Custom Tuning 6.0's ? Any CNG / Propane Tuners out there

[907DAVE]

Originally Posted by cleatus12r

Not knowing what to tune in/out for CNG, I can't help you with any tuning data but I can say that nothing should need to be changed as far as fuel rates go. Injection timing maybe just a bit but the fuel rates should only need to be changed by your right foot (less accelerator input for any given load/engine speed).

That was my thought as well, with the CNG on, you would not need to push as hard on the pedal to maintain speed.

How much would timing matter?

[cleatus12r]

My thought with the injection timing is in regards to flame travel in the cylinder. CNG's rate of combustion is faster than that of diesel fuel. Once the diesel fuel ignites, the CNG will spontaneously ignite as well but it will burn faster, possibly creating a pressure spike large enough to cause damage.

Think of it this way. In some instances, the injection event is commanded 30+ degrees BTDC. It doesn't always happen there and ignition doesn't always occur instantaneously, but there is some mad advance there. If you are running straight LPG or CNG in a gasoline vehicle, the ignition timing will be set near stock levels of 8-12 degrees (maybe just a little more advanced). If you're igniting the CNG at 20+ degrees BTDC, it's going to combust, expand, and be done burning by the time the piston reaches TDC.

Now the actual concentration of CNG per unit of ambient air is much lower than that of what a dedicated CNG-fueled vehicle will see so the detrimental effects of CNG will probably be realized only when a whole boat load of the gas is used.

These are just a couple thoughts I have.

[jgw50]

Awesome info guys. I've been reading as much as I can on the ECU logic and agree that I could just pump CNG in and the computer would compensate. I'd like to take it a step further however as I do not want to be pushing this motor.

So, my plan is to try and creat a Diesel tune that will reduce the amount of diesel given for a certain load / RPM.
I'll then create a map in my CNG ecu to replace that lost diesel. I'll also look into the timing issue and definitely try and stay on top of knock. Here's an interesting article on diesel cylinder pressure vs. CNG cylinder pressure.

http://www.scipub.org/fulltext/ajeas/ajeas21212-216.pdf

[cleatus12r]

Originally Posted by jgw50

Awesome info guys. I've been reading as much as I can on the ECU logic and agree that I could just pump CNG in and the computer would compensate. I'd like to take it a step further however as I do not want to be pushing this motor.

So, my plan is to try and creat a Diesel tune that will reduce the amount of diesel given for a certain load / RPM.
I'll then create a map in my CNG ecu to replace that lost diesel. I'll also look into the timing issue and definitely try and stay on top of knock. Here's an interesting article on diesel cylinder pressure vs. CNG cylinder pressure.

http://www.scipub.org/fulltext/ajeas/ajeas21212-216.pdf

I don't know what this "compensation" you're describing would be.

"replace that lost diesel"?

I'm not trying to be a jerk or anything but do you know how a diesel engine operates?

"So, my plan is to try and creat a Diesel tune that will reduce the amount of diesel given for a certain load / RPM."

I can't help but think that you may be confusing gasoline engine operation with diesel engine operation.