Heated Fuel

[wagonman76]

Ive thought about putting in an extra piece of fuel line and wrapping it around the exhaust crossover which is already pretty close to the fuel line. Only thing Id worry about with super hot fuel is possibly melting the injectors.

[Twerp]

With "super" hot fuel, I would worry more about a Hollywood style car explosion than melting fuel injectors. Then again, I don't pretend to know that much about the combustion physics of gasoline.

[cfg83]

wagonman76 -

Originally Posted by wagonman76

Ive thought about putting in an extra piece of fuel line and wrapping it around the exhaust crossover which is already pretty close to the fuel line. Only thing Id worry about with super hot fuel is possibly melting the injectors.

I have one but I haven't installed it. My mechanic didn't want to. If it's properly installed and a good design, then I think the main worry would be vapor lock :

Vapor lock - Wikipedia, the free encyclopedia

It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, resulting in transient loss of power or complete stalling.

But, from what I have read on wikipedia, vapor lock is more of a low-pressure fuel-line carburetor issue than a high-pressure fuel-injection issue.

Here are some fuel ignition comparisons :

Ignition Temperature of Gasoline

The minimum ignition temperature at atmospheric pressure 
for some substances are: 

Carbon          400 C =  752 F 
Gasoline        260 C =  500 F 
Hydrogen        580 C = 1076 F 
Carbon Monoxide 610 C = 1130 F 
Methane         630 C = 1166 F

Question: What would the ignition temperature be at modern fuel injection PSI?!?!?!?

CarloSW2

[Andyman]

I found some information about Smokey Yunick's "Hot Vapor Cycle Engine" here.

Adiabatic Engine - Hot Vapor Cycle Engine - Henry "Smokey" Yunick

He was able to get a big increase in efficiency. His engine used a low pressure turbocharger and very hot intake air. He had a secret method of avoiding knocking. It may have been water injection.

I think I have an article about this in a Popular Science magazine.

I found another forum discussing this topic here.
Engine & fuel engineering - Smokey's Adiabatic Engine

[vtec-e]

Originally Posted by Andyman

I found some information about Smokey Yunick's "Hot Vapor Cycle Engine" here.

Adiabatic Engine - Hot Vapor Cycle Engine - Henry "Smokey" Yunick

He was able to get a big increase in efficiency. His engine used a low pressure turbocharger and very hot intake air. He had a secret method of avoiding knocking. It may have been water injection.

I think I have an article about this in a Popular Science magazine.

I found another forum discussing this topic here.
Engine & fuel engineering - Smokey's Adiabatic Engine

Nice link andyman. This sounds like a dream come true. I wonder if we'll ever see this kind of thing on the road in our lifetime?

ollie

[NeilBlanchard]

Hi y'all,

An interesting variation on this was method used in the Ducati SuperMono: rather than try to spray a mist into the large (and high rev'ing) cylinder -- they just squirted a stream of fuel in, and it vaporized when it hit the very hot piston crown.

I wonder if such a method would improve combustion in a more typical engine?

[mopo3]

To me I wouldn't think a casual warming of the fuel wouldn't help fuel economy, because the engine is already running about 190-200 deg F and when the cold (relative) fuel hits the chamber it "cools" the chamber by "absorbing" the heat then it combusts and heats the chamber up after the expansion phase.

actually thinking about it you would do better to reduce the amount of heat generated in that combustion while still getting the expansion necessary to get you down the road. If you could delay the valves on the compression side, so that you expansion is greater than the combustion that should reduce the amount of fuel converted to heat, while still giving the expansion, therefore saving fuel.

pressure*volume=moles*gas constant*temperature (pv=nrt), I think this explains it better. If at the end of the expansion stroke (max volume) you can not increase the volume so the pressure will increase. pretend the max volume is 1 and the absolute pressure is positive (duh) then 1*(increasing number) will get larger and larger until the combustion is complete. so as the pressure increases then the temperature will increase as well. All the heat generated by the car is typically waste heat and leaves the car through the exhaust, radiator, and not as wastefully to heat the drivers cabin.

[vtec-e]

Man, i wish i knew more of my physics and chemistry! At the end of the day, i just want to know the truth! Hot fuel, cold fuel, hot air, cold air etc. I know engines are different but not that different!

ollie

[hondaworkshop]

I think the real benefits occur when you can actually use enough heat to practically vaporize the fuel, without causing the side effects. It will burn much cleaner than liquid fuel.

Remember these guys?

FuelVapor Technologies - fuel efficient vehicle automobile high mileage ale'

For those wanting to experiment, I'd say you would want to safely route exhaust heat to the fuel rail, and then maybe insulate it too. I dont think coolant temps will be enough. The best results would come from being able to re-tune the A/F mixtue maps with a laptop (a-la-moates). I imagine there will be some side effects to deal with, like spark plug wear, O2 sensor wear, higher NOX emissions.

Someone is going to do it though. And its going to be great.

[solarguy]

If there were huge, or even moderate gains available by heating the fuel so it would vaporize better, then converting a gasoline engine to run on propane would absolutely show those gains. Propane is as vaporized as a fuel can get. Fuel economy generally does not improve when you perform such a conversion. The exception is if you have an inefficient gasoline fuel delivery system to start with, like dirty injectors, then propane shows some modest gains.

The above discussion refers to gallons of gasoline equivalent propane use, i.e., they accounted for the fact that propane is less energy dense, even in the liquid form.

To me, that says there is not much to gain from heating liquid fuels.

Finest regards,

troy