WTF does that mean? It's about density changes caused by heat. Returning the fuel before the area where density matters (supply rails) is what the stock system does and is part of the reason we have a regulated return was because it returned to much starving the injectors. Returning fuel before the injectors will just mean less fuel to cool the injectors and remove the heat in that key point of the system. Im saying to cool the fuel pre supply rails as much as possible and allow for a lower set regulator psi which results in more flow to the take and more heat taken to the tank. IDK what your thinking but your ego I'm smarter comment leads me to believe your not.
I'm going to throw something out there for you that may or may not have come to your attention in relation to your above thoughts.
Now, concerning the idea of whether or not to send the fuel back to the tank before entering the heads, or to send it on through the heads and then back to the tank in the quest for the lowest fuel temperature at the injectors, here are my thoughts:
If you send the fuel through the heads before returning it to the tank, the fuel temperature will obviously increase at the tank, pre-pump in the filter and everywhere ahead of the heads themselves. This
will increase problems with vaporizing the fuel on the inlet side of the pump, bar none, no questions asked. Whatever the line sizes you run, and whatever the atmo maintained in the inlet side of the circuit, the heat
will be greater if you run the fuel through the headrails like coolant passages before sending it back to the tank all the time, and this will increase the required pressure for the inlet side of the circuit to keep the fuel from vaporizing in any bends, fittings, filtration or the like.
But..... we're talking about the temperature
at the injectors right? Well, when you are at low fuel demands, like crusing around empty, idling and general bs driving (99% of the time) the fuel will almost certainly be cooler at the injectors with a "flow through" setup than with a "static" setup where the fuel will reside in the headrails for quite a while before being consumed.
However..... what about moderate to heavy fuel demands at part to full power?
In these situations, I point is reached where the fuel is traveling through the heads at basically full pump speed. In these situations it honestly makes no difference whether or not the system plumbed "flow through" or "static", as the regulator is basically closed in both cases, as the fuel pumps outflow is almost 100% directed to the injectors. The fuel is basically leaving the pump and never coming back to the tank until you lift.
It is in these conditions that the temperature of the fuel to the injectors is simply the temperature of the fuel in the tank, as it's literally blasting straight from the tank, into the cylinder bores as fast as the injectors can put it there, and at nearly 100% pump capacity (otherwise you sized your pump a bit large for your needs).
And in these conditions, the "static" system is delivering fuel at a LOWER temperature... because the fuel system temp is lower because it wasn't being used as an auxiliary radiator for the engine while you were sitting in the drive-thru at wendy's for 10 minutes.
A flow through system will worsen problems of vaporization (often termed "air entrainment") because of increased pre-pump and in-tank fuel temperatures due to the fuel always passing through the heads, and then under high demands (full power) this higher temperature fuel is what the injectors still see.
The static system will run the injectors on hotter fuel than the "flow through" system when tooling around town, but it will also run the pump, filter(s) and lines at a lower temperature all the time.
Then when you let the big dog eat, the hot fuel is quickly consumed by the injectors, and they are then fed a nice, steady diet of lower temperature fuel when it really matters.
Switching from "flow through" to "static" my frame-mounted spin-on filter went from 100+ degrees on the laser gun to just above ambient. I can't recall the exact values as it's been a number of years, but it was shocking how much heat a flow through system puts into the fuel.
The question you have to ask yourself is whether or not you want hot fuel going to the engine and running through your pump and filtration systems, or if it would make sense to have your pump and filtration systems working with basically ambient fuel temperature all the time, and the injectors running on hot fuel when at low power, and then basically ambient fuel temp at full power.
If you want to optimize for idle to part-throttle, go flow through. If you want to optimize for wide open power, go static.
IMO.
oke:
