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.