Have ordered the values for fuel selector and tank return, and H3 heat exchanger from www.biotuning.co.uk.

With the aim of reducing purge time it's best to reduce the amount of components down stream of the fuel selector valve. By using dual standard landrover filter/housing it possible eliminate fuel from the purge if filter, and HE are upstream of valve.

Have researched and cut through some of the myth and facts. A great resource is the wealth of knowledge onthe forums as http://www.vegetableoildiesel.co.uk/forum/index.php. Here are some of my random notes regarding this type of installation in a Defender 300tdi:

The defender TDi fuel filters are large, eliminating it from the purge cycle will reduce cycle time. So dual filters are best before the selector valve.

Landrover TDi's are fitted with Bosch injection pumps, these are VERY tolerant to cold vegoil.

The problem comes from the DIRECT Injection system of the landrover Tdi. The engines will suffer long term with polymerization, coking, piston ring wear, loss of compression and eventual failure if vegoil is injected through cold injectors onto cold engine pistons. Even running a single tank with a % blend of veg/dino is a bad idea long term - yes it might run fine now...

So hence dual tank system. Start up on diesel until engine temperature is adequate to switch to vegoil safely, and shutdown by first purging on Diesel to remove all veg-oil from the system.

The HE on the fuel line is not exactly necessary with a Landrover Tdi. But including a GOOD heat exchanger in the system will help ease winter clogging and reduce stress on the lift pump. Good heat exchanger = flat plate design not glow plug heaters!

My intended install is as per this diagram...

Prior to install - temperatures measured around the engine of the truck then up to operating temp. Infrared thermometer used:

Injectors: 84 deg C average
Injector pipes near injector union: 64 degC average
IP PUMP INLET : 50 DEG C
IP PUMP OURLET: 50 DEG C
IP PUMP BODY: 60DEG
LIFT PUMP: 41 ?
FUEL FILTER CANISTER: 50 DEG C
HEATER IN /OUT PIPES : 86 DEG C
CYLINDER HEAD: 95 DEG C AVERAGE ON FUEL SIDE

**EDIT UPDATE JUNE 2010**
Just over a couple years since the install and the system has more than paid for itself. Couple of notes and observations on my install...

During cold winter I the lift pump does occasionally struggle on 100% SVO with the result of the occasional lull in the revs and overall performance hit. I found the truck be really happy with I guess a % mix of diesel - hard to judge the ratio really as I do not measure it so lets say 'some' diesel to thin out the SVO somewhat makes for normal running.

On my nano-expeditions when SVO has long run out and I am using diesel in both tanks I find that after a few hours on the road there is a performance drop with no top end power. I have put this dowen to the diesel being heated too high as it is going through the Heat Exchanger, after a couple hours driving the fuel in tank would be pretty warm too. I have not read that diesel doesn't like being too warm in my research but I can say disconnecting the HE cured the issue. So with that in mind I think it might be beneficial to place a shut off valve inline with the HE water supply so in time when running diesel in both tank the HE can be isolated. P.S I last had that problem in NOV and I have yet to reconnect the HE. Can't say I used that much of a heavier mix of diesel during the winter and I have been running 100% SVO this spring without issue so goes to prove the HE is not really needed.

Bit of an on going project this. Have been playing with using veg-oil as fuel for awhile and will shortly do a full conversion over to a twin tank system - 6 port fuel change over valve - decent heat exchanger.

There are plenty of different options for installing a twin tank: Under wheel arch, genuine CSW aux tank, custom tank mounted in loadbay etc but I want to exploit the 110's capability of using an under seat tank.
If I didn't have 2nd row set of door this would be easy, fit a fuel tank off a landrover 90 and drill hole for the filler in the side and pump it in. Unfortunately the doors and footwell get in way of that plan.
Next idea was to obtain a underseat tank form a military series landrover, or lightweight or series 1. These have the benefit of being filled from the top after flipping the seat base. So I purchased a suitable tank... but whoever said they fit a 110 was a f'ing liar who never tried it or they slung the tank so low it would be lost on first offroad trip. A good 5 inches too long.
Not wanting to attempt a re-fab of the series tank (cut n shut!) so I took another look at the 90 option. Instead of messing with measurement - it was easier to obtain and tank and suck and see what would be need to be done to fit.

First of all the cubby box under driver seat needs removing by drilling out the rivets. Contrary to popular belief this part of seat box is steel not alloy. With it removed the drive side of seat box is pretty weak. So out with disc cutter to remove the top portion of the removed 'cubby box'. This is then riveted back in place to strengthen the seat box back up again.
Next offering up the 90's tank the first thing to make contact was the filler breather pipe and the filler neck. So these had to go...

Cut off and a blanking plate welded over. To ensure of no leaks due to dodgy welds I coated the area with glass fibre resin. With that done the tank could be raised up to where it supposed to be on par with the 90's installation.
Next I need to install a new under seat filler. I had the option of removing the big one from the Series fuel tank or using the side filler from the 90. No wanting to ruin the series tank I opted to butcher the 90 filler which I also got the the scrap yard at same time as the tank.
So slice and dice with the grinder gave me a nice short filler neck. Out with the jigsaw to give me a hole in the tank. Out with the welder and resin to finish...


That about it for the mods on the tank itself, just need a coat of paint. Fits in the hole nice...

Next job will be to bracket it so it stays in that position without be having the trolley jack holding it there :D

UPDATE: Front tank bracket made from the original 90's bracket, reversed the mounting points so it fits the 110's trailing arm bracket. The rear just need extending with longer bolts to lock it in position and picking up on exsisting holes in the outrigger (drilled out to accept 10mm bolts).
Tank painted, waxoyled and fitted. Fuel lines fitted and run up into the engine bay ready for next stage.