Looking for help building a Gas Vapor system

[Hersbird]

The way I do it is to atomize my fuel with an injector in each intake runner. Then the valve opens and the piston sucks it in to a very hot cylinder where as its compressed 11 times normal becomes a vapor. Then the spark plug lights it off.
The other way I used to do it on my pickup was by running propane which easily flashes to a vapor without heating.
Why you would want to do it outside of the saftey of the combustion chamber with regular gasoline is a mystery.

[racprops]

done

[oil pan 4]

Then why don't propane engines get a huge MPG boost over gasoline engines?
After all propane is a vapor.
Propane is a super heated vapor at atmospheric pressure at room temperature. You are trying to turn gasoline into a super heated vapor.

[Frank Lee]

Originally Posted by racprops

For the past couple of decades I have found reports of super high mileage cars running on 100% gasoline vapor.

Numbers in the 80 to 120 MPG out of old V8s are most common.

Most of these old vapor systems have many faults, the biggest one being heating gasoline in a can to get vapor…which can work fine but any leakage of the vapor and boom.

A common mistake is to use the exhaust heat to vaporize the gasoline, this fails because ones the ICE IS on vapor it cools down cutting the exhaust heat and the car stalls.

The numbers do not lie, an ICE only uses about 30% of the incoming fuel to move the car, the rest is burned after the power stroke and during exhaust and is where all the heat the cooling system must handle comes from.

A correctly controlled vapor system COULD burn only what is needed to produce the power stroke and have no left over burning fuel after the power stroke.

Thus it is possible to save/not use some 60 to 70% or the fuel currently need to power the car.

That is you would only use about 30 to 40% of what you now use.

Old V8s were lucky to ever crack 20 mpg. But let's be charitable and use 20.

Let's also be charitable ('tis the season) and say we'll save 60%, or use 40% of the 20:

20 / .4 = 50 mpg

That's a long way from 80-120 mpg. In fact it's an exponentially long way.

There must be an error in my analysis.

A little help please!

[oil pan 4]

Originally Posted by Frank Lee

Old V8s were lucky to ever crack 20 mpg. But let's be charitable and use 20.

Let's also be charitable ('tis the season) and say we'll save 60%, or use 40% of the 20:

20 / .4 = 50 mpg

That's a long way from 80-120 mpg. In fact it's an exponentially long way.

There must be an error in my analysis.

A little help please!

Extraordinary claims need extraordinary evidence.
Those 100mpg V8 carburetor engine guys were always big on claims, short on proof.

[cRiPpLe_rOoStEr]

Maybe you'd be better off with a heated intake manifold, like some older dedicated-ethanol cars in Brazil used to have. In gassers, this setup had been used in the Fiat 124-series engines.

[Frank Lee]

The big old American V8s all had that.

[cRiPpLe_rOoStEr]

So, since a heated intake manifold couldn't do any "miracle", what else could be attempted? Though I'm not so sure if a vaporizer like the ones used in some LPG conversions would be so safe at all, it seems to be the last option I would eventually consider for an attempt to run on gasoline vapors.

[Frank Lee]

They not only had exhaust crossover passages that routed hot exhaust under the carb, they had thermostatically controlled hot air intakes on the air cleaner snorkel.

[cRiPpLe_rOoStEr]

Originally Posted by Frank Lee

They not only had exhaust crossover passages that routed hot exhaust under the carb, they had thermostatically controlled hot air intakes on the air cleaner snorkel.

The Fiat 124-series engine and dedicated-ethanol variants of other small engines resorted to the engine coolant to heat the intake manifold instead of exhaust crossover passages.