Can a fuel pre-heater improve MPG?

There's all kinds of snake oil claiming to increase fuel economy. In practice this won't do anything for you, the fuel injectors spray a fine mist of atomized fuel and this hits the back of the hot intake valves which further vaporizes it. Heating the fuel will do little more than promoting vapor lock, as well as the hotter less dense fuel will alter the flow rate of the injectors and increase vapor loss as the hot fuel is returned to the tank through the return line. Manufactures actually take steps to *reduce* the heating of fuel, hence the use of return-less injection systems in some cars.

In a nutshell, don't screw with the fuel system. LH-Jetronic is already very good, any "improvements" are just as likely to make things worse.

Keep up on maintenance, increase tire pressure, run synthetic fluids, remove excess cargo, drive with a lighter foot, these all have very real and measurable effects on fuel economy without doing any goofy modifications. A Volvo turbo with an automatic transmission is just not particularly fuel efficient.

"James Sweet" wrote in message news:CwT5k.74863$bs3.42174@trnddc07... : : geronimo wrote: : >

: > I saw an article on internet saying that if one adds a fuel pre-heater : > on the fuel line ahead of the fuel rail, it improves mileage by : > increasing the combustion efficiency. Its easy to do on my 740 or : > nearly any car, you could just bend a long piece of copper tubing into : > a U-shape, silver- solder brass barb fittings on the ends, and re-rout : > the fuel line through it. The pre-heater assy is mounted against the : > radiator. It makes sense that hot fuel would burn better than cold : > fuel being injectd into the cylinders, but whether it would make any : > real appreciable diference on my 82 740 turbo or not...I don't know. : > Could it possibly induce a vapor -lock when restarting the engine when : > still hot? : : : There's all kinds of snake oil claiming to increase fuel economy. In : practice this won't do anything for you, the fuel injectors spray a fine : mist of atomized fuel and this hits the back of the hot intake valves : which further vaporizes it. Heating the fuel will do little more than : promoting vapor lock, as well as the hotter less dense fuel will alter : the flow rate of the injectors and increase vapor loss as the hot fuel : is returned to the tank through the return line. Manufactures actually : take steps to *reduce* the heating of fuel, hence the use of return-less : injection systems in some cars. : : In a nutshell, don't screw with the fuel system. LH-Jetronic is already : very good, any "improvements" are just as likely to make things worse. : : Keep up on maintenance, increase tire pressure, run synthetic fluids, : remove excess cargo, drive with a lighter foot, these all have very real : and measurable effects on fuel economy without doing any goofy : modifications. A Volvo turbo with an automatic transmission is just not : particularly fuel efficient.

This idea took me back a few years to the time in the UK when I was the proud owner of a 1949 Jowet Bradford. A precursor of the minivan I suppose. After all it WAS a converted van, with seats and windows, all driven by a horizontally opposed ("boxer"-type") flat-twin of an astounding 1005 cc........ The thing is the inlet manifold was in the form of an arch rising from each of the two H.O. cylinders. Surrounding the manifold was an outer water jacket. On top of the arch was mounted the carburetor. The whole thing was in the form of a beautiful aluminum casting.

The result: The atomized fuel and air mixture headed down the two arms of the manifold arch towards the cylinders, heated by the coolant rising from the cylinders, which then continued from the top of the arch forward to the top of the radiator This was different from heating the liquid fuel. Incredibly there was no water pump. The Owner's Manual offered one "for use in the tropics........"

It seems to contradict the theory behind intercoolers for turbos, but worked very well. It always started easily in all weathers, never experienced vapor lock and reliably transported the family from N.E. Scotland to the South coast of England on several occasions, as well as being a "daily driver".

Andy I.

Well the difference there is that an intercooler is not to improve efficiency or help vaporize fuel, but to cool the charge air to prevent detonation. After being compressed by the turbocharger, the air can be very hot, and it's just air, not a fuel/air mixture.

I always have to laugh when I read "tricks" like this. Wouldn't you think that every car manufacturer would have implemented a fuel pre-heater if this was improving fuel efficiency?

Let it be known that I also do not believe the consipracy stories that car manufacturers deliberatly make their cars less fuel efficient for the benefit of petrol companies.

BTW: my car does have a carburettor heater. That is: the carburettor has a line to the cooling fluid. Keeps from freezing in the winter.

Maarten Maarten

These are good suggestions. With 100% of my driving done in stop-and-go traffic in a city with really bad roads (New Orleans), I was averaging about 19 mpg in my S60 (2005 2.5T). Changing the air-filter to a K&N, and keeping the tires properly inflated (35 psi), improved my fuel efficiency to a steady 20 mpg. Driving with a much lighter foot gives me almost 22 (average for the last three tankfuls is 21.7).

AC