Took the drive up to Plover, WI yesterday to have Charlie Rossier (Rossier Dyno Reserach) install the supercharger pulley he sells. Charlie has done a dozen or so of these conversions, so has the routine down to about 4 hours. I did not spend the time or money to have my S dynoed before & after, but RDR has done a few & has comparative hp/torque graphs on their website. The good news is that the BMW ECU seems to compensate well for the increased air flow - Charlie tells me he typically sees air/fuel ratios still in the 11:1 range. I would tend to believe this, as I put 200 fairly aggressive miles on the new setup & the temp gage never moved above the normal reading. Tremendous upgrade for the price - $400 installed. Every gear pulls like one ratio lower.

Downsides: fuel mileage suffers (expected); seems to induce a little torque steer (not bad, just feel that additional power going through the front wheels); I'll probably eat up my new Bridgstone S03's a little sooner; & the threat to my drivers license has gone up a notch or two. Nothing unexpected - just the price of fun.

Had a great time kibbitzing w/ Charlie as he worked, & he didn't even charge extra for putting up with **** MINI owner looking over his shoulder all morning.

 

>>Downsides: fuel mileage suffers (expected);

That's odd, everyone who has posted on MCO about fuel mileage with the pulley all say the fuel economy went up. Are you sure your drop in MPG wasn't due to your spirited motoring?

 

The fuel mileage does get better - if you can keep your foot out of it. Typically, folks just enjoy the new power too much not to plant the right pedal as often as possible, so the mileage does go down .

4 hours?? I agree that those A/F ratios are typical. We see anywhere from 9-10/1 with a stock MCS, and after the pulley it usually changes only minmally - 11/1 or so. 14/1 is about as lean as I would go safely, and the software out there does just that - only slightly more conservatively at 13/1 reaching redline. As I keep saying, the software is a bonus, not a requirement.

Go out and enjoy!

Randy

 

Randy,

On the average, what are the torque increases people are seeing with the pulley install? Mean? Low? High? Sorry to get so technical and mathematical on you, but I'd like to be able to give decent answers when people ask me about it. Thanks!

 

Here's my before-and-after results (with both stock and MTH chip). Torque and HP gains were very similar:

 

>>Here's my before-and-after results (with both stock and MTH chip). Torque and HP gains were very similar:
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Was the rest of the car stock (no mods to intake or exhaust)?

 

We see pretty consistent numbers - usually the gains in torque are 15 ft-lbs. I have seen as low as 12 and as high as 23 (!).

The 23 ft-lbs was on a car that before the pulley had the Madness intake and the Borla exhaust, and in addition to the pulley, we changed to the Magnaflow, so that 23 includes the gain from both the pulley and the Magnaflow. Without the exhaust change, I'm sure the number would have been more in the mean of 15 or so.

I have seen dyno numbers from 15 or so cars, so that number I'm pretty confident in.

Hope that helps!

Randy

 

>>Hope that helps!

Sure does!

See you in PHX in October!

 

I have discovered why my PERCIEVED fuel mileage worsened (besides a heavier foot): I am in the habit of resetting the trip odometer at each fill-up. Disconnecting the ECU for the Pulley swap apparently reset the trip odo., so it looked like the fuel gage was dropping unusually fast.