Metal vs Plastic Train Horns

Do not even CONSIDER using anything less than ABS plastic.  It won’t last.  ABS can at least stand up to heat and abuse.

ABS is cheaper than metal, particularly because metal prices are on the rise.  Typically, however, if you are finding an extremely low cost metal (close to ABS) unless it’s used, it’s because the metal alloy is weak or it is plated.  Keep that in mind.  That’s not the same as solid metal.

ABS can typically stand up to rocks (especially important if you are mounting under a vehicle) whereas metal may ding or dent, depending on the size of rock and how fast you are driving.

Metal allows for extra vibration, and hence, a louder horn in general.  However, the size of the horn and compressor also contribute to loudness and sound output.  So if you are comparing a small metal horn with a small compressor, to a large ABS horn, with a large compressor, there might not be a significant a difference in loudness.  Make sense?


Common Questions

Do all train horns/air horns need a compressor/tank system?

Train Horn Compressor

The only horns that do not need a compressor/tank system are direct drive models.  Direct drive models come with a pump that shoots the air directly into the horn, vs pressurizing it in tank.  Direct drives will be louder than a stock horn, but not as loud as those that use a separate compressor/tank system.

Marine Outlaw,


What determines the loudness and type of sound of an air horn/train horn?

Of course, the larger the train horn, typically the louder and deeper the sound.  This is because the larger, broader trumpets allow more air flow at one time and will be a lower pitch than a more narrow trumpet that is restricting air flow somewhat and resulting in a higher pitch.  Also, the larger horns typically accommodate larger compressors and air systems, which also improves loudness.

 Where, on the vehicle, should I mount my train horn/air horn?

Depending on your vehicle, some air horns will fit under the hood or behind the grill.  This is ideal in terms protecting the horn itself.  However, most people must install under the vehicle on a body rail, due to space restrictions.  If under the body or behind an open grill, you will want to angle the horns in a position that is slightly downward.  This protects the inside of the trumpets from debris, dirt and liquid collecting.  Also, from something (such as a rock) getting stuck inside the trumpet.  Downward facing trumpets also allow anything (such as water) to drip back out of the horn automatically.  This also prevents unnecessary wear and tear on the horns.

 See also our  ”Compressor Mounting & Advice Post”

Compressor Mounting & Advice



Never mount an unsealed compressor outside of the vehicle.  If water, dirt or debris is allowed to enter the intake, it will damage your compressor.  Ensure you have a sealed air system before externally mounting.

Do not mount your compressor below the tank.  The tank and/or the leader hose can create condensation, that will then leak into the compressor below.  You do not want moisture entering your compressor.

Do not mount a compressor upside-down.  Any other angle is acceptable, but mounting upside-down will not allow the compressor to cool properly and could burn it up.

Do not over tighten the leader hose.  This can cause your check valve to malfunction, in which case, the compressor will not fill the air tank properly.

If your compressor is not filling your air tank… you may need to loosen the check valve.

Use the pressure switch that came with your kit to be safe.  Pressure switches can vary in pressure rating.  Not using a pressure switch at all is not advised.

Know your compressor’s maximum working pressure.  Do not run your compressor beyond this pressure limit, doing so increases your risk of damage greatly.

Know your duty cycle.  Every compressor has a duty cycle, indicating how long it can run before it needs to stop and cool down.  If you run it too long, or don’t allow enough cool down time, it will over heat and burn up.  Know the duty cycle and only run your compressor within it’s limits to avoid damage.

If your compressor won’t stop running, or runs longer than it should… there is most likely a problem with your pressure switch, for example, it could be leaking.  You should disconnect power from the system until you have determined and fixed the problem to prevent damage.

The Low Down

The higher the PSI, the louder your horn will be; 200 PSI being the max.  PSI Stands for Pound Per Square Inch).

The bigger the air tank, the longer your horn will sound; often times, also  longer it will take to fill the air tank again to re-sound.

The lower the AMP draw, the better the compressor; max should be 30

Pay attention to the gauge of your air line.  It DOES effect the volume and quality as well.

You want typically at least a 3 Gallon talk to run multiple horns.

A manual air valve, vs electric, will help you adjust the sound

How A Train Horn Works

Train horns operate by compressed air, flowing through a horn, and producing oscillation (via a diaphram assembly enclosed with a power chamber).  When air is applied to the horn, the diaphragm vibrates against a nozzel and produces sound.

The configuration and dimensions of the trumpet assembly, or “bell” determine the  frequency produced (measured in Hertz).