I've done a lot of reading here and it seems that the concensus is:

15% = good power and no problems on the street nor track
19% = better power and no problems on the street.... but track?

Those of you with the 19% *and* who also track your Mini, can you add your input? BTW - If I go 19% then I would definitely also do the GIAC and bigger injectors.

Both Webb and Mini-Madness do not recommend the 19% for track use; they both use 15% on their track cars. I have a hard time going against the advice of two tuners that do a lot of track testing and have no vested interest in 15% vs. 19%. Are they correct or are they behind the times?

Thanks for any input!

 

There seems to be lot of mixed review with that subject. I personally am running the 19%. Lot of other people are also running the 19% without problems. If you are worried about damaging the motor, you can also run 17% pulley. You can run 15% sc pulley with a 2 % crank pulley. There is a couple of members of NAM that are running the 19% with a 4% crank pulley.

I prefer the 19% for its low end power. At the track I would shift a bit short of redline to play it safe.

 

I'm running 18% on the track and since that mod have done about 7 -9 track days. No problems so far, but I'm about to take it back down to 15%. One reason is that I'm being talked out of the lightwieght crank pulley that I'm now using. It's the Alta +3%.
It's really hard to take this step thoutgh as I truely like the power I'm getting from this combo. Not sure what I'll be doing.

 

Running 19 with Lightweight crank pulley purely for track and no probs. Even in high temps it has no probs (so far...... )

 

15% plus 2% crank pulley = FUN No problems, so far

 

Why are you taking the light weight crank pulley off? Is ther a problem with running that setup?

 

I've had no problems at all, .... but I am pushing the car harder these days and may up the rev limiter. I'm just being told by some that anything over 15% on the track (consistently on the track) will end up screwing up the SC.

Still not sure what I will do at this point. I'm about to go nuts on the motor mods so I need to think this out wisely (which is not something I'm known for)

 

I've had 19 pulley for 18 months and track car 1-2 times monthly w/o any issues- just added injectors/GIAC last month- I do not run more than 20-25 minutes at a time on track. I change my belt routinely- I also try to shift about 6500 PRM-I've had absolutely no issues nor has anyone else here with 19 had issues, except need to replace belt more often.
If i was doing more than just super lap, track days, driving schools- if i was into wheel to wheel racing where much more time spent on track- i'd probably switch to 15 pulley.

 

Sounds exactly like my position

 

Thanks for all the input. I'm still undecided. I keep wavering back and forth on 15% vs. 19%. It seems that some people have had no problems with the 19% on the track, but if it were really that good, why doesn't Webb and Mini-Madness have it on their own cars?

At MMW I did not get a chance to speak with Randy since he was quite busy doing various installs, but I talked to George from Mini-Madness and he seemed quite convinced that the 19% should not be tracked.

 

Personally I would never use a 19% "pulley", on the track. It's just too small in diamiter and my concern would be with the belt. That's why I'm using the 15% and +3% crank.
Now I just need to worry about the SC .....
My gusess is that Webb would concure with George.

 

i have yet to track my car but i have the 16% M7 on my car and its nice on power. Take it all the way to readline with no problems.

 

I'm strongly considering running that same combo, the 15% plus 3% pulley and was wondering how it was on the street?

 

What George told me, and I have read supporting anecdotes from Randy, is that the 19% makes more power in the lower rpm range, making it a great street mod. However, at the higher rpm range (typical track use), the 19% has gone past the adiabatic efficiency of the SC. This results in extra heat rather than extra power. So at high rpm, the 19% makes about the same amount of power as the 15%, but with less reliability in theory because of the extra heat.

I have not had a chance to confirm this by comparing dyno charts of the 15% and 19%. Has anyone done this?

 

Onasled - Any concerns about excessive heat from high RPM supercharger use? Perhaps a 17% SC pulley + 2% crank pulley might be the way to go for track, plus the GIAC and larger injectors...

 

...if one went to a 15% + 4% combination, one could go either way fairly easily, not so?

 

My concern is adding too much speed to the accessories (from the 4% crank pulley). Not sure how real of an issue this is though.

 

There are several SC on ebay in the UK for under $200. The shipping is about $130