If I understand correctly, low-boost turbos can spool up quickly, and then use a waste gate as to not over-spin as the rpms climb, yes?

And superchargers, their speed rises linearly with motor rpms, yes?

Does anyone manufacture a SC with "CVT" drive? Such that it could spool up quickly at low speeds when throttle is opened, and then maintain constant rpms even as the motor rpms rise? Perhaps through a trick planetary gear or something.

 

Hi xorbe...Don't understand your supercharger talk, but some people at Caliberforumz have talked about getting more performance out of the CVT in the Dodge Caliber. Jatco, owned by Nissan, makes the CVT for the Caliber & the Nissan Versa. The internal hydraulic pressures approach 1000psi under hard acceleration for the Caliber(the same for Versa?). Both CVTs drive similarly & limit rpms & acceleration from 0 to 20mph, I think so CVT activity (which would be highest at low speed) will not coincide with high pressures. Durability should increase. From 45 to 65+MPH, CVT acceleration is good, outperforming all similarly powered 4 speed automatic transmissions.

Anyhow, for CVTs that are computer acceleration limited, the people at Caliberforumz think you could do lots to improve power, but the CVT computer control would still limit that performance enhancement from reaching the wheels.

Something that enforces this thinking is that the 285 HP SRT Caliber coming out will only have the 5 speed & the CVT will not be available.

 

When I say CVT, I am not referring to the vehicle's transmission. I mean that the input spindle into the supercharger has a continuously variable ratio. Hence, "CVT supercharger". But, I don't know how it could be mechanically designed to fit in a small space and be reliable.

 

I'll go you one better..

How about a DFI engine that runs in standard Otto mode, transitions into Atkinson cycle mode with low to moderate engine loading and then into Miller cycle mode for high levels of engine loading.

Low displacement Otto/Atkinson cycle engine with absolutely STELLAR FE for simply cruising along at a relatively constant speed but performs like a HUGE V8 when you put your foot "down".

All with modern day off-the-shelf, already in daily use, technology.

What is needed:

A. A positive displacement SuperCharger engine/electric combination differential drive using the Toyota HSD e/CVT technique.

B. A variable intake valve closing delay system and control, say using "extended" VVT-i as is used in the newest Prius and the 2010 RX450h to transition between Otto engine mode with low engine loading and into Atkinson cycle mode for moderate to high engine loads/loading.

Base/static/native engine compression ratio would be ~15-16:1. With low engine loading, partial A/F cylinder charge, that would remain the effective CR. As engine loading rises that CR would undoubtedly result in detonation so the VVT-i would be used to delay intake valve closing, thereby (incrementally..??) lowering the CR as the cylinder charge rises.

At FULL engine loading, say equivalent to WOT(***), VVT-i would reduce the effective, before BOOST, CR to ~10:1. Boost, intercooled boost, would, of course, raise the effective CR back up to ~15-16:1.

All the while the power stroke expansion ratio would remain 15-16:1

Would we call that an Otto/Atkinson/Miller/West cycle engine...??

*** No actual throttle plate required, the variable speed positive displacement SC would provide the throttling function.

 

The Rotrex superchargers have a traction oil drive CVT.. It works in the same way as the NU Vinci bicycle transmission does... It makes boost right off of idle if you step down in the throttle.

 

Okay I want a supercharger for my 08 Honda fit. Any link would be nice.