CNG Dual Fuel?

[GorillaSooner]

Hey, Random question. I've recently taken an interest in the CNG dual fuel system. Apparently, you can install this system that allows you to use both gasoline and CNG. The appeal comes in that CNG is the equivalent to $0.99/gallon. I'm in OKC so CNG is a lot more prevalent here at gas stations, and from what I can tell the upgrade would run about $2500 to $5000.

My question is, has anyone on the board here done this or looked into it? Is the cost accurate? Anyone think it is worth it? IMO, anytime your vehicle can run on more than one types of fuel it is a good thing but I'm a little scared about messing up a good thing (the 4Runner as is).

 

[Petromaniac]

I have considered it as my employer offers incentives for us to convert. I am not sure that there is a kit for Toyotas yet, but even if there was where would you stick the tank? To get any range it would have to be rather large. My company has fleet vehicles with CNG and for the pickups it works great. There is plenty of bed space to spare. We also have a Civic and the gas tank had to be replaced, so it is CNG only and has a range of only 200 miles or so on a full tank. 4Runners have good storage space, but the back would become unusable with a tank in it (if you wanted a tank at 3500 psi inside the cabin). The spare tire spot would be another option but I wouldn't want it there for wheeling. It is great tech for fleet vehicles but I think it has a little ways to go for the average consumer.

 

[thebwlife]

Think you need to add 50% on to the cost. I've priced out multiple ones and none (from a quality company) have been under $7500. The super cheap kits aren't CARB compliant and don't carry very good warranties. If you really run the real cost of ownership on it, they are not really cost cutting at this point. You can by a lot of gas for $7500 bucks. Also CNG will go up like .50 once the OK tax credit runs out at the end of this year.

 

[Whiplash Willy]

I have heard of conversions done on a Tundra and a FJ. One of the bigger problems are the tanks which are large and heavy, and the range isn't all that great. Maybe we could put 2 tanks where the spare tire is, but even then we would be lucky to see a 100 mile range. Plus, you have to wounder how running CNG will effect your engine in the long run.

Trucks make the most sense, because you can put big tanks in the bed, but then you lose valuable bed space.

Tundra Conversion:
CNG Your Ride - YouTube

FJ Conversion Link:
How to Install a CNG System on a 2011 FJ - Toyota FJ Cruiser Forum

http://www.fjcruiserforums.com/forums/engine-performance/143058-cng-conversion-alternative.html#post2101736

I would love to see someone do a conversion on a 4runner though, and see long term results.

 

[homeyclaus]

Willy is right - it's the CNG tanks that suck.

CNG used to be at around 2200 psi, which requires a pretty heavy tank. Also, even with that amount of compression, the energy density really isn't very high.

LPG or LNG is a much better system. LPG is liquid propane mostly, and it stays liquid at less than 300 psi, so it has much better density.

Both systems, however, are awesome because of the engine longevity you get - you're not burning a solvent any more. Gasoline thins the oil coating on your cylinder walls as it is compressed, resulting in additional wear and stuff. LPG and CNG systems also pollute less at a wider range of operating temperatures.

On the flip side, LPG engines are hard to get going when it's 40 below out, and all of the gas regulators have a coolant feed to warm them for this reason.

 

[thebwlife]

CNG is now offered at 3000 or 3500 psi. 2 tank units in the spare tire place 9gal equivilant on a Tahoe get about 150-175 miles.

Willy is right - it's the CNG tanks that suck.

CNG used to be at around 2200 psi, which requires a pretty heavy tank. Also, even with that amount of compression, the energy density really isn't very high.

LPG or LNG is a much better system. LPG is liquid propane mostly, and it stays liquid at less than 300 psi, so it has much better density.

Both systems, however, are awesome because of the engine longevity you get - you're not burning a solvent any more. Gasoline thins the oil coating on your cylinder walls as it is compressed, resulting in additional wear and stuff. LPG and CNG systems also pollute less at a wider range of operating temperatures.

On the flip side, LPG engines are hard to get going when it's 40 below out, and all of the gas regulators have a coolant feed to warm them for this reason.

 

[homeyclaus]

CNG is now offered at 3000 or 3500 psi. 2 tank units in the spare tire place 9gal equivilant on a Tahoe get about 150-175 miles.

Better. Still not LPG though.

 

[Whiplash Willy]

Obviously putting one of these systems on your 4runner would void the warranty, but what I would like to know is how the CNG system works with your ECU and Mapping. Also, how it compensates for the differences in A/F ratio when running on CNG, and if any problems/damage could come from that, like if the aftermarket CNG software doesn't properly communicate with your ECU.

I drive about 60 miles a day, and at 18mpg, with gas at $4/gal, I am spending about $13.20 a day on just gas! So something like this could give me a ROI in a few years, but it wouldn't be worth it unless I could be 100% sure it would be safe for my engine.

 

[homeyclaus]

Toyota would have to prove that the addition of the system caused the failure to deny a warranty claim.

The modern systems I have seen in Europe start with gasoline, and then switch over to the alternate fuel once the engine is running. From an ECU perspective, the new systems patch into the same measures the ECU uses to calculate gasoline fuel/air mix, but have a coprocessor that maps out the alternate fuel air mix. The ECU is pretty much convinced that gasoline is still being burned.

 

[thebwlife]

Obviously putting one of these systems on your 4runner would void the warranty, but what I would like to know is how the CNG system works with your ECU and Mapping. Also, how it compensates for the differences in A/F ratio when running on CNG, and if any problems/damage could come from that, like if the aftermarket CNG software doesn't properly communicate with your ECU.

I drive about 60 miles a day, and at 18mpg, with gas at $4/gal, I am spending about $13.20 a day on just gas! So something like this could give me a ROI in a few years, but it wouldn't be worth it unless I could be 100% sure it would be safe for my engine.

Not to argue with you but it would take like 5-7 years to break even. The part of your equation is the $1.50-$2.25 per/gal cost of CNG pending where you live. That's assuming that CNG (at its lowest cost in 20 years) doesn't go up! I drive CNG trucks all the time - all Chevys trucks and tahoes, Fords - f-150 & f-250. No matter what you read - in practice they have about 30% less power and 20% less mpg than gas.

 

[1engineer]

Toyota would have to prove that the addition of the system caused the failure to deny a warranty claim.

The modern systems I have seen in Europe start with gasoline, and then switch over to the alternate fuel once the engine is running. From an ECU perspective, the new systems patch into the same measures the ECU uses to calculate gasoline fuel/air mix, but have a coprocessor that maps out the alternate fuel air mix. The ECU is pretty much convinced that gasoline is still being burned.

Homey is correct. The most practical way I have read about is a bi fuel mixture which is basically an efficiency exercise. What happens is this:
You start out and accelerate with gasoline
After reaching cruising speed the new coprocessor switches over to CNG

The basic parts needed are a coprocessor, additional gauges, a 4 gallon tank and the biggie is new fuel injectors + plumbing.

The price is around $3,500.00 once they get it up to a decent quantity.

The small CNG tank will add range at a reduced cost thereby making your vehicle more efficient from a cost perspective, not from a true mechanical efficiency point. There are inherent advantages and disadvantages to both fuels. This method looks to use the advantages of CNG (low cost) and minimize the disadvantages of CNG which are low temp performance and lower energy output by using gasoline in startup and acceleration conditions.

Last point: To those posters that think adding a CNG tank to the bed of a truck is safer than adding it to the inside of a SUV need to realize that if that tank blows sheet metal will not even slow it down. With that said, CNG is as safe as the vehicle you are driving now and maybe safer depending on the statistics.

 

[Reata]

Fewer vehicles with CNG, thus better stats on safety? Right?

 

[1engineer]

Fewer vehicles with CNG, thus better stats on safety? Right?

Lol not quite. I know as well as anyone what can be done with numbers haha. Some stats say that CNG is safer than gasoline, some say it will cause the end of the world. Just have to look at who is funding the study.

 

[Canazes9]

Lol not quite. I know as well as anyone what can be done with numbers haha. Some stats say that CNG is safer than gasoline, some say it will cause the end of the world. Just have to look at who is funding the study.

Greg,

I've been enjoying a lot of your posts, lots of wisdom.

Problem:

Your avatar ain't working for me!

I respectfully suggest a solution:



Hopefully we can reach a compromise...

David

 

[The Waco Kid]

Just make sure you don't have any leaks... (This is all I could think about while reading this thread)

FJ GO BOOM :jaw drop:


And yes I realize this was acetylene... but still.

 

[Antman]

Greg,

I've been enjoying a lot of your posts, lots of wisdom.

Problem:

Your avatar ain't working for me!

I respectfully suggest a solution:



Hopefully we can reach a compromise...

David

I hope the "compromise" isn't 1Eng shaving his legs for a new pic.

He only sees in black and white, you know.

 

[mform]

Tanks are key to this discussion. In the locomotive business, this is being solved with CNG in a separate tender car behind the chooch. Not a very practical approach on the highway. Also, there is technology in development for simultaneous diesel/CNG duel-fueling.

 

[thebwlife]

Tanks are key to this discussion. In the locomotive business, this is being solved with CNG in a separate tender car behind the chooch. Not a very practical approach on the highway. Also, there is technology in development for simultaneous diesel/CNG duel-fueling.

Honestly non of these guys have researched the tanks. I work for the company that had pushed these for 5 years all over the country. They developed the "CNG in a box" system with GE. These tanks have to be tested and certified. Just like any other tank high pressure system. They are not just air tanks people can buy - they hold 3500psi

 

[mace.]

Honestly non of these guys have researched the tanks. I work for the company that had pushed these for 5 years all over the country. They developed the "CNG in a box" system with GE. These tanks have to be tested and certified. Just like any other tank high pressure system. They are not just air tanks people can buy - they hold 3500psi

Anyone can go buy a tank that holds 3500psi. Some people even strap them to their backs.

 

[thebwlife]

Anyone can go buy a tank that holds 3500psi. Some people even strap them to their backs.

Honestly that's how some are made. Some are just steel too. The lighter the tank the more expensive they get.

Here is a place that has lots of info on them. Its not far from my house, I've priced out my 4Runner twice with them.

CNG Interstate

I think we may do a Tahoe in bi fuel CNG for my wife. We have tons of them at work and I can get one with 4x4 and like 30K miles for under $35k. We have a leasing program for employees and when the leases are up they sell them outright to our employees.