On the other hand...LaPointe says his fuel heaters using the top rad hose heat the fuel to coolant temp summer and winter....due to their high efficiency. In an email.

You might also try using a regular coolant thermostat (160F?) to control the fuel heat by controlling the coolant heat where it circulates thru the heater? Or just a shutoff valve adjusted according to summer or winter.

I'm going to try making one this winter using hardware store parts and using the heater lines for use in winter.

https://www.mpgresearch.com/viewtopic...ight=fuel+heat

Can't say much for the mpg testing, but the heater design looks to be OK. Need to run the coolant and fuel in opposite directions for efficiency...there is an earlier discussion with more info.

I don't know where people get this idea of putting a fuel heater in/on/around the rad hose. That's no good! That temp varies too much. You have to put it where it feels the coolant under the thermostat and is kept at a constant working temp. That doesn't happen after the thermostat. That coolant is only warm after the engine feels too much heat. Keep the fuel heater at the working temp of the engine.

BMac -

I think the idea is to reclaim the waste heat from the coolant (i.e. get it for free).

Maybe this is more of what you think would work :

Hotline Electric In-Line Fuel Heater
https://www.arctic-fox.com/sitepages/pid20.php
Attachment 1015
Assuming the current draw is low, then this could be a way to discreetly control the fuel temperature. But, the fact that it's in contact with the fuel (it's intended for diesel, not gasoline) seems too dangerous to me.

CarloSW2

No! The idea is to heat the fuel for mpg gains. Keeping it at a constant temp will work better than having it vary all the time.

As for the electric current in the fuel line, like Charles Nelson Pogue said when asked if his carburetor was dangerous because it heated the fuel, "THAT'S NONSENSE, IT'S NOT DANGEROUS UNTIL THE GASOLINE COMES IN CONTACT WITH OXYGEN!"

As several people have mentioned, the temperature of the fuel must be kept consistant to see at what temperature you attain maximum effeciency. This will be different for every engine. I had designed a system for my Matrix shortly after I had bought it. The system included provisions to monitor and control temperature at will. Little did I know that the fuel rail was already heated. If anyone is interested, I laid out my plans pretty well in the thread below. So, feel free to duplicate my work and give it a try.

fuel heater

Daox- I couldn't get the above link to work.

How about circulating gas through the radiator's transmission cooler lines?

I recently replaced my radiator. It was a generic model which includes the transmission cooler line in the lower tank. These lines are unused and still capped since I have a manual transmission. My engine has a carb, so my fuel pressure should only be about 5-7 lbs.


My intake manifold has coolant circulating through it and gets hot, so I wonder if the carb/gas gets hot enough as it is now.

BMac -

I didn't make myself clear. I think the original *idea* went like this :

1 - Diesels "warm up" cold diesel fuel using engine coolant-based heat exchangers.
2 - Why can't we use this pre-existing method to heat gasoline for MPG gains?

If this could work for gasoline, then it would be "for free" in the sense that it wouldn't add load to the engine.

But, as you say, a variable heat source is a "bad design" to begin with.

Thanks for the answer. That's what I was hoping to hear.

Correct me on this. There are never any "air bubbles" in the line? But maybe it's even safer than I think. Would gasoline even ignite between 125 degrees F and 150 degrees F?

CarloSW2

Try again, it is finicky sometimes. If that still doesn't work I'll work some copy/paste magic.

Many motors have a throttle body/carb coolant loop which may be tapped off of the block coolant circuit. Seems like that would be the ideal source to tap into.

Edit: Oops, I guess Erik sortof already mentioned that possibility. Regardless, my understanding is that this coolant loop is more of a safety feature to prevent freezing the butterfly rather than to heat fuel - which I suppose raises the question: If you tap into it to heat the fuel, would enough heat remain to keep the throttle plate from freezing open?!?!

With a V6 I owned there was a fairly substantial TB coolant hose, but with a current 4 cyl the hose is way too small.

I'm going to attempt to use the heater hose...where I will try to setup a bypass so that the flow is split between the heater and the fuel heater...probably just using a larger water shutoff valve as used with home water systems. (have used a small toilet shutoff valve with no problems)

This assumes the coolant will flow thru the heater core easier than the fuel heater....blocking the flow to the core...forces it thru the fuel heater.

This would allow regulating the coolant flow thru the fuel heater...and could even be used in summer by allowing the heater core to remain set on HOT (valve open). The fuel heater itself would need to be over designed for a high temp exchange....espec for winter. Hoping enough heat is left over for the inside heater.

Using elect power to heat the fuel is self defeating...espec when there is waste heat from coolant in summer at least.