Let’s hypothetically say that I have a design for a variable-ratio pulley which allows an engine tuner to tailor the pulley-to-engine RPM ratio so that it is either progressive or regressive – from stock size to 20% in conventional pulley-reduction terms. In addition, the progression/regression curve can be tailored to meet the needs of a specific engine. Any interest? This may be ideal for dual-charged engines.

 

Sorry, I meant ratio.

 

maybe a better disciption of just what this pulley will do would help.

 

merely some minor thinking here... but i think wat he means is that the pulley changes size depend on engine load... for example, the pulley may remain at 20%reduction at the low to 3 grand to take advantage of the low end torque of a high reduction pulley, as engine speed rises the pulley changes size to say 15% or even back to stock to keep the supercharger from overrevving..

that's just my take, and if someone can come up with something like that it'd be incredible

 

I'm not sure I fully understand your idea here, but if you plan to change pully size at different RPM's then your also going to need to change the tension of the belt. Also I'm not a supercharger expert but wouldn't you want the amount of boost going in the engine to be the same throughout the RPM range? If the pulley progressively got smaller as rpms got higher I think it would create a turbo lag effect, and on the other hand if it got larger I think it would make for an interesting torque and power curve that would not be desired. Also it sounds like no matter what your idea will create more moving parts which increases the risk of something breaking. You may have already thought about this stuff and came up with another way around it, but from what you have explained so far it sounds like you may have issues with everything I have listed. None the less always good to think about ways to improve the mini .

 

That is exactly the idea. Both pulleys and the belt would be replaced with what is essentially a very simple and compact CVT primary drive setup similar to what is used on modern Vespa transmissions. It consists of an adjustable variator, which would replace the engine pulley and a small clutch, which would replace the supercharger pulley or vice versa. The level of progression could be altered by using variator weights.

 

what about a clutch type mechanism for hte super charger...that way the super charger gets you off the line but once you ahve spooled the turbo...you can have to boost go much higher from the turbo and the charger shut off

 

Maybe I just didn't get enough sleep last night but here is the CVT skinny. The aftermarket ones made by Malossi are absolutely bulletproof. Anyway, it is just a crazy idea. It doesn't even have to work - just give you bragging rights!

http://www.flexistentialist.org/arch...cs_const.shtml

 

What kind of fuel mapping would this beast need?

 

I have yet to see any sort of variable ratio pulley setup that uses a multirib belt. There are lots of similar setups using V-belts in industrial machinery, outdoor power equipment, etc. The problem I see is that a V-belt would not work well in the horsepower requirement range that a supercharger needs. A miniature CVT-style metal belt system would be better, but there is the RPM range issue there as well.

 

The boost on a supercharger IS NOT the same throughout the RPM range as it is. The faster the engine spins, the faster the supercharger spins.

As for the variable idea, however, it seems like A LOT of work for a little low-end gain. I mean what is the smallest pulley you could use? 20%? 22% tops maybe? Then make it larger at higher RPMs to reduce max boost. Again just seems like a big job to be able to get a little more torque down low. The best thing about a reduction pulley, IMO, is the incredible bang for the buck. It's basically the cheapest, effective mod for the MINI ($300-400 installed) and transforms the vehicle big time. And the best part about a smaller pulley like the 19% is it completely transforms it (b/c of all the low-end torque which the stock MINI has NONE) and it costs the same as a 15%!

But if you do decide to do it, I'm anxious to see how it goes!

 

Like I said, this was just an idea brought on by sleep deprivation. It would definitely work but, like a few posters said, there would probably be no advantage to it. The Malossi Variator is capable of handling over 40 BHP at 10,000+ RPM, so strength would not be an issue. Plus I have since been told that AMG experimented with a similar setup a few years ago and scrapped the plans, although I cannot find any resources to confirm it. Oh well. Remember, I come from the school that takes 35mph Lambrettas and tries to make 'em go 100! http://www.100-mph-lambretta.com/
No such things as "can't do it and won't work.

 

Sorry I guess I left my post a little unclear. I know how a superchargers boost increases as the rpms increase because the supercharger is driven off of the engine. What I meant to say was I dont think a drastic change in boost is really something you would want.

Like others have said I don't think a CVT could handle the hp or abuse that would be thrown at it if it was converted into a supercharger pulley. I think you would also lose hp initially (who knows how much?) because the pulley will be heavier and require more force to spin.

Also I dont know about the rest of you guys but I like to heel and toe downshift. Think about the effect this pulley would have if your blipping the throttle under braking.

 

If a CVT drive mechanism could be made reliable, lightweight, compact, and affordable, it could optimize the behavior of the supercharger to provide a much better torque curve. Specifically, you could make lots more boost at lower rpm, while reducing the parasitic loss at high rpm.

I wasn't aware of AMG having a CVT design, but they definitely had a clutch mechanism on the supercharger drive.

 

wow

this is probably one of the best ideas so far for a modification.

makes a lot of the other "performance modification" products look more like "utter defecation" wastes of time.

Good idea! I hope something comes out of it.

 

Thats a lot of extra rotating mass.

 

but really nifty rotating mass.

after all... even jesus weighed a little bit. And apparently had very large feet.