VO Return HIH through Coolant Return? Critique and advise.

[ZukiFrodo]

I will be running my fuel supply HIH with copper or aluminum tube for the fuel within heater hose for the coolant.

The way I see it, there are two "tank to IP" systems: 1) the supply system where hot coolant is being supplied from the head and through various exchangers to the tank's heat exchanger, while fuel is being supplied from the tank to the IP through the same progressively hotter exchangers, and 2) the return system, where coolant is returning to the heater core circuit from the tank, and excess fuel is returned to the tank from the injectors.

I plan to segregate these systems in order to maintain the highest possible temp in the supply system (afraid that a marriage with the return system could actually lower supply temps).

Here are my questions:
1) Understanding that I am planning a full VO return to tank, am I picturing the tank/IP circuits correctly?
2) Is there logic in separating the supply from the return system?
3) If separated, is there benefit of the return system being HIH, like the supply system? Any reason not to?

[cgoodwin]

To simplify this will require an illustration, possibly animated, give me a little time.


Chris

[vegipete]

[snip] where coolant is returning to the heater core circuit from the tank [snip]

Here are my questions:
1) Understanding that I am planning a full VO return to tank, am I picturing the tank/IP circuits correctly?
2) Is there logic in separating the supply from the return system?
3) If separated, is there benefit of the return system being HIH, like the supply system? Any reason not to?

Makes sense to me. The hot, outgoing coolant does not need to heat the warm returning coolant so separating the two lines to prevent thermal contact seems like a good idea. You have to run the fuel and coolant returns somewhere, so why not put one inside the other? Just make sure the coolant hose is large enough to ensure sufficient coolant flow.

Just to make sure, the VO coolant loop is in parallel with the heater core loop, not in series.

P.

[ZukiFrodo]

Chris, your latest Frybrid system diagram that includes the coolant system is exactly how I'm picturing things, with the addition of a heat exchanger atop the VO filter (I've got a spare VW coolant/oil heat exchanger). Thank you very much for taking the time to draw this diagram.

[cgoodwin]

Zook -

Sorry I forgot to reply and tell you it was done. Also with the VW coolant/oil exchanger. you will find that it will not work with the VW fuel filter as the threaded shaft is small on the fuel filter mount and larger on the oil filter, as a consequence the hole in the center of the cooler/heater is too large to seal arounf the stud for the fuel filter. I make my "Budget Filters" by using a racing oil filter mount and have a CNC machined long tube milled with oil filter threads on one end and fuel filter threads milled on the other, a shoulder must also me machined into this peice as without it nothing holds the cooler on OR seals it. It must be sealed or the fuel will bypass the filter altogether.

It is possible to make one using the stock fuel filter mount and another CNC piece but I abandoned this as although these are available in junk yards, a business can not rely on a supply of parts from junk yards, and from VW they are $189.00, hence the re-design. Also the cooler/heater is $275 from the dealer, I took the filter project seriously only after I located a German source for new ones at a better cost.

Chris

[ZukiFrodo]

Chris, I have the exchanger and can get filters locally... would you be willing to sell me the other stuff I'd need? Let me know.