Quote:
Originally Posted by sgtlethargic
Is small, light, and aerodynamic gonna do it with a gas engine that's at 20% throttle, even if it's a smaller 4banger?
|
If by "do it" you mean get 100 mpg, then no, probably not.
Nor will a diesel of enough HP for what most people would consider adequate performance, installed in such a car do it. Jack McCornack is a member here, and has a 32 hp Kubota diesel-powered car of about this size. Prior to going for a better streamlined body, it was getting about 60 MPG at 60 mph. They are now getting almost 80 mpg, apparently, with the better streamlining.
The Riley figures are completely misleading, unless you read the fine print. Nobody else quotes mileage at 35 mph. (The auto manufacturers are not allowed to engage in such shenanigans.) 80 mpg at 60 might be reasonable. 70mpg in a real EPA highway test would be about right. By headlining 128 mpg, they are off to a bad start, so I am skeptical of everything they claim. The streamlining is awful, because the flow will separate as it turns the corner above the back window -- its "all show, no go."
In the VLC from Edison, you can see what is required to get 100mpg in a gasoline-engined car: a very small engine with specialized control to avoid pumping losses, 800 lbs, really excellent aerodynamics, including fully faired-in wheels. I doubt that there is a a diesel engine of around 20 hp that provides the same efficiency as the VLC engine. A 20 HP diesel will weigh twice as much as a 20 hp gas engine, and when new, cost more than twice as much.
Probably the surplus sites, Ebay, and farm equipment junkyards would be good places to look for used (or surplus) 20 hp diesel engines.