Right up front I am new to train horns so some terms or lingo I might not understand if there is any train horn specific lingo. I just installed a set of horns on my pick up and I love the sound and they have a decent volume at the moment. What I want to know is what relation does the size of air line have to the volume of the horn ? Currently I have 1/4" air line on it and I am using a lanyard to activate the horn rather than a push button or switch. The compressor is high volume rated for 140 psi going to a 5 gallon tank rated for 125 psi.
What horns have you got and how have you done your install? If you have the Shockers then you could go up to 1/2" between tank and the air solenoid to ensure maximum flow and efficiency out of your horns.
There Dragon express horns rated at 152db made by Wolo . there no longer listed on their site but there the chrome plated steel version of the Siberian express they have listed I know there not top of the line but they are nice and have a great sound for me. I ran 1/4" line through the whole system I removed the solenoid and installed a pull lanyard in the cab. Its a direct 1/4 " line from the lanyard to the horns. there mounted under the tool box in my truck bed. So far I haven’t charged the system over 90 psi due to a few small leaks I haven’t had time to plug (its set up to run at 125 psi).
The airline needs to be big enough to not be a restriction. (same goes for the valve and other fittings.) Is your airline 1/4" ID rubber hose -or- 1/4" OD plastic tube?
What kind of horns are they? Some consume more air than others - especially real trainhorns.
^^^posted same time.
Hmmm. Link to lanyard valve? It ~could~ be a restriction.
I don’t have a link for the lanyard valve sorry. Its a lanyard valve designed for semi trucks air horns. So I know it has the airflow needed for the job. I got it at work I drive trucks for a living lol. and the air line is 1/4/od plastic line. Im gussing i should change to 1/4 id rubber ?
Yeah, the ID of that tube is real small.
If you’re going to upgrade, you might as well get 1/2" DOT tubing.
I was considering moving up in line size but was hoping the 1/4" OD would be right for it . The horn came with a 10’ length of 14" OD line so I assumed it was the correct size for that horn. how much volume would that add to the air system using a 5 gallon tank and about 35’ of 1/2 air line rather than 1/4" ?
Are you serious with 35 feet? Keep in mind that restriction to flow increases with hose length. If you need to run long air supply lines then definitely up the size to 1/2 or even 3/4".
well the line runs from the compressor to the tank about 2’ away then from the tank under the truck along the frame to the front of the cab and into the passenger compartment at the steering column and up to the lanyard and air gauge mounted on the drivers side pillar. Then it fallows the same path back to the horns in the bed on the drivers side under my box. Its the most efficient way I see to mount the compressor, tank, and horns some place out of my way while still keeping them accessible and protected from damage. My tool box is a shallow box so there is room to mount every thing there and the space is for the most part unusable because of the box. I never know restriction increased with a longer line. So basically as its set up now my tank may have 125 psi but by the time the air gets to the horns it wont have that pressure to really work them to their potential ?
LOL - Truck… yeah OK, now I’m with ya 
Pressure will equalize throughout the system so if it’s 125 in the tank it’ll also be that at your valve. Flow rate is where you’ll notice the impact. So if you get a sharp burst initially which quickly trails off you have too much flow restriction. If you want a demo of that principle get a short piece of garden hose and try to blow through it - the longer you make that hose the harder it is to blow through it as you have to shift all the air that’s inside it.
A quick and dirty way to test your optimum setup is to bench test the horns on a very short hose linked directly to your tank. You can then compare your output to your vehicle install.
By the way… does the truck not have an air supply you can tap into?
No existing air supply to tap into I installed them on my 2000 dodge ram 1500. Ill try the bench test you suggest and compare the sound but as its set up now I can blow the horn and I get a good steady tone without any trail off. Its a sharp burst as you say and stays steady even with a long blast. I have only taken the system up to 90 psi so far but even at that I am getting a steady nice tone with decent volume it will match the power of a stock air horn on the 2011 international semi truck I drive at work at 30 psi and trumps the semi horn at 90 psi. The max pressure for the air system I put together is 125 psi.
1/2" line will make them alot louder. I had a horn similar to yours, and it had a 1/4 solenoid valve. I thought I knew what loud was…then I switched to 1/2…and then I changed to the Shockers :). If you switch you will need a larger valve to give unrestricted flow. Like this one-
http://www.hornblasters.com/products/details.php?i=half-inch-manual-train-horn-valve
I really want to stick with a pull lanyard rather than a valve for my system. But a larger line might be in the future for me. I should be able to move up from 1/4’ to 3/8’ with out changing out the valve. Im not looking for extreme volume from these horns just a nice loud horn with a steady tone. Later on I plan on adding a quick connect line off the tank for airing up tires or a small impact for the unplanned roadside needs and that will be a 1/2’ to 3/4’ line