Submitted: Sunday, Mar 26, 2006 at 16:21
ThreadID: 32179 Views:3813 Replies:4 FollowUps:5
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Been fascinated by concept of adding LPG to diesel engines for a long time so I got a gas ticket and spent 12 months developing a system for electronic diesel application, mainly cos I have a TD5 Extreme. I didn't like the way commercial systems worked as they didn't supply additional air to burn the gas properly. Also I couldn't afford the price tag.
Results were outstanding. I chipped the car first and then put the gas system on. It now has around 200hp, up from about 120, at the flywheel which gives 150hp at the wheels on the dyno. It has 40% more torque than a Gen111 V8. No increase in fuel consumption, no increase in exhaust gas temp and no mods to the engine.
Not bad for a pommy diesel!!
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Reply By: Member - Paul S (VIC) - Sunday, Mar 26, 2006 at 16:35

Sunday, Mar 26, 2006 at 16:35
I know what you mean by price tag Damper. I was quoted $4k+ to fit diesel/gas to my new hilux. Even though this turbo'd lux is very torquie, I'd love to have the extra grunt for towing.

The only two fitters I know of in Melbourne seem to have the monopoly on this technology. As far as I can see there is no reason why it should be so much more than a petrol/gas fit.

AnswerID: 162971

Follow Up By: Damper - Sunday, Mar 26, 2006 at 16:44

Sunday, Mar 26, 2006 at 16:44
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.
FollowupID: 417734

Reply By: Peter 2 - Sunday, Mar 26, 2006 at 16:37

Sunday, Mar 26, 2006 at 16:37
How hard is it to fit, any mods required to the engine itself and how much does it cost?
Is it possible for the mechanically minded to fit?
I realise the gas tank etc has to fitted professionally but what about the rest.
AnswerID: 162973

Follow Up By: Damper - Sunday, Mar 26, 2006 at 17:15

Sunday, Mar 26, 2006 at 17:15
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.
FollowupID: 417737

Reply By: Tim HJ61 (WA) - Sunday, Mar 26, 2006 at 17:28

Sunday, Mar 26, 2006 at 17:28
Some of the info I've seen on these systems say you don't need to get all electronic, and can use a 'safe' i.e. on the low side volume of gas and have it controlled by the boost on the turbo. No idea how these work or what is required to fit them. It'd be a pity to have to add electronics to a good old fashioned turbo diesel - such as the 12HT in my cruiser, just to run an add on like gas fumigation.

The other part of these systems are the safety aspect of cutting off the gas when the motor is off, and fitting up the tank. All important to be designed and done correctly.

It's a pity these systems do cost so much as they'd be a boon for diesel owners. Given that there is a fair bit of development work needed to get all this right, I guess the sellers are wanting to make a bit of a return on that side of the investment too.

Good luck to you Damper


AnswerID: 162986

Follow Up By: Damper - Sunday, Mar 26, 2006 at 17:46

Sunday, Mar 26, 2006 at 17:46
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
FollowupID: 417739

Follow Up By: Tim HJ61 (WA) - Sunday, Mar 26, 2006 at 18:08

Sunday, Mar 26, 2006 at 18:08
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.

FollowupID: 417743

Reply By: ellmcg - Monday, Mar 27, 2006 at 10:25

Monday, Mar 27, 2006 at 10:25
So can these sort of systems be tuned for better fuel consumption rather than better performance?
AnswerID: 163101

Follow Up By: Damper - Monday, Mar 27, 2006 at 12:04

Monday, Mar 27, 2006 at 12:04
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.
FollowupID: 417876

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