I am planning on upgrading to the alta 15% reduction pulley. I was also told about adding a eurosports alternator pulley. I have searched the forums and could not find much info on this. Is it a good idea or not? Anyone out there have any opinions to share?


Eurosport Underdriven Alternator Pully
Claims: This allows for a power increase and more responsive throttle input! Another nice feature of the alternator pulley is that fact that it takes up the slack in the factory belt when you reduce the supercharger pulley. In other words, you can use your stock belt when you change out the supercharger pulley in conjunction with the alternator pulley.

The Eurosport Alternator pulley is slightly larger than stock...thus, slightly "underdriving" the alternator and giving you an extra 3-6 hp!

 

hey, im interested on it too! if you get more info please post it! thanks!

Carlos

 

hey, got the 411 on the the pulley... basically the pulley it is a little bit larger than stock (underdrive) and it will create a less drag to the engines rotation since it has to spin less, it will give you a better iddle responce and over all throttle responce because of the less drag and weight...

one thing to keep in mind is that since the alternator pulley will spin less at low speeds you will lose some electrical power generated by the alternator and it might affect your car if you have a very large multimedia system in your car other than that you are ok... but how drives a cooper s at low RPMs anyways???????????

in my case i have a light weight crank pulley, a 19% pulley and smaller belt. to what he states it will work fine and will improve my cars overall performance...

I wanna thank JB from eurosport for all the info.....

hope this helps!

 

The next question is how hard is to change the alternator pulley. Have you seen where that thing is?

Dave

 

I am dropping my MINI off at a local shop in the morning to have a 15% reduction pulley and overdrive alternator pulley installed. When I spoke with the sales guy he suggested also doing the alternator pully since it was easy to do it at the same time.

I will let you know how it goes. Although it will be hard to say what difference the alt. pulley makes since the supercharger pulley is going in at the same time.

 

Cool, let me know how the car runs I know it’s hard to tell but in idle it should respond better to throttle input...



Also let me know if see any kind of fading in your lights at idle.



I’m going to do that next but I got to wait a little I have spent too much money already on my car….



Thanks man!

 

Nomios,

How did the install go? Am also interested in the alternator pulley swap and want to know the details of the install. Does the alternator have to be removed or can the swap be accomplished with the alternator in the car?

Hope the install went well for you.
John Petrich in Seattle

 

I bought my 2003 MCS about three months ago, and have been busy adding the usual upgrades. I knew I wanted a reduction pulley, but did not want to do it myself. When I purchased my MINI the only mods were the 18" wheels (or so I thought). I purchased from a dealership. An hour or so after dropping my MINI off with Vesko, the guy who did the install for me, he called to tell me I already had the Alta 15% reduction pulley!!! I told him to go ahead with the alt. pulley (didn’t have that). So it turns out I am able to get a good idea of what this upgrade has done.



I have to admit that idle is much smoother. I do also see a slight change when accelerating. Not sure about additional hp, but I doubt you would really be able to feel the supposed 3-6 hp gain with the butt dyno. As for loss of electrical generation, I see no ill effects. I don't run any multimedia stuff. I just have my h/k, and am happy with that. I parked in front of my garage last night with my lights on to see if I could notice a dimming at idle. I am happy to report that I could see no dimming/brightening when idling or accelerating.

I am not sure if the alternator must be pulled. I will try and ask Vesko. Ended up costing me 200 for this, but I can't really complain since I was planning on dropping around 500 for this and the Alta pulley.

 

I tired like to install it without removing the alternator but with no success. A different approach will be taken today.

Dave

 

Sounds like you do have to take it out

 

Increasing the diameter of the pulley does the same thing as decreasing the diameter of the MINI‘s supercharger pulley - it alters the relationship of engine RPMs to that of the related component, whether it be an alternator or supercharger. Decreasing the size increases the speed of the component and increasing the size of the pulley reduces it’s speed. Keep in mind, though, that putting a reduction pulley on a supercharger does not increase the speed that the engine, belt, or alternator turns - only the speed of supercharger itself. So changing a supercharger pulley doesn’t automatically mean that it is a good idea to change the alternator pulley because the relationship in engine's RPM to that of alternator's RPM has not changed, only that of the supercharger to the engine. The fact that a person with a pulley fitted may have a higher propensity to drive the car in anger - and thus at higher-than-typical RPMs - may justify the change, though. But I don't see how changing the pulley would increase performance. The larger alternator pulley was done to the early classic Cooper works Minis to reduce the RPMs that the alternator turned in order to extend the generator/alternator’s bearing (bushing) life since the alternators were designed to run at “typical“ RPMs.

 

I had "heard" (I think on this site) a long time ago that changing the alternator pulley on the S wasn't a good idea. Maybe b/c of all the electrical equipment on the MINI, I'm not sure. Doesn't the engine and power steering fan run off this too? With all the electronics on the MINI, could this wear out the battery sooner if the alternator isn't getting enough power.

Another HUGE concern I think would be warranty. If you change the alternator pulley - heck that's worse than changing the supercharger pulley. Now the dealer can deny warranty work on anything run off the alternator - which is just about anything (A/C, wipers, lights, etc...)

 

How much larger is the alternator pulley? Any idea what the power rating is for the alternator?

 

I am sorry but I do not have all the technical data that you are looking for. Here is a link to the manufacturer. http://www.eurosporthighperformance.com/mini.html
I am sure they can help you.

I fully understand about belt speed, warranty, and alternator out put at lower engine RPMs.

Dave

 

What I was getting at, is judging by the percentage change in size, as well as the power consumption of the alternator, it should be possible to find out if their theoretical 3-6 hp gain is possible at all.

 

I don’t think a gain of HP is realistic at all. I am only looking at preventing a loss.


Dave

 

Not sure about on exact size diff, but here is a pic

http://www.minituner.com/images.original/952.jpg

 

Looks to be about 20% larger to me.

 

Andy, you obviously know your stuff, and I am pretty new to this. I have a couple of questions.

If you decrease the size of the supercharger pulley, it then spins faster. Does this then also increase the rotation of the alternator pulley?

If the above is true, I was thinking the larger alt pulley would sort of balance things back out???

 

Since the driving pulley (crankshaft pulley) is not changed, only the driven pulley of the supercharger, only the supercharger (and the attached water pump) will experience the increased rotational speed from the reduced pulley size. All other accessories are driven at the same speed in relation to the engine speed as before. Increasing the size of the driven pulley of the alternator will cause it to spin slower, reducing the drag on the engine slightly, mostly at high engine speeds. The other advantage for us is that a slightly larger pulley on the alternator makes up for the extra slack in the belt that results in adding a smaller pulley on the supercharger. Here is where things balance out.

Only real problem with slowing down the alternator is that it's output will be correspondingly reduced at idle and low engine speeds. This results in a lower voltage at idle with accessories running and increased drain on the battery. The ECU will try to compensate by raising the idle speed during periods of high current usage (lights on, a/c on, engine fan running) at idle. The cars do this already without an alternator pulley, but will be more frequent with it.

 

maybe you can use your stock blower pulley on the alternator when you go for the pulley mod

 

Ok, the answer is no, the alternator does not have to be removed from the car if the proper tools are used.
I also believe the idle is smother and acceleration is more responsive. I also tested at idle for over 30 minuets HK stereo on, AC on, and Xenon headlights on, except for the AC switching on and off (normal) I see no difference.


Dave