If You Were Going To Build A 200mpg Car..

[GasSavers_Ryland]

Originally Posted by Erik

Ryland- wow, that was a great project- thanks for the pics and info

In the pics, it looks like the engine has a centrifugal clutch and then the honda clutch was also in there on an intermediate shaft. I am curious- why did you use two clutches?

I had that question alot, and the answer is, I couldn't find a 11 tooth sprocket for #35 chain that fit my budget, so I sized a centrifugal clutch that I already had.
A number of years back I started building my 3rd vehicle for that competition, then I got to old to enter, but my current design has the motorcycle clutch mounted dirrectly on the 3.5hp engines drive shaft, with a free wheel for coasting, and a 80 tooth sprocket on the drive wheel, cutting it down to a single chain, and a total of 4 sets of bearings in the drive train, two in the engine, and two in the drive wheel.
I'm at odds as to if I want to finish that vehicle just so I can find out what it could do on a closed track, or if I should invist my energy in to starting from scrach and build something that is street leagle, I'm leaning twards the street leagle end, so now it's simply a matter of finding the time and money to put twards the project.
If you check out the rest of the High Mileage Vehicle Competition there is some interesting ideas, not all of them good of course, and I admit that some of it hasn't been updated in a while, but it's still fun to look at.

[trautotuning]

I was looking at these engines and maybe that would work, the 16hp model;

http://www.maxtool.com/hmpg/powermax...ermax_main.htm

?? But I do not know about their fuel consumption but I doubt it would be high. Hell, for the price, I could even put two in there and turn on off when on highway cruising or something similar... ?

[VetteOwner]

well think about this, if you can run lets say a 4hp lwnmower engine full rpm for hours on only liek a 1/4 of a gallon? its gotta be pretty good...

[Lug_Nut]

Originally Posted by VetteOwner

well think about this, if you can run lets say a 4hp lwnmower engine full rpm for hours on only liek a 1/4 of a gallon? its gotta be pretty good...

Since the 4 hp engine doesn't have to produce 4 hp to run at zero load at top rpm, it doesn't have to consume fuel at the rate needed to make 4 hp.
Start your car's engine. Let it idle. Slowly bring the engine speed up to 2000 rpm. How much do you need to press the accelerator?
Now try driving the car with the same amount of accelerator pedal stroke....

My hypothetical 200 mpg design would have three wheels, two up front steering, one in back driven. Better lateral support during turns, 25% less rolling resistance, no differential parasitic drag, self supporting when stopped.
The moped/scooter donor route for driveline components might be an easy means of grafting someone else's engineering work onto my vehicle, A complete engine (preferably water cooled), transmission (mechanical geared vs. belt), and final drive wheel and brake would allow almost 1/3 the construction to be done by others.
Maintain motorcycle handle bars (registration easier in my state for a three wheeled motorcycle versus a three wheeled car and allows HOV use).
Low weight, smooth aerodynamics, small profile, low and wide up front, tall and narrow out back (like a tetra-pak) also means a constant cross sectional area.
And what I really think would be ideal, a lateral G sensing tilt/lean control. A small hydraulic pump transfers fluid between front shocks to raise one and lower the other. The customary 'coil over' springs maintain equal extension when the pump is not running. The diverter valve to select which way to lean is a simple pendulum. As the vehicle turns (or the road "crowns"), the pendulum shifts thus opening one shock's fill port while opening the other to drain. When the trike leans enough to match the relative pendulum position the fluid transfer stops.
The drag of the pump will cut mpg, but the self lean ability might be worthwhile.

And now...back to reality.

[JanGeo]

I have the 2.5hp Honda engine and they rate it at 1800watts output and a 25% fuel conversion efficiency. This is a well built little motor with low oil cut off - pull start over head valves gas tank and muffler mounted on the motor and about 12lbs in weight. I literally started this engine up and held it in one hand while reving the motor with the other hand. Then I realized how smooth and quiet an electric motor was.

[GasSavers_Ryland]

if you check out http://www.trupower.com/honda/honda-gx-engines.htm they give specs for all of their over head cam honda engines, including pounds of fuel used per horse power per hour, the 4hp modle came out to 1/12 of a gallon of fuel per hp per hour, alowing for a gallon to last for 3 hours while putting out it's peek of 4hp.
some other sites, like for the Hatz diesel engine, give a nice chart, so you can see how the fuel useage changes over the verying engine speed and power output.
I've alwas been tempted to my a hybrid based off the idea that under load the engine vaccum drops, hook a vaccum idaphram to the electric motor throttle, so if you accelerate hard, the electric motor kicks in.

[QDM]

Consider using a 100cc to 250cc 4 stroke single cylinder dirt bike as the back half of your car. That way you've got the rear suspension, engine, transmission, brake, etc.. Also the dirt bike engines are usually built for low RPM power and use efficient chain drive rather than variable belt drive. Start out with a street legal "dual sport" bike and just keep the license plate on your finished car.

Don't bother with the complicated leaning system. If you keep most of the weight on the front end a tadpole design 3 wheeler handles very well. Have a look at the old Morgan three wheelers that they used to race.

Q

Originally Posted by Lug_Nut

Since the 4 hp engine doesn't have to produce 4 hp to run at zero load at top rpm, it doesn't have to consume fuel at the rate needed to make 4 hp.
Start your car's engine. Let it idle. Slowly bring the engine speed up to 2000 rpm. How much do you need to press the accelerator?
Now try driving the car with the same amount of accelerator pedal stroke....

My hypothetical 200 mpg design would have three wheels, two up front steering, one in back driven. Better lateral support during turns, 25% less rolling resistance, no differential parasitic drag, self supporting when stopped.
The moped/scooter donor route for driveline components might be an easy means of grafting someone else's engineering work onto my vehicle, A complete engine (preferably water cooled), transmission (mechanical geared vs. belt), and final drive wheel and brake would allow almost 1/3 the construction to be done by others.
Maintain motorcycle handle bars (registration easier in my state for a three wheeled motorcycle versus a three wheeled car and allows HOV use).
Low weight, smooth aerodynamics, small profile, low and wide up front, tall and narrow out back (like a tetra-pak) also means a constant cross sectional area.
And what I really think would be ideal, a lateral G sensing tilt/lean control. A small hydraulic pump transfers fluid between front shocks to raise one and lower the other. The customary 'coil over' springs maintain equal extension when the pump is not running. The diverter valve to select which way to lean is a simple pendulum. As the vehicle turns (or the road "crowns"), the pendulum shifts thus opening one shock's fill port while opening the other to drain. When the trike leans enough to match the relative pendulum position the fluid transfer stops.
The drag of the pump will cut mpg, but the self lean ability might be worthwhile.

And now...back to reality.

[JanGeo]

Stop trying to make a car out of a motorcycle engine when you are better off enclosing the motorcycle. There were some cycles convered to enclosed and the transmissions were geared a lot taller because they would top out in the 130mph range because of the aero body added to them.

Check out . . .
http://autos.groups.yahoo.com/group/...oters/messages

[DRW]

How about a fully enclosed streamlined recumbent bike with a 6.5HP motor on the back? It's almost feasible for a home mechanic.

[Fourthbean]

I have been looking at the possibility of either adding a small diesel that is geared for 70MPH to a current working vehicle. Or replacing the current engine with a bit larger diesel engine which is still much smaller than anything we can get on the market. The changfa engine is what the "10hp chevy metro" used, I have seen claims of this engine lasting 12,000 miles before needing a re-ring and then still running another 10k after that. At 40MPH average speed that is 480,000 miles before any repairs! (one of my concerns with a small engine was the longevity).

So after looking around it seems I could get a ~20HP Changfa for under 1000 dollars! There is one on ebay currently HERE.

My next hurdle in my brain is to find a transmission which will take advantage of the torque of a diesel. If I do something like this I want to be able to cruise comfortably at 70MPH, which means if the peak RPM on one of these engines is 3-3.6k I would want a transmission that was at 2.5k at 70. I think this is what I would want anyhow. I haven't gone so far as to find hp/torque curves for these engines.

If 60-70MPG can be had from a vx engine mated to an HF tranny in a crx, what could be done with a 20HP diesel mated to an HF tranny in the same car? Granted this would be MUCH slower than the vx (which is probably pretty snappy).


The other idea I was bouncing around in my head was to do a fifth wheel with a ~15HP diesel connected that was one speed geared for optimal economy at 70MPH. This would allow the normal operation, merging, and city driving while still being able to jump on the highway and get a comfortable 80-100MPG (estimated).

Those are just a couple things I had floating around today while at work.