In singapore the petrol prices are increasing and many sellers are offering CNG cars as alternative.
Anyone with experiences on CNG cars, and I would like to consider using CNG for my next change of car.
The figures given by sales personnel are often mixed with much untruth.
Anyone cares to enlighten me on CNG cars and their advantages as well as disadvantages.
Singapore is planning to open up more CNG refuelling stations by year end.
Thanks for your advice.
Sorry, I thought it was so common a word.
CNG stands for Compressed Natural Gas, as part of the gas found inside the crude oil well, which is normally burned off, and nowaday they are sold as Natural Gas.
CNG compressed the Natural gas and used them to feed directly into the engine of petrol engine car. Not too sure of the extact way - but I guess by pass the petrol fuel filter into the injection block.
Hope this clarifies CNG.
With regards.
Thanks for the clarification.
The US National Parks service uses natural gas for many of its vehicles but I do not know of any mass produced cars that run on natural gas. Hydrogen-powered cars seem to be the next big thing. I know GM and Honda are producing hydrogen-powered cars now but I do not think either is widely available.
The problem with natural gas and/or hydrogen gas is there is limited infrastructure to fill these types of vehicles. California has discussed adding hydrogen filling stations throughout the state. I am not sure what the timeline is for adding these stations though. Those of us that do not live in California have no access to hydrogen filling stations.
CNG/LPG cars are widely available from the factory in Australia, as well as in most of australias export markets.
General consensus is that while it is cheap, it burns a lot hotter than standard petrol so you need hardened valves and heads to deal with it. Most aftermarket CNG/LPG conversions only really deal with the mixer and the tank but not the valve hardening - so its ushually best to choose a car that came from the factory specifically set up to run gas.
Also, you can expect reduced power outputs because most engines are specifically designed to run on petrol rather than gas.
Yes, thank you Andrew426, for the info
| Quote: |
General consensus is that while it is cheap, it burns a lot hotter than standard petrol so you need hardened valves and heads to deal with it. Most aftermarket CNG/LPG conversions only really deal with the mixer and the tank but not the valve hardening - so its ushually best to choose a car that came from the factory specifically set up to run gas.
Also, you can expect reduced power outputs because most engines are specifically designed to run on petrol rather than gas. |
It is good to know these, as in Singapore, most of the options is for retro-fitting the CNG into the new/used cars. I was given the impression that that is all involved.
Currently, I have not really seen many carmakers selling cars specifically for CNG in Singapore.
Will have to visit several of them before I make a choice.
Thanks and by the way - is CNG becoming widespread in NZ? (Since you are from there).
With regards. I was told that you still need to run on petrol, and switch over to CNG when the RPM runs above 2000 revolution per minutes.
This puzzled me, as am I looking at CNG or CNG+petrol cars?
anyone cares to enlighten me on this?
With regards.
CNG/LPG was way more common here in the 70s and 80s, but seems to be coming back now and we are seeing more dual-fuel cars.
Most CNG/LPG cars need to start on petrol and be switched over to gas once they have heated up, similar to a choke on an old carbed engine. Also a lot of people with CNG/LPG cars will switch to petrol if they need a little extra power for hills, towing etc.
That being said, occasionally you do see LPG dedicated cars that have had the entire petrol fuel system removed and run solely on gas.
CNG is used in Delhi, India. Its a lot cleaner fuel and also increases the life of the engines... U can change to it if u want to... I feel u wont regret
Wow, it is great to have
1. So many from different parts of the world reviewing (India, US, Singapore, NZ, Australia)
2. Different technologies (CNG and now LPG and even Hydrogen)
3. Different time era (From past era where CNG/LPG is used and a comeback now)
4. Even how the technolgy works (CNG needs petrol to heat up, and to have extra power).
Good I am truly gaining lots of useful information.
But sorry to said - it is still unsettled as the scope is widening, and I have to made a decision on my next car based on my country's available options.
Truly thankful for all your valuable contributions, and I am sure I will be making a more "informed" choice than before this thread of discussion.
With best regards - do keep the discussion going, we can learn more.
OK so here is my first post, I thought I'd post here first since I love this stuff and have plans of my own, on how to costruct a vehicle that runs on gaseous fuels.
I worked in a shop in Denver Colorado for 4 years building custom cars and hot rods. Prior to that I spent pent 9 years as an auto mechanic and at one point held an ASE Master certification. Cars and Trucks are pretty cool, but the Auto industry is kind of a downer, and I now work as a Network Engineer, and make a lot more money.
Anyhow, given my extensive knowledge of vehicles and the ICE (Internal Combustion Engine) I have a few things to let you in on.
1st off any ICE does not care if it runs on CNG/LPG, Propane, Map Gas, Gasoline, Alcohol, hydrogen, Brown's Gas (H2O2) or any other fuel that you can think of. Really the only concern that you have in running an engine on Gaseous fuels is the burn ratio. What that means is the fuel to air ratio. Gasoline has a very narrow range of burn. It has to burn between 14.5 to 15.8 parts of air to one part of fuel. Basically if you can imagine 15 little equal size cubes of air, and on equal size cube of fuel. OK because gasoline runs in a narrow range, and has additives in it to slow the rate of combustion, it can be burned in a high compression engine. Fuels like CNG/LPG Hydrogen, etc have a much wider burn ratio. Take hydrogen for instance, it has a burn ratio of between 12 thru 20 to one. Low Octane gas has a slightly wider burn range than high octane fuel, and as such causes predetonation. This is a condition where the fuel ignites from compression before the spark plug ignites the fuel. The ratteling that you hear from predetonation is actually the piston ratteling in the bore, and if it becomes to severe it can cause major damage. Shatter pistons and the like. The cure for predetonation is to lower the compression ratio. This does sacrafice horsepower, high compression engines make substantially more horsepower. By lowering the compression ratio you can burn fuels of varying ratios, and not have the concern of predetonation. In computer controlled engines predetonation is not near a concern since these engines have an anti-knock sensor and will retard the timing to control it. This is done by the computer, and the driver never knows what is going on.
After having done quite a bit of research I can tell you that an engine running between 8 and 9 to 1 compression will handle almost any fuel you can dump in it. Oh, Compression ratio is similar to fuel ratio, the difference being say 8 to one compression is where you take 8 equal cubes of air and compress them to 1 same size cube of air. When compression ratios start getting much over 9 to 1, running on alternate fuels can be problematic.
As far as fuels go so much about tempature and their destuctive forces on un-hardened valves is myth. 1st off any valve is hardened steel. Putting hardened seats in cylinder head to accomdate hotter fuels is just propaganda by manufacturers to get you to one continue to burn gasoline, and two to sell parts. It is BS and here is why!
First off I have built 2 propane powered 4X's nice thing about propane over Gas is that you can carry extra cylinders over Jerry cans on the trail, and they are much less likely to get punctured. Plus you compress the fuel in the tank and can get a much longer range out of the same size tank of gasoline. The problem that I had with both these trucks is that they ran too cool and did not warm up enough to get the heater and defroster to work well. Had to put in a higher temp thermostat which then created a too hot condition when run on gasoline, since they were dual fuel vehicles and did have a small gasoline tank in them. I do not have experience with CNG or LPG, but given my experience with Gasoline I do doubt the claims that they run hotter than it. Gasoline is a very hot running fuel!!
Back in the 80's I was still driving a 1970 Pontiac GTO with a 10.75 to 1 compression 400 Cubic inch V8 engine. It was built to run on leaded gasoline. I was told repeatedly that it would burn valves and cause damage to the heads if I ran it on unleaded gasoline without adding hardened seats and valves to the engine. Since I do all my own work I felt it was a waist of money to add parts to a damn good running engine. I figured screw it, I'd run it on unleaded gasoline until it burnt a valve and then I'd pull the heads and have them converted. In essence I'd only convert over after it failed.
I'm here to tell you, I ran 85K miles on that engine, and it was still running very strong, and a compression check revealed minor loss of compression over what it was new, which was more than acceptable for an engine with 85K miles on it. After that I sold the car, I am still friends with the guy I sold it to, he restored it, but declined to rebuild the engine since it ran so strong, the engine to this day has about 128K miles on it, almost all on unleaded fuel and has never burnt a valve!!
As far as California goes I belive they have a 2010 date to have hydrogen powered highways, that is enough hydrogen refueling stations to be able to drive around the state in a hydrogen powered car.
I have a 1979 Chevy 1 ton Pickup. I plan on running it on dual fuels, on liquid fuel tank for gasoline, alcohol, etc. and one compressed fuel tank for gaseous fuels.
Impco sells gaseous fuel components to convert engines!
http://www.impco.ws/products.htm
They also sell whole engines gaseous fuel ready.
As far as having to start them when cold on gasoline I would say no from my experience, the propane trucks I built started fine on some very cold colorado mornings on propane alone!
Most manufacturers like Chevy, Ford, Dodge, Toyota etc. produce gaseous fuel vehicles for fleets and industry use.
Here's a link about FAQs from a gaseous fuel vehicle website has pages on Ford CNG trucks!
http://www.uniongas.com/aboutus/aboutng/ngv/faqs.asp
Also here is alink to a website about hydrogen powered highways!
http://www.hydrogencarsnow.com/hydrogen-highway.htm
For my truck I plan on building in a second altenator on the engine and running an onboard electrolyzer and using brown's gas that compresses off the electrolyzer into the gaseous fuel tank.
The down side of running hydrogen is that hydrogen being a very small atom under compression will over time compromise the strength of the tank. It impregnates that metal and makes it brittle. So tanks only have around a 2 year service life. Supposedly there were a few manufacturers that were going to come out with hydide tanks. But that is another story.
I say convert your vehicle to run on gaseous fuels, great idea. Before you do so, don't turst me or anyone else, go search out as much information on it for yourself on the web. Yahoo has some great discussion boards on it, and find out as much as you can so you know what you are talking about when you go to have the work done!!
Good luck with all of it!!
Dave Thanks BigGeek for that very comprehensive feedback to this thread.
I am sure you are truly the "hands-on" type, no wonder you switch to networking.
I am also sure that not many will imagine themselves fixing the vehicle themselves.
It was truly a eye-opener for me.
Thanks and do take lots of pre-cautions on your experiments/hobby as others can be affected if there is any mistakes done.
Thanks and with best regards.
shenyl,
Thanks for the reply!
No problem on the safety aspect of it, not to worry, as you can tell I research things pretty well before I start actually doing the work.
I hope that you make the move to gaseous fuels as I feel that it is a great alternative to gasoline!
Keep us posted on what decision you make and how it goes!
