Quote:
Originally Posted by Gelbster
Markus,
Your perspective is interesting because you are involved with a Porsche M96 world that is closed to most of us because of language. The English-speaking world gravitates to the American based forums so we seldom discover differences and nuances in say Germany/Austria/Switzerland
A specific example is the IMSB issue. From what little I can read on German Porsche forums, the cylindrical roller bearing is quite a popular alternative and was used much earlier than here in the Anglo Porsche world. Is that true? And which specific version of the cylindrical roller bearing is used? Do they all use the SKF NUP204 bearing or local equivalent? I ask because we all made such a fuss about "thrust control" when Vertex introduced it here.But I do not find that issue discussed in Germany. This is interesting because RND in the U.S.A. make a big deal about this.
Roller Bearing IMS Retrofit Kit – RND Engines
Here is the alleged German alternative with no mention of thrust control from a "colorful" source:
Currently for sale - ************ ************ ************ ************ ************ ************ ************MB MOTORSPORTS
The vendor has a questionble reputation on Forums but perhaps his German-sourced products are indeed good? |
Hello Gelbster,
to be honest, most independent Porsche engine rebuiders i know in the Stuttgart and Germany area use all ball-bearing ISMBs that are like the OEM design. They say replace it with every clutch and use the right oil and change the oil yearly. Why is that? Because the other solutions are quite too expensive.
Might be different calculation for an AT car. But it also seems that AT cars fail less from an ISMB. But they also fail. Cracked heads, failing tensioners, oval cylinders from overheating, hydrolocking… you know better than me what else can fail.
The roller bearing ISMBs are not that popular, because of the same subjects. They generate more friction, so the generate more heat. And because the IMS is running at the same rpm than the engine, these types of bearings are more at their limits than ball-bearings. Just check the specs of the roller bearing manufacturers. An remember that the engines revs higher than the max. rpm given at max. power. Mine revs up around 6.900 rpm until it hits the rev limiter while max. power is at 6.200 rpm in my S.
Thrust control is another topic. Most people think of engines as a static system. But they are installed in a car with engine part torques, drive train torques, g-forces in cornering, acceleration, braking, road bumps… So you have additional mass moments. And concerning the valve train and IMS most of these masses are compensated by the IMS bearing and IMS bearing mount.
The M96 engines that failed very early from an ISMB had mostly engine case problems (986 and 996). And these engines were all replaced by Porsche with new OEM engines. In general they didn't repair them, they replaced them. So there was a cause for that.
There are IMSB kits with oil feed. From my POV this is more discussed im germany forums. What happens if the oil feed fails and is it useful to use oil pressure for an additional oil feed, when the oil system wasn't designed for that. The overall opinion is not to use additional oil IMSB feeds in this specific engines.
But you also keep in mind that in Germany the cars are used in a different way than in the US. We have also speed limits but we have also parts on the Autobahn where we don't have speed limits. You have the tail of the dragon – mostly with speed limits. We have the alps and the Black Forest with an official speed limit of 100 Km/h on normal roads. But who cares.
Maybe race tracks seems to be similar. But there are also climate differences. We don't have that very warm summers like you have in Texas or Arizona. So maybe there is a lot different that can affect an engine oil system and cooling system.
IMSB kits. OK, there is lot of stuff around, because there is much fear and so you can do a lot of money out of kits that contain some stuff you and me can buy and manufacture for 50-100 bucks in a limited edition. Also the guys are Porsche drivers, so the only know Porsche prices and will pay them. The more expensive the better.
What does Made in Germany exactly mean. Does it mean the bearing is made by FAG or anybody else in Germany. Or does it mean the whole components are designed and made in Germany. Reminds somehow on Apple. Designed in Cupertino, made in Asia at the cheapest fabrication facility they could find.
Which doesn't mean the products can fail because they are badly designed by supplier parts – i know what i'm talking about when it comes to Apple graphic cards with Nvidia or ATI chipsets.
The MB Motorsports IMSB seems to contain parts from NTN which is located in Germany but has production factories all over europe. For example in Romania, Russia - where production costs are cheaper. And if you take a look at the extraction tool i would say go for the latest LN extraction tool.
As for the RND engines kit. The manual looks good. Hope everybody uses it. Heard of some DIY people that didn't lock camshafts/crankshaft and didn't remove tensioners. Saw it lately in a video. You can imagine the results. Don't see why Made in Japan should be less good than Made in Germany.
I know one kit that is really designed and made in Germany. That is by FVD Brombacher and has ceramic ball bearings. But that doesn't mean it is better or less good than others. And it is also not cheap (Porsche drivers don't care about money
) - around 470 Euros without toolkit.
In the end i would say go for a local manufacturer. Because first it is no rocket science. And second it doesn't make sense to pay a lot of money for shipping, taxes and duties to import things. If you have an excellent ball or roller-bearing manufacturer in the US or where you live, why not use local stuff?
And as always, these are just my 2 cents. Maybe other people have other opinions. Maybe other people read other forums or have other sources and background. There is a lot of information (and misinformation) around. So just my 2 cents.
Regards, Markus