I've read a lot about CAI and WAI - and understand cold air is best for a diesel - but I can't recall reading anything about any benefit from warming the fuel itself...
My VAG diesel does have a temperature controlled valve in the fuel return that can dump warm fuel from the injector-pump back into the top of the fuel filter to help prevent waxing/blockage of the filter in cold weather.
But I noticed while tinkering today that after I P&G'd on a 14 mile round trip the injector pump hardly warmed up at all...
So I was wondering if there might be any efficiency benefit if I was to run a longer fuel supply pipe around my top radiator hose to warm it up a bit?
I know it is essential to warm up fuel in order to run vegetable oil (to reduce viscosity) - but would it make any difference at all with straight diesel fuel??
TIA