The 15% to the 19% is 2 things, first is a less drastic bend around the pulley, and second, it's more surface area on the pulley. The first, I'm not 100% sure how much it affects the belt. I'm not sure is an issue of speed as much as it is an issue of slipage. I thnk that is the largest cause for belt failure. Any chance that you can reduce slipage, it will conserve belt length. I agree that the belt will more faster, and cause the alternator to turn faster, but the amount of HP drawn from the Alternator Vs. the Supercharger is almost nothing, for 1, it is not doing anything other then spinning against a small magnetic force, and 2, it has a much larger surface area to the belt for very little, if no chance of slipage. Let me know if this helps you

 

Dan,
I cant really follow what you're saying. Would you mind editing this post so its understandable? Thanks.

 

my point was that the belt as it flexes around pulleys is subjected to stress related to both the belt speed and inversely, the pulley radius

 

I'll try to organize my thoughts..

JLM Stated 2 things.

First that the Radius has an effect to the belt life
Second that the speed has an effect.

What I was trying to state that both of those are factors in belt length, but the largest factor to a failure of a belt is slipage. That has the largest effect on the belt, first being friction of the belt slipping against the pulley, second being heat.

With a larger diamater pulley, both the crank and the SC Pulley (not stating there is any slipage on the stock crank pulley) there will be more contact area of the belt and the SC pulley. This enlarged contact area will help the belt drive the supercharger, with a less chance for slipage.

Lets say that on average a belt with no slipage can last 15K miles. If it runs 5% faster, that means that it will traverse the pulleys 5% more in that same ammount of time, so you may only get 14250 on the same belt. Again that is with no slipage. Now, if you bring slipage into the mix, as seen with the heat generated on a track event, you can go though a belt in a very short time. Say 1-2 track events as shown by the failures that we have seen. If by increasing the contact patch of the SC pulley, you can either severly reduce the chance for slipage, or eliminate it, then you can go many more events with out a failure.

Again, this is all theory right now, but it seems to make sense to me. Let me know if this clears it up for you.

 

MINIPilo, how does your pulley compare size-wise to the Alta aluminum crank pulley?

 

I don't believe that they have released an oversized pulley. So ours is 5% larger.

For anyone that wants the stock size pulley, we can make them as well, for the same price.

 

Here's the thread with their info: https://www.northamericanmotoring.co...ad.php?t=39154

 

Then we are about 3% larger then what they have. I'm not sure what their exact sizes are, but if you go to the first page, you will see our information.

 

Dan, do you have this item available for sale, are u providing the belt along with the pulley?????

 

It will be released for sale soon. it is in the testing phase. Depending on need, a belt may be included.

 

Hi Dan,
here in germany we do a lot of high rev and high speed driving on our autobahn (with no speed restriction ). Most of us using 56,5mm pully, 15% reduction, a 19% reduction is (I guess) to much considering our driving caracteristics.
Are you able to produce a 2% or 3% bigger crank pully instead of your 5% increase?
Best regards,
Mick

 

We can make any custom size.

 

Dan, have you had any chance to do any tests/compile any results?

 

When I am done testing, I will post all results.

 

 

some more reading about torsional dampers:

http://www.fluidampr.com/problem.htm

 

Many thanks for the reference. I'll try to track down the SAE paper from 1979, unless you can post it .

It appears that the problem of crankshaft torsional vibration may be quite important for very high performance applications such as drag racing. Perhaps one can extend the logic to modified Minis that are taken to the track? How about fairly aggressive street driving? Would you also comment on the use/availability of a fluid damping system in a Mini that is pulling 200+ whp?

Thanks,

 

Just so that you know that our dampers are based on a straightforward clutch/brake design. Over 20 years of experience (from our Manufacturer) have proven that the clutch/break design is superior in dampening torsional vibrations and durability. The design might be simple, but there is nothing simple about the craftsmanship and performance built into each and every damper. Also, Our damper uses neither liquids, which gel or leak, nor rubber, which loses elasticity. Our design is simple and based on a concept so successful that it has been used longer than any other damper design.

We believe that Dampening is very important to a higher performing mini's engine.

 

Are you going to offer this damper in only 1 oversize? I am interested in a unit that will bring me from a 15% to a 19% overdrive of the supercharger. The reason I'm talking in percentages is that I want to use it with a software program designed for a 19% overdrive of the supercharger. I think that most tuners work to tune their software to a certain pulley as that is a popular upgrade. I don't have a booste gauge so I don't have a way to gauge any differences in boost,but I do know what percentage of overdrive to specify.
I guess that it's the long way of saying that I would be interested in a oversize that brings me to the same supercharger speed as a 19% pulley while keeping the 15% pulley. I think that a lighter weight, oversize damper is the soundest solution to get to 19% without the belt durability problems that some people have experienced.

 

AS posted on the first page

 

Do you see any potential problems using a lighter crank pulley if the car has a lightened flywheel? Thanks,

 

I do not forsee any problems. We are handling Harmoncs with the Damper, so operations should be the same as with the stock Damper.

 

Just an update. We are just about ready for production. Having to make one change to the Pulley, and it will be set.



Just a side note on Harmonics and Harmonic Dampers. The harmonic damper does not aid in the balancing of the Crank Shaft. I've see it stated that the Crank shaft is Balanced to a tolerance of Grams. This does not apply towards the use of a Harmonic Damper. The Harmonic Damper's Function is to Dampen the Vibrations Created by the Pulse of the Combustion Cycle.

 

Is there a group buy currently?

 

if there is, I'm in.