Fuel Heater

[lowbridescape]

There's lot's of discussion about Warm Air Inlet. But I haven't seen anything about fuel heaters. Obviously, you would have to avoid temperatures that would result in spontaneous combustion. But would heated fuel improve vaporization? Or do the fuel manifolds used with multi-port fuel injection already achieve this effect?

[civic_matic_00]

Originally Posted by lowbridescape

There's lot's of discussion about Warm Air Inlet. But I haven't seen anything about fuel heaters. Obviously, you would have to avoid temperatures that would result in spontaneous combustion. But would heated fuel improve vaporization? Or do the fuel manifolds used with multi-port fuel injection already achieve this effect?

I have a fuel heater made from brass fittings attached to the top radiator hose. it's giving me around 2 to 3 mpgs more although I can not accurately gauge the FE increase since I do not have a scangauge (I simply calculate the total miles for each tank for every mod I make).

planning on changing the heater to copper tubing since RoadWarrior has pointed out on another thread that copper helps break down ethanol into ketones and H2 (I've posted links on that same thread proving that copper does help in the dehydrogenation of ethanol). RW knows his stuff!

yes, you should be careful where you place that heater. even if the fuel might not boil within the heater since it is presurized, I would still be careful how much hot the fuel gets. some say that the more heat the better the fuel vaporizes, that might be true but I just don't want to take that chance.

Also, I have read in other sites that acetone/xylene additives would help the fuel vaporize better and coupled with the heater, would get better combustion. I do use acetone and xylene (and some synthetic oil) as additives (along with upgrades to my ignition system) but not on my current tank of gas (treating my engine with lubrilon products right now). I've been getting good results so far....that is IF I maintain good driving habits (keep on using hypermiling techniques).

[GasSavers_RoadWarrior]

It may have good effects on some vehicles, but very little on others. Some vehicles more or less have "factory" fuel heat. In Vee engines the fuel rail is usually sitting snuggly between the banks getting quite toasty. In normal multipoint and sequential fuel injection practice the injectors at low load and demand (90% of normal driving) are spraying into a closed intake port, where the fuel has enough time to soak heat out of the head and evaporate in the port. It should however offer some theoretical thermodynamic efficiency savings, due to not "robbing" heat directly from the head, and using "waste" heat instead, and about 10% saving in the 10% of the driving regime where the injector is spraying through an open valve, but these would be rather small.

On low pressure TBI systems and carbed induction systems any amount of fuel heat is problematic, causing "percolation" and vapor lock.

It may however provide synergistic benefits with some other modifications, such as any catalytic reformers in the ports, fuel lines or added to the fuel.

One other synergistic benefit is the potential that pre-heating would allow a more even temperature across the cylinder head, because the fuel wouldn't cool off the intakes so much. This may allow leaner mixtures to run with less chance of detonation. A highly homogenous charge and temperature distribution is favored for some approaches to running lean without uncontrolled pre-ignition.

[ShadowWorks]

How hot can the fuel be in a rail before we are asking for trouble?

I was thinking about wrapping some copper brake pipe around my fuel rail that would be tee'ed into my hot water hose, so around water temperatures of around 90 degrees Celsius, would that be ok?

[GasSavers_RoadWarrior]

Shouldn't be any worries about using coolant heat above an injection pressure of about 35psi. The higher pressure keeps it superheated until pressure is released at the injector, where it will instantly "flash boil" and vaporise.

I wouldn't mess around with exhaust heat fuel heaters unless I was trying to get kerosene to run or something.

[DRW]

There's a minor inconvenience associated with heating the fuel too hot: re-starting the engine when it's hot. That's because the fuel sitting in the line next to the engine could vaporise in the line. It can cause hard starts and stumbling in the first few seconds after starting.

If you have symptoms like these, maybe the fuel heater is working a little too well.

[ShadowWorks]

Originally Posted by DRW

There's a minor inconvenience associated with heating the fuel too hot: re-starting the engine when it's hot.

It can cause hard starts and stumbling in the first few seconds after starting.

Actually this does happen to my car, the fuel regulator has a small chamber on the head that warms the fuel before it enters the fuel rail, hum,,,,,,, I have no idea of the temperature post and pre rail, can anybody recommend a cheap decent infra red thermometer?

[bones33]

Originally Posted by ShadowWorks

Actually this does happen to my car, the fuel regulator has a small chamber on the head that warms the fuel before it enters the fuel rail, hum,,,,,,, I have no idea of the temperature post and pre rail, can anybody recommend a cheap decent infra red thermometer?

Harbor Fright has one on sale for like 10 bucks! If you happen to have one in your area.

Nevermind, I don't think they have stores in Scotland.

[ShadowWorks]

Na they don't, Ebay is the big Monster that everybody looks to buy things from now, I think a Infra red thermometer is a good tool in the quest for FE.

[Raysp30]

I put a fuel heater in my car about a week ago. I can't test results accurately because I also did like half a dozen other mods to the car the same weekend.

I bought about 18 feet of hose and conneted it to the return line of the engine coolant (not sure if I have names of parts right, but it's the smaller hose that recirculates the coolant). Anyhow, I replaced the factory 1 foot hose and rerouted it down along the fuel line, almost to where the fuel filter is by the rear wheels. Brought the hose back and connected it to the coolant tank.

I just installed a probe thermometer so I can monitor it while driving. It's not entirely accurate since I have the thermometer taped to the outside of the hose, but it was reading between 115-120F once warmed up.