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Diesel gas injection systems

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Diesel gas injection systems

Postby 404wanderer » Wed Jun 03, 2015 8:40 am

Hi all,

I was wondering what your collective thoughts were on Diesel Gas Injection Systems. I've seen a couple on the market, some whose selling point is injecting gas when idling, others the exact opposite. Does anybody have any experience of these systems or have any recommendations to suppliers / installers?

Just to clarify, these are the systems which inject LPG into the engine while it is running on diesel, not an LPG conversion.
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Re: Diesel gas injection systems

Postby rustbucket » Wed Jun 03, 2015 11:54 am

Plenty of those conversions done in the states.
I am on an American busnuts board and the owner has done a home conversion using LPG but he only uses it on hills, injects at 4 psi by memory on his 8v71. He swears by it for hill climbing which is where the 2 stroke DD's are weak.
Now we have a Lithium battery pack and 3 Kw of solar we are almost all electric, so we are looking at doing similar with the 36 Kg of LPG we are currently carrying.
I believe the effect is similar to running in the rain when there is more cold dense air jammed into each cylinder and they just run so much sweeter, long hills you expect to be changing down on are surmounted in 6th gear and you are left going WTF ?

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Re: Diesel gas injection systems

Postby daler » Sun Apr 03, 2016 9:11 am

Depend on what motor you have whether its worth while.
I have done it a couple of times with great results.
If you have an old bus and it blows black smoke under load it will help heaps. You only want a very small amount of gas. How it works is that old motors are very inefficient and dont burn all the diesel being tipped into them, the gas gives a much better bang burning all that fuel that is normally wasted.
if you want more info PM me and i can explain it all to you.
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Re: Diesel gas injection systems

Postby qbb469 » Fri Apr 22, 2016 12:57 am

Adding LPG will up the cetane a point or two. So slightly More complete and stable combustion. In low concentrations. It will of course start losing Cetane after a particular concentration.
Same reason why the Fischer tropsch diesel from gas to liquids plants makes the bus want to pull harder. Higher cetane.
Cetane is the diesel equivalent of petrol octane number.
The cooling effect of LPG liquid to gas transition isn't going to have much effect unless you're dumping a large amount in.

Watch your turbo temps if you're squeezing more out of the motor. Particularly if running b10 diesel as well.
BTW there's 40 odd free HP going to electric fans without pushing the motor any harder.
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Re: Diesel gas injection systems

Postby rustbucket » Sun Apr 24, 2016 10:05 am

Beware of looking for "free" HP just by using thermatics.

If going down this road you MUST know how much air the original fan moves, and then get somewhere close to that with thermatics, then thermatics are suitable.
There are a few ways to do this, double sided fans (each side of rad, pushing and pulling), another radiator etc etc

HOWEVER, energy is energy and if you simply move the energy generation for your cooling fans to your alternator, it is not free

In VP when I switch the main banks on 2 radiators to alt power you can hear the engine idle come down as the extra load comes on it.
Where we win is by driving the 4 banks of fans via the 3 Kw of solar and the Liths battery pack.
When the sun is high and higher air temps mean less cooling efficiency you have extra solar power for the fans, when the sun is low, air is cooler, less fans needed.
Even with 4 x 14" high performance fans (have the 16" motors in them) on the original radiator (serviced) plus 2 x 16" fans on an additional PWR custom radiator VP has trouble staying below the 80 deg C we want to run her at, imagine the scenario, summer day of 40 deg, climbing C Gap or T range then the long drag up to Stanthorpe where you have to push lots of fuel down her throat, the 2 rads simply do not cut it.
So I recently added a third I had lying around to the trailer, now never a problem.

Just shows you what you need to do to get your thermatics to match the performance of the original fan, designed for the job.

BTW the original fan on VP moved 7,000 ltrs of air a second at full noise gives you some idea of what you have to aim for
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Re: Diesel gas injection systems

Postby jerry » Tue May 17, 2016 2:50 pm

best one was made by a wa firm ,
had it done to my kw caterpillar engine ,not many doing it now but old hume truck and car repairs in Euroa were doing it worth a call 0407326832

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