Centrifugal blowers and Variable belt drives

[Techno97]

Can centrifugal superchargers use a variable belt drive such as Snowmobiles use?
I have a project that if they can would simplify it.
This isn't a car use but wonder why this isn't done?
To be clear. Running the blower at a high speed/boost with minimal engine RPM. Running the blower at its best speed/ boost level almost at all RPMs.

 

[GregLocock]

Yes you could do this.

The reason you don't on a car is that a typical supercharger for a car needs a 40 hp drive. Small cheap efficient 40 hp variable drives are rather rare.

Cheers

Greg Locock

 

[SMOKEY44211]

Techno97 Take a peek under the hood of a 57 Studebaker Golden Hawk. Its got just what you are looking for.---Phil

 

[crysta1c1ear]

http://www.promotingnotallowed.eu.com/files/PromotingnotallowedSBCview.jpg

How many gears do you want your supercharger to have?
If two or three is enough, just buy a supercharger with an automatic transmission in it. I assume the reason you want the gears is just keep the boost up when engine RPM drops, is it?

 

[Techno97]

Don't sleds put out this kind of power? How expensive can this drive be?
An auto tranny- haven't seen any listed with the blowers so don't know what they weigh or cost.

Stude is out. I'm sure if I found one it would cost a fortune and not available for production anyway.

A constant speed centrifugal or a normal screw type blower. For an engine I'm trying to build. Doesn't use the pistons for pumping. 2-cycle.

 

[Tmoose]

"Studebaker" superchargers

http://www.paxtonauto.com/about/

 

[curious125]

your right techno97.
A large number of sleds (almost all) put out more than 40hp and up into the 100's.
You could use this setup but you will have to change the springs in the primary clutch. In a sled the primary doesn't "hook-up" untill 2000 or more RPM (on average)But is easilly changed by changing the springs.

You can buy a primary and secondary clutch kits with different ratings. I'm sure that you will find one that catches your fancy.

Check out

http://www.comet-oem.com/comet

They should have something.


Jason

 

[SMOKEY44211]

The drive setup on the Stude was simple and effective. Anyone with a lathe could duplicate it for something less then a fortune.-----------Phil

 

[Ataloss]

I did some research into this a couple of years ago and was looking at using a snowmobile transmission. The issue with snowmobile transmissions was their incredibly low efficiency (40-50% IIRC).

While this may not matter at low engine speeds where running the supercharger at full speed can provide more than enough air to overcome this, when you're in the upper RPM range you'll be losing a lot of power compared to driving the same supercharger at the same speed with a conventional pulley.

You can also do a search at the US patent website, there were quite a few patents detailing different methods of driving superchargers.

Bob

 

[Tmoose]

The Studebaker Packard ( and modern Paxton?) system used throttle position to engage the planetary ball friction drive and rev up the 'charger with no change in engine rpm.

Snow mobile drives balance rpm and torque sensing in curious ways. They keep the engine at a fairly even, fairly high rpm, when the engine's main job is to drive the rear wheels. I'm not sure how a fairly standard one would drive a supercharger.
-----------------------------------------------------
On the snow -

The front (drive) pulley "size" is always trying to be "larger", limited only by what the rear pulley allows it to be.

At part throttle, low load, they shift "up" by means of the front pulley being allowed to get larger, and the rear one relenting and getting smaller. But, If the engine revs rise, the front pulley tries extra hard to be narrow, and a large diameter, and the rear pulley gives up, and becomes smaller (high gear), and the engine revs drop back a bit.
-----------------------------------------
Driving a 'charger on the highway -

Apply throttle, and the denser manifold pressure would mean more charger load/torque, and the drive would "down shift," because the rear driven pulley's torque sensing ramps would force it to assume a bigger diameter, and hard enough to overcome the front pulley and force it to be smaller and slow down the charger for less boost. Then when the engine did speed up a little, the drive pulley would get narrow, and bigger diameter, and drive the 'charger faster.

I'm thinking that with standard kinds of pulley logic the 'charger response >might< be even more logarithmic than the natural behaviour of a centrifugal 'charger. boooooOOOOST.

 

[Techno97]

Thanks for the inputs. I don't think a centrifugal will work for me after all. I have to do more research but they apparently are limited on boost levels. Shooting for 28 psi.

The engine I'm trying to build (not modify) is for an outboard use.
The engine is using supercharging in place of piston pumping so need a decent amount of pressure at cranking speeds to cruising speeds.The engine supplies none. It needs huge amounts of power on demand to get the boat moving and get on plane. If it doesn't get on plane all the other HP produced is useless.
The reasons for so much boost at the low rpm levels. No gears on a boat for reaching the peak power range.

 

[Majik]

Some drag racing superchargers available from vortec should be able to create your 28psi.. but you're not gonna have anything "marine" duty enough to push that... nothing you could log alot of hours on.. you could do turbos because you will have a long WOT condition.. they would definitly spool depending on your prop design..

 

[tbuelna]

Techno97:

Don't know if it will help, but a few years ago Garrett developed a "hydraulic assist" turbo. I understand it actually made it into production for a short time.

It consists of a standard turbocharger with a hydraulic pelton wheel in the center housing that rapidly spun up the centrifugal compressor when there was not enough exhaust energy passing over the turbine to do so.

If it is something that interests you, look up a guy named Dave Kapich:

http://patft.uspto.gov/netacgi/nph-...ND+supercharger&RS=IN/kapich+AND+supercharger