effect of fuel cooling

Hi Qubert,
Don't know the answer to your question but if you are going to cool it beware the cloud point on diesel. This is the temperature where it begins to wax up.

Provided the fuel in not cooled to the cloud point, then physics would have it that as the fuel gets colder the volume contracts. Thus if the injectors are admitting a fixed volume to the cylinders then the mass of fuel increases and hence the number of carbon atoms. Thus with more fuel to burn, more energy is released to provide power provided also that the stoichiochemical ratio is maintained..

yes that is all correct. and i know that the old 2 stroke gm's ( 892 , 692 , 1692 , 671 etc etc ) they had a problem with running hot fuel it, used to burn holes in pistons ( direct injection ) . so obviuosly there is a dangerous point for those with direct inj . so those with ye olde pre-cos diesels have a bigger scope to work with ............

when i say fuel cooling its only to 30 - 25 deg celsius , not much less...as long as its constant

while with air (or gases/vapours) it becomes denser with cooler temps, this is not really the case with liquids. Try it out by getting 2 plastic coke bottles, fill one with air and one full with water. Put them in the fridge and see which one sucks down and which doesnt. Take it further and cool the water to the point that it changes state and see what happens-the "exploding can phenomenom".

thats why they fit intercoolers to turbo'd and supercharged engines...and even water injection

Believe the electronically controlled diesels have a fuel temperature sensor and compensate for the fuel temperature.

with most new electronic diesels having oxygen sensors in the exhaust, I would presume that they are constantly monitoring the fuel/air ratio and hence the very slight gain you might get from having denser fuel is already being compensated for by the computer ie. its putting the max fuel in to gain the most effienct combustion. Cooling the fuel will achieve zilch!!

if its an older mechanical pump then it may be of benefit but I doubt you'd notice any real world difference.

the rotary pumps on the cruiser 1HZ actually return approx 4/5 of the fuel they pump, back to the tank. This is their way of cooling themselves (and lubricating). This is also why you don't run around on near empty tanks all the time during summer as the small volume of fuel will get hotter and hotter as it circulates. Switching between tanks (to allow the fuel to cool) is a good idea if you have to run at low fuel levels.

first thing I would do is measure the temp of the fuel entering your pump. you might find that its not much above ambient temp and hence you'll get very little cooling effect anyway.

let us know what you do anyway.

Don't the old diesel fuel pumps have a return line that would circulate cool fuel from the tank?

Honky

Methanol fuel (100%) used in racing cars is so cold it cools the intake air charge to the extent that intercooling isn't required on turbo/supercharged engines.
Regards Andrew.