So is using the M7 2% crank pully used with a 17% under drive sc pully
going to be unsafe on the steet? wiil this over-rev the stock mini supercharger?
what are your thoughts on this?
i'm ready to do the install but hesitating on keeping my 17% and switching it with a 15% pully. i did like the way the 19% felt but at the time i didn't have the 380cc injectors and safcII like i have now on my mini.

JSWMCS

 

Been running 19% + 2% crank for just over 2 years now. Also have the 380 injectors and the safcII. Haven't had a problem. Also been Autox it for just over a year. I did just recently broke a belt which took out the pulleys. So i have a Tensioner stop on order which i like most highly recommending getting

 

how old was the belt?
what is your max boost with that combo at redline?

 

belt was going on 2years as well.. just over 26,000 miles on the belt

Boost accorrding to the safcII max i saw was 1.21 which if i recall was around 22 lbs. not sure.. cant remember exactly what your suppose to times it by.. been over a year since some one asked that.

 

1.21 bar is 17.5 psi of boost.
thanks for the info.
14.50 psi is 1 bar of boost.

 

I have 17.5psi with just a 17% pulley, I wonder if the smaller gives no more boost?

 

boost pressure does vary by local elevation.
so it depends what part of the country you are in and condition of your super charger.

 

oh also the quality/accuracy of your boost gauge is also an issue!

 

The stock crank pulley has a damper where the after market larger pulleys don't. I would therefore be cautious about installing the larger crank pulley because of the unknown long term effect it could have on your engine. BMW install the damper for a reason. PSI figures are insignificant comapred to a broken engine!

Having said that, if you do opt for the 2% crank pulley then you should also install a larger alternator pulley to compensate, otherwise the alternator will over-spin. I know Craven Speed sell a 2% crank pulley and compensating alternator pulley as a kit.

 

maybe i'll consider getting th cravenspeed combo set of pullys?
JSWMCS

 

on the boost pressure.. Also when i went to the GTT intercooler i lost some pressure build up. About .2 tenths. This was when i was running the 15% pulley at the time.

 

Insanity! That is turning that Super Charger REALLY FAST. No heat issues? Detonation? I wouldn't run that in Texas.