Thread: D-gas versus Dieselgas

Originally Posted by justinc

Pat, yes I do think a Tdi fuelling tweak and pump timing improvement(plunger lift to 1.6mm) will also help the gas to be more effective. Also, critically valve clearances need to be perfect (.008" / .208mm) to make full use of the gas/ diesel mixture.

Paul, when did your Tdi last have the tappets set? And, has there been any fuelling upgrades done, 500 degrees seems too cold (IE standard fuelling) for upstream temps. I typically can adjust these to give 600+ and the difference is remarkable. Did one recently in a 110, and because he is now in a higher gear up hills etc, he is now using LESS fuel over a given distance/ trip.

JC

Hi JC,

Interesting. The tappets have not been done for a long time, mostly because I don't know how to turn over the engine. It is easy with a petrol engine, whip out the plugs and grab the fan belt. How does one turn over a diesel by hand?

As far as I know the fuelling has never been touched. I am suspicious of the EGT - the pyro head is from Therma-guard and the gauge is a VDO analog gauge. There may be an incompatibility. In normal driving on a flat road at 100 k's (with my heavy, wind-sock camper on the back) it sits at about 400 degrees, or up to 450 if I am pushing in to a strong headwind.

I think my engine is running well for a 300tdi, just based on the fact that it performs about the same as either of my TD5 Defenders, but has better low down power than either TD5.

Even if the lack of benefit was overcome by re-setting the tappets, I would still be worried about the widely varying gas percentage. Do you have any comment on that? Is it normal to have such a huge variation (8.5% to 25% on similar driving) in gas percentage? How likely is it to do damage to the engine if the percentage suddenly did shoot up? The first tank I used with a 45 jet used over 40% gas. The engine was pretty noisy!

Cheers,

Paul

Originally Posted by Dougal

Figures like that make me question the probe location. Does it extend right into the gas flow or is it being "heat sinked" by the manfold or plate it's mounted in?

My 4BD1T pulls 430C upstream of the turbo on a flat road at 100km/h.

Hi Dougal,

Yes, I was wondering about the heatsinking. It is slow to respond. When I back right off, it takes about 5 to 10 seconds for the temperature reading to drop. The pyro head is mounted in the middle of the EGR blanking plate. Not sure what else I could do to avoid the heatsink effect.

Cheers,

Paul

Paul My truck does start to pull up once it reaches a 100k's,it will still go to 130 on a straight piece of road but it has done that from new.I also run 255/85 tyres so it is stightly overgeared.With the gas useage remember that it is boost controlled so it will go up and down depending on how much throttle you give it.I found with mine,remember I haven't had it long is that I can sit on 100 and them switch the gas on and off,on I can lift my foot and it will stay there,it's happy to cruise along and it will get economy but in town it brings the power on earlier,in third you can notice it well.It isn't a tyre burner,I can feel the engine being just a bit more willing,I also notice a bit decrease in exhaust smoke,I gun it in fourth will diesel it puffs smoke,D/G there is bugger all.Thanks for the imput JC,a pyro will be on order. Pat

A couple of stuff ups in the last paragraph but you get the picture!. Pat

450-500 does sound a bit low. I have a Madman EGT gauge fitted and yesterday towing a tadem trailer with just under a ton in it I was hitting over 650 at the end of some long hills. That said I managed to maintain the 110kmh speed limit most of the time. Only having the gas injection made this possible. The gas doesn't seem to effect the EGT and I think it actually makes the engine slightly quieter with a little less of the diesel rattle. Mine has also had the feul pump modified by LRAoutomotive.

Mines the same,less diesel rattle.That can only be a good thing,I think it is also the reason my temp is down slightly. Pat

Originally Posted by PAT303

Mines the same,less diesel rattle.That can only be a good thing,I think it is also the reason my temp is down slightly. Pat

Well I'm buggered if I know! That was one of the prime reasons I went with D-gas - the promise of less diesel knock, along with the promise of less smoke and cleaner oil gave me the feeling it would be a 'kindness' to the engine.

Instead, with reducing jet size I eventually got down to no extra noise but certainly never less noise. I also didn't get less smoke and the oil got black just as quick.

It feels like we are all on different planets!

It seems gas fumigation works for some engines and not others. It is about 50-50 amongst those I talk to. Half say it works, half say it's a dud. I wanted to get my Oka done too, but I can't know if it will work on my particular engine or not and it's just not worth the gamble.

D-gas were helpful in so far as they continually told me it worked, patted me and stroked me and told me how happy I would be once I had it set up properly, and they sent me plenty of jets to try. However, when I lost patience and said I wanted them to honour their money-back guarantee they point blank refused. When I threatened to take them to court, they just refused further contact.

The installer has verbally agreed to a refund, but I feel that unless D-gas come to the party I won't actually get the refund. I have two others ready to join a class action for a refund - any other takers here? The more we get, the better our chances.

Cheers,

Paul

Does it seem the issues are with the D-Gas system? I have a Dieselgas Australia system which I have been pleased with since installation. The reason I eventually put the system on was after speaking with someone else who also had the Dieselgas Australia System fitted and was also very happy.