by the way guys you can't just ad 15% +2% to get 17% it doesn't work that way... we are working in %'s which mean that things change exponentially

 

So what does it mean? 15 + 2 equates to what if it were just the SC?

 

I thought about that because every vendor selling these pullies has sold them saying 15/16/17 + 1-4% larger = 16,17%, etc...

 

In this day of expensive petrol, what is the effect of the pulley changes?

 

Your joking right

 

No. I have no clue. I've not had my car a month yet and I just wondered.

 

If the stock SC is turning 10,000 rpm and 15% smaller SC pulley is added,
the SC will turn 11,500 rpm (10000 x 1.15).
If a 2% larger crank pulley is added, the SC will turn 11,730 rpm
(11500 x 1.02).
15 + 2 = 17.3
15 + 3 = 18.45
15 + 4 = 19.6

 

You can't really added the over crank and reduction pulley percentages to get new effective percentage because the percentages (or ratios) are based on different denominators (ie 102% of 5.4" cranksize pulley and 85% of 2.58" SC pulley).

MINI Cooper SC Crank/Pulley Options

__________ Crank________ Supercharger__ Crank 2 SC______ Redline
__________ Pulley________Pulley________ Ratio____________RPM
Stock______5.4__________ 2.58__________ 2.09____________ 6250

__________ Over________ Reduction____ New____________Eff. %
__________ Crank________Pulley________Ratio__________Reductio n______ SC RPM @ redline
Stock______0%__________ 0%____________2.09____________0%____________ 13081
JCW_______0%__________ 14.7%_________ 2.45__________ 14.7%__________ 15336
__________ 0%______ ____15%__________ 2.46__________ 15.0%__________ 15390
__________ 2%__________ 15%__________ 2.51__________ 16.7%__________ 15698
__________ 4%__________ 15%__________ 2.56__________ 18.3%__________ 16005
__________ 0%__________ 17%__________ 2.52__________ 17.0%__________ 15761
__________ 2%__________ 17%__________ 2.57__________ 18.6%__________ 16076
__________ 4%__________ 17%__________ 2.62__________ 20.2%__________ 16391
__________ 0%__________ 19%__________ 2.58__________ 19.0%__________ 16150
__________ 2%__________ 19%__________ 2.64__________ 20.6%__________ 16473
__________ 4%__________ 19%__________ 2.69__________ 22.1%__________ 16796

 

THANKS. This makes perfect sense. Saying that it changes "expotentially" makes no sense at all because the difference between +1 and +4 crank pulley would be ... astronomical.

so I guess 19 +4 would be REALLY bad

 

Just think "more gas stops"

 

PARDON ME... forgive me for not being a cunning linguist...

The "meat and potatoes" of the whole message is that you can NOT simply add 2%+15%... (but thanks for bagging on my verbage...)
because you are dealing in percentages you can not just add the percentages together to get the change... Obviously many other people understood my post... i just can't believe that none of this has been brought up before... i mean how long have these crank pulleys been sold? and everyone has been just adding the two together...

anyways... im just glad that some light has finally been shed on the subject... the 15+2 thing has always irked me... kind of like a pet peave... anyways more important things in life i guess

happy motoring

 

Isellem ... you wrote "which mean that things change exponentially" I was trying to understand how these things work and did NOT understand what you wrote because that made no sense. Thats not bagging on your semantics, I was taking you seriously I believed what you wrote.

Maybe others dont understand what exponentially means, sorry if I do! no Worries, We all understand now and its good

 

You might not want to let the ladies hear you say that.....

 

greg...


the ladies no better....

thanks for the comment out of left field

 

Ya, i guess i should eh? I took my MCS back to the mini dealership for the both pulley installed... well.... i guess i trusted them too much? wut that tech had told, made me worried for so many freaking days.. untill i brought up the question here! (Nice mini owners here) o well.. but it's nice that the tech actually load the JCW program for me, and it's free! Good! The gain in power is dramatic... can't really express it in words. but sure u can feel endless power. Nice supercharger sound. really really nice, i can't let go of throttle everytime when i hear it, n just keep on going faster n up gear! Bad! rattle SOUND comming from engine bay at low rpm when driving. At idle, just rattle. Just bought and installed M7 lowring springs too! they look great with the 1.3 inch drop, about 2 fingers fit in the gap, and they really handles good, though going thru potholes are REALLY a pain in the ***! thinking of getting a Blow Off Valve! Sound even better!