Exhaust System

[drumking]

Does a NGV vehicle benefit the same as gasoline with a performance exhaust? I have purchased a CNG truck with not exhaust. I could go up to a 3" based on the reccomendation of a muffler guy with no cng experience or reinstall a factory 2 1/2." Any input?

[Curtis]

Re: Exhaust System

Generally any vehicle will benefit from being able to breathe better. Not being a mechanic/muffler tech I'm not sure what to advise to you. Too big an exaust could eliminate some of the backpressure the engine needs.

Is the truck a Ford?

You might consider a K&N air filter first and see what you get from a less expensive upgrade. A gaseous fuel displaces air in the engine, therefore the reduction in power, even with a higher octane fuel. Therefore, the more airflow the better... a supercharger would give that puppy some umph.

[drumking]

Re: Exhaust System

I have an F-250. I don't see any reason if it was gas to not put a 3" exhaust on it. I just am too new to CNG to know about displacements and other factors that could effect engine requirements

[neongreen]

Re: Exhaust System

All of the usual mods to gas engines will also help your CNG motor as long as it doesn't mess up the air metering.

[BRodri]

Re: Exhaust System

Let it breathe. I've got 2.5" true dual pipes no cats 24" cherrybombs and down spouts right before my rear axle haven't had a problem in 50,000 miles. but depending upon where you live at you might not be able to go as free as i can. but it does make a difference and while you are doing this just go ahead and do the whole K&N thing (i wish i could, 5" intake at my CNG carburator.) hope this helped.

[RaulLasVegas]

Re: Exhaust System

Larger exhaust reduces backpressure that is used for cylinder evacuation at lower RPM's. If you increase your exhaust size, you will decrease the power at the low end. Larger exhaust helps evacuation at higher RPM's. The same holds true for the intake side. Bigger is better, but only at higher RPM's. The parts are all tied together. What is the RPM range ALL the parts of your engine are designed for?

[drumking]

Re: Exhaust System

I guess if I'll go 3" and K&N. If the airflow doesn't effect CNG in a bad way, then I'll be hot rodding in my CNG f-250 and all the chicks will dig me.

[neongreen]

Re: Exhaust System

That's what I like to hear!
In all honesty, that ought to be a good modification for more midrange power, assuming you mean single 3" (if you mean dual 3", dont do it, go dual 2.25 or 2.5")

[BRodri]

Re: Exhaust System

im with you on that one i think that 3" is way to large to go duals no backpressure at all. the 2.5" sounds great dualled and alot cheaper for the muffler or glasspaks.

[drumking]

Re: Exhaust System

yep single 3 inch is how I'm going. thanks for the feedback folks