Answer: V8 Engines

The loudest siren ever built was, and remains, the Chrysler Air Raid Siren. These sirens were manufactured during World War II and the Cold War to serve as extremely loud and far-reaching air raid warning devices.

How extremely loud? The sirens featured a bank of six enormous horns connected to a two-stage air compressor and rotary chopper system powered by a huge FirePower Hemi V8 engine and could produce a siren wail rated at 138 dB at 100 feet. The sirens could be heard 20-25 miles away depending on the terrain features. Each siren weighed 2.7 tons, was built atop a quarter section of a Dodge truck chassis rail, and produced 180 horsepower to drive the siren.

If you need an extra sense of just how powerful the sirens were, consider this fascinating tidbit. The U.S. Navy found that they could use them to clear fog off of an airfield. The pressure of the sound waves was so intense that it would cause the water droplets in the air to collide with each other until they were heavy enough to fall as rain and clear the air.

Federal agencies funded the installation of these massive sirens, known as “Big Red Whistles” because of their fire-engine-red paint jobs, in cities across America. Although now decommissioned, there are still dozens of the loud behemoths tucked away on rooftops and towers across the United States—although you might be surprised to find that many of them are missing their V8 engines. Many of the engines from the old Big Red Whistles ended up living out the end of their days in custom hot rods.