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Old 15th October 2014, 20:23   #301
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Default Re: ARTICLE: CNG vs LPG Comparision

Hello guys,
Does anyone know if there's any specific reason why CNG and LPG fuel indicators are always in the form of green LEDs, and not an analogue or digital gauge like petrol and diesel?
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Old 15th October 2014, 20:39   #302
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Originally Posted by RonXRi94 View Post
Hello guys,
Does anyone know if there's any specific reason why CNG and LPG fuel indicators are always in the form of green LEDs, and not an analogue or digital gauge like petrol and diesel?

Maybe they're like that here in India, but thats not necessarily true in other parts of the world. I have owned cars with LPG where the normal petrol gauge automatically became the LPG level when switching to LPG and vice versa.

If you image google for LPG gauge you will find a vast array of both LED as well as gauges in all sort of shapes and formats.

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Old 16th October 2014, 11:21   #303
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Default Re: ARTICLE: CNG vs LPG Comparision

Availability of these alternate fuels need to be taken into account. I was in Goa for a year with my wagon r duo and the nearest LPG gas was at a distance of some 30-35 kms. So not feasible and economical. In a years time, the pipe choked and no way I could fill gas on my return to Pune. Had to shell out a decent amount to get it rectified. Plus the LPG smell gets into cabin which can be disturbing. Also experienced power loss as compared to petrol.
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Old 17th October 2014, 08:53   #304
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Default Re: ARTICLE: CNG vs LPG Comparision

I'm using WagonR Lxi Duo for the last two years. Luckily for me, lpg station is available on my way to office and I had done around 25000 kms in under 2 years, with quite a few vacation trips. During my long trips, I use
http://www.iac.org.in/alds-stations to check out the LPG stations enroute. (Not sure if this link is shared already). Note that the information on this site about the fuel pumps is not 100% accurate, but it served my purpose, I would say up to 75%.

Regarding power loss on LPG, I actually have the reverse issue. I observe a bit of power lag when i run on petrol compared to lpg. All my city runs are on LPG above 95% of the time. And my highway runs are above 80% on LPG(thanks to the above link)...Does it have anything to do regarding the power loss on petrol?

I did not bother to check with Maruti SA's regarding this as most of my running is on lpg and I don't want them to try something and screw up my LPG performance.

By the way, I recently tried sedate driving (80-100) no high revs (not my regular style) on my recent highway trip and mileage returned as 16 kmpl. Can it be bettered?

Any inputs from experts are hugely appreciated...
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Old 17th October 2014, 10:07   #305
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Default Re: ARTICLE: CNG vs LPG Comparision

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Originally Posted by ramassrs View Post
I live in Bangalore and am keen on owning / using a CNG kit fitted car for obvious reasons of economy and eco-friendliness of the fuel.

I welcome readers/participants in this forum to provide any update on this.
Thanks.
Sorry for late reply bro, saw your post only. CNG is already available in Bangalore and you can see various boards saying gail pipeline do not dig. They are also laying pipes in the whitefield railway station area for CNG. Some industries in Hoskote/ kolar road are getting gas for genset use. But setting up pumps will require additional setup in terms of end of line compressors and in line too. All this may take some time. Next year we will see host of activities, the biggest hurdle in CNG is now the APM pricing once that is set right (increased) by the government we will see more production of CNG and thus better availablility.

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Originally Posted by CoolCarNi View Post
Availability of these alternate fuels need to be taken into account. I was in Goa for a year with my wagon r duo and the nearest LPG gas was at a distance of some 30-35 kms. So not feasible and economical. In a years time, the pipe choked and no way I could fill gas on my return to Pune. Had to shell out a decent amount to get it rectified. Plus the LPG smell gets into cabin which can be disturbing. Also experienced power loss as compared to petrol.
One should understand the nature of these fules before using them. LPG is heavy and combustible thus resides at the bottom of floors (in this case boot floor) on the other hand CNG is lighter and required 5-15% concentration to burn. Thus will vanish in air and many times not burn.

The octane numbe rof LPG is around 110, as compared to petrol the flame propagation in gaseous fules is slow thus they give less power for the same petrol engine. A LPG / CNG engine, will need a proper designed ventury (fuel mixing device) or a computer based fuel valve or injector, revised timing and a higher comp ration to harpen the same powe out of these.

Since LPG is still imported, it is not that economical to run. And since these fules are dry they cause wear to the top end of the car. Also LPG contains an additive methyl mercaptan which gives this foul odour to the smell less gas so that it is easy to detect. Since the gas is heavy and possible source of fire when leaked. Where as CNG does not need one. However in power plants we still use gas leak detectors even for CNG.

The cause of blocking of pipes could be due to this residual Methyl mercaptan clogging up.

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Originally Posted by mrbaddy View Post
Regarding power loss on LPG, I actually have the reverse issue. I observe a bit of power lag when i run on petrol compared to lpg. All my city runs are on LPG above 95% of the time. And my highway runs are above 80% on LPG(thanks to the above link)...Does it have anything to do regarding the power loss on petrol?

I did not bother to check with Maruti SA's regarding this as most of my running is on lpg and I don't want them to try something and screw up my LPG performance.

By the way, I recently tried sedate driving (80-100) no high revs (not my regular style) on my recent highway trip and mileage returned as 16 kmpl. Can it be bettered?

Any inputs from experts are hugely appreciated...
Mrbaddy, please provided info on the make and type of kit installed. Secondly is the efficiency that you quote is on petrol or on LPG.

If you give us better information as to - close loop or open loop kit, Nox ppm and O2 %. last tune up done on petrol. Conditions and type of plugs, KM on them. Air filter condition, we can guide you further.

In general the lack of performance in petrol on LPG vehicles is due to clogging of injectors due to deposits. Or simply put clogging of fuel paths.
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Old 17th October 2014, 10:26   #306
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Smile Re: ARTICLE: CNG vs LPG Comparision

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Originally Posted by manishalive View Post
Mrbaddy, please provided info on the make and type of kit installed. Secondly is the efficiency that you quote is on petrol or on LPG.

If you give us better information as to - close loop or open loop kit, Nox ppm and O2 %. last tune up done on petrol. Conditions and type of plugs, KM on them. Air filter condition, we can guide you further.

In general the lack of performance in petrol on LPG vehicles is due to clogging of injectors due to deposits. Or simply put clogging of fuel paths.
Thanks Manish for the quick reply. LPG kit is factory fitted that comes with WagonR Duo (make 2011). If the details you requested cannot be made from that, I'll check the manuals and will update tomorrow..

I bought the vehicle with 10000 on ODO from Varun finance (kind of good deal, non payment of finance by previous owner). So I'm not sure how it is run previously. For the last 25000km, about 95% is run on LPG. And I did regular service for the last two years. No tune up specifically.

As will be quoted by other enthusiasts, I'm more of a driver till now instead of an owner.. I'm learning lot of things after joining team bhp.
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Old 17th October 2014, 10:56   #307
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Default Re: ARTICLE: CNG vs LPG Comparision

Some small info about the fuel tanks, LPG tanks are designed to store fuel at a pressure of 7-8 bar, for usage on vehicles it is tested to an internal pressure of 48bar, so a LPG tank is many times stronger and safer than petrol/diesel tanks and can withstand any pressure deviations. Unlike petrol/diesel tanks, in a LPG tank the fuel is released via a safety valve and if the pressure inside the tank increases above a preset safety level, the valve blows off, this preset pressure level is always much lesser than the pressure at which tank will explode, so an explosion is avoided unless with a source of ignition nearby
The major reason for complaints like poor performance is the use of domestic gas and closed loop LPG kits. Domestic gas contains mercaptan which is used for smelling a leak, this is corrosive in nature. Use of domestic gas with sequential injection kits causes clogging of injectors and subsequent drop in performance. Doemstic gas also damages the engine components because of its dense nature. AutoLPG is the best form of any LPG and does not have corrosive characteristics and does not cause any wear and tear as claimed by people.
I have used LPG cars extensively with both OEM fitted and after market kits and can vouch for its performance. Forget the SA of Maruti or anyone they do not have any idea of LPG kits or usage. From my own experience with Trident I have seen that the the service guy or the SA could not identify the LPG kit fitted in our vehicles when we gave it for servicing, only after seeing the spare wheel outisde they asked? I suggest using platinum or iridium spark plugs, it helps and also lasting for a long time.
LPG is a clean burning fuel than petrol. The safety methods are not followed during LPG kit installation, the filler valve is fitted inside the boot because people do not like to have it outside as people still carry a feeling of LPG cars as cheap, some people hide the valves under rear bumper. Switch to Auto LPG and sequential injection kits you will have no complaints. Hyundai is the only OEM still using age old LPG kits in their cars, Maruti and GM have switched over to sequential injection kits.

Last edited by deehunk : 17th October 2014 at 10:58.
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Old 24th October 2014, 21:58   #308
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Originally Posted by deehunk View Post
Some small info about the fuel tanks, LPG tanks are designed to store fuel at a pressure of 7-8 bar, for usage on vehicles it is tested to an internal pressure of 48bar, so a LPG tank is many times stronger and safer than petrol/diesel tanks and can withstand any pressure deviations. Unlike petrol/diesel tanks, in a LPG tank the fuel is released via a safety valve and if the pressure inside the tank increases above a preset safety level, the valve blows off, this preset pressure level is always much lesser than the pressure at which tank will explode, so an explosion is avoided unless with a source of ignition nearby

Most modern petrol cars these days have a pressurized fuel system, as part of the overall emission control. So, there tends to be valves to accommodate for (over) pressure and vacuum. Obviously, pressures are much lower then on LPG tanks, but they are pressurized.

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Old 28th October 2014, 16:01   #309
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Default Re: ARTICLE: CNG vs LPG Comparision

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Originally Posted by deehunk View Post
AutoLPG is the best form of any LPG and does not have corrosive characteristics and does not cause any wear and tear as claimed by people.
Dear deehunk, There will still be wear and tear on account of dry and non lubricating nature of LPG. How much depends on the metallurgy of cylinder head components. Also closed loop kits are a must and the sequential injection kit is also a type of closed loop. Just that like single point injection and multi point injection. Sequential though is better.


Quote:
I have used LPG cars extensively with both OEM fitted and after market kits and can vouch for its performance. I suggest using platinum or iridium spark plugs, it helps and also lasting for a long time.
True, LPG kits need a good amount of spark, a Healthy Ignition system will help.
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Old 28th October 2014, 17:14   #310
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Default Re: ARTICLE: CNG vs LPG Comparision

The compression ratio of AutoLPG is 10:1, just like petrol. The basic difference in closed loop kit and sequential injection is the way it functions, the former type makes a MPFI car like semi-carburetor type by mixing LPG with Air before letting it into the intake manifold. Closed loop systems are only an improvement over the open loop system used in early days. It uses a single point mixer and vaporiser similar to open loop system, the difference is the mixture is controlled by a mixture controller. The mixture controller reads mixture information from the vehicle's Oxygen or Lambda sensor mounted in the exhaust, an actuator in the form of stepper motor type valve, moves in and out to vary the amount of gas allowed into the engine. This is the only improvement it has over an open loop system but still prone to back firing.
Sequential kits eliminate backfiring in LPG mode as they have injectors fitted to the intake manifold just like petrol injectors and fuel injection is precisely controlled by a dedicated ECM unlike the closed loop kit based on requirement. Cedia was the first car in India to have a sequential injection system then followed by Spark, its unfortunate that both these vehicles are not manufactured anymore. The biggest advantage is the auto switch over mode to petrol when LPG level drops in the tank preventing stalling of vehicle middle of the road.
Closed loop kits can be used only on cars with CI intake manifold and not on new gen cars which have a heat resistant plastic intake manifold and cannot withstand backfire in LPG mode. Nice to see some information exchange after a long time on this thread.

Last edited by deehunk : 28th October 2014 at 17:16.
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Old 28th October 2014, 19:27   #311
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Default Re: ARTICLE: CNG vs LPG Comparision

I have shared a link here for all fellow bhpians, this site has the most useful and relevant information about using LPG as a fuel and the type of kits available in market with detailed explaination.
http://www.go-lpg.co.uk/
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