Which would you rather use, the alta tapered bore pulley or the P&D intreference fit pulley? What are the advantages of one over the other?

 

they both work just fine.

The Alta Pulley is a bit more forgiving with installation, but it is a little heavier too. The P&D pulley has one shot to be fit to the shaft before the collar cools, but it's lighter than the Alta. It's just a matter of personal preference. They both at 15% reductions.

 

from a manufacturing point of view. they both have their issues:
the press-on requires a high precision honed bore (we fit the hole ID to +/-.00015" of the factory press on pulley bore).
the taper fit requires less overall accuracy (bore +/- .001&quot, but the mating tapers require precision.
Both require CNC machining; the press fit then gets honed (like a con rod).

From a reliability point of view, the interference fit is a time proven method, the Eaton factory uses it on hundreds of thousands of blowers, and over a hundred of the P&D pulleys have been accumulating mileage with no failures. Since the blower can draw 40hp at full speed, the shaft fit is important. The taper fit relies on screw tightness to produce the shaft fit; presumably if done right it would hold, but the testing sample is still minute compared to the Eaton results.

From an installation point of view, the taper fit is easier. It is four bolts, whereas the interference method requires heating and finesse.
My guess is the racer mentality would place more emphasis on bullet-proof reliabilty and the more casual home shop would be more interested in ease of install.

we actually tried out the taper fit design first, but rejected it in favor of a path of more proven reliability (in this application), but that was before anyone had a reduced size pulley and we were covering our bets. We may offer the taper fit as an alternate.

 

Which type is sold by:

Mini Madness?

Mini Mania?

MINI Motorsport?

 

I have the P&D Pulley and I love it. It even looks cool. If you are having a good shop (Like the guys over at helix) do the install for you go with the P&D. It's really well made! However, if you are going to try and do it yourself... you may want to get the easier to install one. (Unless you are very proficient mecahnically and feel you can heat up the pulley core and slip it on with a pair of pliers)

I didn't want to go with the tapered one because I felt less secure about it's fit. I also didn't feel like monkeying around with a hot pulley so I had the guys at Helix do it. (They are also only ~30 minutes from where I live)

Either way you'll be happy with the 15% reduction pulley!

 

Me, personally, I wouldn't use an taper. I prefer knowing there's NO WAY it could slip, unlike a screwed down taper pulley.

Can't speak for the others, but Madness pulley is a 2 piece interference.

R

 

>>Me, personally, I wouldn't use an taper. I prefer knowing there's NO WAY it could slip, unlike a screwed down taper pulley.
>>
>>

... and yet the pulley is screwed down to the interference-fit hub - don't forget the Lock-tite!
Taper-hubs have been used in industrial applications for a long time and subjected to stresses and unballanced vibrations that no automobile ever sees ... and they dont fall off ...
I'm not here to say one is better than another, just that they are different but both suitable ...

 

>> ... and yet the pulley is screwed down to the interference-fit hub - don't forget the Lock-tite!

True true, but if one of the 6 bolts snaps or loosens, the pulley is not going to slip. But if one of the bolt loosened/snaped holding it on...well, another story completely. Obviously it's Vegas odds for them to have any problems, so really either is just fine. It just comes down to preference I guess.

R

 

Guys, I thought likewise about the weight in trying to decide. It was a main consideration for me, at one time. Here is a thread with some healthy discussion:

http://www.mini2.com/forum/showthrea...=pulley+weight

As far as secureness goes, well, the taper bore is a stronger fit, according Randy - 4 posts down:

http://www.mini2.com/forum/showthrea...=pulley+weight

Granted, screws can loosen I suppose. And while we might see the option to change/interchange pullies as useless now, maybe not later? 15% is the way to go now. 20% apparently is not. A 15% redecution doesn't seem to impact A/F at all, or at least minimally. Anyone try 16 or 17? I'm sure probably so during the testing phase of this mod... But if not, and all is well with A/F figures, etc, maybe different pullies sizes might be a viable option later. If that does come to fruition, a taper bore would be desirable.

Decisions, decisions...

 

A little detour: how will this mod affect the engine if you get stuck in bumper to bumper grid lock? I would like to do it but am concerned

 

In bumper-to-bumper traffic, the pulley will be spinning the supercharger faster than it would be stock, but in both cases the rotors are spinning in free air due to the Eaton's internal bypass valve. I haven't noticed any difference in 6k+ miles of pulleyed bliss.

Personally I like the Helix/P&D design since I also got a stock-sized pulley. I can return the pulley size to stock for testing, or for racing in mods-limited classes.

 

Andy, Thank you for your support

 

Great to see a thread on this!! :smile:

As a real novice, yet enthusiast, I was going with the RandyBMC recommended/installed ALTA Pulley.

Since weight isn't a problem, according to jlm & tONYb's data & informative links (thanks guys!) I figured it's something to trust Randy of MINI Motor Sports with. I've rarely made better decisions!

It may be something you can do yourself if you're mechanically inclined, - after sourcing a "crow's foot" Pulley-puller, an ALTA tapered-bore pulley (for ease of installation) & DIYs from MCO (here) by Randy of MINI MotorSports

Thanks much Randy! Yes, as jlm suggested, the tapered-bore pulley install is most surely a concern for a novice with HP+ dreams.

Giddy-up!
-sb

_________________
MINI: The best horse for the buck!

 

Sugar, I'm in on the installs this weekend as well. If you're around on Saturday I'll be there!

Jim

 

Thanks for all you comments, I still can't decide. But I'm leaning towards the ALTA pulley since my shop hasn't done a pulley installtion yet.

TonyB:

According to your attachments...RandyBMC prefers the taper fit pulley?

 

Randy was stating Sunday, while putting on my ALTA pulley that it was best because of torque tests done on several models. It was the one that held up the best.

It is amazing the amount of increase that JUST the pulley provides. If you can get in a pulley party, go for it.

The ALTA is also almost foolproof because it uses a compression-like fitting instead of heating it up and pushing it on. Randy was stating that the heat-up one has several margins of error. One, it is hot when you put it on, so gloves are necessary. Two, you have about 5 seconds to get it on. Three, you could damage the shaft seal with the heat, so you have to immediately pour water on it to cool it off. and Five, you have to get it right the first time, flush with the shaft and lined up.

Anyway, Randy did a great job. ALTA is my pick. Hope you all do to. It was really not that bad of an install.

 

when is someone going to make one that looks like factory?

 

The ALTA pulley is a really nice piece of CNC and the engineering is right for staying put and self-alining and thier for its hard too screw up and after watching RANDY put it on I'm glad I found him cause its a tricky job that a inexperieced person can screw up your toy ...I mean car.... ws