Fuel Coolers - How beneficial are they?

[chrissev]

I was just going to hook an automatic transmission cooler into the return line (those are cheap and/or free). I would think putting it on the feed would probably make the pump have to work too hard to draw in the fuel.

if you put it on the return line you'll pop all the little return hoses off of the injectors because of too much back pressure.

[vwmike]

I was just going to hook an automatic transmission cooler into the return line (those are cheap and/or free). I would think putting it on the feed would probably make the pump have to work too hard to draw in the fuel.

if you put it on the return line you'll pop all the little return hoses off of the injectors because of too much back pressure.

hmm.... I wouldn't think there would be much backpressure from the cooler, but maybe...  :?:

[steve]

Isn't the Summit/Moroso stuff for drag racing where you put ice in the can?  But the question remains, is cooling beneficial to power...  

In the gas engine sense, the cold fuel helps cool the air charge which makes it denser and you can suck in more air/fuel mixture.  Thus more power.  

If it only makes the fuel denser so you can get more fuel in then now you have an improper AF mixture.  You could do the same thing with a simple carburetor jet change.  

There's a limit though.  You could start icing up your carburetor.  This is a concern on alcohol motors due to the much higher latent heat of vaporization.  The fuel evaporating gets the carburetor so cold that ice starts forming in various places it shouldn’t

This same mechanism won't work in a diesel because no fuel evaporates and no charge air cooling will happen.  Perhaps you could use LP fumigation, alcohol injection, water injection, or intercooling to cool the air going into the intake.  Or just crank up the fuel and smoke it like you didn’t care.  I suspect that these methods will have more effect on power output.

[vwmike]

Isn't the Summit/Moroso stuff for drag racing where you put ice in the can?  But the question remains, is cooling beneficial to power...  

In the gas engine sense, the cold fuel helps cool the air charge which makes it denser and you can suck in more air/fuel mixture.  Thus more power.  

If it only makes the fuel denser so you can get more fuel in then now you have an improper AF mixture.  You could do the same thing with a simple carburetor jet change.  

There's a limit though.  You could start icing up your carburetor.  This is a concern on alcohol motors due to the much higher latent heat of vaporization.  The fuel evaporating gets the carburetor so cold that ice starts forming in various places it shouldn’t

This same mechanism won't work in a diesel because no fuel evaporates and no charge air cooling will happen.  Perhaps you could use LP fumigation, alcohol injection, water injection, or intercooling to cool the air going into the intake.  Or just crank up the fuel and smoke it like you didn’t care.  I suspect that these methods will have more effect on power output.

I don't think you meant that it was, but lot of what happens on the alcohol cars and whatnot isn't all that relavent to this discussion. Regardless, it is good information. If in fuel, colder temperatures drive the molecules closer together then the result of cooling the fuel would be more "potent" fuel being injected into the combustion chamber. As for messing with the mixture, that really doesn't seem to be a concern because how much power you make with a diesel is all about how much fuel you can inject and still maintain safe operating temperatures (EGT's). Therefore, since we have a fixed oriface and mechanical pumping limits, a more dense fuel charge would increase power output potential. Of course this is making the assumption that you've maxed out your fueling potential. In the same aspect, I wonder if it would help or hurt mileage. The cold can really is for one time use though. I think a normal liquid/air cooler would work just fine.  

[QuickTD]

This same mechanism won't work in a diesel because no fuel evaporates and no charge air cooling will happen.

 Absolutely correct. Fuel temperature control on a diesel would be about consistancy, not power. I just want the same power whether the engine was just started or if it has been idling in traffic for 2 hours. If I only wanted more fuel I could just crank the quantity adjuster in some more. I'm not quite at the limit yet, very close though...

[racer_x]

Well, after 2 hours of sitting in traffic, you would also have to worry about heat soak in your cooler.

I just don't think the benefits would be much for a fuel cooler on a diesel engine. And you could usually get the same increase in fueling by adjusting the pump. But it's your car, and if you want to try it, go for it. It's not going to hurt anything, and there's no real risk to yourself or anyone else.