Thread: D-gas versus Dieselgas

I have the Deisel gas Australia system and happy with it. I definatley change gears less with the gas on and have a higher top speed. My total fuel consumption is unchanged at just over 10l per 100km. My gas consumption is always between 18-20% of total. I have a 300tdi in an 87 Rangie with 265/75R16. Haven't had it dynoed but there is a long hill just before my house which I can drive flat out without the gas but with the gas I have to back off. Also much better when towing a trailer. I just wish it helped a bit more of idle.

Originally Posted by Wilbur

Pat,

By the way, watch out for that knocking. It may be urelated, but since having that knock, my car uses a litre of oil avery 2,500 k's. Before that, I never topped up the oil between services. Rgds, Paul

Just a question,

is this because all the diesel is getting burnt, with the gas, and not leeking into the oil.

As I don't use any oil, but have got an oil leek on the stump (std 300 Tdi) So I think with my oil leek, I must be getting deisel (soot) into the oil, as I don't use much oil in 10k????

I would like to get gas, sounding like not worth getting?

Originally Posted by hook

Just a question,

is this because all the diesel is getting burnt, with the gas, and not leeking into the oil.

As I don't use any oil, but have got an oil leek on the stump (std 300 Tdi) So I think with my oil leek, I must be getting deisel (soot) into the oil, as I don't use much oil in 10k????

I would like to get gas, sounding like not worth getting?

Interesting question Hook, I hadn't thought of that. Maybe diesel had been auto-topping up the oil, but it did still use oil after I stopped using the gas.

For your car, remember a little oil goes a LONGGG way. Even a small leak can make it seem that your sump should be empty very soon. I prefer to believe that your wonderful 300tdi engine simply doesn't burn oil!

It may be worth getting gas, maybe I have just been unlucky, or chose the wrong system. Markb seems to get results with a different type of system, really I prefer testing with at least a stop-watch. There are just too many variables when tesing by feel.
Paul

Hi all,

I would greatly value any comments on this idea.

The D-gas system injects gas in proportion to the manifold pressure generated by the turbo. I find that I do get a (small) improvement in performance at partial throttle but not at full throttle.

I am wondering if maybe the manifold pressure doesn't increase after about 2/3rds throttle, so that choosing a jet that doesn't over-gas at partial throttle will result in insufficient gas at full throttle?

Alternatively, with a jet chosen for good operation at full throttle it would be over-gassing and possibly damaging the engine at partial throttle. The worry is that damage can be done before the noise is audible. (This is from the D-gas website).

This may explain why Markb seems to be getting better results. I think the Diesel-gas Australia system has lots of sensors to control gas flow rather than just relying on manifold pressure.

Any comments please?

Thanks,

Paul

Originally Posted by Wilbur

Hi all,

I would greatly value any comments on this idea.

The D-gas system injects gas in proportion to the manifold pressure generated by the turbo. I find that I do get a (small) improvement in performance at partial throttle but not at full throttle.

I am wondering if maybe the manifold pressure doesn't increase after about 2/3rds throttle, so that choosing a jet that doesn't over-gas at partial throttle will result in insufficient gas at full throttle?

Alternatively, with a jet chosen for good operation at full throttle it would be over-gassing and possibly damaging the engine at partial throttle. The worry is that damage can be done before the noise is audible. (This is from the D-gas website).

This may explain why Markb seems to be getting better results. I think the Diesel-gas Australia system has lots of sensors to control gas flow rather than just relying on manifold pressure.

Any comments please?

Thanks,

Paul

That would be very easy to measure to confirm your theory (or otherwise). Just fit a boost guage/manometer, and measure boost as a function of throttle position.

If they inject based on boost pressure, boost would be highest when you back off the accelerator (just before the wastegate opens) - so there would be a noticeable lag there???

I've had a D-Gas system on my 300Tdi Defender for around 6 months or so and wouldn't bother with it again.
Slight difference in power but nowhere near what I was led to believe and was hoping for when pulling the camper.
Certainly not enough to improve pulling power up hills which is what I really wanted.
No discernable difference in oil cleanliness either although proper lab. testing may show it to be cleaner.
Overall I don't think it was worth the 4K it cost (3K rebate in WA) and I really really hate the damn tank hanging down under the drivers side!
Cheers.
Alan.

I want to give a huge thanks for this thread. I was considering either selling the disco or doing the d-gas and an interstate buyer pulled out of the sale so was just about to book in to get diesel gas done but now my mind is made up for sure. For the 2k out of pocket I would of had pretty high expectations so I'm so pleased to of seen this.

Thanks again. But sorry for all the people who ahve fitted it and were not happy with the system.

Paul were are the boost valve and gas feed valve?.Are they reading correctly?.I think the reason you aren't getting power is because you aren't feeding it enough gas.I would change to a 40thou jet.My defender is booked in to be dynoed on the 8th,I also am getting it tuned in both diesel and gas to get it right.Two power runs and a tune for $250.I will post up results but I wonder if a good tune is what most of these vehicles need,I had the disco done when I fitted the gas,it turned it right around. Pat