bearings need attention is sort of a lose lose scenario.

But for someone who drive's his car seldom, uses it mostly for short trips, to advise him to drive the car like it was stolen could hasten an IMS (or other) failure.

There is some benefit for subjecting the engine to higher rpms... but the benefit comes not necessarily from the higher rpms but in the higher g forces the car and engine is subjected too.

This activity causes the oil that is caught in the IMS (which is hollow and open at one end based on pictures I've seen of IMSs) gets sloshed around and the oil partially exchanged with fresher oil, oil that contains less water and gasoline dilution.

As a result the IMS seal is not compromised or if it is the oil that makes its way into the bearing is of better condition.

Additionally the oil that remains in the shaft and puddled at the bottom of the bearing race(s) is less corrosive and as a consequence the bearing races, *****, separators are not corrosively attacked and do not suffer minor surface corrosion damage that over time can escalate into major failure.

Interesting point of view is Porsche and BMW and Mercedes cars/engines still have too much of their European heritage which came about from the usage these cars experienced. This usage involved (and still does to a certain extent) lower ambient operating temperatures and fewer short trips and less time spent idly in traffic.

The engines are not well suited for the type of driving most cars experience in the USA. Higher ambient temperatures in most of the US. Shorter trips. More traffic congestion thus more idling.

OTOH Japanese engines developed for use in Japan are better suited for use in the USA cause driving conditions in Japan are similar to USA. Ambient temperature notwithstanding. Japanese driving is in mostly congested conditions with short trips, slow trips, and lots of idling.

Drive your Porsche like you stole it is I think bad advice.

Drive your Porsche like you were in Germany is better. To expand upon this: Avoid short trips. Avoid congestion. Avoid prolonged or excessive idling. Take longer trips. Sure, use more of the engine's rpm band if you want as long as engine up to operating temperature. And always consider changing the oil/filter more frequently.

Sincerely,

Macster.

Tippy

I googled EHD and it makes sense why the Engineer said what he said.

peavynation

Good points, Macster. I agree with you, I wouldn't advise everyone to drive their P cars all the time like they stole them either, but there still is some truth in it to an extent. You're points on stop and go traffic are interesting. Although, IMO, other than actual engine design itself, I would think that any engine built to proper tolerances would be fine in both long and short drive conditions. I don't think any engine loves to be idled excessively, and there are plenty of Japanese cars with short and long miles on them that hold up for 300k.

I think in the end it boils down to the quality of the engineering that went into the motor design in the first place, the QC of the engine build from the factory, and routine maintenance. P dropped the ball on a few parts of the M96 design IMO, and so routine maintenance plays an even bigger part. General-public Japanese cars (i.e. Civics, Corollas, etc) typically don't get driven like a Porsche either. And when they do, many times excessive smoke will be the result from the pipe.

You have to admit that the longevity of Japanese motors as a whole is something to be admired.

onefastviking

So what you are basically saying is....... if you have had an IMS failure you aren't driving hard,or fast enough !

BruceP

I agree that the core issue with this Porsche is that it is not well suited to the way most us are forced to drive it.

I agree that operating this engine closer to its peak of efficiency rpm-wise is going to extend its life (those who recall the famous Autofarm article will remember that premature wear of its reciprocating parts is not one of the M96's vices).

I agree that more frequent oil changes are the cheapest possible preventative maintenance (German car companies stretch recommended intervals to the max in order to avoid environmental levies on lifetime petroleum consumption).

Macster's final paragraph sums it up nicely for me. Plus this: After I saw how much oil came out of my IMS, the idea of it vibrating around in there was quite terrifying. Now, I put an extra premium on smoothness, especially at launch. Clutches are cheaper than motors.

Tippy

The point of the OP is the ball bearing for the IMS is better suited for high-RPM, not so much the engine as a whole.

peavynation

TY Tippy.

Macster

Well, my search found it refers to electrically charged fluids and the effects this has on them. I fail to see how this applies for engine oil is not electrically charged, though perhaps the oil can build up a static charge?

Extremely agitated fluid -- like water -- can build up a static charge: IIRC this was the cause of some tanker ship explosions as the water being blasted about by high pressure nozzles inside the ship's storage tanks during cleaning of these tanks would develop a static charge that if the static electrical charge discharged at the wrong time -- with the presence of an explosive atmosphere in the tank -- this could trigger an explosion.

Obviously there must be some other meaning.

Higher engine speeds mean higher loads on all engine parts, and more heat from of course the increase in fuel burned and the increase in heat generated by internal friction.

This added load and heat requires more from an oil, not less. I fail to see how increasing the load and heat that an oil must deal with is beneficial to a bearing that is by some accounts not up the task to begin with and by the opinion of some knowledgeable people lubricated with an oil that may not be up to the task either.

Sincerely,

Macster.

peavynation

Macster, I think you're thinking of the wrong EHD. What you found is Electrohydrodynamic properties, but I believe the EHD as it pertains to this application is Elastohydrodynamic.

http://www.engineersedge.com/lubrica...ubrication.htm

chsu74

That is all I can contribute to this thread as well. No engineering degree in my pocket.

Torontoworker

Officer: Do you know how fast you were going?

996 Owner: Why yes officer, I was just going fast enough to prevent an IMS failure.

peavynation

LOL!! If you were a chick you might be able to get away with that. I new a gal who would speed, get pulled over, and would tell the officer, "the garage man said that I needed to keep the pointer (then points at the tack) at 4 or 5 for the engine to last the longest." And then she'd give the officer those big, sad, scared eyes. But it would work! I'd like to see a dude try that and not get thrown in jail!