Quote:
Originally Posted by t vago
That might be true for a Diesel engine. That is decidedly not true for a gasoline engine.
A significant amount of the work done by a gasoline engine is to create and maintain a vacuum in the intake manifold. A higher intake manifold vacuum requires more work from the gasoline engine. Also, varying the intake manifold vacuum is much the same as speeding up and slowing down - gasoline is wasted in shooting for a target speed when going up and down hills.
DWL is an attempt to provide a constant intake manifold vacuum, regardless of speed. Of course, not a whole lot can be done with going down a hill (other than to go into neutral), but for level roads or going up hills, it's better than maintaining a constant speed.
|
Gasoline is wasted driving anywhere whether up or down or flat.
Can you explain why constant intake manifold vacuum is the most efficient? Show me on a BSFC map, or equations, or a simulation.