Honk Like You Mean It! Photos & Story By Denny Hao & Kevin Butler
We're a firm believer of the statement "If it walks like a duck, talks like a duck... it's got to be a duck." Well, in the world of lifted trucks, if it's as tall as a big rig, smokes like a big rig but it sounds like a Civic... what gives?
An attempt to honk reveals the "Meep! Meep!" akin to that of the Road Runner being chased by Wile E. Coyote rather than that of a Peterbilt! To minimize manufacturing costs of vehicles, automakers cut costs anywhere they can. One of the first things to go is the horn.
After dropping tons of money transforming your truck to the near stature of a semi-truck, the only item left on the checklist is a set of gauges and air horns. After all, we have to make it "talk like a duck," right?
On a semi-truck, air horns are a simple matter of adding a line to the air tank used by the air brakes, adding a manual pull valve, and bolting the horns to the top of the cab. On your standard light-duty truck, however, there is no existing air system. The brakes are hydraulic, and the horn is electric. So that leaves you with a whole lot of nothing to power those air horns!
So step one to installing air horns is getting the "air" part of the horns on your truck. Granted the primary purpose of an on-board air system is to provide a medium for the air horns to function. However, secondary functions include air for your tires, air bags, or air tools. But for the time being, we'll focus on air horns.
An on-board air system consist of a few components - namely a 12 volt DC compressor and an air tank. Figuring a place to mount them will be the most difficult part. Originally, we intended to tuck them up on the frame rail underneath the cab. However, due to space limitations with the AMP Research Power Steps, we hatched plan B. Looking at the truck, the only real estate left was the stock spare tire sat location - under the bed. Since a spare 40" tire no cannot fit in the stock location, we decided that would be the perfect location for the tank and a compressor. The kit from Grover Air Horns (A Division of Gabbert Equipment Inc.) included a set of Grover dual trumpet air horns measuring 27 and 29 inches, and all the required hoses, fittings, solenoid valves, compressor, and horns. Since every installation is custom, you will still need to go to the hardware store to purchase a few pipe (NPT) fittings and bolts to properly mount everything.
The supplied air horns are rather large. The dual-tone horns measure 25" and 30" long, with a bell diameter of 7 5/16".
After a few attempts to determine the best way to mount the compressor, tank, and horns in the stock spare tire location, the solution was to build a sub-frame. This sub-frame would support all the components, including the horns. Building the sub-frame off the truck and installing the complete assembly as a unit greatly facilitated the installation and proved invaluable later for troubleshooting.
To keep things "stock" appearing in the cab, the switches for horn activation were kept to a minimum. The factory horn button in the steering wheel activated either the stock or air horns, depending on the position of the hidden switch. I mean, in an emergency, who wants to fumble around to look for a separate switch when instinct leads our palm to the center of the steering wheel. The hidden switch also allows the user to keep the horn in the factory setting when not traveling on surface streets to comply with Johnny Law.
With the new on-board air system, we needed to devise a way to monitor the tank pressure to see how much "oomph" we had left in the tank. We turned to Autometer and their line of specialty gauges to keep track of vital engine parameters in addition to air tank pressures. A quick trip to their webpage revealed the exact air pressure gauge we were looking for. While we were upgrading, we decided to keep tabs on a few more truck vitals as well. Since both trucks were already equipped with Autometer gauges, upgrading was rather easy. Autometer supplies various gauges to monitor almost all of the trucks' vitals, and various mounting solutions as well. Both trucks (one equipped with an automatic transmission, the other with a manual) had a boost (aka MAP) and EGT (Exhaust Gas Temperature, or pyrometer) gauge. The Autometer dual A-pillar pods was replaced with the quad A-pillar pods, and the Ultra Lite series gauges were upgraded with Autometer's new LED gauge lighting kit.
The automatic equipped truck has Ford's new 6.0 liter Powerstroke, with the Torqshift 5 speed automatic. Although the dashboard has a so-called transmission temperature gauge, it does not have the resolution needed for the driver to properly monitor the temperatures. So a transmission temperature gauge was added to the pre-existing gauges.
The other truck with the ZF 6-Speed manual transmission, does not require a transmission temperature gauge. Instead, with a heavily modified fuel delivery system from ITP Diesel, we decided to keep track of the fuel pressure to ensure the pump is able to keep up with the demands of the engine!
Installed, the gauges and the air horn system complement each other perfectly. A quick blip of the horn reveals a small drop in tank pressure. And when the pressure reaches the set level of the hysteresis pressure switch, the pump automatically switches itself on, until it reaches the high level of the switch. All this in monitored in the cab via the newly installed gauges!
Additionally, the LED retrofit kit works great in the gauge applications. The green and blue LEDs supplied for each truck brings out the clarity of the gauges without losing any lighting power. All the gauges are very well illuminated. However, the boost gauge, evident in both trucks, did appear a bit dim. This may be a result of the shortened distance between the gauge face and the bezel. If it were a recessed a few more millimeters, it would definitely have provided better lighting.
The final word? Having the system installed for a few months, everything has worked flawlessly. Take the time to properly find all the leaks in the air system. It will prove invaluable in the long run for the compressor longevity. Additionally, for the larger air horns, a larger tank and a higher flow compressor would prove to be better combination. However, any toot of the horns longer than two seconds can be bad, so perhaps it's better to stick with the smaller setup. Water intrusion (if any) into the horns are quickly remedied with a quick toot of the horns.
Special thanks to Kris Carlson at Autometer and Jason Gabbert at Gabbert Equipment.
In memory of David Au Cheong Hoi.
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