Everyone knows that hit diesel burns more efficiently. Could it be ford, designed the dead head system to hold the fuel in the rail to preheat it before being injected? The only problem it really has is air intrapment. So is it actually more efficient to run a rr system. I wonder if there is a noticeable in tank temp between the 2. Just curious. I know there are slot of ideas out there!

 

The stock fuel system IS, technically, a "regulated" return. It's just that the pressure regulation and return occurs BEFORE the fuel is routed to the head.

The fuel temperature of the MARKETED regulated return systems out there will be much hotter than the stock system on the Super Duty trucks. Advantages? Not much to hotter fuel. However, a fuel cooler is a good idea if you're worried about evaporative emissions or fuel expansion in the tank.

 

I know that once the fuel gets to the engine, it gets warmed up considerably. The factory supply line runs up the front of the block and then to the fuel bowl. The fuel bowl itself is physically attached to the HPOP reservoir and just above the HPOP itself. There is a lot of heat in that area and the fuel has no choice, but to absorb a lot of it. I ran my e99 for a short test drive one day and then checked some temperatures on the engine.

The alternator housing was at 199*, the fuel bowl was 195*, as was the fuel rail. I think the fuel gets plenty enough heat.... Regulated return, or not...