Vegetable oil heater for Nissan Patrol conversion

This is from a recent email to Bennyspoon about a recently acquired Kim Hotstart engine heater...I got it from the tipshop for $10. I'm talking about ways to change into an SVO/WVO preheater (Straight vegetable oil or Used vegetable oil):

I will probably remove and throw out the element - was considering doing a 12V or similar conversion, but I don't want to run a 2nd alternator, or even to take 50 Amps from an existing, rewired one.
Original voltage/wattage is 480AC/4000W - so no way can I get this from 12 or 24DC anyway.

The element will be replaced with coiled stainless, coupled out through the ends.

But the decision to be made is as follows:

a) Use it as a kind of plenum chamber or surge tank, with the big cavity containing fuel and being heated by water flow through the small internal coiled line.

or

b) Use it as a conventional heat exchanger, with the big chamber inline with the water jacket, and having the fuel delivered via the coil within the water chamber.

There are good reasons for a) and b) - but I'll go into them later.

More info and pics tomorrow.

(Was in the tipshop as is used from some vehicle (train or earthmover maybe?), or generator)

Dave