Looped return advice

[NCR]

Here is a rough drawing of my current two tank setup:


I originally set this up to be able to run Biodiesel in the winter. It worked great and that was without the FPHE. Lines are HOH, system is Veggiestroke style. Recently I added the FPHE shown in the drawing because I want to run SVO. As you can see I run a non-looped reurn to the tank. Currently with the FPHE installed I am seeing fuel temps of 150 degrees before the engine. This isn't quite as high as I was hoping for. I was hoping for at least 170. So I am thinking about looping my return line to boost the temps and get away from returning once heated VO to my tank, rather I'd like to use the fuel I am already heating once.

The problem I run into is that I have my FPR after the heads, my purge is T'd into the return line right after the FPR and I don't want to run any more lines, as everything is already bundled nicely. So can I still just loop my return in between the filter and VO tank. I think I should be able to. What do you think? The thing I am worried about is still being able to purge.
Here's what it would look like:

[ToddT]

What will keep your diesel from going through the heads and into the Veg tank? If by Vegistroke style, does that mean the old way of check valves in the manifold prior to the heads?

As I understand your drawing, the FPR on the WVO side will probably be set at a higher pressure, say 75psi. The stock regulator is usually around 50psi. That means when you run on diesel, the heads will have trouble getting enough pressure to the injectors in that the FPR on the outlet side will be dumping it all out the back.

I'd add a three port solenoid valve after the fuel leaves the heads and just split the flow to the respective tanks... diesel when on diesel, WVO when on grease. This should be before it goes through the WVO pressure regulator.

[NCR]

Originally Posted by ToddT

What will keep your diesel from going through the heads and into the Veg tank? If by Vegistroke style, does that mean the old way of check valves in the manifold prior to the heads?

As I understand your drawing, the FPR on the WVO side will probably be set at a higher pressure, say 75psi. The stock regulator is usually around 50psi. That means when you run on diesel, the heads will have trouble getting enough pressure to the injectors in that the FPR on the outlet side will be dumping it all out the back.

You are correct, but because the WVO is set to 75psi it does not allow anything past it till the pressure raises to over 75psi. In this case when running on diesel at stock pressure will never happen. That's how diesel never gets to the WVO tank.

[ToddT]

You're right... never dawned on me! Thanks... and good thinking.

I wasn't keeping in mind that the FPR would not let anything through until OVER the set pressure rating. I know better. Just wasn't thinking it through.

[leongriffin]

There really isn't much reason to heat your SVO/WVO more than what it takes to move the oil to the engine. Your engine will/should be plenty hot when you switch over to veggie; it will dictate the temperature of the oil at injection more than any amount of pre-heating of the oil itself.

If you wanted to make your system sweeter, look at setting up an automated controller for switchover and purge.

Leon Griffin
WVO Designs