Engine Drivetrain 1st Gen Cooper S Most liked posts in thread: Exact Time to Failure

Not precisely.
I mean that is a good guess/approximation for warranty purposes, but more accurately the SC life is determined by revolutions as a first order variable, not miles. Miles happens to be easy to measure and easy for the consumer to understand.

Carrying this to the extreme, you can stress to fail a SC strapped to a bench with a drill motor hooked to it, so no miles. You could also get one to last much longer than the 100K mile assumption if the vehicle spent 100% of the time in 6th gear at 50mph.

To increase the accuracy of your remaining life calculations you need to understand the usage model utilized to calculate the 100K miles. This usage model will boil down to a specific number of SC revolutions. Then you need to compare that model to your driving habits and adjust accordingly.

There are other operating condition parameters involved in the usage model like, temperature, engine load, boost levels, etc., but you get the idea.

Yes, math can be fun.

 

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OK, I am sure both of you violated some sort of site policy with all of that, so I am issuing strikes.

 

Here’s the first mistaken assumption, the 15% difference is only relevant to the pulley, not revolutions of the supercharger lobes; it only spins about 10% faster with a 15% pulley.

 

Nothing is 100% mathematical with cars.

If your car was built on a Wednesday, I would say the car will last 15% longer than a Monday or Friday.

 

Another thing... Wear isn't linear. To first order it goes as the square of the speed. First thing is that a 15% really "wears" not at 15% faster, but a bit more than 30% faster. This is just a "rule of thumb" and isn't absolute. I'd change "exact" to "Approximated" and it's a good start. Most comparisons like this though assume the driving profile in the two cases is the same, but you really need some estimate of what percent of the time things are at what RPM to do anything reasonable with this... It's such a mess of interrelated suff that most just do a very simplistic estimate of relative wear, then do a survey of the populations to look at how they really change.

Things like this are "guides to the eye" more than anything else.

Matt

 

Another thing to pick apart....

really this is an estimate with an accuracy of at best a few percent, more likely a few 10s of percents. That means you only need one or two significant figures, and can do lots of rounding to make the math easier. Now in the days of Excel and electronic calculators, it's easy to carry way more precision than is needed, but it doesn't really increase accuracy....

Also, the 100k mile lifetime isn't a failure distance, it, at best, is an average failure distance where individual units may last much, much longer, or sadly, much shorter. It needs to be biased by driving style, because, as on poster put it, rotational numbers and distance aren't exactly correlated.

Here's an easier estimate of SC lifetime,

I drive my car hard. Should expect problems any time after 50k-60k.

I baby my car. I should expect little or no problems with my SC till well past 100k.

Of course, with some of the early WP gear failures, none of these estimates are worth anything.

Matt

 

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Ummm, I got lost in the math. :arf:

We had an 05 MCS on the Dyno Friday, it is driven hard and fast. We had limited boost and the prime suspect is SC failure in progress. About 82K on the MINI.

Don

 

Is there any distinction in the failures of S/C between the early (02-04) uncoated and later coated S/C's?

Is one tending to last longer than others?

Show we create some sort of poll or survey to gather info on S/C failures?

 

Yes, let's poll the people on this one. Make sure to include the proper variables, and NOT just miles.

 

Survey software has been installed and now it's time for the steep learning curve.

 

Well great then, let me know if you need some help with alpha testing and traveling the learning curve road.