CNG + Diesel

http://www.ksl.com/?nid=148&sid=4698603
Thought this was an interesting news article. Want to get opinions on this so please post your thoughts!

This is nothing more than an adaptation of Bully Dog's propane injection kit. Nothing really new here.

35 mpg ! Sure if you only quantify the diesel consumed and not the additional fuel supplied by the CNG. More HP & Torque. Again this is what you get when you add additional fuel to consume the excess air that a diesel normally runs with. Not rocket science by any means.

Advert is trying to capitalize on the general publics math and science illiteracy !!!!!

Diesels running CNG have been around for at least a decade or so. Check out the Napa Valley Wine Trains FPA4 locomotives.

good to know, i was unaware of the CNG added to diesel. It would seem that this is old technology.

CNG in a TDI

110 MPG is the goal. My brother operates an aftermarket installation and general automotive repair shop and in the last few months of oil fueled peril has done numerous CNG conversions in vehicles. I visited his shop during an installation in a V10 F350. It was a mess, with ECU harnesses torn apart and an intake manifold in pieces. However, a few days ago, he informed me that this week he will begin the installation of a CNG system into a Volkswagen TDI. Unfortunately, I didn't ask about the year or model. Today though, I got a look at the vitals of the system. Of course, the most inconvienent part is an approximately 5 gallon CNG tank to be mounted in the trunk. The tank was not at the shop at the time, so I do not know the exact dimensions. From there, the CNG will run to the front of the car to a pressure regulator. The regulator has a CNG input and output, as well as an input and output for engine coolant circulation. Apparently, as I was explained, CNG isn't too different from diesel in that it must reach a specified temperature to be combustible, which the engine coolant facilitates. From there, unlike a CNG system in a gasoline based engine with an injector for each cylinder, the CNG goes to a singular injector. The injector is a circular ring with a 4-5 inch outer diameter, and an inner diameter approximately 1-1.5 inch smaller. Inside the ring is an injection "slit" that is open around the entire circumference of the inner portion of the ring, as well as having a helical design on the interior to swirl the incoming air. It is installed in the intake between the IC and manifold. I don't know the exact details of the precise location or fitment, but I would imagine just before the EGR. The injector is signaled by the fuel injection electrical so that with every pulse of a diesel injector, CNG is also injected into the intake manifold. There is a digital "gauge" which consists of four lights to indicate CNG tank level and includes the CNG On/Off button that mounts in the dash a la rear defroster/heated seats style. I hope to be able to document the process of installation. The owner of the car is also allowing my brother to keep the car for approximately 1-2 weeks after installation to serve as an extended driveability road test. The expectations are fuel mileage in three digits as well as a noticeable performance increase. I don't know how much I'll be able to be involved in the process, with school as well as SEMA going on this week, but I'm hoping that I can at least give a rudimentary description and summary of the results. Even if the results only partially fulfill the expectations we have, it will do nothing but further illustrate the versatility and amazing design of the little diesels we love.

dunlin182 said:

http://www.ksl.com/?nid=148&sid=4698603
Thought this was an interesting news article. Want to get opinions on this so please post your thoughts!

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"It's gonna be an explosion of diesel-powered natural gas vehicles," Toomey said.

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Poorly chosen words...

There are many different types of set-ups for CNG and LPG. I've been running LPG on my truck for quite awhile now and did notice a significant increase in mpg's (from 16 to 23-24) but you do eventually run into the cost of the supplementary fuel going up and it being a wash. I am still saving about a dollar a gallon, but not as much as I used to (3.52 a gallon).

Right now CNG is cheaper than LPG but I can see the cost rising with the "new" found craze of CNG injection.

Also, keep in mind that for the cost to energy benefit, I believe that LPG packs more heat energy than CNG, but I could be wrong.

And the last thing to mention is that ANY type of supplementary fuel should be used sparingly......when you get greedy, you will regret it

99.5stroker said:

Also, keep in mind that for the cost to energy benefit, I believe that LPG packs more heat energy than CNG, but I could be wrong.

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As someone who has lived in homes both heated with CNG and now in one with LPG, I can confirm this. I cook with both, had the gas grill plumbed into the CNG system at the old house, and I can tell you that (just a seat of the pants-or cooktop, as it were-analysis) LPG burns hotter, more BTUs per unit, quicker boiling of water, etc. It's just got more oomph.

Just as an update to the CNG kit my brother was putting into a Jetta TDI, it is now finished and returned to the customer. I got a chance to go visit his shop on Friday, and of course, he had returned the car to the customer on Monday, so no pictures. My brother held on to the car to do a semi-long term test driveability test. His most excited response, "That thing is a rocket!" So, significant performance enhancements were observed. I never got to see the car nor ride along, so my guess from the way he's describing it would probably be equivilant to having an tune put in. He tried to drive to car long enough to evaluate the fuel consuption, which was expected to be about 100 miles per gallon diesel. He wasn't able to keep a hold of the car long enough to get a serious sample, but he is confident that if those aren't the figures, than it is at least very probable to obtain that kind of effieciency. I didn't ask him how much CNG was consumed, but at 60 cents per gallon, the cost is minimal. I have to ask him about that though. I know he has talked with other TDI owners that have expressed interest in installing CNG systems, so hopefully I'll have another chance to document it. If you guys have any questions you want me to pass along to my brother, just let me know.

Picture Update

The filler neck, required by regulation to be outside of the vehicle



The tank, 7.5 gallon



The valve assembly. There is a tube that leaves the valve assembly under the plastic cover, it can then be seen in the right side of the picture going into the intake tube. Inside the pipe is where the fogger ring rests, injecting fuel into the intake. The tubes on the left are just for coolant circulation, CNG likes to be warm.



The switch on the dash to activate or deactivate the CNG. The five indicator lights across the bottom act as a fuel level gauge. The fuel level is monitored by the pressure sensor which is the black cylinder towards the bottom of the picture on the valve assembly.

as has been stated several times above, be sure to do the math before you do the install. I used my regular "cannonball vacation" run from here near D.C. to Norfolk (virginia beach) as my basis, and long story short, once i factored everything together, the 360 mile round trip wound up being $5 cheaper running a CNG kit on the diesel. Now, running strictly on CNG is pretty cool, i saw a monster fire truck with an 800hp 7.0L V8 running on strait CNG, it was pretty awesome, but it wasnt a diesel engine.


edit. the numbers i ran were based on my 1986 M1009 diesel Blazer that normally gets around 23mpg on the highway at 55-60 in the slow lane.

does anyone know the cost of the CNG kit? Has anyone had any of the claims documented? What was the mpg after the install?

CaseyBrewer said:

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How are they going to get to the spare tire?

MethylEster said:

This is nothing more than an adaptation of Bully Dog's propane injection kit. Nothing really new here.

35 mpg ! Sure if you only quantify the diesel consumed and not the additional fuel supplied by the CNG. More HP & Torque. Again this is what you get when you add additional fuel to consume the excess air that a diesel normally runs with. Not rocket science by any means.

Advert is trying to capitalize on the general publics math and science illiteracy !!!!!

Click to expand...

Actually, dual fuel CI engines were common long before someone thought of spraying propane for extra power.

Stationary diesel engines for power generation have been using it for half a century. These engines have similar startup time as aero-derivative turbines but much higher overall thermodynamic efficiencies. The total natural gas is less than 2% of the total charge so preignition is not a problem. Natural gas provides 70% of the fuel.

They are also used in some liquified natural gas tanker ships. The boil-off produces more than enough gas to propel the ship.

How long does that 5 gallon tank last?

Would this work with Recycled Landfill Gas? (Methane)... since it can work in most natural gas applications?

Forgive my ignorance on CNG and its overall properties. I know dad's company switched from Natural gas to Recycled Landfill Gas (RLG) and they haven't had any complications in like 5+ years of use in boilers.

kcfoxie said:

How long does that 5 gallon tank last?

Would this work with Recycled Landfill Gas? (Methane)... since it can work in most natural gas applications?

Forgive my ignorance on CNG and its overall properties. I know dad's company switched from Natural gas to Recycled Landfill Gas (RLG) and they haven't had any complications in like 5+ years of use in boilers.

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Methane is Natural Gas.

So then it should work assuming it was compressed and filled into the tank?

Now the question is what the hell would that smell like?

kcfoxie said:

So then it should work assuming it was compressed and filled into the tank?

Now the question is what the hell would that smell like?

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It should. Just gotta make sure there is no moisture and other crap in it though. Couldn't tell you what it would smell like, but Methane itself is odorless.

Biogenic methane is usually a bit low on purity as it costs money to treat it. Mostly, H2S and water vapor are removed. Amine treating can be used to drop CO2 levels as well. But it has appreciable N2 which makes compressing it a bit difficult.