Quote:
Originally Posted by NeilBlanchard
The Revetec design doubles the efficiency of a crankshaft design. If some of the other major losses could be addressed, then could the efficiency go above 50%? Is 60% possible?
The major problems with most current ICE designs:
Poor geometric / mechanical torque due to the inherent limitations of the sinusoidal motion of the piston and the connecting rod's angle relative to the crankshaft (vs a rotary design or an electric motor)
Long time periods between power strokes, requiring relatively large flywheels.
Large mechanical drag from the valvetrain having to work against the springs.
The acceleration and deceleration of the piston and connecting rods.
The brief / momentary pressure buildup of the fuel burn (vs the constant pressure reserve of a head of steam, for example)
The need to pump oil through tiny passageways, and to generate electricity.
The need to warm up to reach ideal operating temperature.
The amount of waste heat requires a lot of "stuff" and requires a lot more aerodynamic drag to be able to dump it out of the vehicle.
The relatively narrow torque band, requiring a multi-ratio transmission -- basically as many gears as possible. Seven or eight gears would be better than merely three to five.
The need to idle while not actually being used.
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I haven't really researched the Revetech, but I do know that cam replacements for con rods are nothing new. If they worked I'd think that after all these decades of development I'd at least be able to get one on a lawnmower or something.
All other points above are addressed to some degree... but not all on the same piece of equipment.
Con rod torque xfer> turbines
Power strokes> multi cylinders; 2 strokers
Valvtrain power requirements> 2 strokers; opposed pistons
Recip mass> short stroke geometry; small size (think Honda 50)
Intermittent combustion> turbines; is it necessarily a bad thing?
Oil pumping> 2 strokers, splash lube (think old Briggs and Stratton)
Electricity requirement> diesel; glow plug ignition; magneto (as a low drag source)
Need to warm up> heat storage ala Prius thermos bottle; preheat via various methods
Heat rejection> air cooling; water cooling (marine); thermosiphon
Narrow torque> dunno, 2 or 3 gears works for me
Need to idle> no they don't