Torotrak Supercharger

[Trefoil]

Torotrak released a centrifugal supercharger design with a cvt transmission inside. This allows for a dynamic response SC that is more capable of achieving ideal boost pressures over a traditional planetary gear designed centrifugal or roots/tvs SC.

Here is a neat video link:

Aftermarket companies might need to take note considering the implications that this brings.

[wbradley]

Impressive. All using traction fluid too.

I guess there is significant electronics to drive the CVT. Interesting design, it is toroidal.

Would be interesting to hear if it will sound different due to the CVT.

Turbos can have variable vanes, so now centri sc's can have a variable input gear.

The company website states the tech is designed to allow smaller engines to provide greater output. Net result cited, a 1 L engine produces similar power to a 1.5 L but with greater efficiency due to less or smaller cylinders creating lower friction and pumping loss.

I dont think the initial development is oriented toward high performance. More so, high efficiency.

[Lantana frs]

Seems like an answer to a question thats never been asked.

[Ultramaroon]

Oh, it's been asked many times. Maximum efficiency, of the compressor stage in this case, has always been the goal. Cost, weight, and reliability always get in the way.

Looks interesting!

[Trefoil]

Originally Posted by Lantana frs

Seems like an answer to a question thats never been asked.

It addresses the issue of turbo lag and SC efficiency drop off. Neither are ideal situations for consumers on top of the obvious longevity issues associated with strain on affected engine components.

The engineering answers through lowering compression or strengthening critical rotating assembly components lead toward efficiency sapping issues to deal with rapid force(F=MA) changes by the sudden increase in Volumetric Efficiency.

[Summerwolf]

I cant see this becoming viable any time soon. Look at current cvt technology in transmissions.

[chaoscentral]

Not a very new concept. Procharger has had a similar one out for a few years in the muscle car market

https://www.procharger.com/procharger-i1

[CSG Mike]

Originally Posted by Trefoil

It addresses the issue of turbo lag and SC efficiency drop off. Neither are ideal situations for consumers on top of the obvious longevity issues associated with strain on affected engine components.

The engineering answers through lowering compression or strengthening critical rotating assembly components lead toward efficiency sapping issues to deal with rapid force(F=MA) changes by the sudden increase in Volumetric Efficiency.

There's still going to be a lag, while the boost is ramped up. This is almost exactly a halfway point between a turbocharger and a traditional centrifugal supercharger.

[Ultramaroon]

Originally Posted by CSG Mike

There's still going to be a lag

Hmmm... good point. Latency's a bitch.

[mitch t]

I don't see why this shouldn't be perfectly viable.

1. CVT transmissions have been around for 30+years, in the snowmobile industry, and are reliable and tuneable with zero electronics.

2. With this properly set up, it could work as well as a vane style blower. By changing the ratio so the supercharger keeps spinning fast at low engine RPM, you could have the same level boost available everywhere.

We had a guy running a snowmobile trans on a centrifugal many years ago, on a Porsche 914, and it worked really well. Nearly full boost just off idle, and super linear power delivery.

[wbradley]

Pretty sure the ratio of the toroidal rollers is electrically actuated. The blowoff/bypass valve will be doing more blowing with boost at lower RPMs. This thing could build boost lower and taper the vanes higher up at cruise. This looks (to me) like a sensible next step in the automotive centri design. A stage 2, we can call it. Make this thing the equavelant of a twin scroll with added top end. Considering this possibility is like seeing the Rotrex design for the first time for me. Then again I know not much about transmissions.

[stevo585]

It is interesting that no OEM manufacture uses centrifugal superchargers they all use the positive displacement type. This should tell you something...

Well ok Koenigsegg used them at one time.

[wbradley]

Originally Posted by stevo585

It is interesting that no OEM manufacture uses centrifugal superchargers they all use the positive displacement type. This should tell you something...

Well ok Koenigsegg used them at one time.

A lot of small watercraft engines use them. HKS supplies Yamaha I think.

Centris are very small, which is a plus but they dont provide a ton of low torque so a manufacturer must confidently build an engine for sustained high revs like an S2000 if they are going the performance route. That and the reduced reliability/lifespan of the belt.

[stevo585]

Originally Posted by wbradley

A lot of small watercraft engines use them. HKS supplies Yamaha I think.

Centris are very small, which is a plus but they dont provide a ton of low torque so a manufacturer must confidently build an engine for sustained high revs like an S2000 if they are going the performance route. That and the reduced reliability/lifespan of the belt.

I was talking cars but ok yes "jet skis" have them and it works because as you mentioned jet skis run WOT a lot of the time. I was on a Kawi 250x once lots of fun.

The lack of low end or really much midrange <5k is why OEMs don't use them as it would be a dissatisfier to the normal driver. Hence the flood of small turbo engines from just about every make.