Quick Q:

Whats the diameter of a stock supecharger pulley compared to the 15% S/C pulley?

Thanks.

Also, what supporting mods should I have before going to the smaller pulley? I have CAI so far, do I need exhaust?

 

15% smaller. E.g. a 17% reduction pulley has a 17% smaller diameter. For a visual, check out my pics comparing the OEM pulley to my Webb Motorworks 15% reduction pulley
The only thing you absolutely need is a smaller drive belt. Because the new pulley is smaller, the old belt may slip when used with a smaller pulley and it is recommended to replace this. Some people suggest going for cooler-rated spark plugs e.g. It would also be good if you have some miles on the car to check the belt tensioner and see if you need a new one. A tensioner-removal tool will make the install go more smoothly. When you're under the hood I also recommend installing a belt-tensioner stop. Many companies make them but here's one.

Anything else, like a cat-back exhaust, header, etc will enhance performance but is not necessary at all. An ECU tune is another thing that would help to get more out of your CAI and pulley. Have fun!

 

In terms of the relative dimensions, this post at MINI2 suggests that the diameter of the stock s/c pulley is 65.5mm, so 15% reduction would be ~55.675mm and 17% would be ~54.365mm... assuming my math is right.

FWIW, the CravenSpeed site says:

... which seems to match the calculations above (i.e., 54.365mm = 17% reduction).

 

Thanks for your reply guys, I understood it's a 15% reduction in size, I was just curious on the diameter. I come from a supercharged grand prix and all the pulleys were listed at sizes, not as percentage of reduction. The stock pulley was a 3.8", I went down to a 3.4", and so forth. I thought it was weird I couldn't seem to find diameters on the pulleys. That was just me being curious. Yes, coming from the Grand Prix, I know I would need a smaller belt.

Yes, a tune would be good. I will look at the Ten Stop. Colder plugs and better wires too? Wouldn't hurt, it has 42 K miles (68Kms)

 

15% pulley kit with belt and MSD ignition kit is my first mod plan. I'm really just posting in this thread for quick reference since I keep forgetting the sizes and the search engine doesn't always pull up what I'm looking for. Is there way to have a thread saves in a favorites within the forum, like in the user CP or somewhere? That would be a nice feature. Thanks.


-Gunner

 

I recently did my 15% pulley package via wmw. This is what I swapped while I was in there; charger pulley, plugs, belt, belt tensioner, tensioner stop, crank pulley, and thermostat housing gasket. All known to fail and some point. Just my opinion. Crank seal would be a good idea also.

 

If I had the money I would rebuilt the whole engine, SC, cooling system, power steering system and transmission while I was in there.

This car was in rough shape and needs a lot of TLC. I figure some time down the road this will become my project tuner instead of my daily commuter.

 

unless there's something wrong with your current coil pack, don't expect any improvement there. Really, no reason to veer from OEM. Save your mod money for things that will actually make a difference.