Let's Dispel the Myths!
 

Ok, here's a shout out to all the newbies, whether literally, or technically. There are a few points you NEED to know before diving in and posting and causing gearheads like me to pull their hair out (even though I have a shaved head, so it gets painful up there!)

Just because there is a new model year does NOT mean there are any changes to the vehicle specification. Take notes:

Here is the breakdown in [edited] supercharger pulley ratios, crank pulley is 5.460":
Guess what? These ratios apply for EVERY model year to date! :thumbsup: Simple!

Next: you're wondering: "woah, how does the 2005 MCS and JCW have a whopping 7 advertised horsepower more?" Answer: ECU programming. Yes yes yes, the stock MCS exhaust is different, but look at the deltas, 7HP more base and JCW, and the JCW cat-back is the same as previous years, and the whole system delta is still identical. Hence, the base MCS cat-back just sounds different to earlier years. Myth Busted! :eek:

Next: please, for my scalps sake, use the SEARCH function! :eek2: There's nothing more annoying than reading 3 essentially identical threads regarding a freak-out thread whether getting the tried-tested-and-true 15% pulley is "safe" :roll: . Hopefully you get the idea.

I reserve the right to add addendums to this post :lol:
Cheers, Happy Searching old threads....then reading them.....then asking your local Tuner if you have questions....then Motoring!
Love, your obsessive Moderator,
Ryan

:lol: :lol: :lol:

Freak! :lol: :thumbsup: :razz:

I haven't cut one up, but I have removed an '05 exhaust, and I have it on the wall with the 30-40 other stock units. Unless it is internally baffled differently, it is the same as the earlier units.

Anyone taken one apart? If not, and I get bored, I will.

Randy

OMG! I WORSHIP Cartman....he da MAN! :lol: :lol: :lol: :grin:

Clover :cool:

That's a wee bit oversimplfied. I'd like to at least *think* that the extra money I spent on the way cool airbox (I'm addicted to 4.5k+ rpm now) and larger injectors get me at least 2 hp :wink: Since the MCS went from 163 to 168 hp (5hp delta) and the JCW kit went from 200 to 207hp (7hp delta). So hopefully my extra $800 in new JCW kit goodies got me those 2 hp!

oops yea - forgot that the rest of the world gets a 170HP '05 MCS whereas the USA gets shafted (as usual) with the lower HP version, in this case a 168HP '05 MCS. In the JCW Upgrade kit - the bigger injectors are no doubt to fudge the safety factor; the JCW airbox is probably the major helper for that +2HP additional-delta for the Upgrade kit. Alas, we're starting to split hairs here.

Speaking of JCW versus Aftermarket - this argument is beaten to death so much that even the bat used to beat it has already broken! *Keeping it simply put: Two solutions for two very different Motorers.

How about posting about the "lose your warranty" myth on aftermarket parts. This one is beat to death as well.

This is another one for your list ...

The only difference in horsepower ratings between the US and the rest of the World is the "units" in which they are expressed.

From A Dictionary of Units of Measurement:

brake horsepower (bhp)horsepower (hp)metric horsepowerMINI Cooper S horsepower ratings:

Builds thru June 2004 = 120 kW = 161 hp = 163 PS
Builds from July 2004 = 125 kW = 168 hp = 170 PS

JCW Cooper S horsepower ratings:

Old Kit = 147 kW = 197 hp = 200 PS
New Kit = 154 kW = 207 hp = 210 PS

I remember very clearly that RandyBMC told me the JCW pulley is a 14.8% (not 13.8%). RandyBMC - you're thoughts? :sly:

Question from 6th gear...umm....is 15% pully safe for my Mini:grin:

Where's the "search" key? Is it next to "any key"?

RUN...........:lol:

Ryan,

Is this because of a red-line change or just better mapping? Also does this mean my 2003 MCS with the latest v39 software will get additional HP as compared to older v36 software?

I was off a bit, but I'm still closer than what others are saying. With both pulleys in my hand, the JCW is 2.21" (the 15% is 2.19") and stock is 2.58".

2.21/2.58=.856 Which means that the JCW is a 14.4% reduction. I stand on that!!

Randy

here are some more #'s:


crankshaft pulley: 5.460" dia (weighs 7 lbs!)
stock blower pulley: 2.580

standard blower speed up: 5.46/2.58 = 2.12%

true 15%: 2.193 (P&D 15%= 2.19)
true 17%: 2.141 (P&D 17%= 2.14)
true 19%: 2.090 (P&D 19%= 2.07; equals 19.8%):o

Here's an interesting little snippet from the Bosch Automotive Handbook about pulleys. For a standard 6-rib DIN 7687, the effective diameter is the diameter of the pulley peaks plus 3.2 mm (0.126" for you sliderule types :lol: ). This of course applies to both the drive and the driven pulleys.

So, stock:

(5.460+0.126)/(2.58+0.126)=
5.586/2.706 = 2.06

This matches up nicely with the MINI tech documents. :thumbsup:

I agree totally. It shouldn't be lose your warranty. It should be: fight to keep your warranty with aftermarket parts.:roll:


Paul

Using my calculations, the percentage increase in blower speed for each pulley over stock is:

stock: 0% (duh!)
jcw: 15.8%
p&d "15%": 16.8%
p&d "17%": 19.4%
p&d "19%": 23.2%

I hope this didn't lose anyone - but great info!! Andy you are a rock star genius :smile: .


What worries me is that folks don;t really know what percentages we are referring to. I even hear the pulley called a "15 degree" pulley from time to time, which furthers my concern for the average Joe getting lost in the facts.

The 15% we are referring to is the reduction in circumference of the supercharger pulley itself. The supercharger is driven by this pulley through the crankshaft pulley, so the smaller you go, the faster the supercharger spins.

The supercharger itself has a ratio to the pulley, making the effective spin up greater than the percentage reduction of the pulley - which is what jlm and andy have posted.

We spin the supercharger faster to do one or both of two things - compress the air or increase the volume. By increasing density, we are increasing the potential energy of the intake charge. Since d=p/t, compressing the air gives more pressure, increasing density (as long as we don't too hot).

Hope that helps!
Randy

Here's a chart illustrating boost levels for stock, 15%, and 19%. Results vary based on condition of the supercharger, belt, bypass valve, etc. as well as other components on the car such as intake, exhaust, etc. But, this should give a good illustration of how much pullies increase boost at all RPM:

http://www.ross-tech.net/andy/mini/01519pulleyboost.png

For the record.... the search is not all to friendly sometimes and returns so many results that after awhile I get dizzy....

My apologies for getting the whole pulley vs. warranty thing started...

I did try and search just so I wouldn't get blasted..... Oh well, I guess it is just in my nature to muck it all up!

Do you have temps to go with this data?
 

Hi Andy,

do you have the temp after the intercooler for these runs? If you plot the pressure divided by the absolute temp, then you get molecular denisity. Just showing the boost levels without the temps overstates the benefit. But you have done much more of this than me, so I'm sure you have more info as well.

If you don't have the temps, if you have the HP numbers, you could fudge them backwards... But it wouldn't be as accurate.

Matt

It's great info, but the variables between two cars blow away the control. Any chance you could get the info on the same day in the same car? If I had the software, I'd do it!


Randy

Lots of reading here:

https://www.northamericanmotoring.co...ad.php?t=23089

and here:

https://www.northamericanmotoring.co...ad.php?t=23248