Dual Fuel Cars.

[MikeAce]

Hi all, i have 2 tow cars, one LPG 1.8 16V Vectra and just bought a TDCI (130) Mondeo for the little lady.

I have to admit the LPG does lose power, especially on motor ways, i hate all the taxation on fuel which is why i went lpg, but sadly, for towing, its not the best.

I will just run the wifes mondeo from now on with the caravan.

 

[CliveV]

Hi MH

My "love/hate" relationship with "government" is easily explained - but you do have to know how the system works.

The DTI (in this case) asks an independent research source (for example the data of CO2 emissions recently obtained and published by The Guardian was carried out by the University of East Anglia) - and then chooses to publish the results if it suits the political "masters" of the day or not as in this case. However, even politicians have a knack of shooting themselves in the foot (so there's a comfort for you! - LOL!)and they introduced the "Freedom of Information Act" which The Guardian used to obtain the information.

So, whilst it may be a whopping great big surprise to you, it is not for some of us, that a lot of the DTI and other Governmental Agency Research is really rather good!

You just have to appreciate that the stuff that comes out of politicians mouths is "SPUN" to get the best out of the data. You only have to look at the way Phoney Care "spent" the same money three times on the NHS to realise that!

At the end of the day - LPG is 26% cheaper than diesel based upon the Vectra data looked at on here earlier. It is about 50% cheaper than petrol.

It requires not catalytic converter.

Emissions at MOT time are NOT a problem!

Engine oil stays clean!

OK - valve wear may be increased very slightly! - But as Craig puts it so well, 200K is not bad!

All I know is that after many hundreds of thousands of miles, the bores on my old RR were fine; compression was within original factory limits, if the valves were excessively worn, the engine never hinted that it was getting "wheezy".

I do not knock diesels - in fact I think the new V6 TD engine in the LR3 is AWSOME!

Why do you insist on trying the widdle all over the very concept of LPG? - Because based on most feedback on here, as well as the DTI site and the fact that the "pollution tax" on LPG is HALF that of diesel - you do not have a leg to stand on!

But - every time LPG is mentioned - up you pop" - sucking your teeth - saying "You don't wanna do that".

Trouble is some of already have!

And it works! - it is cheaper! Better for the environment! And better for your engine!

The Aussies will tell you how beneficial LPG is within a diesel engine! - Injecting LPG into the diesel engine increases efficiency by improving the total burn.

Such systems are becoming available here.

I am amazed that with all your expertise you have not come across its use with diesel!

Finally - for those who have stayed or are about to stay at my local "Dr David Bellamy" approved (LOL!) Sandy Balls campsite - you will be pleased to hear that all their Vauxhall Astra vans used on site are DUAL FUEL - Petrol/LPG.

No wonder it has won all the environmental awards - despite Dr Bellamys input !!!!

LMAO!!!!

 

[CliveV]

Hi Craig/David/Mike

Thanks for posting you experiences - I can never understand why people want to knock LPG? - It is a no brainer to me.

If performance on LPG is much worse than petrol Mike, have you set the plugs at 80% of normal?

As Craig stated - the calorific value of LPG is less than petrol so you do need to reset the ignition characteristics to get the best out of it. Advancing the timing a bit helps as well as reduced gap on the spark plugs.

Also - the ignition system does need to be spot on. If you have old HT leads and an old LT lead, it may pay you to change these.

Once set up ciorrectly the higher octane rating of LPG enables the engine to run far smoother and with equivelent power as for petrol.

 

[mcghee]

Hi Mike. I would say in the case of the Vectra you're probably right. I'm not criticising your choice of vehicle, but an 1800 is a relatively small engine which doesn't produce massive torque to start with, so the slight reduction when running LPG may well be a bugbear. My Jeep and many other LPG vehicles, on the other hand, have fairly large engines (4litres in my case) which by the nature of their design are produce huge torque and so the small drop when running gas isn't noticable. But as I said in my last post, just like drivers who switched to diesel years ago, I didn't switch to LPG for it's performance benefits but for cost. I'd say you're right though, and I'd pull a figure out the air and say if your engines less than about 3litres LPG may not be the way to go if you want ultimate power.

 

[CliveV]

Interestingly Mike/Craig

The Astra Vans at Sandy Balls Campsite seem to run without any problems re power. The were supplied as "Factory Fitted" - however they do not tow caravans or anything else for that matter.

The mate of mine with the 2L Subaru Forester tho' tows all sorts like me and finds no problem at all.

 

[mcghee]

A couple of the councils around my area run some LPG Astras as well and are over the moon with them. I wonder if factory LPG systems use an engine management programme which ensures the engine runs identically on either fuel? The chap who converted my Jeep used to run an Audi S8 LPG and said if he was in a hurry he'd flick it over to petrol. Having said that, the newer systems like mine have the LPG system controlled by the engine management anyway, which is possibly why I don't notice a difference. Here's an interesting theory: Up until recently gas systems have been no more than an inverted cooker ring, basically a gas carburettor. If you took any modern fuel injected engine and swapped it over to carbs you'd get less power, but the new LPG systems use separate injectors the same as the petrol system. So maybe there is a power difference on older systems but not on newer ones?

 

[MONKEY1]

Clive,

No I haven't seen a LPg/Diesel yet, I have seen some Italian Lombardi Diesels which can run on duel fuel but these where for plant machinery an were only 600-700 cc. We have had CNG powered trucks over here for some time the only company that operates them in any numbers is Morrison Supermarkets.

Interestingly British Gas got a number of suppliers to Demo 8 wheelers some time ago. But when they went to place an order the fixed cost lease was massive because of the depreciation and the whole idea went nowhere. This was despite the vehicles fuel cost was 60 % lower than diesel. The issue was that the trucks averaged under 20K per year in mileage. So the fuel saving was say

 

[MikeAce]

Clive,

No I haven't seen a LPg/Diesel yet, I have seen some Italian Lombardi Diesels which can run on duel fuel but these where for plant machinery an were only 600-700 cc. We have had CNG powered trucks over here for some time the only company that operates them in any numbers is Morrison Supermarkets.

Interestingly British Gas got a number of suppliers to Demo 8 wheelers some time ago. But when they went to place an order the fixed cost lease was massive because of the depreciation and the whole idea went nowhere. This was despite the vehicles fuel cost was 60 % lower than diesel. The issue was that the trucks averaged under 20K per year in mileage. So the fuel saving was say

 

[MikeAce]

i think perhaps i didnt post in enough detail to explain my situation.

Craig, I adore LPG, every time i fill my tank for less than 15 quid i smile to myself knowing that i have a full tank from the change in my ash tray, i would not knock lpg, the wife may have the diesel mondeo but she drives 1 mile to work and a mile back each day, i run about 500 miles a week with work so you can imagine the savings i make running gas.

Craig, you are quite right regarding the choice of vehicle (vectra) it is at best a poor tow car, perhaps i did not make a fair comparison.

my point should have stated that at some points of a typical journey towing i would flick the switch to petrol to gain that extra bit of power when going up hill or in traffic, i noticed a substantial loss of lpg power compaired to petrol, i think the key is to get a 3 litre lpg and not a little 1.8. i never chose the vectra as a tow car, it was what i had when i bought the caravan.

All in all, i love my lpg, just not for towing, if my engine was bigger, then perhaps it would be different matter.

 

[DavidW1]

I see this is still running so it must be an interesting thread and it has for the most part remained good natured which makes a pleasent change fom some topics, Lets clear up a few half truths and myths though.

Yes an ICE engine will develop less BHP running on LPG than petrol - It can though, with the latest injection technology get very close. (the old model Vauxhall 2.0 multivalve is only 1BHP less at max power on LPG)

Yes MPG figures running on LPG are lower, maybe up to 10% less but that misses the point entirely - a litre of unleaded costs about 40% less at the pumps than petrol.

Yes ignition and plugs require different settings for running on LPG - again modern gas injection systems have a seperate ECU which interacts with the vehicles main ECU to produce the optimum settings and nulify petrol only circuits.

Yes valve damage can occur using LPG, particularly on older engines - it can be prevented by using Flashlube or similar.

Yes on older carb engines and single point injection systems, backfires and lumpy running can occur - usually the result of poorley maintained ignition systems or defective cooling sytems. (not enough heat to vapourisers)

Maintenance costs are higher on an LPG vehicle - wrong! at least on the latest systems which are virtually fit and foget with only a small filter to wash or replace every 2 years or so.

Yes gas tanks can be bulky and add extra weight - so does a towing arm but I never hear people going on about that and a doughnut tank is an efficient space saver.

And finally yes LPG is greener - in spite of the anti vote sticking up for diesel, until I see Transport for London allowing diesel powered vehicles exemption from the conjestion charge I will never agree with you.

 

[DavidW1]

That is a litre of LPG is 40% cheaper than petrol, of course

 

[CliveV]

Well thanks a lot David! - I was just about to say virtually the same so now will not bother!!! LOL!

As for the types of LPG systems - I am in a bit of a quandary there myself at the moment. My old RR was a Carb one - therefore the LPG system was just as said before - inverted gas rings in each inlet.

Now I have a non LPG (but not for long!) 3.9L V8 Discovery that should really have the latest injection system LPG kit. But this does cost over

 

[CliveV]

Clive,

No I haven't seen a LPg/Diesel yet, I have seen some Italian Lombardi Diesels which can run on duel fuel but these where for plant machinery an were only 600-700 cc. We have had CNG powered trucks over here for some time the only company that operates them in any numbers is Morrison Supermarkets.

Interestingly British Gas got a number of suppliers to Demo 8 wheelers some time ago. But when they went to place an order the fixed cost lease was massive because of the depreciation and the whole idea went nowhere. This was despite the vehicles fuel cost was 60 % lower than diesel. The issue was that the trucks averaged under 20K per year in mileage. So the fuel saving was say

 

[DavidW1]

Single point injection has come on a bit - the injectors have been improved and the electronics are more sophisticated but it is still compromised when compared with Sequential Injection. The compensation for ignition curve and mixture ratio requirements, for example, are cruder or non existant.

However, having said that, as long as your lump is mecanically up to scratch and particularly the ignition components, you would be hard put to measure the difference in economy and performance between the two types of LPG system with a big V8 such as yours.

A blowoff valve in the airbox would still be a requirement on a single point I guess as If something does "slip" in the system they are not always fail safe and the resultant backfires can be destructive to manifolds, which was forever thus.

Single points, in my experience, also have a longer warm up period before the switch over to gas, probably because of the cruder delivery - some owners isolate the thermostat in the vapouriser and manually switch the changeover valve to overcome this but you can experience lumpy running and stalling or even the odd bacfire unless care is taken with the driving style!

In contrast the best injection systems will change over to gas within 5 seconds if the outside air temp is above 15 degrees and running is virtually the same as petrol during the warm up period.

I would query one aspect of your quandry, namely the need to remove the heads; whilst admitting a rusty experience of the Rover V8 it is the intake manifold that takes the drilling on most engine applications and this is not normally the "expensive" part of the operation as some can even be reworked in situ. I think it is in the tankage area that most expense occurs and if you can put up with an inboard other than underslung or doughnut, that might get the cost down so that you can afford injection.

So Clive, I suppose I am saying go for Injection if you can tolerate an inboard tank and afford the slightly higher cost to get a smoother, trouble free system with the edge in performance and drivability.

Whoops I've just thought of a snag - if and when you come to sell the beast an inboard tank is definately not a good marketing point!

So change that advise to - Injection systems have the edge in all aspects and if you can afford it go for the best - a car thus fitted will also be easier to sell.

 

[whitetop]

WOW...what a response.

Thought I might get a couple of replies but not this many. Even though some of the posts are very technical, its helps give an overall picture. I was originally looking at the pump cost for LPG vs Petrol/Diesel. I really hadn't thought of the possible tech issues regards engine wear etc etc

Thanks to all the replies, I now have a good list of things to consider.

Many thanks to all who have...and may still contribute..

David

 

[CliveV]

Hi David W

Thanks for that - your points are exactly the same as mine. I suppose the main problem is that my friend with a 3.5L V8 RR has the single point system and finds no problem with it at all.

I have only come across one person with a multipoint sequential system (on a Discovery V8 identical to mine) and whilst he too was pleased with it, the difference seemed negligible to me and he agreed that the extra

 

[CliveV]

WOW...what a response.

Thought I might get a couple of replies but not this many. Even though some of the posts are very technical, its helps give an overall picture. I was originally looking at the pump cost for LPG vs Petrol/Diesel. I really hadn't thought of the possible tech issues regards engine wear etc etc

Thanks to all the replies, I now have a good list of things to consider.

Many thanks to all who have...and may still contribute..

David

David - do look at the DTI website I flagged up earlier. Good solid info and some excellent case histories as well as the background on why LPG is taxed less and will remain lower taxed for some time.

I think this thread shows that those that use LPG love it. Those that do not hate the fact that we get cheap clean fuell!!!

 

[peter_5095480]

I towed with 1.6 16v scenic auto with LPG, part ex`d the car after removing the conversion had it refitted to my 2.0 16v espace and now love it. love being able to go out for a drive in the country with the family and having money in my pocket for extras not in the Chancellors. yes I still tow and no there is no noticeable change in power. Modern LPG multipoint systems mimic the ecu so run much the same. there is a small drop in MPG but who cares at 39.9ppl.

 

[Bigpow_5039962]

Just a couple of quick notes. Not all garages do the same work,so dont go for the cheapest (ive seen bad work). V8 range rovers are an excellent conversion. LPG does creat a lot of water in the exhaust system s make sure you give it some good runs to stop the rot. I know of someone that runs on bottle gas as well in a rangerover with an balloon kit , not sure if its legal buts its a cheap way to get about ....

 

[CliveV]

Illegal most certainly.

Not least because his insurance will null & void because it is not an approved system.

This guy is remarkably stupid Bigpow. He is putting his safety and the safety of all those around him in jeopardy.

 

[Bigpow_5039962]

Clive hes been running it for years and as you said insurance wise its illegal if it wasn't informed but its the same systems in principle as hot air balloons, fork lifts (I had one for years with a bottle behind me) and caravans so its quite safe in principle.