warmer fuel?
 

I was reading an article that mentioned this: "the fuel line was insulated and heated so the gasoline entered the combustion chambers as lean vapor."

I hadn't heard that before. Anyone have experience with this?

...sounds like the prelude to "...vapor lock..." conditions.

Background info: this was a technique used to win the 1973 shell mpg competition. It was a modified opel, achieving 376 mpg at 30mph.

Link or it didn't happen!

Now that I have more than 5 posts, link...

Souped Down 1959 Opel T-1 Gets 376.59 mpg : TreeHugger

Surfacant:
Surfactant - Wikipedia, the free encyclopedia

While it's technically not a surfacant, heat energy has a similar effect by lowering surface tension. This improves both atomization and vaporization.

Gasoline is made of a variety of hydrocarbon molecules with a mix of vaporization temps. Some of them do not flash vaporize until the temp reaches around 400*F. The problem is that many of the hydrocarbons will flash vaporize at temps well under 200*F, so that problems like vapor-lock will pop up unless contingency measures are taken against it.


The main point is that some heat does help, especially in situations where atomization or vaporization is poor. This is common with wet-flow induction systems (carburetor & TBI), and in very cold conditions.
A fuel system under high pressure can handle more heat, but don't forget about your fuel vapor recovery system. Heating the fuel can overwhelm the vapor control/recovery, so again contingency measures have to be taken to handle the extra vapor from the tank.

MPFI with the injector spraying on the back of the intake valves will show the least improvement from heating the fuel. That's not to say it doesn't work at all, but every system responds slightly differently, so you'd have to try it out and then decide if it's worth the trouble.

ummm you don't want to heat the tank just the lines to the injectors that way the is no effect on the vapor control/recovery system..

The problem is for many fuel injected vehicles, they get fuel pressure off a common fuel rail maintained at X pressure. Any fuel not used gets returned back to tank from pressure regulator return line (which ends up being most of the fuel ).
So its hard to heat fuel after rail (between injector and fuel rail ) as there no room with injector mounted right into rail .

Honda does not use return line on fuel rail, they have pump and fuel regulator in gas tank and run constant fuel pressure over the whole load . So with only 1 fuel line to rail I could see this being warmed up a bit (water warmer off heater core line) but not sure how much this would help with modern injectors as noted in above posts .

I believe all gasoline vehicles since OBDII (1996) have gotten rid of return style fuel systems. I believe the change came because it reduces evaporative emissions.

Transonic Combustion | Ultra-high Efficiency Fuel Injection Systems

regards
Mech

Right. If you don't have a return-style fuel pressure regulator then you're in luck because extra tank vapor isn't an issue.

I was talking about return-style systems, which is what I'm almost always working with. It's not always a bad thing, and if you route the extra vapor back to the intake the adaptive fueling will cut back a small amount on the injector pulse-width. Ideally all of the tank vapor gets routed back to the intake and burns. The main problem with the warm fuel (if it's too warm) in the tank is pressure build-up after engine shut-down.
A similar circumstance is created whenever a heat-shield between the exhaust and the fuel tank falls off. I have seen it expand the fuel (and vapor) to the point that fuel would leak out of the fill-tube and high-pressure vent.
Warm fuel does expand and will therefor throw off your fill measurements and mpg calculation if you're filling at inconsistent fuel temps.