Originally Posted by syntrix

I for one, would like to see these dyno plots.

I could say that I have gained 50hp with a secret magnet on the fuel line. But we all know that's silly

Originally Posted by Ryephile

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! 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!

Next: please, for my scalps sake, use the SEARCH function! 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" . Hopefully you get the idea.

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

Originally Posted by Battle Cattle

Myth buster times...

Ok I was looking at getting the alta CAI... but this dumb idea struck me...isnt it just sucking the hot air from around the engine? if so what would be the gain? More air? Or is it truely sucking air from the cowl which is ambient temp? If someone could explain it to me that would be great... even some crude (MSPaint) pictures would be helpful!

-Josh

Originally Posted by RandyBMC

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

Originally Posted by Brynster

"Small" - "Medium" - and "Large" works for me

Originally Posted by rafthos

So was your silly magnet oriented n/s or s/n in relation to the fuel flow in the line, how powerful of a magnet did you use, and did you insulate your butt dyno against magnetic interference when testing?

Originally Posted by andy@ross-tech.com

That's still a little confusing since the smaller the pulley, the bigger the gains. How about:

Goldilocks: 0% (stock)
Baby Bear: 15%
Mama Bear: 17%
Papa Bear: 19%

Originally Posted by lhoboy

It's easy to pontificate regarding the use of the Search function, but this forum has got the worst search engine I have ever seen. Hours of search through irrelevant threads before anything useful can be found. But then again, I'm just a dumb MINI driver who loses an additional 40 IQ points whenever I sit in the SPUD.

Originally Posted by Byron

You won;t notice much performance increase between pulleys until you put larger injectors in and ecu with the 19%

Originally Posted by etalj

I plan to put in JCW 380cc injectors as well, with my 15%.....the injectors should release equal benefits with all the pulleys though, cos as i said, most ppl think its all about how much boost there is. Density is wat we're looking for, and if we're, making too much heat, what's the point, cos heat works against pressure in the battle for more density.

Originally Posted by greatgro

Luckily testing has shown that the 19% does not make too much heat!

Originally Posted by etalj

ok so, even though Randy Webb and a few others have said that the 15% pulley makes more power, would you back a 17% over a 15% pulley'd MCS in a 1/4 mile run, or 0-60mph run, or top-speed run, due to the change in torque spread? (I really wish the companies would offer a torque/power graph for each of the three pullies)

Originally Posted by greatgro

15% makes more power than what? A 17% or 19%? Anyone that said that is out of their mind! A 17% makes more power (torque and horses) than a 15% and a 19% makes more power (torque and horses) than a 17%. Theoretically heat could be an issue, but testing has shown this is not the case. IMO, the 19% is the hands down winner for everyday use. And I've had both the 15% and 19% and had the 19% with and without an ECU upgrade. If you're only going to do one mod, get a 19% pulley. Sure a properly tuned ECU really makes it better but even with the stock ECU, a 19% pulley is still the best mod you can do for the "grin" factor.

Originally Posted by etalj

FYI, http://store.webbmotorsports.com/ind...in_page=page_3 Apart from power concerns, he says its "50/50" on the belt snapping during track use? I wonder if this is true.......i wanna be able to track my car, and i don't want my belt to snap

Originally Posted by greatgro

FYI, Randi isn't the only one who's done testing on these pullies. If you were going to track it 50% of the time, maybe you are better off especially if the extra power isn't that important to you. As for the power concerns, they are not true. Again, I've had both pullies - if the 19% really does generate a lot more heat then it must generate a lot more power/boost to overcompensate b/c it definitely does. Also from the numbers I've seen, the 19% makes considerably more boost and at lower RPMs with only minimal heat increases. That's why for me, the 19% seems like the ideal pulley size. And while we're at it, the 19% is really more than 19%. It's practically 20%. It's just called 19 so people don't freak out.