Contemplating CNG conversion

[Movin]

I'm calling bull on gasoline providing lubrication to the cylinders and top end. That's what oil is for.

Okay, call it bull, you still play the same game when the head gasket
fails, CNG does not extend the life of gaskets or bearing wear caused
every time you start an engine. Anytime the motor moves there is wear
at all metal to metal surfaces until oil arrives. CNG as a gas provides no
cooling to the valves as liquid fuel does. Engines not designed to shed
the extra heat will suffer as described. Now back to the bull..what did
lead do in gasoline ? The current gasoline additives are not added to gaseous
fuels.

California Bi-fuel ford contours are available free to cheap because of top
end failure and automatic transmission failure. They have all you need to convert a festiva. That little word "convert" is an education.....

[ejp2fast]

Engines not designed to shed
the extra heat will suffer as described.

That is a good point, about heat dissipation. I wonder just how much "hotter" the valvetrain would run, if any, on CNG? Something else to think about.

I wonder what honda did to the Civic GX (engine D16B5 / D17A7) differently from the other gas honda engines? (Beside 12.5:1 compression).

Also, this Ford Service Vehicle with the excessive wear to the top end, would have been designed for gasoline, not CNG.

[ejp2fast]

I did find this link on differences in 98-00 Civic GX comparing to the Ex. Appears there are no real significant differences in the valvetrain.

[ejp2fast]

Here is a PDF link from a Engineering professor in Malaysia in 2003 on "Valve Train Investigation for CNG Engine Application" and covers mainly valve overlap periods with 3 different Camshaft profiles comparing Petrol vs CNG

[Larry Hampton]

Okay, what happens when 3000 or 3600 psi gas expands? It gets cold!!!

Yes, I know it doesn't get 3000 at the injector, way back when we ran propane, if the humidity was high you could frost up the carb even in the dead of summer.

And gas Contours in Oklahoma have the.same problems, its not inherent to CNG.

[ejp2fast]

Talked to a mechanic at a local CNG station (ONG guy). All of their 600 vehicle fleet is bi-fuel, they start up the vehicles on gas, then when it reaches operating temp, it switches over to CNG. As far as longevity, he said they haven't had problems with engines with lots of miles, as the seals get lubrication upon that initial start up. Also, he said that the CNG only vehicles have hardened valves. (like the Civic GX).

Upon more research, gasoline does provide lubrication to the combustion chamber area (valve seats, cylinder walls) from the little unburned fuel. The top end valvetrain is not effected, as that is lubbed from the regular oil with proper oil pressure.

[ejp2fast]

Okay, what happens when 3000 or 3600 psi gas expands? It gets cold!!!

Yes, I know it doesn't get 3000 at the injector, way back when we ran propane, if the humidity was high you could frost up the carb even in the dead of summer.

And gas Contours in Oklahoma have the.same problems, its not inherent to CNG.

PV=nRT thats the ideal gas law. P=pressure V=volume n=moles of gas R=gas constant and T= temperature.

keeping everything constant but pressure, as pressure decreases, then volume goes up as long as nRT constant. As pressure decreases with constant volume, then T goes down as long as nR constant.

So its the same concept with pressururized spray cans, as the pressure goes down, temp will too, like the your instance of frost on the carb with high humidity.

To address your "Okay, what happens when 3000 or 3600 psi gas expands? It gets cold!!!" statement:
gas expands = volume goes up. if volume goes up keeping same pressure, then temp will go up.