crazy idea ?

[d0sitmatr]

good points, I completely forgot about going in reverse

oh well, Im sure it would be a good project if I had the money to burn, but not as something I may wish to drive often some day

[jkv357]

Cycle engines in general aren't very fuel-efficient for their displacement.

As noted, cycle engines are typically tuned for high power at high revs, and torque usually is not very good compared to the same displacement auto engine. 1000cc sport bikes and 1800cc Goldwings generally produce mileage in the 30 MPG range.

There are some cycles that can do pretty well, like the Ninja 250 and SV 650, but they wouldn't have enough power to move a vehicle of any size. You'd also have some problems running A/C, power steering, and any other accessories.

The little Ninjas usually run in the 70 MPG range, but can hit 90/100 MPG (as seen here).

I have a SV650 that does pretty good by cycle standards (50+ city and 60hwy), but it's pretty lame compared to what some of the vehicles here can do.


Jay

[d0sitmatr]

oh, I wasnt planning on running any accessories outside of an alternator, I dont use the AC for myself, only my son/wife on occasion, and I prefer a car without PS.

my gsxr750 was able to net me on average 45mpg, but I know it could do much better since I never really rode it too conservatively
it was just a thought, I mean, looking at those smart cars really made me think it was possible, until it was brought up about reverse

[duane1]

Also consider the weight of a bike will amost always be substantially less than any car you are putting it in, which will drastically effect mileage.

Examples of Bike Engined car (BEC) builds can be found at LocostUSA.com • Index page

Most are built as low weight track cars

[cleanspeed1]

Look up the builders of Legends race cars, they have all the couplers and differentials to make it happen.

[Arragonis]

Instead of a bike engine, what about a Kei car engine from Japan - these are designed to have usable power. This Suzuki I think is more or less what you are thinking of ?



EDIT - Wiki-B@@dy-Pedia article here. Engine was a 657cc tripple with a turbo and 63 hp.

[dcb]

Not to be a poo, but turbo on a gasser is a bad omen for good bsfc. And kei cars are all but non-existent here, I think someone had a honda beat and was getting maybe 40mpg.

Maybe you could sleeve a honda or metro 3cyl? Keep the longer stroke but reduce the bore. If Harley engines weren't so stupid pricey I would entertain one of those over a 10krpm motorbike engine for use in a car (maybe a harley clone) for efficiency.

The harleys were the first ones to toodle their way into the 100mpg range in the vetter challenge, and the 400+mpg bike had 1 less cylinder than that and was well optimized for size and long stroke.

I assume the goal is better efficiency.

http://www.youtube.com/watch?v=z6JQv2MCq8c

[larrybuck]

I was at the Portland Historic Races a week ago, and spotted a displayed Crosley roadster with the OEM body less bumpers.

He had 12" tires so skinny, you probably could buy replacements as trailer tires at any Walmart! (lol!)

He had "slotted" his stock wheels at a dangerous to the eye level. Visualize the appearance of a typical 60's American car's cowl drainage slots as an example; and you have a rough idea.

I spoke briefly w the owner, and he claimed the total weight was 850#.

My idea for the 673 V-twin has a lot to do with sound image as much as mpg.
I'm picturing a baby '55 Chevy w maybe a modern alum. frame mimicing the Honda coupe wheelbase. The quasi Harley sound nearly fits the V-8 image.

If an extreme light foam type body were used, plus the Silverwing's shaft drive; I think it would be a fun project.

It would be so light, one could push it backwards easily if needed.

Granted I have a vivid imagination, but a bike/car with a roof here in rainy land w a unique touch is the stuff dreams are meant for!

An earlier 500cc Silverwing eng. could be downsized in cc's; still make the same sounds, and perhaps gain better mpg's that way as long as car weight is very low!

My idea is to make smaller cars more appealing by having classic looks w micro weight!

[cleanspeed1]

That buggy is like a cross between a Caterham, an Ariel Atom and a Morgan three wheeler ( but with the extra wheel ).

[Frank Lee]

Motorcycle engines are not efficient as has been noted; in addition their drivetrains are very "lossy" with transfer chains all over the freeking place in addition to the normal transmission gear losses AND in the case of the SilverWing a most inefficient shaft drive.

If you are aiming for max efficiency I would look elsewhere than a bike! Or, separate the bike engine from the rest of the drivetrain, re-cam (and re-carb?) it so it does have some semblence of efficiency, and come up with a different drivetrain that doesn't suck so much power.

P.S. Silverwings don't sound like V8s either; the V-Max V4 is the closest thing to an automotive V8 I've ever heard. And I have them both.