Does the full JCW upgrade include a new pulley? If yes, what % is it? Can you buy that from the dealer or any other source?

Thanks

 

I read somewhere that it was just under a 14% reduction in size compared to the stock pulley. YMMV.

 

You can get several sizes of pulleys from Helix .

The closest to the JCW size in an aftermarket would be 15%.

 

A search for "JCW pulley myth" will reveal a critical thread for learning about pulley reduction percentages. On that thread, you will find that the JCW reduction is 14.3%

 

If you were to install just a JCW pulley, wouldn't that keep your warranty intact with the benefit of better performance than stock?

 

Installation of the JCW Kit entails replacing the stock supercharger with one with a reduction pulley.

 

Along with replacement of the stock head and larger (higher capacity) injectors, among other items. And yes, if preservation of factory warranty coverage is an issue, the least painful approach is to go with a JCW kit that is installed by a BMW/MINI dealer.

 

A clarification...

Just the pulley installation does not ensure warranty coverage. You must purchase/install the whole kit and have it installed at a MINI dealer for the warranty to remain intact.

Theo

 

The JCW kit comes with a 14.3% reduction pulley. The pulley does not come as a separate part. It is already installed onto a new supercharger.