Stroke of supercharger genius?! - I think so!!!
 

I have been massing parts books for various mechanical and electronic devices for months now in preperation to my (hopefully) eventual debut into BATTLEBOTS.

Now I have seen the device I am about to describe in just about every flavor you can think of.

When it comes to overrevving the supercharger, i know that a bigger pully will fix this, but as we all know, you will lose bottom end boost.

The device I am thinking of is a variable rate, vbelt drive pully.

There are two faces to a v drive pulley, facing each other at an angle. (obviously)

The pulleys im thinking of are capable of spreading their faces apart or moving them together.

This can be done based on rotational speed, or done by electric servo.

In all cases there is an idler pulley in the belt-line to maintain tension on the belt at any speed.

I'm thinking, that if there were a way to actually mount one of these pulleys on a supercharger, then the pulley could be adusted to rotate the S/C at high speed when at low engine rpm, and then back off and rotate the S/C at lower rpm at higher engine speed.

If then, you were able to actually MAP the pully adjuster servos' function into a HALTECH or some other aftermarket engine management system, then the supercharger could be programmed to provide maximum boost ON DEMAND and NEVER redline the supercharger in the process.

Imagine stomping on the gas, and the Haltech, noticing that the gas is to the floor, and the engine is at low rpm, adjusts the pully on the S/C to be at max available RPM, and then constantly backs off and advances the pulley to engine ratio as the power curve changes.

Hmmmmmm..........

GENIUS I say, PURE GENUIS!

(Im convinced anyway...)
What do you think?!! IS this mapping possible?!
Lets do it! - Im Buying!

Always tinkering...............
Sniper_X :stick:

You're talking about a CVT, for a supercharger

Sounds like it would work but it would be a lot of fabrication i think. How would the powerband look then? Not the climbing hp levels with rpm as is usually seen with centrifugal blowers but way more low, and midrange.... a flat(or close to) hp curve?

Theoretically perfectly flat

There are ways to add a 2 speed type clutch driven system onto a supercharger so it would adjust automatically instead of trying to redesign the whole engine bay for a conventional supercharger. Change the supercharger not the car. The concept is worth the brain power but the price would be insane until it went mainstream.

Well, by two speeds, you mean that after a certain speed is reached, it changes "gears"?

My pulley has an infinite range of pully ratios.

Arent these things press on anyway?
Wouldnt these pullys be easy to install on the S/C?

The ider arm mount would need to be fabricated, but it needs very little room, to operate.

I think one of thee pulleys from the mfgr costs about $500.

I know its expensive, but its like adding a supercharger that is always perfect for the speed your going, I'd pay $500 for that.

(I know theres more costs to it thatn that, but for an extra $1000 in total, i think that the "perfect" S/C might be worth it.

i do believe that is a stroke of genious, making it work will have to be also :) lol

i would pay up to 1k for it also, full boost at all rpm's would freakin kick some major ass.

man what a kick in the ass that would be, run 2nd gear to 3k rpm and floor the go pedal, imagine what kind of "seat of the pants" affect that would give ya :) mmmm :D:D:D

I know.

Ive been up thinking about the mechanics of this.

Well, see, ill supercharge normally at first, then play.

Would this mod out preform a turbo?!

(remember to think of reliability and all that)

Why not just use a superior design supercharger that will make the max boost you want at low rpm and bypass the rest of the boost at higher rpms. A twin screw axial S/C (Lysholm) is much more efficient than rootes and is great at high rpm. The Mazda Millenia S uses one for its Miller cycle engine and I believe it makes 15 psi from 2000rpm up or something. The engine design called for lots of boost on the low end since the intake valves are open so long on the compression stroke in a Miller cycle engine.
The CVT S/C pullies are a fine idea, but possibly complex-look how long it has taken the auto industry to make CVTs reliable in cars. Well, if you do do it make sure you have a clutch in there as well for off boost cruising for better MPG.

ITs been done, and its old technology, It was done on some of the first factory superhcarged cars of the 60's, it was found however that a fixed pulley gave a linear boost curve which made more overall power and a much flater torque curve, I think though the pulley was activated by boost, and not by rpm dependency, I can't see a variable drive lasting any longer at 8500 rpm than a centrif superharger gearbox. If it could be done though with a quick actuator, and controller, the centrif could be maintianed in its sweet spot on the compressor map, at all times and activated just off idle..Full boost and full cfm all the way through rev line, a perfect world...
Perhaps a torque converter for the centrifugal with a 'stall speed' would be a more viable approach, or some sort of variable viscous coupling like more various auto trannies are starting to get, this is beyond the realm of homebiulders but is probably the path best sought... Max

these ideas are also good ones, but they are "passive" type controls and require a more complex, installation i think.

the variable rate pulley i speak of comes in about 20 different configurations and can handle VERY high speeds.

Now the idea of a clutch was thought of by me, but so long ago i forgot to mention it in my inital post.

many of the confiurations have electric clutches already built into the servo system.

Kinda like an A/C compressor.

This way, you can shut the S/C down completely.

Would the car breath right then though?

Great minds think alike...
 

When I first found out the Nelson kit overspins the sc, I was pretty pissed off. Nothing like finding out you just spent $3200 on a setup that would void the warranty and not being able to get any support from either the kit assembler (Nelson Superchargers) or the retailer (Mariah Motorsports).

At any rate, I've thought about the variable diameter pulley. The problem with the V-belt is that you'd need one strong belt, my sc kit uses a wide 5-rib belt, and if its not on tight enough you get slippage at high rpms. But what if you had a pulley whose diameter got larger at a specific rpm, kind of like the way (I think) some motors have their camshaft lobes change size by opening up oil ports internally and letting the pressure move the lobes? You get to a high enough rpm or boost pressure, and the sc pulley gets bigger, allowing you to spin it faster still.

Well this is what the initial post here suggests, and the vaiable rate pulley in my design does "get bigger" by adjusting the drive surfaces to be closer togenter as the RPM goes, up.

This causes the belt to ride higher on the outside of the pulley and effectively makes the "driven" pulley bigger..

But contrary to your suggestion, bigger pulleys spin slower, not faster.

This is the whole idea to slow the S/C down at high rpm.

this avoids overrevving the S/C.

Sorry, wasn't too clear. When I said having a bigger pulley lets you spin it faster, I meant it lets you rev the engine higher without overspinning the sc. We're in agreement, I just haven't had enough coffee this morning to explain myself coherently. :D

Question:

Did you have to port yyour engine?
Replace apex seals?

certainly you didnt just bolt all this onto a stock engine....
I know you must have a least changed the injectors, right?

Whats your story on this mod?

Check out his very nice website for all your answers (listed in the bottom of his post.)

You guys have two pulleys to play with. The one on the S/C will slow S/C down as it gets bigger; the one on the crank will speed it up as it gets bigger- so either way this CVT worked (bigger at high rpm or smaller) could be employed. I guess you could employ centrifugal force and tinker w/ different weights to make it get bigger at higher rpm (like the rear tire of a dragster growing at high rpm so they don't need gearing.) Damn it, now youve got me thinking about it:mad:
I still maintain a good cheap Mazda Lyshom S/C would avoid this problem, I got mine for a couple of hundred $$ with very low miles. Without a Haltech though I have to find a way to LOWER the boost at low rpm (and high) to use it on my TII. I want to build up a TII block with lots of port duration and high rpm potential (since the S/C was designed to work w/ those) and use the S/C with a NPR truck I/C (no boost lag on this S//C) and a dual headeres exhaust!! But I am in no hurry, 10psi is nice on my TII.

No porting of the engine.
Running stock 2mm seals.
I've upgraded to 550cc/min secondary injectors, and the Rotary Performance fuel pump, other than that everything is stock. According to the shop that put the kit together, if I hadn't upgraded my intake (K&N cone filter) and exhaust (header, high flow cat, catback) I wouldn't have had to change anything.

If you have any other questions, let me know.

Actually putting TWO CVT pulleys would be very complex, cost prohibitive and make management of the pulleys insane..

Only one pulley is required, and that makes this nearly cost prohibitive, however, its doable.

I've just discovered this thread, and I have to say DAMN!

It's a good concept. I'm just starting to plan a big custom SC job for my FB for sometime next year, and this idea has very excited!

i am thinking of this more in the way a 2 speed clutch works in a model rc car. if you have ever taken one apart from a serpent or a proceed u will understand the concept.. see:

www.hpi.com
www.serpent.com


this isnt what u are thinking of but would be more effective!
scott

Good idea with teh RC Clutch. Maybe use a mountain bike type shifter with a heavy duty chain, but that would be damn dangerous expensive heavy and costly. So yeah.
I was thinking, for a turbo, put an extended axle (erm i dunno the real name) and attach a belt and i dunno how but so when the exhaust gas spins the turbo faster than the belt than it disengages or well goes free.
Hmmmm I should try to think this up better.
This way you can have a huge turbo and have not too much turbo lag from the exhuast gas having to spin it up, because it would be belt driven.

I just came across this thread on an unrelated search, but it is definitely an interesting idea.

I just wanted to add that if you're looking to basically add a belt-based (as opposed to the Honda chain style) CVT to a supercharger. you should look into a snowmobile.

If I'm not mistaken, many (most?, all?) snowmobiles use this type of transmission. I think it's a fairly simple design, that adjusts via rpm. (springs, etc. inside of pulleys).

Rather that getting fancy pulley's fabricated, and then devising some sort of control system, with any luck you may be able to just lift one off a snowmobile with some minor modifications.

Jeremy

I remember reading about hydraulic superchargers somewhere a few years ago (AlliedSignal makes (made?) them but I can't seem to find them on their website) - the concept was a turbo compressor spun by a hydraulic motor. One of the cool things this allows is freedom in placement of the supercharger; ie put it next to your FMIC and run the hydraulic lines back to a pump on your drive belt. 'Boost' control would be by bypassing hydraulic fliud.

Henrik
87TII

I remember reading about those too. A hydrocharger I think they called them.