CNG conversion

[MadMac]

We're going to get a new 1.6l Sonic for my wife and I'm contemplating with a CNG conversion for that small beast.

Still having an Optra with LPG which while cheap is a lousy open loop system (injecting the gas just after the air filter without control for the engine's computer and burning some 10l/100km), I'd be interested in some closed loop options, if available.

I know LPG to some extend but haven't really touched CNG with it's high pressure fuel and whatever comes after the tank. Certainly more complicated than LPG, which also makes it more dangerous to let some local "experts" handle it.

Any suggestions where to start and what/where to look for? Bangkok or Chiang Mai would be good. Thanks!

[thailoht]

This is an quite an interesting approach!

Maybe it's the terminology that confuses me, but why are closed looped systems preferable to open looped systems? Why is 'injecting the gas just after the air filter without control for the engine's computer' in your open looped system a bad setup?

Also, how is the interior volume of space of your Sonic, isn't this car supposed to have one of the largest in its class?

[VocalNeal]

I have a "simple" system. Have you calculated how many kms you will have to drive to pay for a "hitech" injection system? 10l/100km seems OK that is about 1.25bhat/km. If you have a 45l tank that is about 450kms per tank. You'll only get about 200 from CNG.

Unless my math is wrong. Sonic gets 6.5l/100 kms on petrol. So at 28% less for E85 that's about 8.3l @23.58 = 195 baht/100kms. Based on your Optra it would take about 60,000 kms to pay for the injected LPG conversion at current prices.

On the other hand I think E85 is rarer than LPG. But if you live near a station!

BTW I notice that for some reason the 1.6 Sonic doesn't list power steering as a feature. Are you sure your wife doesn't want power steering? (But I've been wrong before)

Edited December 7, 2013 by VocalNeal

[thailoht]

I have a "simple" system. Have you calculated how many kms you will have to drive to pay for a "hitech" injection system? 10l/100km seems OK that is about 1.25bhat/km. If you have a 45l tank that is about 450kms per tank. You'll only get about 200 from CNG.

Unless my math is wrong. Sonic gets 6.5l/100 kms on petrol. So at 28% less for E85 that's about 8.3l @23.58 = 195 baht/100kms. Based on your Optra it would take about 60,000 kms to pay for the injected LPG conversion at current prices.

On the other hand I think E85 is rarer than LPG. But if you live near a station!

BTW I notice that for some reason the 1.6 Sonic doesn't list power steering as a feature. Are you sure your wife doesn't want power steering? (But I've been wrong before)

Some very interesting points:

- Must drive ~60,000km to 'pay' for the cost of a LPG conversion.

- Sonic's FE ~15.3L/km or a whopping 36 mpg!

- The Thai version of the Sonic doesn't list power steering??

Thanx!

[MadMac]

I don't think there is any new car without power steering. Perhaps a terminology issue. They have some electric assisted power steering. Whatever that means. Doesn't really matter as long as she doesn't scratch the walls .

For the LPG with the open loop, the intake of gas is purely regulated by the air flow. There is no proper injection (on/off) and the engine runs almost always sub-optimal. Simple indication for this is the O2 sensor, you can read this with an OBE analyser. Also as a result the yellow engine light comes on every now and then. Besides that the fuel consumption is way too high with 10l/100km, but for the low price it doesn't matter.

Calculation wise, don't know how you arrived at 60000km, other that your petrol price assumption of 23.58B is slightly too low

Realistically I can drive the 700+ km from Bangkok to Chiang Mai for 1000B on LPG or for 2000B on Petrol. A typical LPG conversion cost ~20000B. This means after 20 trips or 14000km it paid for itself, that is in less than one year. Given a closed loop system which should drastically reduce consumption and CNG at 1/3 of the petrol price it should break even earlier. The open variable here is the availability and price of such closed loop system.

[Spoonman]

Chevrolet Thailand website lists the LT Sonic comes with Electric Power Steering but the LTZ does not.

[MadMac]

No idea about the power steering and the website. Will let you know, when we have the car .

[Spoonman]

No idea about the power steering and the website. Will let you know, when we have the car .

http://en.chevrolet.co.th/cars/sonic-5-door/features-and-specs/features-and-specs.html

[MadMac]

It's a mistake on the website, the brochure has "Power Steering" for all models.

https://en.chevrolet.co.th/bypass/download/th/Sonic_Brochure_EN.pdf

Edited December 7, 2013 by MadMac

[Spoonman]

Well there you go.

[thailoht]

No idea about the power steering and the website. Will let you know, when we have the car .

http://en.chevrolet.co.th/cars/sonic-5-door/features-and-specs/features-and-specs.html

It's a mistake on the website, the brochure has "Power Steering" for all models.

https://en.chevrolet.co.th/bypass/download/th/Sonic_Brochure_EN.pdf

Is this model shipped from the USA and assembled here?

[VocalNeal]

Calculation wise, don't know how you arrived at 60000km, other that your petrol price assumption of 23.58B is slightly too low

Realistically I can drive the 700+ km from Bangkok to Chiang Mai for 1000B on LPG or for 2000B on Petrol. A typical LPG conversion cost ~20000B. This means after 20 trips or 14000km it paid for itself, that is in less than one year. Given a closed loop system which should drastically reduce consumption and CNG at 1/3 of the petrol price it should break even earlier. The open variable here is the availability and price of such closed loop system.

I used the E85 price from http://www.eppo.go.th/retail_prices.html 23.58 Baht/l.

As a Sonic can use E85 and as you are concerned with economy that is the cheapest fuel. I factored in the lower calorific value at 28%. I used 40,000 baht for the "injection" conversion as you said you wanted a "closed loop" system.

If you install a simple system like the one I have, assume 20,000 is correct and also as yesterday I paid 13.53 for a litre of LPG. It will take 36,000 kms to pay for itself. If the cost is more than 20,000 well...

Maybe I could add that my calculations get a saving of .55 Baht per km from LPG over E85. E85 at 195 baht/100kms (using Sonic numbers from the internet) and now 135 baht/100kms using your 10l/100kms from your Optra.

As I said I have been wrong before. Please feel free to check my numbers.

I am happy with LPG after 150,000+ kms but the numbers have to be crunched. Not doing so would result in an average Joe public driver being conned into a 40,000 baht system and at 2000 kms per month driving would take 36 months to just to pay for the conversion. ( Less if using Shell V Power!)

Edited December 8, 2013 by VocalNeal

[MadMac]

@VocalNeal

Thanks, got it now . I was comparing it to the Optra, not the Sonic with E85. Actually I saw E85 at Caltex today. With that you are probably right. That changes the game. The cheapest LPG here in CNX is 14.25B. So it's about 9B cheaper. CNG is rather rare it seems but haven't really looked out for that.

Have to see how much the car burns in real life conditions, then do the maths.