LPG Conversion - 1 Km for 1 Baht?

[Edge]

Long time since i looked in to this,

U use more cng per km/mile compared to LPG (25-40% more) Hence fewer miles on a tank

CNG uses bigger injector nozzles hence not interchangable with LPG

LPG is stored in liqued form at high pressure and needs a low pressure vaporator.(True for CNG?)

CNG is more readily availible in Asia compared to LPG.

 

As said above - in Thailand the lack of CNG stations is one of the reasons it isn't popular.

 

That may change over time of course.

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[Cartmanfinn]

Price of NGV is 10,50 baht/kg, LPG is 21,13 Baht/kg. LPG prices are more likely to go up because it is not produced in Thailand. Thailand has its own sources of NGV and it is also subsidized by Thai government.

[Edge]

Price of NGV is 10,50 baht/kg, LPG is 21,13 Baht/kg. LPG prices are more likely to go up because it is not produced in Thailand. Thailand has its own sources of NGV and it is also subsidized by Thai government.

 

21.83?

 

Did I not pay 12.?? yesterday?

 

If it lasts a year I'll be fine and I guess all those LPG stations will be fcuked or change over to NGV?

 

Then I'll change too perhaps, but if enough people go with NGV then the Govy won't need to subsidise it any more right?

.

[Edge]

edit...................

[Cartmanfinn]

21.83?

 

Did I not pay 12.?? yesterday?

 

If it lasts a year I'll be fine and I guess all those LPG stations will be fcuked or change over to NGV?

 

Then I'll change too perhaps, but if enough people go with NGV then the Govy won't need to subsidise it any more right?

.

 

LPG is sold by liter at gas stations, NGV is sold by kg. Density of LPG is about 500 grams/liter. Thus NGV is about 50 % cheaper than LPG.

[Edge]

LPG is sold by liter at gas stations, NGV is sold by kg. Density of LPG is about 500 grams/liter. Thus NGV is about 50 % cheaper than LPG.

 

Ah - beg your pardon.

 

Apparently the prices of both are only pegged until 15th August too.

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[ChiliHead]

The long queues for CNG aren't just because of a lack of stations. CNG is a gas, so it must be pumped into the tank at pressure. This takes more time than to fill up with LPG (a liquid). To make matters worse, some of the older stations have lower pressure and will take longer. Then as if that wasn't bad enough, sometimes you have the big trucks with 8 LPG tanks to fill.

 

And as someone pointed out, you don't get much range on CNG. A friend had CNG and while it was good for saving money on long trips it required a lot of stops.

 

I doubt all the LPG stations will close. The Thais depend on LPG for cooking. I guess they might start a 2 tier pricing structure for cooking use vs. vehicle, but I can't see them discontinuing it.

[ytnom]

Always have used LPG here in Thailand.

Some facts for the interested:

 

LPG is stored in Liquid form at relatively low pressure. It is a gas at atmospheric pressure (the pressure of the air around us) but at around 5 kg/sqcm (bar or 72 PSI) it becomes Liquid. roughly 250 liters of gas become compressed into 1 liter of Liquid LPG.

It is normally stored at around 7 bar (100 PSI). This would mean that a 50 liter tank can actually hold 12,500 liters of LPG in gas form!

 

This is the biggest difference with CNG/NGV. CNG does not compress into Liquid, so to get any usefull amount of gas into a tank, it needs to get squeezed in at very high pressure, normally between 200 and 250 Bar (3000 to 3600 PSI).

Even at this pressure, they still don't come near having the same storage capacity as an LPG tank, which directly results in the lower range you get out of a tank.

Additionally, a tank holding up to pressures this high has to be pretty strong, and this will weigh heavily. Often when getting a car converted to CNG also involves beefing up the rear suspension!

 

An equivalent sized CNG tank will have about 40% of the range compared to LPG. So 180 to 220 Km on CNG, similar sized LPG tank will give you between 400 and 500 km of range!

 

The calorific value of LPG is lower then that of petrol, so liter per liter you will get less mileage out of LPG. With a good tuned modern system (sequential multipoint) this difference should be around 15%. So when you calculate savings you cannot only use the price/liter difference, you have to accomodate for the fact that you'll burn 15% more LPG per kilometer!

 

Safety wise, both cng and lpg are very safe when using modern, certified systems. The negative of LPG is that it is heavier then air, so when you have a leak it can pool in a low area and sit their until blown away by wind, or burned. CNG is lighter, so it disperses very quickly into the air.

 

The drawback of CNG is the high pressures used. If a tank would fail (during an accident for example), fire will not be your worry, but rather pieces of tank and car getting catapulted away at very high speeds! The whole system has to be much beefier, from tank, to pipes, everything.

 

LPG has a very high ocatne number (over 110), so if wanted you could modify your car engine (higher turbo boost pressure, higher compression ratio's, different ignition timing) and get much more power and efficiency out of the engine compared to petrol. However, the engine would probably self destruct pretty fast if tried to run on petrol, hence not done on road cars.

 

Another thing to be very carefull with. Both LPG and CNG burn at a significantly higher temperature then petrol. Inside the combustion chamber this is no problem as the engine's cooling system can easily handle the heat. Maybe colder plugs might be needed to avoid them wearing out to fast.

The problem lies with the valves and the valve seats. Especially on modern 16 valve engines, you have a fairly big chance of needing to do a top end overhaul after between 80,000 and 150,000 km. This can eat drastically into your savings made running LPG.

On modern engines you are advised to install a "valve saver" system. This sytem continuoulsy injects 2 stroke oil, albeit a a much lower rate the a 2 stroke engine would use. This helps to coold down the valves signifficantly.

 

Older 8 valve engines usually can run forever on LPG. As do turbocharged engines as they already have better heat resistant valves and seats.

The volvo 700 and 900 series engines (b230), the VW v5 engines (used in the older carvelle's) are perfect to run on LPG, and due to their poor economy also realize very big savings!

 

Then finally on pump prices.

Both LPG and CNG are heavily subsidized. Not sure on the real price of CNG, but LPG without subsidies would cost roughly 40% of the price of petrol (not gasohol, straight petrol) so currently probaly 17 to 18 Baht per liter.

 

Will the Thai government remove or lessen these subsidies? Very hard to predict. On both CNG and LPG it's almost political suicide to do so.

With CNG they'll have all the taxi's and a big amount of truck drivers/operators very angry. It would eventually even influence retail prices of pretty much everything transported by road and so increase cost of living for the average Thai citizen.

 

With LPG it's even harder. Thailand cooks on LPG. If every houshold, restaurant, and roadside stall suddenly has to pay 50% more for their tank of cooking gas, cost of life will increase substantially.

 

Several of the recent different governments have talked about it (the last 5 years or so now), and even tried to implement, with big protests as a result and finally "indefinite" postponement of such plans...

 

Some other tips, installing either LPG or CNG will invalidate any warranty you still might have.

AFAIK there are no new cars being sold with factory fitted LPG, but quite a few with CNG.

 

Following spring to mind:

Chevrolet Optra

TATA pick up truck (ONLY cng, so not dual fuel)

Mitsubishi Lancer (old model)

Mitsubishi Triton (single cab, mega cab and dual cab), all 2,4 liter manual gear.

A few models of the Proton passenger cars.

 

The above all come with full factory warranty, usually 3 years 100,000 km

 

Hope this can be usfull to some!

 

Cheers

 

 

pffff, made me thirsty

[gogo dog]

Great information thank you Ytnom. As soon as my car is out of warranty it's going to get a LPG kit.

[Hellbender]

Great information thank you Ytnom. As soon as my car is out of warranty it's going to get a LPG kit.

I don't know about Thailand but many authorized car dealer are retro fitter of LPG/CNG kit thus the warranty of car is valid or you can go for extended warranty.

 

BTW world known LPG as a cooking gas and CNG with more commercial use.

 

Edit: Why not speak to your car dealer about installing a LPG kit and continue with warranty. Just a phone call i guess.

Edited August 9, 2012 by Hellbender

[ytnom]

I don't know about Thailand but many authorized car dealer are retro fitter of LPG/CNG kit thus the warranty of car is valid or you can go for extended warranty.

 

BTW world known LPG as a cooking gas and CNG with more commercial use.

 

Edit: Why not speak to your car dealer about installing a LPG kit and continue with warranty. Just a phone call i guess.

They won't do the warranty (asked before!)

 

The main reason is with the factory installed CNG kits, they also change the valve seats and valves. They do modify the engine itself to be able to take the extra heat.

[Edge]

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The calorific value of LPG is lower then that of petrol, so liter per liter you will get less mileage out of LPG. With a good tuned modern system (sequential multipoint) this difference should be around 15%. So when you calculate savings you cannot only use the price/liter difference, you have to accomodate for the fact that you'll burn 15% more LPG per kilometer!

...................................................

 

Thank you for the most comprehensive assessment so far, especially as it relates to Thailand.

Having read it, I can't help feeling that this should have been the thread opener and my OP just a practical example.

 

I'm still very happy with my conversion.

The first tank full was not run as a trial and I deliberately ran it out of LPG to check that it switched to petrol and back correctly, which it did.

Interestingly (?) after a brief stop, when I set off again after it switched to petrol, it once more ran on LPG for about 10 kms before switching again.

 

My Donut is the 51 litre size and when I filled up it took almost 47 litres (612 Baht) which is as the garage suggested, about 5 litres before empty. That's what made the small 41 litre size i.e. 36 usable, less appealing.

 

Having reset the odometer, I now wait to see how far my 612 Baht takes me.

With regard to the title, please note the '?' mark.

I'm not really that optimistic.

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[bodbod]

easy way to work it out if your car dose 10 mpg on petrol you will get 18 mpg on gas ish i have run on gas for years will never go back to derv

[ytnom]

Here in Thailand it's also an easy and exact calculation!

 

If you know your cost per km on petrol, then you divide by the liter price of the petrol, multiply by the price of LPG and then add 15%!

 

So currently if your car runs on gasohol 91 and costs 3 Baht/km you'll get following:

 

3 / 36.5 =0,0822

0,0822 X 11.5 =0,945

0,945 + 15% = 1.087 Baht/km

 

At current prices it indeed means 3 times more km for your hard earned money!

 

You only need around 12000 km for payback...

 

And it's so much more fun filling up for 500 - 600 Baht, compared to 1500 - 2000 Baht on petrol!

[Edge]

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At current prices it indeed means 3 times more km for your hard earned money!

You only need around 12000 km for payback...

And it's so much more fun filling up for 500 - 600 Baht, compared to 1500 - 2000 Baht on petrol!

 

HaHa - I've got to agree with you on the fun part.

 

I'm afraid I didn't do exact calculations before re' petrol, but guessed roughly as you've said.

 

The only other factor which may come into play is that if one was a little frugal with the A/C and the use of the accelerator running on petrol, the lower cost might result in less care being taken to be fuel efficient.

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