Kleinn HK9 Train Horn System

Kleinn HK9 Train Horn System

If you’ve been to any diesel event over the past few years, you’ll understand that a set of train air horns on your rig is becoming more of a requirement than a luxury. While many could argue it’s not a logical investment, the side benefit of having air horns, other than getting noticed immediately, is the supporting on-board air system required to run them. For most enthusiasts, having on-board air comes in handy for airing up tires and toys, plus you get some cool train horns as the bonus.

Air horns have been on big rigs, and obviously trains, for decades as safety warning devices. They are loud and effective. But for diesel owners wanting to really get noticed, and scare the pants off of unsuspecting bystanders, air horns are the way to go. So in search of the most complete and loudest system around for our own Project Cowboy Cadillac, a 2006 Super Duty, we ventured to Tucson, Arizona, to visit the folks at Kleinn Automotive Air Horns. They claim to have the loudest and coolest setup available, and they were up for the challenge.

1 The Kleinn HK9 contains all of the parts needed for a typical install. First, we pulled everything out and planned where each major component would be installed.
2 For this installation, we’re installing the air compressor and tank inside the truck bed toolbox.


3A & 3B To use as little floor space inside the toolbox as possible, the compressor and air tank were laid out and temporarily positioned in preparation for drilling and installation.
4 During tank preparation, all fittings will be located in places that are appropriate to the orientation of the air tank. The drain should always be at the lowest part of the tank facing downwards, while the pressure switch and safety valve are located at the highest points on the air tank.
5 In order to keep as much off the floor of the toolbox as possible, the mounting location is marked in a location just under the lid.
6 With the mounting holes for the tank marked, four holes were drilled to allow the tank to be mounted out of the way.
7 The horns contained in the HK9 are Kleinn Model 730 Demon Train Horns. All 730 horns are shipped with a single valve pre-installed, but are also available with a valve upgrade to make them sound even louder. These things are huge, and made from spun steel that Kleinn finishes with this XCR 2.0 “everything-resistant” coating.
8 The compressor sits just below and inboard of the air tank, so it was bolted down first. Note: all wiring for the electrical was run before the compressor was bolted down to make sure that the installation is as clean as possible.
9 With the tank ready for installation, it was lifted into position and also bolted down. The open port on the right side is our air compressor inlet, to which the stainless steel braided leader hose from the 6450RC compressor will be installed.
10 While this fitting is not part of the kit, the truck’s owner wanted an easier way to attach the supplied tire inflator to the tank, so we installed this 90-degree compression fitting.


11A & 11B To make getting air from the tank for use with air tools or tire inflation simple, the quick connect coupler was installed in the face of the toolbox – to the right of the passenger-side lid release.

Their HK9 Pro Blaster Train Horn System features the brand-new Kleinn Model 730 Demon train horn. Unlike other train horns, these are built to take on the worst that the elements have to offer and keep coming back for more. Made from spun steel with stainless steel diaphragms and protected by Kleinn’s XCR 2.0 extreme corrosion-resistant coating, the Demon not only performs well, but will look great doing it for years to come. Also included in the HK9 Pro Blaster Kit is a 5-gallon heavy-duty steel air tank, a Kleinn 6450RC 100% duty cycle oil-less air compressor, a convenient tire inflation hose, and every part and fitting needed for a typical, professional installation.

To fully enable the lungs of the Demon and to turn up the volume, an Ultra BlastMaster valve upgrade kit (P/N 6890) was also included, which adds two more Kleinn VX6003 heavy-duty valves, all required fittings and additional ½-inch DOT-rated air line needed to get maximum high-pressure airflow from the air tank to each trumpet to create serious sound.

12 Completely bolted down and ready for plumbing, the air tank and compressor end up using very little space in the toolbox and will provide a 150-psi, 100% duty cycle air source to power the truck’s horns as well as smaller pneumatic tools if needed.


13A & 13B Remember when we said that the Model 730 Demon was big? Well, we weren’t lying. To make space for the cleanest installation possible, the spare tire mount was removed.
14 With the spare tire and spare tire mount out of the way, we have a clear path to the truck’s rear crossmember, which will give us a perfect spot to install the horn base with all three massive 730 horns in the same space. A few minutes with a heavy-duty drill was all it took to create mounting space.
15 After drilling, the 730 assembly was lifted into place and bolted down. The horn uses a lot of space, but can be separated from the base if needed for separate horn installations where space is obtained at a premium. Three ½-inch air lines were routed from the horns to a union that’s fed directly by the tank via another ½-inch air line as part of the Ultra Blastmaster Valve Upgrade.
16 After the horn assembly was bolted down, we checked the strength of the installation by trying to move the longest trumpet of the assembly. The Model 730 Demon comes with three assemblies that allow you to lock down the trumpets to keep them from moving or vibrating.
17 For our installation, the only trumpet that was of concern was the longest of the three. Luckily for us, the trumpet passed under another crossmember.
18 Next, the button that will be used to blast the HK9 system’s horn was installed in the dash. The standard Kleinn horn button is a smaller black unit called a Mini Detonator, but for this installation the owner opted for the larger red standard Detonator.
19 WIRING: Wiring the system is very straightforward. A relay is used to allow the compressor’s on/off functions to be controlled by the vehicle’s ignition switch while still drawing power from the battery. Using a relay also helps prolong the life of the pressure switch by reducing experienced amp draw:
• Post 87: Compressor power wire
• Post 86: Ground
• Post 30: Battery (fused power @ 25 amps)
• Post 85: One leg of pressure switch
To wire the solenoid valves, power and ground is jumped across each valve and terminates in a single power and a single ground lead. The power lead goes to the button that will honk the horns, while the other is ground, which can be terminated at the chassis. To give power to the switch, simply run power from the remaining lead on the button to the battery.
20 With all connections made, power was added to the system by making the power connection coming from post 30 on the relay. The system was run until shutoff and tested for air leaks throughout using soapy water and a spray bottle.
21 Completely installed, the HK9 system is incredibly loud (rated at 158.8 db) and features an air system with enough working power to do just about anything you want it to do.

While the installation may seem involved based on all the fittings, valves, switches and lines that come with the kit, the install can be done by anyone with basic tools and the ability to make a few electrical connections. For our install, Matz Truck Accessories of Tucson was the shop that took on the job, with Kleinn reps doing all the work. Since being meticulous is the name of the game when it involves air and electrical fittings, the job took the better part of the day. We installed the tank and compressor inside the toolbox of the truck, and mounted the horns underneath where the stock spare tire was for an ultra-clean install. And with the ½-inch-line upgrades, we ended up with not only a capable on-board air system, but the loudest train horns on the market.

If you’re interested in making your diesel stand out at an event, and having an on-board air system as well, then check into Kleinn’s full lineup of air systems and train horns. And if you want to hear this truck’s system in action, visit www.kleinn.com/videos.htm. DW

Can You Make It Even Louder?

Kleinn offers loud horns, as well as a way to make them even louder! BlastMaster and Ultra BlastMaster Train Horn Valve Upgrade kits are available for the largest train horns, depending on the model. To get the maximum volume out of the horns, we’re adding the Ultra BlastMaster upgrade to the HK9 system we’re installing. Two more heavy-duty electric valves, fittings, manifold and air line work together to deliver the most air possible to each individual horn.


The Ultra BlastMaster comes with a four-way manifold that takes air from the 5-gallon tank and distributes it evenly to each of the three train horn trumpets.
A single valve is attached to each horn base as shown, using a nipple and a compression fitting for each valve. When plumbed, ½-inch DOT air line will be attached directly to each horn for maximum airflow and volume.
Two extra VX6003 heavy-duty brass valves allow maximum air pressure to be delivered to each horn at the same time, which allows maximum volume and virtually no lag time from the push of the horn button to the soiling of your pants. To install the valves, the trumpets must be removed from the horn base. Have a buddy help you by holding the horn base while you turn each trumpet from the largest end.
With all valves installed and tightened, the trumpets were reinstalled on the horn base. Be sure to use a couple of drops of Loctite on each trumpet during reassembly to ensure that the horns do not become loose over time.
Our installer routed the power wires for each high-performance valve through the wire housing for the next valve for a clean, uncluttered appearance.

Kleinn Air Horns
2094 N. Dragoon St.
Tucson, AZ 85745

Matz Truck Accessories
4535 S 12th Ave.
Tucson, AZ 85714



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