I just thought I'd stroke the inventor type mind . But it would be the best of both worlds I could come up with something but I thought , I'd give some one else a chance

 

to make it better, it should be made from titanium (Ti)

 

It would be awesome!!

Imagine, let's say 19% from 0 to 4500RPM and 15% from 4500 to redline.

I would buy it for sure!

 

make just a 25% and i'd go with that all day. Why would I want less power?

 

Well, don't forget that above a certain rotor speed, superchargers like the one the MINI has don't do much more than beat the crap out of the air and add heat without adding much power.
Also, the supercharger, like the engine itself, has a redline. If you overdrive the supercharger by 25%, you're going to have to reduce the usable redline of the engine to avoid overspinning the supercharger. Since horsepower is proportional to engine RPM, reducing the redline is going to cost you power - probably more power than you gained from overdriving the supercharger in the first place.

 

This is how the system works; at idle or cruising you have no reason for spinning the sc too much so the drive is at a mininum ,when there is a demand for power the drive goes to 25% ,when the sc reaches max rpm it tapers the drive back down to keep the sc from overspinning. ECU controlled of course.

 

It would need to be clutch controlled...and really, there isn't much room in that small space to drop in that type of hardware. Also, your MOI would increase, potentially stealing some power from the engine on spool-up.

Actually, I would think that you would want the 25% at lower rpms, ramping down to the 15% at higher rpm. Getting the initial greater boost in the low range, while still protecting from redlining your SC.

 

JPMM,
I agree with the potential value of a variable-geometry drive pulley. My comments were in regards to Rhubbard's post advocating a fixed-ratio 25% pulley, which I do NOT think would be of much value for our cars.

 

There was a certain element of sarcasm in my post.

 

I'd think a system like the Nissan Extroid CVT would have the most potential in this application. http://www.autozine.org/technical_sc...vt.htm#Extroid
Just make it really small and make the input the supercharger pulley with the output shaft hooked to the supercharger itself.

 

and actually came up with a bit of a design.... But there isn't much room there, it would be expensive, and I honestly don't know if there's place in the marketplace for it....

But since the PUTi Pulley sells, this might too! But I can't see spending the same on a pulley that you could spend on a head!

Matt

 

If I were to design it I think I would just use a smooth tapered SC shaft "pulley" and control the position of the belt along the taper by moving the position of the crank pulley along the shaft. The position optimized for most effecient SC rpm.

 

but you've got to make a system that does everything in the 3/4" space that is there in front of the pulley. You have to make it strong enough to do about 40 HP, and cheap enough to be less than a twin-charge kit. Those are the challenges....

Matt

 

also don't forget that in the end 6000k rpm and up the hp levels will not differ from a 15%... sure you are getting more area under the curve... but belt tension is going to be an issue as well... lots of "issues" that would have to be worked through. the amount of torque added probably still wouldn't justify the cost

 

I;ll throw this out then

Variable geometry SC

(Couse switiching to a larger screw SC is probably cheaper; but you can say it in a advertising video like Porchse and make it sound fast right )

 

OR what about getting a variable drive pulley for supercharger, 25% to 13% and the vendors/tuners to work on the new and latest Eaton Twin Vortices Series (TVS) roots-type supercharger that features "four-lobe rotors and high-flow inlet and outlet ports that greatly enhance thermal efficiency, deliver higher volumetric capacity, and enable higher operating speeds. The TVS supercharger is capable of running with a high thermal efficiency (up to 76 percent) across a very wide operating range." From eatonperformance.com!

Here's the link: http://www.eatonperformance.com/superchargers/TVS.html

 

Check out this video clip! http://www.eatonperformance.com/supe...ideo-clip.html

I love the internal by-pass valve!

 

I don't think updating to a newer spec but same size SC will give much return. Only with a bigger ,higher flow SC ,in its correct curve, blowing more air will you see more power with less heat. But there's no space for a bigger one.The Efficiency route is expensive ,with all that cylinder head porting,bigger intercooler,cam crap, .We need more cool forced induction. I guess feeding the supercharger with a turbo is a good ,(hot?) route.
The variable drive would have been a good trick Better fuel economy and more power.

 

Put a 23% pulley on but some how make the pully slip or something at a tunable SC RPM range. Clutches wear I work on copiers and paper feed clutches registration clutches die all the time. mabye if there was a way to make a 23% attached to the supercharger shaft via spring loaded sumthin that would loose grip by the speed at wich its spining governed by the strength of the spring tension. Oooh ooooh or a solenoid that BAAAAM! locks that sucker in wait no that wont work. dang!

 

There are patents out there for this.
Either magnetic or fluid driven. I doubt either will fit in the current physical constraints.
Think automatic transmission for the SC.

 

Don't know if it's an engineering/mechanical possibility, but what about devising a sc pulley with a diameter that would expand with centrifugal force? At rest, it would be smaller, and as rpms climbed, it would (somehow) expand to create a larger diameter, thereby spinning the sc a little slower. It would theoretically be similar to a cvt.

OR, more realistically, how about a dual-belt drive system. Two crank pulleys, two sc pulleys, two belts. The larger sc pulley is connected to the shaft by a centrifugal clutch. SC runs off the smaller pulley until a set rpm, at which point the centrifugal clutch engages and activates the larger pulley, which takes over. In addition to the centrifugal clutch to drive the larger pulley, you'd also need to devise a method to drive the sc shaft off the different pulleys. Perhaps something similar to the spin-off screw arrangement that starter motors use to disengage the drive gear once the engine fires and starts spinning faster that the starter. Or possibly a shaft-within-a-shaft setup with or without a fluid coupling arrangement.

I've got to wonder about reliability issues over the long haul when you start adding more, intricate moveable parts, but I'm sure that was a concern with things like four and five valve engines and VTEC, etc.