exhaust systems

[dr. d]

in my opinion, if manufacturers designed their mufflers' insides right, and angled the descent of their mufflers into the tailpipe,
there may be little need to drill drainage holes.

[Yatta]

With the heat and pressure of the exhaust gases, any condensation (likely minute anyway) will just dry off and be expelled later on.

[oj88]

in my opinion, if manufacturers designed their mufflers' insides right, and angled the descent of their mufflers into the tailpipe,
there may be little need to drill drainage holes.

The muffler is a chamber and it's installed almost always, horizontally. The outlet pipe is more often than not, higher than the lowest part of the muffler. It has to be standing vertically to make sure water doesn't accumulate.

With the heat and pressure of the exhaust gases, any condensation (likely minute anyway) will just dry off and be expelled later on.

Good point. Though water is a by-product of combustion so there's always a steady supply of it, however minute, every time the engine is running. It may be possible that high ambient temperature and high EGT is enough to vaporize whatever amount of water has collected. But that may be dependent on a lot of other factors.

[dr. d]

The muffler is a chamber and it's installed almost always, horizontally. The outlet pipe is more often than not, higher than the lowest part of the muffler. It has to be standing vertically to make sure water doesn't accumulate.

.

why?
exhaust gas is very fluid, and is not easily prone to the effects of gravity.

it does not have to be perfectly vertical.
to effect gravity drainage, a mild slant is fine, in my view.

[oj88]

why?
exhaust gas is very fluid, and is not easily prone to the effects of gravity.

it does not have to be perfectly vertical.
to effect gravity drainage, a mild slant is fine, in my view.

When hot vaporized water (ie. steam) from the exhaust gas gets into contact with the relatively cooler surfaces of the exhaust system, it changes state (condenses) to water. It then collects on the lowest parts of the exhaust system due to gravity. One such area is the muffler.

[Yatta]

Those of us who have diesel-powered cars, and even those who prefer gas, we sometimes spray water into the exhaust pipes to clean out the soot and carbon build up, especially prior to the annual registration (I know one here even custom-rigged a pipe fitting just for this purpose). Once you start up the engine, water left inside gets pushed out with some force. So I would not really worry about this.

[oj88]

It's predominantly a problem in cold weather or climate. Less of a problem in hot weather, but it's there regardless.

[jick.cejoco]

It's predominantly a problem in cold weather or climate. Less of a problem in hot weather, but it's there regardless.

in dry areas or low relative humidity, the steam from the exhaust is less obvious but the byproduct of oxidation( combustion) of hydrocarbon + oxygen will always result in the formation of H2O. you can't avoid this phenomenon. in the case of dirty diesels, the soot usually combines with this condensed water droplets. the fuels which contain traces of sulfur too, creates some acidic compounds as H2SO4 or sulfuric acid that accelerates corrosion on the exhaust system.

a perfectly working catalytic converter(reduction catalyst and oxidation catalyst) converts the pollutants into inert elements. the reduction catalyst breaks down the NOx(when the combustion temperatures reaches or exceeds around 2500 degrees fahrenheit) into O2 and N2. then the freed up oxygen is fed to the oxidation catalyst to further oxidize the CO and HC(unburned or incompletely burned fuel)

[jick.cejoco]

With the heat and pressure of the exhaust gases, any condensation (likely minute anyway) will just dry off and be expelled later on.

the maximum allowable exhaust backpressure on most cars is 1.25 psig right before the catalytic converter. behind the catcon is usually at atmospheric pressure or 1 BAR. the pressure is not sufficient to expel the accumulated water condensation

[Yatta]

the maximum allowable exhaust backpressure on most cars is 1.25 psig right before the catalytic converter. behind the catcon is usually at atmospheric pressure or 1 BAR. the pressure is not sufficient to expel the accumulated water condensation

Yeah its not...