Thread: isuzu & LPG

Originally Posted by Dougal

I've got 3120 litres/min for a 3.9L engine at 2000rpm, I'm using 80% VE.
I get 772 litres of vapour at 20C and sealevel from 3 litres of lpg
772/60 = 12.86 litres/min of vapour into the engine.

So 12.86/3120 = 0.4%

This is exactly the same fumigation rate I ran into detonation with.

12.86 l/min of vapour has the same energy content as 32cc/min of diesel.
That's 3L of liquid LPG equivalent to 1.9L of diesel.
It's 20kw worth of fuel which would result in about 7kw of crank power.

OK so you are right, as soon as all the diesels on gas in oz realise this they will all go bang at once. Cheers!

But yours was at idle wasn't it?

Bee utey. Yes that was at idle.
I figured that running cold at idle would have the least propensity to detonate and also the best conditions to identify detonation.

Unlike a petrol engine detonation won't kill a more heavily built diesel straight away. It'll be accumulating damage and mainly to the pistons and rings. I've heard industrial users finding increased metal counts in oil samples when using gas fumigation and I beleive detonation would be the cause.

Originally Posted by slug_burner

Mechanically injected diesel can produce extra power as a result of tweaking the pump but it appears to be difficult to get the extra power without black smoke. Is this what limits the power output of diesels or is it just a detuned engine has greater longivety?

Diesels mainly smoke because they can't get enough air to burn the fuel. If you just wind up the fuel without providing more air then it probably will smoke.
If you increase the turbo boost pressure and keep up with intercooling requirements with fuel increases then you won't have any more smoke than at stock settings.
It all comes down to air/fuel ratios. Too rich and they smoke. The figures I've found for production diesels show they run about 22:1 at max power and not richer than 18:1 anywhere. Stoich on a diesel is 14.55:1 but you'll usually start smoking at 18:1 and get more and more smoke as they run richer.

I don't have time to delve into the lpg diesel issues.

The SAE organisation send me lots of stuff that I don't usually follow up, but I see that lots of technologies are being researched and seminars held to inform members on latest developments.

I get other newsletters and the like from companies like BorgWarner who seem to have grabbed the turbo market for many of the newer diesel engines.

It is clear that engine manufacturers are committing a lot of $$$ to research and it is showing up in the new diesel engines.

But I can not recall seeing any examples or interest in lpg diesel from engine makers. If anyone has a list of engine manufactures who have embraced LPG diesel, I would be interested in seeing it.

Take from that whatever you like!

Originally Posted by Bush65

With a turbo diesel, if you double the fuel at the same engine rpm and have upgraded the turbo and suitable intercooler to provide the air needed to burn it properly, then the power and torque should be approximately doubled.

(edit) there are some reasons why they won't double, but will approximately double.

The need for increased mass airflow, means the air density in the combustion chamber is increased, and so the spray pattern from the injectors is affected - injectors need to be reset for higher pressure if you want to get back same effect.

To get double fuel rate the injection event finishes later - to finish earlier will need larger elements in the pump and more nozzle holes in the injectors.
(end edit)

The facts are that the later 4BD1T engines produce 90 kW at 3000 rpm in stock condition i.e pump calibrated to provide 70 mm^3 per pump stroke.

My stock pump has been on a test bench and calibrated to provide 170+ mm^3 per stroke (test bench showed that it could go to 180 mm^3 per stroke).

I have seen evidence that the 4BD1T can easily exceed 600Nm torque with pump adjustment and suitable turbo.

The way I read the posts, Dougal's comment regarding increased power adequate for most people here by tweaking the fuel injection pump was directed at big guy.

It seems to me that big guy is a self appointed expert on how bad Isuzu engines are and how good the Land Rover 300TDi is in comparison. He takes every opportunity to heap rubbish on the Isuzu engine and the drivers of same. In my opinion he knows very little about them and my guess is that what knowledge he has is probably based on the series 3 with 4BD1 - not a very good reference for what a 4BD1T intended for vehicle use is like.

It was big guy that showed how little he knows and claimed:


He is a big guy when it comes to slinging insults, but he can't take it when he is called out.

Thank you for your kind words.
I am not a fan of the isuzu, I do not pretend to be.
Been in a couple and No, I don't like them.
I do get the reasoning as to why you like them but I find them too agricultural.
As said before many times I have 2 very close friends with them and one doing a conversion now. Way more power than my current old Disco but I still don't like the bone shaking big truck thing.

I respect the idea of a very reliable outfit one has when fitted. End of that story.
I have not been in a series 3 Isuzu so no such references there! Not sure how that came about.

I do like a bit of a stir and if miss-construded at times than so be it.

If a Isuzu does get 600 NM on a dyno I will print these pages and eat them and my words and stand forever corrected.

I do a lot of research on a whole lot of matters which is just part of my line of work. The net is now full of very usefull and factual information. Claims I put forward are based on real life experience and those gathered via research.

So, in other words what I do claim is what I know and have seen for myself and or sourced and found to be true.
If I have to go on a diet of paper soon so be it.

Bushie, please do not make this personnel and make insults and slanging matches, I am a very easy going fella but no one likes things to escalate, I put up with morons in one of my business ventures as it is and on here like to keep things a bit lite hearted.

Originally Posted by Bush65

I don't have time to delve into the lpg diesel issues.

The SAE organisation send me lots of stuff that I don't usually follow up, but I see that lots of technologies are being researched and seminars held to inform members on latest developments.

I get other newsletters and the like from companies like BorgWarner who seem to have grabbed the turbo market for many of the newer diesel engines.

It is clear that engine manufacturers are committing a lot of $$$ to research and it is showing up in the new diesel engines.

But I can not recall seeing any examples or interest in lpg diesel from engine makers. If anyone has a list of engine manufactures who have embraced LPG diesel, I would be interested in seeing it.

Take from that whatever you like!

This is what to take.
The fact is that LPG is being quickly overtaken by LNG in the HDV (Heavy duty vehicle) market. At the end of the day the correctly aspirated differences are nilch, LNG does require a bigger tank, but on a truck ( & Bus) there is no issue with space. Where the big difference is in price & availability.How does 35cents a litre ( adjusted to LPG energy value) sound?? Australia is a bit behind the world in taking up LNG but there are sites springing up - around 20 at present- to cater for HDV's fuelling up on LNG. There are companies using the stuff in house ( E.G. Murray Goulburn running its tankers around)

What has this to do with an Isuzu getting fumigated?? - Its the same principle..

The fact is, companies have insisted on confidentiality as they all want a competitive advantage & you simply wont get user reports. LPG worked really well, but has not got the price advantage locally. On a world front, and with LNG, there is now a new generation of direct Gas engines, so fumigation in trucks will be relegated to small fleets.

Here are a couple of links to support my comments. Tasmania is taking it on & Toll Transport are involved.

Dual-Fuel™

Mercedes-Benz delivers first natural gas Econic semi — Autoblog Green

EPA Tasmania - BOC Ltd Liquid Natural Gas Plant Westbury

Originally Posted by DeeJay

This is what to take.
The fact is that LPG is being quickly overtaken by LNG in the HDV (Heavy duty vehicle) market. At the end of the day the correctly aspirated differences are nilch, LNG does require a bigger tank, but on a truck ( & Bus) there is no issue with space. Where the big difference is in price & availability.How does 35cents a litre ( adjusted to LPG energy value) sound?? Australia is a bit behind the world in taking up LNG but there are sites springing up - around 20 at present- to cater for HDV's fuelling up on LNG. There are companies using the stuff in house ( E.G. Murray Goulburn running its tankers around)

What has this to do with an Isuzu getting fumigated?? - Its the same principle..

The fact is, companies have insisted on confidentiality as they all want a competitive advantage & you simply wont get user reports. LPG worked really well, but has not got the price advantage locally. On a world front, and with LNG, there is now a new generation of direct Gas engines, so fumigation in trucks will be relegated to small fleets.

Here are a couple of links to support my comments. Tasmania is taking it on & Toll Transport are involved.

Dual-Fuel™

Mercedes-Benz delivers first natural gas Econic semi — Autoblog Green

EPA Tasmania - BOC Ltd Liquid Natural Gas Plant Westbury

That is different technology to what was being discussed in this thread.

Certainly there are several engine manufactures with engines for running on LPG or LNG. And they are popular for the likes of buses running around cities.

A diesel engine needs extensive changes to operate with LPG or LNG like that. They are not bolted on LPG systems.

You haven't shown any engine manufacturer that use diesel injection with a small amount of LPG added to the air as in what is often called diesel fumigation, which was what I was talking about.

Originally Posted by Bush65

You haven't shown any engine manufacturer that use diesel injection with a small amount of LPG added to the air as in what is often called diesel fumigation, which was what I was talking about.

For mobile engines there are none. Not a single manufacturer that I have found advocates or allows gas fumigation of their diesels.

I keep hearing rumours of large industrial engines which run on both diesel and gas, but I've been unable to get any specific information on them.
MAN allegedly make some but I can't even find model numbers. I took their factory tour in March (Augsburg) but my Deutsch wasn't good enough to ask the appropriate questions or understand the answers. A good friend works there but he hasn't been able to find any specifics either.

*edit*
Found information on the MAN dual fuel engines. It's a new publication.
http://viewer.zmags.com/publication/...38#/cd5dc038/8
Page 8 gives the specifics for their gas fuelling, the gas must be compressible to 250 bar without forming condensate.
That rules out LPG straight off as unsuitable. At 20C it only takes 6 bar to condense LPG.

plenty of people running d-gas setups in lesser engines than a 4bd