If you're installing a 15% reduction pulley and your stock belt is near-new, you can keep the stock belt. Or, you can get a shorter belt.

Here's a chart from Alta's website that shows the appropriate belt for various combinations of crankshaft and supercharger pullies:

 

I repeated the measurement again, this time on a GP’s supercharger pulley, and nothing has changed, 2.285 for the pulley.

 

My SC just went out in my 2003. I ordered a JCW SC to replace it. I had the mechanic measure and I measured also... It's 11% (rounded from 10.xxx). I had a stock, jcw and 15% on hand for comparison. Needless to say the jcw pulley is now a paper weight on my desk.

 

I repeat my wager again:

"If I was a bettin' man, my money would be on a 65mm stock pulley, and a 58mm JCW pulley. But that is just me."

 

So now, after all this math and testing. Shall we run 15%?16%?17%? Please advice!!!!

 

If you track the car 15% is best way to fly.

 

Thats what the opinion here seems to lean to.If my SC crapped out I'd look at a 15% because of the summer heat.

 

I do not do track. Only street racing and very minimal street drags. 16%?

 

im glad this thread ended at the climax with no conclusion to the original question

 

as with a lot of threads, the 2 main things to know about the JCW pulley are these:

1. If you have a stock pulley, don't bother with a JCW (if you could find one) go with a 15%-17%-19%, depending on your driving & wants. (thats a different topic)

2. JCW pulleys are notorious for being real MF'rs to remove, many have had to be cut off, so if your planning a swap go with at least a 17%, the real world boost gains of just going to a 15% over the JCW usually just aren't worth the effort it takes to change it.

 

I've been wondering the same thing about the pulley on my 03' JCW. Not sure if it's worth going up to a 15% from the JCW 11% pulley. Way back with this post started the OP said that he had the GP re-map flash on his 05' JCW.......I never saw anywhere where he said how, or who did the flash for him.

Not to change topics, but I'd like to get either the 05' JCW flash, or GP flash done to my 03' JCW before I change the pulley and upgrade to the 380cc injectors. Anyone have any info?

 

I'm not sure the Dealer would flash your 200 hp JCW with the 210 flash as it requires the air box and the 380 injectors to achieve that hp.

The other option would be a custom turn as you're talking about a larger pulley.

My car is a 210 hp model from the factory with a custom tune, RMW, that improved the drivability. I got a 9 fpt increase and 12 a hp gain.

Overall I'm quite happy.

Hope this helps...

 

That's not that big of a problem to solve. I already have the air box, and I'm waiting to put the 380cc injectors in until I can find out some more info on the 210 flash.

 

Hello, everyone!

I have Mini Cooper S 2004 JCW. Today after the quick inspection I noticed that my serpentine belt and belt tensioner not in the best condition, my suggestion is that idler pulley will be in the same as well. Can someone tell me please part number for all three parts? (serpentine belt, idler pulley, and belt tensioner) for JCW R53?

Plus I want to change the oil in the supercharger, any recommendations? What do you guys think about ACDeloco? Is it ok?

One more question. Is there any difference between valve cover gaskets in R53 and R53 JCW? Or they are the same?

Thank you in advance!

 

OEM (ACDelco) Tensioner:



Gates Belt (60535):



Yes to ACDelco supercharger oil.

Same valve cover gaskets.

Are you leaving the JCW supercharger pulley in place (11.4%) or upgrading to 15%, 16% or 17%?

If upgrading the pulley, get the colder range spark plugs (BKR7EQUP)