So I was sitting around thinking today (AKA avoiding doing real work), and I wondered if anyone had thought about designing a fuel/oil cooler to replace the coolant/oil cooler and in lieu of going with the air cooler.
I think it might be useful for a number of reasons:
1. Fuel is much much cooler than your coolant and would therefor cool the oil much faster.
2. You don't need to be moving for it to be effective, useful if you idle a lot.
3. It would heat the fuel up, aiding atomization and better combustion.
Any thoughts? This certainly isn't something that I'm going to go do any time soon as I'm no McGyver, but it seemed way better than trying to cool oil with something that's already 190!
P.S. Only other consideration I'd think would be to ensure that in the cooler the fuel was pumped at a higher pressure than the oil, so if it suffered a leak, you'd get fuel in your oil instead of oil in your fuel...
I see a few issues...
1.) yes, the fuel may be cooler than the coolant, but once you run fuel through the cooler and back into the tank you warm the remaining fuel in the tank with no way to cool it, except through the plastic/metal of the tank into the air. Thus you would quickly heat the fuel beyond useful heat transfer delta.
2.) the more fuel you use, the less coolant you have hence enhancing the problem stated above.
3.) cooler diesel fuel is actually better for combustion and atomization. Just like air, you get more power and cleaner combustion from cooler fuel, hence why some engines (Detroit, Cat...etc) have fuel coolers as well.
4.) having The fuel pressure higher than the oil pressure would happen just from the operating pressures of both systems. But, fuel dilution of crankcase oil is a big concern in diesel engines. You dilute and therefor lose the lubrication of the oil which increases wear and heat stress which results in potentially massive failures. Oil in the fuel would be the lesser of two evils, but even then you would be on borrowed time as the oil in the crankcase disappears.
Just my two cense.
2004 CC/LB F-350XLT 6.0L
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