Hello,

I currently have the JCW setup on my '05 MCS and have the Alta 2% crank pulley (not installed yet). Will this 2% crank pulley (effectively) spin up my supercharger as though I have a 15% - 16% supercharger pulley?
I don't want to eliminate the balancer on the OEM crank pulley if I am not going to gain anything from the 2%. However, it seems that some of the ECU flashes out there are based on a 15% supercharger pulley and that is my next, and hopefully, last engine mod.
Any input will be helpful.

Cheers, Doug.

 

Edited.

 

Yes, the lightened crank pulley will allow your entire engine to spool up much faster. You will also see about 1psi more boost thanks to the oversized pulley.

Side note - We know the JCW pulley is a 14.8% reduction.

 

That's been debated lately in other threads.

 

I just added the 3% Alta pulley to my JCW. The car runs like a raped ape.

I love it!

I am in SM about 4 days a week. You are welcome to try it anytime you would like.

Also, I just put my crank pulley installation kit together. I have all the tools needed to do the installation.

The only tool I am missing is the belt tension tool. I used the socket on the end of the belt tensioner bolt method which actually worked pretty well!

It is definetly a noticable difference that is Killer.

The only issues I have noted so far is a vibration which feels to be under the car, only under too little throttle in first gear when leaving a stop. It feels and sounds like a part of the fender inner liner or something is vibrating. I am not entirely sure it is from this install. It could be from something else.

Jasun

 

To what avail?

 

This thread here. The discussion basically starts on post 14.

 

A valid debate could be held regarding a range of 13.8% - 14.6% (but certainly not 10%). This is what Motoring File magazine cites:

The 200hp JCW kit came with a 13.8% reduction pulley. The 210 hp kit came with a 14.6% reduction.

Anybody thinking they can take a caliper gage to the reduction pulley and the original to measure the reduction, is kidding themselves. The effective diameter of a pulley is measured to the neutral axis of the belt, not easy to determine with a simple measuring stick.