I want to build a 100-mpg car (and I want it to look vintage)

[racprops]

I just have to throw my 2 cents into this:


First how about 100% gas vapor??

Second ever hear of the VW Blue Motion cars?? Rated at 75MPG??

Rich

[racprops]

The claims of an standard ICE only using less that 30% of it fuel to make power and wasting the remainder of the raw gas poured into it is well known. The left over only produces heat that the cooling system must handle.

The theory is IF fed 100% gas vapor it would only need about 20 to 30% of its normal fuel.

So take a car that gets say 30/40MPG and run it on vapor at say the insane 20% of its normal GPH and you have a 100+ MPG car, with out all that body work and so on.

Rich

[lee]

First..some basics ..as I ..see them
diesel will ALLWAYS get better mpg than gas..Ask a trucker.
Turbo will help any diesel LOTS..( been there , done that)
Water injection helps air density, keeps a turbo cooler.

Start ..with a Three cyl. Turbo diesel , with water injection.
next..old school semis had " two speed rear ends" which ..in theory could give
the effect of "double overdrive" ..Squeezing the Horsepower out of the torque. .so to speak.

Recall that a 55 nash metro ..would get great mileage, was a square brick, no plastic, or aluminum even, no fuel injection, no computer. If one swapped a diesel ..gain of 20-30 percent.
If aerodynamic..Huge gain...
LRR tires..more gain still..
I feel it is possible...if approached in this manner. !

KEEP AT IT!!!

[stankoprowski]

You might look at https://www.kineticvehicles.com/MAX.html for some ideas.

[jakobnev]

First how about 100% gas vapor??
The claims of an standard ICE only using less that 30% of it fuel to make power and wasting the remainder of the raw gas poured into it is well known. The left over only produces heat that the cooling system must handle.

The theory is IF fed 100% gas vapor it would only need about 20 to 30% of its normal fuel.

There is a limit to how much heat can be converted to mechanical work in a heat engine, lack of combustion is not the cause of inefficiency in ICEs.

[aardvarcus]

One of the major inefficiencies of a typical gasoline engine is the need to maintain a constant air to fuel ratio requiring a restriction of the air intake via butterfly valve at positions other than wide open throttle. I am not aware of any modern automotive gasoline engines that are functioning properly and have not been messed with by "tuners" that are wasting a significant portion of the fuel by not combusting it.

[freebeard]

Racers run rich to extend the life of the grenade engine they are running.

[racprops]

OK here is the theory behind this claim.

ONLY vapor burns, but getting gasoline into a vapor sate is not easy, so cars rely on the fuel droplets vaporizing on their own, in carbs some happened when was mixed with air from the carb to the combustion chamber. Some might be happening with Throttle Body Injection as there is some little time for the air and fuel to mix on its way to the combustion chamber.

This no longer happens with port injection and direct injection.

So now we have to now rely on the heat in the combustion chamber to try to convert the fuel to vapor, note there is no real time so only 20 to 30% gets converted.

Also gas burning in an ICE needs a lot of lead time so we start this burning up to 40 degrees BEFORE Top Dead Center, and sadly it keeps burning after the power stroke and as it exits the engine and then in the exhaust manifold and so on. ALL wasted.

Vapor on the other hand burns very fast, and needs no advance start to its burning, so it can be fired AT TDC and then can product full power for the power stroke from TDC to BDC (Bottom Dead Center) And it can be all consumed at that point so there is NO burning fuel exiting the engine.

So this will use the same amount of fuel to do the work and none is wasted so the extra 70 to 80% is not needed.

Yes as the normal system is so poorly using the fuel running lean will increase the amount of heat made and thus burn valves etc.

This will not be a problem if ALL the vapor is burned during the combustion and power stroke, and not during the exhaust stroke.

Rich

[jakobnev]

That hypothesis does not fit observation.

Fuel efficiency has gone up since we stopped using carburetors.

Natural gas engines are not 3-5x more efficient than gasoline engines.

If you compress gas, then add heat by burning fuel in it, and expand it back to atmospheric pressure (allowing the gas to do work) then by the time you are back to atmospheric pressure, the gas still has excess heat in it. You cannot convert the energy in this heat to useful work, if a piston is all you have to work with. (if you pardon the pun)

[jojogunn]

This is a diy high mileage car using a Triumph Spitfire chassis. https://rqriley.com/product/centurion-plans/ Someone on this site has a Centurion and logged well past 100 mpg. Use the knowledge from the plans on a stock bodied Spitfire?