'12 now on CNG

[sag2]

OK, I'm having some trouble seeing how you can save anything when you do not have control of the diesel side of things. I have been to school on the new Dodge CNG truck, and it is really a slick system. It uses a Hemi and runs on either gas or CNG depending on the conditions. The difference is the Dodge setup shuts down the gas injectors as it changes to CNG, and vice versa. It is very smooth and seamless transition. It also switches between gas and CNG to keep the gas tank from staying full and the fuel in the tank fresh.
Where I'm having trouble with your conversion is the diesel has no O2 sensor to lean out the diesel as you add the CNG. So unless as you add the CNG there is more fuel available to make power you have less throttle opening that results in less diesel being injected. Ideally you need to shut off the diesel as you switch to CNG to get any significant savings.
Help me understand how this is actually working.

 

[moparguy]

First of all, you can't shut off the diesel completely since it acts as the pilot fuel igniting the cng. Cng won't combust from compression in a diesel engine. You can add cng to the point that you're running as much as 80% cng, but I think Corey has a good safe plan in going with a 50% ratio.

I'll let others speak to the particulars of how modern diesel engines control fuel flow, and with diesels that's what you control is fuel, you have full air or throttle plate opening all the time.

 

[Roostre]

OK, I'm having some trouble seeing how you can save anything when you do not have control of the diesel side of things. I have been to school on the new Dodge CNG truck, and it is really a slick system. It uses a Hemi and runs on either gas or CNG depending on the conditions. The difference is the Dodge setup shuts down the gas injectors as it changes to CNG, and vice versa. It is very smooth and seamless transition. It also switches between gas and CNG to keep the gas tank from staying full and the fuel in the tank fresh.
Where I'm having trouble with your conversion is the diesel has no O2 sensor to lean out the diesel as you add the CNG. So unless as you add the CNG there is more fuel available to make power you have less throttle opening that results in less diesel being injected. Ideally you need to shut off the diesel as you switch to CNG to get any significant savings.
Help me understand how this is actually working.

This regulator works on suction- suction comes from air flow velocity. There are no electronics on the truck modified. At an idle it does not flow enough air to pull any CNG. As soon as you give the truck gas the turbo begins to build boost and pulls a slight vacuum between the inlet and the airbox, which pulls CNG into the system.

The diesel is necessary to ignite the CNG, so you can never shut off the diesel. Let me repeat - THERE ARE NO ELECTRONICS TALKING BETWEEN THE CNG AND THE TRUCK - Just a simple 12V solenoid that turns on the gas regulator. Once the CNG is flowing it is simply a matter of lifting up on the throttle to cut diesel. YES, it really is that simple. The truck just thinks it is coasting downhill; essentially there is no difference. It actually works much better than I expected!

With a diesel no O2 sensor is needed. They can run very lean (100:1) with no issues. When I am cruising around town at a steady 45MPH I am *barely* touching the throttle and the instantaneous mileage is north of 40MPG.

One side affect is that the transmission tends to shift a little early. As soon as Marco gets POD working for 2010-12 trucks I think we can remedy this. Right now if I need more airflow I just shift down a gear.

When I switch the CNG on (only after the truck is fully warmed up) it feels like I just pushed the button on a nitrous bottle!! It really loves the stuff. This morning I was climbing a steep local road that is posted at 40 MPH. Without CNG the instant MPG was about 5; with the CNG on it was about 10.

I hope this helps. My system is very KISS and cheap. I do have one issue and that is a small leak on one of the adjustment bolts that I need to remedy:
#ad

 

[sag2]

OK, that makes sense, you are using less throttle (diesel fuel) to go the same speed because of the additional fuel (CNG) being added.

 

[rscurtis]

Back in the mid-late '90's, there were a number of guys, including several here locally, that were playing with propane injection on the old 12 and early 24-valves. This doesn't appear to be much different in concept. I'm sure that there are some threads back from the early days of TDR that discussed it.

You're correct. Back in those days, propane was used as a power enhancer to use the extra oxygen in the diesel cycle. This is long before we had 400 HP pickups with 800 ft/lb of torque. NG is becoming attractive because of its low cost per BTU. I don't think propane can make that claim, it's not that much cheaper than gasoline.

 

[JHumphries]

So, what happens when you completely let off of the throttle? Does it take longer for the engine to drop to idle?

 

[DiamondDiver]

Back in the 80's and 90's CNG dual fuel was big with the industrial diesel co-genertion market. Colt Pielstick was manufacturing engines in the 10K BHP class that burned CNG with less than 2% diesel as an ignition source.

Augmenting the diesel with CNG is a smart way to go without completely changing the fuel delivery system of the engine. Making the system passively and inherently safe would be my biggest concern. His vacuum regulator delivery system addresses this.

This looks like a feasible economy mod with a relatively short payback.

 

[Roostre]

So, what happens when you completely let off of the throttle? Does it take longer for the engine to drop to idle?

No. It is quite seamless.



Playing around with the idle adjustment I found that the motor will automatically reduce injection of diesel when CNG is introduced at idle. I would imagine that there is a minimum, but it adjusts almost instantly.

 

[Walcott]

very interesting read,keep us informed on forward progress.

 

[EricBu12]

Corey, so you installed the injection point on the tube between the turbo and airbox?. How long would a 12 gal tank last?. Our diesel up here is 3. 65/gal... and going up... I have a 60 gal fuel tank and an extra couple of plastic tanks. . about 700 miles range towing. . if I took out one of the plastic tanks and used CNG. I should see the same range due to less diesel used right?. so $700 was for the system? Where did you get it?

 

[mfurrh55]

Am interested, Where did you get all the parts for this system?, and what do they consist of?, Thanks for the thread, Monte

 

[Roostre]

Corey, so you installed the injection point on the tube between the turbo and airbox?. How long would a 12 gal tank last?. Our diesel up here is 3. 65/gal... and going up... I have a 60 gal fuel tank and an extra couple of plastic tanks. . about 700 miles range towing. . if I took out one of the plastic tanks and used CNG. I should see the same range due to less diesel used right?. so $700 was for the system? Where did you get it?

Its not so much an "injection point" as it is a "suction point". I am using a 3/4" tee right into where the crankcase vent connects right in the inlet of the turbo.



I'm not sure I would run more than about 30% CNG while towing heavy. Peak cylinder pressure issues could cause a head gasket issue. This is why I am running my Smarty JR on SW#0 - which is half power. No way I can overfuel, but with the CNG it still pulls as hard or maybe a little harder than stock.



I pieced my system together- the cylinder came from Craigslist (KSL classifieds works too). My kit was originally designed for a gasoline conversion and came from fleaBay. It included the regulator, gauge, high pressure lines and fittings, etc. Misc clamps, low pressure elbows, etc. . came from local hardware store. My low pressure hose and chafe resistant covering came from Hose and Rubber Supply. Tank was $250. I paid $50 to have the bracket sandblasted and powder coated. Kit was $155 plus $95 shipping.



There is a guy in Clearfield that sells a similar kit that may be less expensive in the long run. He advertises on KSL classifieds. I am in the Millcreek area if you want to check out my install in person I would be happy to show you how it all goes together.



A 12 gallon tank being put in at 50% will last you as long as 24 gallons of diesel normally would. For towing I would drop that to 25%, so 12 gallon tank would last about 48 gallons of diesel. *Hope that makes sense. *

 

[EricBu12]

Neat Corey.
I live over by the #2 airport if you want to come over. . I messaged you my address.

 

[Roostre]

Neat Corey.
I live over by the #2 airport if you want to come over. . I messaged you my address.

Cool. So you have a CNG station right on the corner. We moved from a home near there a few years ago.

OK. I have found one issue with the system I installed. I cannot get the regulator to flow more than about 30% CNG. It works great and I am averaging 26-27 MPG on the lie-o-meter commuting to work like this.

So now I need to decide if I want to get a bigger regulator. I figure I can sell this one to offset the cost of the larger reg. Now I just have to get it approved by the wife/accountant/budget officer.

 

[cerberusiam]

I'm not sure I would run more than about 30% CNG while towing heavy. Peak cylinder pressure issues could cause a head gasket issue. This is why I am running my Smarty JR on SW#0 - which is half power. No way I can overfuel, but with the CNG it still pulls as hard or maybe a little harder than stock.

That is the single biggest point that gets ignored every time this subject comes up and the hoopla gets going. Propane is much worse than CNG and about the first thing that happens EVEN after tryin to explain the problems is the bobble head that figured he found free power is complaining about blowby and excessive oil usage. Yep, not pull it apart and replace rings hoping it din't gouge the cykinder wall. :-laf



That is on a 5. 9. the 6. 7 blows head gaskets if it sneezes too hard. Plain scary just thinking about it because there is no good way to measure the cyinder pressures. Interesting note on how it pulls on SW0 though. With a larger regulator you may be able to increase the power if the cylinder pressures would stay in check.



Now you got me wanting to do this for cross coutry trips, and, I don't do anything like this until I know it is solid. Thanks for the excellent writeup and ideas.

 

[Roostre]

That is the single biggest point that gets ignored every time this subject comes up and the hoopla gets going.

Thanks for emphasizing that - it really cannot be stressed enough. Like anything- a little is good, but too much can be devastating.

My favorite saying is "Pigs get fed, HOGS get slaughtered". We've all been the hog at one time or another... hopefully we can learn from it.

 

[EricBu12]

Corey, I see the regulator is in the bed. . did you plumb the coolant lines to the engine bay? and the suction line? . . No room in the engine bay?

 

[Roostre]

Corey, I see the regulator is in the bed. . did you plumb the coolant lines to the engine bay? and the suction line? . . No room in the engine bay?

Yes, there are coolant lines that go to the heater hoses from the bed along with the suction line. There is room, but it was easier and less invasive this way. I can have it all back to stock in a matter of minutes this way. Also my bed had plastic caps on the front that came out for the hoses to run through, so no drilling or cutting was required.

I did have to drill holes for the mounting bracket on the tank. I plan to put a toolbox over the top it all at some point.

 

[Wingate]

Good job on the install. Simple, doesnt corrupt the factory electronics... looks to be a relatively safe setup.
Its not on a Cummins powered Ram, but I installed a Cat DGB setup on two 1500 hp D3512C engines recently. There is definitely some very serious money to be saved by blending CNG. The Cat system can run up to 70% fuel substitution and maintain the 1500 hp rating and load response time. It monitors for cylinder detonation, cylinder temps, along with the normal monitoring of a modern electronic diesel.
I am positive that Cummins Engine is working on a similar setup for their industrial engines. . but I doubt it would filter down to Dodge, er Ram. . Will have to look to the aftermarket for a bolt on kit...
I agree, stay away from propane substitution, rate of burn is too fast to safely use in part throttle/light load conditions. Keep the propane for grilling hamburgers.

 

[Roostre]

For those asking about the taxes, here is what the pump has posted on it:
#ad


And a little update. I'm now at about 1000 miles on CNG.

I have not found a negative other than losing some bed space. My payback time/mileage is going to move back because a larger tank is going in now that the concept is well proven (to me).

This is saving me between . 07 and . 10 cents per mile so far. Oo.

Found a new CNG station yesterday that is sort of on my way to work. I think I have noted that on level road at 50MPH I am seeing 50MPG on the lie-o-meter, which is about double what it reads without CNG.

Today I reset the lie-o-meter doing steady 65 on level road out of curiosity- it read 35-36 MPG. Keep in mind these are diesel only, but I have not filled the diesel for about 400 miles and the diesel tank is just under half a tank. It is going to be real nice having 20 GGE of CNG on board soon!!