If you knew where the original and first 15% pulley came from? :lol: It really was a number pulled from the air? Made the start of great gatherings of the BBQ's and pulley install weekends for many MINI enthusiasts in 2002-2004. It produced instant results with little money or labor involved to accomplish it. No research was ever done during the time period to determine optimum diameter. Pretty much just a random number that is now the industry aftermarket standard for a first SC pulley change. Realistically speaking the JCW is the lowest reduction pulley you should go if you consider the M45 RPM limited and the set engine rpm rev limit. The JCW SC pulley is good choice for a balance between economy, power increase and reliability.
Funny thing is, is that it took no giant leap in technology nor a genius to figure out that a smaller pulley would produce more HP in our little cars by spinning the SC faster. Pulley size has been a variable sense Superchargers were invented. Drag racers for years have used different size pulleys as an easy way to add or take out power depending on what the track would hold... 15% for the sweet spot and win!
I thought I remembered reading a blurb on Randy Webb's site about how he consulted with Eaton engineers on the ideal reduction size. I don't think it was actually pulled from the air. EDIT: Found some evidence! http://www.motoringfile.com/2006/06/28/mf-review-webb-motorsports-15-pulley/
15% seems to be a very good trade off between power & longevity. I didn't go with a 17% because I knew I would be doing track days & feared killing the supercharger.
....and unless you have Meth injection or something to keep the air cool, in as little as a couple laps you'll also be making more HP with the 15%.
This would be a WTB thread not really for the discussion of the merits of 15% vs any other size. I suggest that if you want to continue along those lines that a new thread is created in the 1st Cooper S Engine Mod area. Thanks for your understanding...
I personally run a ALTA 15% and have tried most all of them. This encludes a combination of crank and pulley to achieve different results. I concluded that for my driving style the 15% and 0 crank worked best for me, but then I do not wind my engine past 6500 either. And don’t need to either to gain the power levels I have. May I repeat to say that the choice of a JCW SC pulley is a safe conservative choice overall. The article referenced did not show the M45 rotor speeds using different reduction pulleys. In doing a little more research you might be surprised about the additional facts not mention in the article. Mark I can see by your comparing a MINI M45 to early style Blowers such as 671,871 or larger that you have never had the pleasure of having one in a car. They are not really the same thing In the 671,871 Blowers some considerations in choosing which Blower drive ratio which includes not limited to, final CR of engine, fuel type, transmission type etc.
Bunch of crap that did nothing to move this along removed. Behave children...some of you are really get close to getting a long term time out again....
Ya know if they do AMVIV9, there ought'a be a boxing ring on the upper parking level. There I said it.
Wow all I did was start a wanted post :confused5: I have no great reason for wanting one. Sorry to disappoint .