I have a real question for you fellow min enthusiasts... although im not sure if ill be able to get an answer

im about to get tuned from bytetronic, which i am super excited about, the BVH and cam will be coming soon, with the 550cc injectors

but during my pretune inspection i need to fill out some information

one of which is which size pully do i have... my answer is i dont know, as it was installed when i purchased the car from the dealership.

i have access to alot of measurement devices since i work in a machine shop.

anyone know the diameters of the respectable S/C pulleys? or atleaste of the stock pully?

 

If you have a stock JCW then I believe its a 13%

 

its not a stock pulley, looks like a minspeed or a madness in silver

 

They USUALLY had a reduction % stamped/engraved in them.....
So most common is a 15%....m7 was basicly the sole 16% maker till way made a batch...and 17%... More common as of the last 4 years or so..especially in the northeast.
Try to get the best picture you can...post it...
Measuring it is not really viable...the sides varry as belt guides from design to design.....
There were also lots of "knock-offs"...a local bmw shop was installing eastern European ones with a odd name when I was looking for one back in 2007 ish....not to mention e-bay...

 

well my plan was to measure the belt width and measure over the pulley and the belt, subtract the size of the belt, and bam pitch diam of the pulley

 

i didnt see any stamping, ill try to upload some pics

looks like i need to do a bit of cleaning haha, bit of corrosion go New England!