Quote:
Originally Posted by drmiller100
the only diesel option I considered is an old vw diesel rabbit, non turbo. 60 horsepower or so, FWD, really light.
I might build one of those, or stuff the engine in my car if I can't get to the 75/75 mark with gasoline.
I own a couple of VW pans. I built several cars off fo those. for a variety of reasons I want FWD.
|
For perspective on engines, chassis, and aero:
Steve Fambro built a gasoline-only Aptera (as one of their numerous prototypes). It had a 660 cc kei car engine. Like all the Apteras, it has excellent aerodynamics and a composite structure. He got 55-60 mpg. The same car with a Civic engine would get about 45-50 mpg.
If you hunt around for the BSFC maps for these engines, you will see that when producing 15-20 hp the 660 is substantially more efficient than the Civic engine at that hp, because it is more heavily loaded.
As a general rule, unless you are planning to create a hybrid, around town mileage will be lower than cruise speed mileage. The Prius is the only car in which both figures are essentially the same.
A good place to start, unless you have unlimited funds, is with the math. You will find that for 100 mpg, your car must need very little HP to go 60 (on the order of 6-8). That means very light weight and excellent aero. Once you have that, then you cannot use a large engine because you also need very low brake specific fuel consumption, which means a highly loaded engine.
Do you have a Cd value for your body, and its frontal area?
Have you calculated the HP requirement at 60?
If you have the data I can run a spreadsheet for you.
Regards,
Ken