diesel/lpg

There isn't much reason for it to be much more than a car fitment. I use a couple of extra electronic bits but these only amount to about $600. So even with dyno tuning and setup it would be hard to justify more than three grand.

The sytem is completely standard from the tank to the converter and uses a particular off the shelf gas computer. This is the part of the system that has to be fitted by a licensed installer. I use a 35litre tank which sits near the chassis rail under the drivers side. The gas goes into the intake between the air cleaner and the turbo via a thing called a "spud" which is a tube with a 45deg angle cut on the end. The tricky bits are a couple of electronic components which I developed which allows the diesel/lpg ratio to automatically vary according to boost and load. These bits interface nicely with the gas computer. I run up to 50% lpg under light load and down to around 15% under heavy load when the cars computer is putting a lot of diesel in. I "trick" the car ecu into reducing overall diesel when gas is on without electronic or engine mods which means there is lots of air to burn the fuels. The extra bits could all be fitted by anyone who can read a simple wiring diagram and can use a spanner.
Tuning is the critical part of the operation to make sure too much gas is not used.
I am thinking of commercialising the system if there is sufficient interest and I couldn't see the price being more than $3000 on an electronically controlled engine - a bit more for a non-electronic turbo diesel as engine must have a TPS and MAP sensor.

Thanks Tim,
Having gone through the process of adding gas without electronic control I found it really inefficient and potentially dangerous to the engine.
Legislated rules for installation look after the safety aspects of any automotive gas system including tank fitment.
Back in the days of owning nice simple diesels with mechanical injection I was a bit like you and didn't like the thought of electronics.
I have to admit, even though I don't really want to, that over the past ten years of owning various vehicles with engine ECU's the electronics have been really reliable components and I have never had a failure. Huh!!
Good to hear from another Sandgroper

Geez, I sound like a luddite. Didn't mean to. The amount of electronic gadgets I have never ceases to amaze passengers, and me sometimes....

My point was really simply to keep the fundamentals of the engine unchanged and not unecessarity add complexity. However you're the one that has done the research and if it's gunna work better with gadgets then that's how it is.

Mind you, adding gas fumigation is not exactly keeping things simple is it! Given the arms in the air responses to bioD or heaven help those running vege oil, adding gas is like developing a scram jet to some people.

Yes, I'm in Perth, and I've got a mate with a nonturbo troopie who was looking closely at gas but put off by the cost. tim @ peoplehelp com au if you want to give me your contact.

Tim

The answer is yes, sort of. The reason that adding lpg to diesel produces more power in the first place is that the gas causes more of the diesel to burn - up to 98% is claimed. So the power increase relates purely to the efficiency increase, which in turn means economy is improved. The problem I have is the LR is so nice to drive with the extra power i tend to use it. I have a small gain in economy ( 9-10km/litre now over 8-9km/litre before) even using the extra power and torque. If I was a bit gentler on the throttle I would gain a lot better economy - but then i've always been a big kid.

If a diesel was tuned with ideal gas/diesel ratios but at factory horsepower, economy would improve out of sight. This actually is my next step. I am going to keep shutting down the diesel input until this happens on the LR. Working the figures back this means that 12-13km/litre is probable.