MPG Time: Heat Exchanger
 

I've just ordered a Dudadiesel heat exchanger I intend to use with the coolant to pre-heat the fuel on my 2000 XJ. I've only found 3 people that have done this on their vehicle and all 3 had fantastic results. I couldn't find where anyone had tried to do something like this and had a bad experience. Two of them wound up copper tubes to some degree to their coolant hoses, one guy used a transmission cooler/heat exchanger from a Ford of some design to do what I am about to do with the Dudadiesel heat exchanger. Has anyone else seen or heard of anything doing something like this? I would have thought I could find more people that had done it online but it appears to not be nearly as common as all the other alternatives that may or may not work... sometimes. (hydrogen, magnets, etc)

I'm waiting on the fuel pressure to bleed back into the fuel tank at the moment. I am converting my non-return style system to a return style using the purge port as a return for the time being, using an adjustable fuel pressure regulator. I just replaced the pump 4 months ago with a Carter unit from RockAuto and the check valve slowly died over the course of two weeks. I've been priming it 5 times every time I start it since... not for long though. It also runs at 60PSI when it's supposed to be 50. I think I'm going to whittle it down to 43-45 and see how it responds. Has anyone else return'ified their setup?

Never heard of it. Are you thinking that pre-heating your fuel will increase efficiency?

Typically we try to keep that area cool to avoid heat soak related start up idle issues.

Yeah, I guess I understand the theory - vaporize the fuel as quickly as possible - which means more energy is conserved or something. I dont really understand it I guess, lol
My XJ seems to do this inherently unless it's cold outside. Fuel rail is always hot as hell

I forgot I made this thread. THe results are in, and there was no change. It did run leaner, and the temporary heat soak at startup was there. The heat soak is when the fuel is so hot that all of it combusts and the AFR's are off the charts so it either barely runs or won't start at all. I can tell because the AFR gauge is always flatlined too lean when that happens at start.

I had the fuel semi heated later on by doing a half heated setup where some got heated and some didn't, then recombined at a fuel filter. It ran better, but still a bit lean on hard acceleration which hurt the power, and the MPG made no difference.

It looks like doing what the racers do might be the best thing; cool it down. I was thinking using the heat exchange to tap into the AC line would work, but I am no longer interested in experimenting with that at the moment. That would be a longer term project, but I think it would have merit (long term) over the options that are out there, where you constantly have to buy and refill CO2 tanks to cool the fuel lines.