Compression Ignition Addict
Join Date: Oct 2008
Location: Hudson Valley, NY region
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Aaron, I'm a little late to the table, sorry. Also, I don't completely understand your DIY setup, but IMO you should definitely purge your FPHE (so should you simone). Poly problems appear to be cropping up with folks using FPHEs - I've seen threads on several forums about it, some with pics. I don't know if it's because they're not purging them or because it's going to happen to all FPHEs b/c of the copper brazing. But one sure way to slow down the poly formation is to "clean it out" with diesel upon every shutdown.
FYI, I didn't have to change my purge time of ~12 seconds when I put my 16-plate FPHE in - that still clears mine out on my setup. The way my auto-purge cycle works on the V3 is: the veg pump stops, a valve on the manifold opens and the diesel pump turns on. So, the diesel is being pushed through the fuel lines on the head, back through the veg fuel lines (no check valve on the veg lines), through the FPHE, into one of the channels in the V3 manifold and then into the return line on the veg tank. (The secondary function of that return line is to allow a small amount of veg oil to regularly flow back through it from the manifold through a tiny little orifice. This keeps the lines forward of the manifold free of air.) My veg system bypasses the stock fuel bowl and the veg lines are connected to the unused fuel "test ports" on the engine. So, because it's deadheaded, I have one-way check valves on the D2 fuel lines on the head. These make sure no veg can be pushed into the diesel lines when the veg pump is running.
So, the upside of dead-heading with some type of small air bleed orifice is a very short purge. The downside is there's a pressure spike every time you start up the motor (pegs my 100psi guage, so not really sure how high it goes). Then, the only thing left to do on shutdown is to let the motor idle for a minute and 1/2 to burn out any veg oil remaining in the motor and refill it all with diesel for the next startup. The V3 does this automatically with a run timer card, but you could do the exact same thing automatically by installing a "turbo cooldown" timer.
I also wanted the option to run diesel through my veg system if I ever ran out of veg. So, I just set up ball valves on my coolant lines. I can shut off a valve at the front end of the system (right after where the hot coolant line is tapped into) and also at the back end of the system (on the return coolant line after the veg oil tank). So, if I close the valves, the FPHE, manifold, tank, etc. get no heat. I'm not sure I understand how you intend to use a normally closed solenoid/valve to do it. Does that mean it would only come open when your turn the system on - or are you putting in a seperate on/off switch to close it automatically?
Regarding the mounting position, I went back and forth on that a lot. Frybrid recommends mounting it with ports up because there's less chance of air in the veg fuel lines causing poly to form. The manufacturer states you get the best heat exchange mounting vertically (like you're describing) or next-best is on it's side. I ended up mounting on it's side because I put mine under the truck and there's no room for vertical orientation. I won't have any air in my veg fuel line, so I figure that's the best of both worlds. You won't have any air in your line either, so you should be good to go mounting vertical - especially since you have the room under the hood.
Hopefully this gives you some ideas and my description was clear. I have a thread on here about changes I made to my system before the winter with lots of pics - hopefully you can see what I'm referencing.
'02 7.3L Excursion Limited; ~160Kmi total; ~75Kmi on WVO
Vegistroke V3 (4/09); HIH, Aux Pump, FPHE (11/10); PHP Gryphon custom; 6637;
WW; Turbomaster; EBPV delete; 4" exhaust; Terminator HPOP; Tru-cool; Evans NPG+;
ARI triple-disc TC; V/B-code springs; Bilsteins; 30mm sway bar; 190A alternator; F650 dash, etc.