thoughts?

[SAMI]

Compressed Natural Gas (CNG) as of October 1, 2006 is $0.736 cents per Gasoline Gallon Equivalent (GGE)


SAVINGS CALCULATOR-

Input Variables
Petrol Fuel Price $3.00
Public CNG Price $0.736
Miles per Day 100
MPG 16
Days per week 5
No of Vehicles 1
Ownership Years 5


Usage Gal.
Daily 6.3
Weekly 31.3
Monthly 130.0
Annually 1,562.5


Miles Driven
Daily 100.0
Weekly 500.0
Monthly 2,080.0
Annually 24,960.0


Savings
Differential Cost $1.56
Daily Savings $9.76
Weekly Savings $48.78
Monthly Savings $202.93

Annual Savings $2,435.16
Total Life Savings $12,175.80

Net Cost Variables
Conversion Cost Estimated $12,500
Utah Income Tax Credit up to $2,500
(available upon qualification)
Federal Tax Credit (est) EPACT '05 $8,000
(depends on GVW of vehicle & EPA Cert)
Airport Voucher Credit $2,000
(for qualified vehicles)


Incentive Total $12,500
Net Cost $0.00
Payback Months $0.00



The conversion cost is estimated and may vary from $10,000 up depending on how much labor and number of tanks are required


Monthly and annual calculations are based on a 50 week year

Note for every $0.10 increase in gas price the annual savings is increased by: $243.52


Utah State HOV Lane Use with permit Available

 

[Brett]

Gay



And I didn't read your thread

 

[SAMI]

Gay



And I didn't read your thread

you can be such an ass... how'r your brakes?:greg:

 

[Kiel]

Where did you get the base cng price of 73 cents. That seems crazy low. I hope your not going by home price

 

[Rot Box]

I've been seriously debating this conversion for my daily driver. Anyone have first hand experience with the swap???

 

[Cody]

brett, you're bringing over that spring compressor tonight right?

 

[Brett]

brett, you're bringing over that spring compressor tonight right?

Hmm...no I was going to Eriks for beers.

 

[Brett]

you can be such an ass... how'r your brakes?:greg:

You tell me, sabotage'er

 

[Meat_]

Where did you get the base cng price of 73 cents. That seems crazy low. I hope your not going by home price

Don't most people fill up at home anyway?

 

[1969 CJ-5]

Don't most people fill up at home anyway?

Thats what People in Phoenix do, Southwest Gas will actually install the equipment for you from what I hear.

Also isn't economy on CNG way worse that Petrol Gas? I had a CNG Van for a couple of weeks while I was at Nellis TDY and we had to fill the stupid thing up every day.

 

[DevinB]

PM Mesha on this board. He has a '99(?) Chevy truck with the CNG conversion. He bought it that way though, but he knows more than the average joe about it.

A couple weeks ago, CNG was actually $0.69/gallon at the pumps. I witnessed this first hand. It took maybe $15 for us to go to Loa/Bicknell area and back in a 3/4 Chevy truck. The trick is that only a few stations have CNG available, so you have to know beforehand where you can stop. Richfield has a station with it, so we filled up at Flying J in Springville on the way down, then Richfield on the way back.

 

[SAMI]

my boss's son owns the company that does these conversions...

 

[Milner]

I have driven several state and Questar cars that were cng. I HATE them!!!! Absolutely GUTLESS. The state ones are dual fuel cng/gas. When you switch it to cng it is seriously about a 30% power loss via the seat-o-the pants dyno
Also on the ones I have driven, all say you MUST run regular gas every few fillups to lubricate the motor (rings/valves/etc). And milage SUCKED on cng!! Probably a 30% loss there too. I am sure these issue can be addressed if a motor is built FOR cng, but I wouldn't want a converted one.
I would do propane long before cng.

 

[Rot Box]

I've ridden in vehicles with the option of using propane or gas, and all of them were very gutless, and consumed what seemed like a lot of fuel when switched to propane..... But vehicles setup for propane only seem to not experience any power loss and get competitive MPP.

I wonder if a vehicle running CNG only can be "tweeked" for more power and economy in any way??? Why would the airport shuttles run it if there wasn't some sort of benefit? Some of those vans have 600+k miles Just a thought.

 

[BCGPER]

I operate and build large natural gas fired engines for a living, but I’ll admit I know nothing about the automotive side of it. With that in mind, I can see some flaws in your calculations, as well as having some questions of my own.

Your figure for CNG seems low considering there is about $.50 tax on a gallon of gas. Are they not taxing CNG like they are gasoline?

Some have mentioned a decrease in power and economy. Natural gas has a fairly low octane rating. It’s likely that you would have to retard your engine timing to prevent detonation. This is the cause of the reduced power and economy. From the few I know operating on CNG, plan on about two MPG less than a comparable gasoline powered vehicle. I don’t believe your figures address this do they?

One item you didn’t address is maintenance. On natural gas you should be able to extend your interval between oil changes substantially. In five years time, that could add up to quite a bit.

The three big downsides to CNG I see are the lack of availability, reduction in power and economy, and the cost of the conversion. Personally, I don’t think this trade off is worth the minor savings.

 

[Floppy Hat]

Your figure for CNG seems low considering there is about $.50 tax on a gallon of gas. Are they not taxing CNG like they are gasoline?

This morning I saw the Flying J in Springville is selling it for $.67. I wondered the same thing about taxes.

 

[Dixon]

I drive a 95 retired mountain fuel 3/4 ton truck that was converted by them. Yes it has less power, yes you have to fill up alot, (14 gal tank) but cost very little to drive, right now in Price it's .63 cents a gal. Cost $8.83 to fill up, if I fill the gas tank it costs 30x$3.10= $93.00 if you figure 14 gal x 3.10= $43.30 $43.30 versis $8.83 I can live with a little less power.

 

[Greg]

How could you build a motor for CNG? I know you can build for propane, more compression, boost, etc. What kind of octane rating does CNG have? Can it be ran well with boost? That would help with the power problem... what about combining CNG w/ propane?

 

[BCGPER]

If I remember correctly from my school days (yeah, that long ago) natural gas has an octane rating in the 82 range. As far as building goes, all the basic performance tips apply with the exception of increasing compression. If you keep your compression ratio in the 8-8.5 range, detonation will be minimal and can be eliminated by retarding the ignition timing slightly.

Natural gas engine love turbos. All I run any more are turbocharged engines. The natural gas engines I've converted from normally aspirated to turbocharged see around a 40% to 50% increase in power. Keep in mind they also use about 40% to 50% more fuel as well. Something to consider in an automotive engine. An aftercooler is also a must, to minimize the chance of detonation.

As far as propane injection goes, I'm having a hard time seeing it as a viable option. Natural gas contains about 1000 btu/cubic foot while propane is up around 2200 (I think?). I think it could be done, but given the different heat content of the fuels, dialing it in would be a long process. That also leaves you with the hassel of not only finding CNG stations, but propane as well.

The simpler solution would be higher displacement, if you're building from scratch. If you want the power of a 350, build it into a 383. If you want the power of a 383, turbo it.

 

[Greg]

Good info BC, thanks for posting up!