Installing a 150 dB air horn; Can you hear me now!?

Discussion in 'Clarity' started by KentuckyKen, May 23, 2019.

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  1. KentuckyKen

    KentuckyKen Well-Known Member

    I got tired of the wimpy horn and saw a YouTube video on some guys startling unsuspecting people with a diesel train air horn. A little Googling found a real diesel train sounding air horn was way too expensive and took up too much room but I found a single air horn for $35 on eBay. And boy is it loud!

    There’s a lot of cheap crap from China, but this one seemed of decent quality (all metal air pump) and came with a relay and fuse for plug and play installation. It was easy peasy by ordering the horn adapter from Honda that plugs into one horn connectors and adapts it to 2 spade lugs. No soldering at all; just wire it in place of one of the horns using the Honda adapter and run the fused wire to the pos battery terminal and the neg wire to a ground. And all the spade lugs in the horn kit are silicone covered. I went over board and used plastic wire loom on the wire going to the battery. I also used zip ties on the friction fit of the hose to the horn and pump.

    By removing the left horn, I was able to use a carriage bolt and nut to secure the pump in the same threaded hole the left horn came from and zip tied the relay to a plastic frame member.

    The horn was a little trickier to get installed. I used a right angled drill to reach in front of the radiators and drill 3 small holes to mount the horn on the aluminum frame member that runs across the front. Not much room there but it can be done if your arms aren’t too big.

    To start, you have to remove the black plastic trim that covers the area between the radiators and the front body panel. To get to that you remove a trim piece that holds down the air intake and then move the air intake back. All the fasteners are the pop up button cap kind (or whatever you call them). You can buy a tool for $6 or just carefully use a screwdriver to pry the cap up. Then lift up the large cover that will now be held on just at the bumper side by some friction plugs. Then it’s just mounting the horn in a hard to reach area, hooking everything up, fishing the fused wire over to the battery and finding a good ground for the neg wire. Fortunately the pos battery terminal has a separate bolt under the plastic cover just made for this.
    This shows the pump to the left of the other horn and the relay zip tied to the frame at left. Fearing corrosion, I sealed the bottom part of the relay where the wires enter with some silicone caulk. The top clear part houses the actual relay components and is replaceable.

    I ended up mangling two of the plastic fasteners and ordered a whole box of assorted ones from eBay for what two would cost from Honda. I’ll be happy to send a couple to whoever needs them.
    I also got lucky and had a couple of short carriage bolts that fit the threaded hole for the horn and the fitting on the pump, and can send one out if you can’t find one and a nut from the hardware store.

    The only trick I found was identifying the pos vs. neg horn contacts. I did that with my trusty cheap and free Harbor Freight VOM. Just mark the one that shows continuity to the neg battery terminal after plugging in the adapter. Then just plug in all the spade connectors according to the instructions.

    As a side note, this exposed the HV battery system coolant expansion tank (page 480) that some have speculated takes some special dielectric coolant since it goes to the battery pack. Well, it has the same color and smell as the fluid in the other two expansion tanks, so I think it’s just regular old Honda long life coolant type 2.
    Also I noticed the radar has a screw adjustment for up and down just like headlights but seems to use shims for L to R.

    Here is the cover back on and you can’t tell it was ever off.

    If anyone wants to try this they can PM me with any questions and I’d be happy to walk them through it over the phone. Except for installing the large air trumpet in a hard to reach area, it’s really quick and easy. And I took a ton of pictures if anyone needs them.

    My Clarity may not get any name recognition but when I blow the horn now, it gets the respect and attention this car deserves!
    I am Clarity, hear me roar!!!
    And make way for my mighty fusion (solar PV) powered car, you pathetic Dino fueled smog belching weenies!

    PS: The electrical hookup caused a hard reset with all the warning lights and I had to recalibrate the TPMS after it reinitialized. Also, I lost the driving history so my EV range estimate went from mid 60s to mid 40s. However, the efficiency as tracked by kWh/mile did not change. With 4 days of driving and o/n charging the EV range estimate is only up to 59 miles. So it looks like it will take at least 5 charge cycles with ~20-25 miles each to return to its usual accuracy. And my HV range estimate increased by a few miles with out adding any gas. But at least the reset didn’t lose any of my settings and now all is back to normal.
    Last edited: May 23, 2019
    Elm, Cash Traylor, PeteWagner and 9 others like this.
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  3. insightman

    insightman Well-Known Member Subscriber

    Many policemen and policewomen go their whole careers without ever firing their guns. I'll be interested to hear what situations come up that cause you to unleash this acoustic weapon.

    I can understand that you wanted this air horn to be instantly available, so you wired it in parallel with the Clarity's horn rather than adding a separate, problematic-to-install and less-accessible button. Do think you'll miss having the option of a little toot-toot (for which the OEM Clarity horn is particularly qualified) for less imperative situations? That makes me ask, why did you leave the Clarity's horn connected at all? Can you even hear it anymore?
    Atkinson, Elm, Texas22Step and 2 others like this.
  4. 2002

    2002 Well-Known Member

    It could have been worse, he could have tied it into the pedestrian warning system :eek:
    Alex800st, Atkinson, laptop and 2 others like this.
  5. KentuckyKen

    KentuckyKen Well-Known Member

    You guys crack me up. It is possible to give it a very, very brief push and not be totally obnoxious. And yes I left the horn on the right hooked up just in case the cheap Chinese air horn conks out on me.
    I will have to admit that I almost want some idiot to do something stupid just so I can blast him with my “acoustic weapon”. I didn’t realize I had weaponized my horn!
  6. Mowcowbell

    Mowcowbell Well-Known Member

    With more and more drivers paying more attention to their phones than piloting their vehicles, I think Ken's upgrade is a great idea. You need something with shock value to get the other drivers eyes to look away from the screen in their hands.
    laptop likes this.
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  8. 4sallypat

    4sallypat Active Member

    I know this is a great project idea!

    I had installed a dual trumpet truck horns in my truck years ago. Air horns really gets people's attention quickly if not startling...

    Remember to parallel the factory horn's 12V power lead and leave the factory horns alone because there is a slight time delay for the air horn compressor to start giving you the ability to briefly tap tap the factory horns and not sound the air horn.
    There are many times I just need to wake up the driver in front by the low level factory horns by tapping...

    Once you lay on the horn, both factory and air horns will sound....
  9. Robert_Alabama

    Robert_Alabama Well-Known Member

    I think I'm a little in the middle on this one. The horn was my first complaint for the Clarity and I bought some good horns, but they are probably closer to 110-115 db. This brought it up to equal to what I think of as a "standard" horn. I like the horn on the 2012 Chevrolet Volt, and the Clarity is now pretty much indistinguishable to it now. 150db seems kind of loud. If I remember this audio stuff right, isn't every 10db doubling the volume? Hopefully they are rounding up a little (exaggerating) to get to 150db. By the way, it was also the first thing my father-in-law wanted changed on his too, so I think most would agree the stock horn is "meep-meep/roadrunner".
  10. sniwallof

    sniwallof Active Member

    Can you post some audio (or a phone video)?
    Daniel M W likes this.
  11. David Towle

    David Towle Active Member

    I think every 3 dB is a doubling in volume!
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  13. KentuckyKen

    KentuckyKen Well-Known Member

    Surprisingly, my cheap air horn that doesn’t have a storage tank has a negligible delay between pressing the center wheel horn “button” and making the racket. It’s almost imperceptible. I attribute that to the short run of the tubing from the compressor to the air horn and its stiffness. I did leave one horn hooked up and would have left the other one hooked up but I went the lazy plug and play no splicing/crimping/soldering way using the Honda horn plug to spade lugs adapter.
  14. jorgie393

    jorgie393 Well-Known Member

    Not to be too pedantic, but on a logarithmic scale like dB:

    -Every 3db doubles the power; every 10db increases the power 10x. So a 150 db sound is 1000 as powerful (in a physics sense) as a 120db sound.

    First, these ratings on horns are very suspect. Like “peak horsepower” on a vacuum.

    Second, the experience of “loudness” is not a physics property; it’s biologic/cognitive. In general, that goes by about a factor of 2 per 10db. So a 150 db horn might be rated by observers as 8x as loud as a 120db horn.

    This last is very fuzzy, as it relates to experience. Anyway, air horns are loud!

    Sent from my iPhone using Inside EVs
    ClarityDoc and Sandroad like this.
  15. Sandroad

    Sandroad Well-Known Member

    I’d like to do this with a rear facing horn for tailgaters. 200 dB should do it.
    Texas22Step likes this.
  16. ClarityDoc

    ClarityDoc Active Member

    Clears the snow off rear facing camera, too!

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  17. Teamchang

    Teamchang Member

    I really want to do this, but I’m chicken.
    Texas22Step likes this.
  18. Texas22Step

    Texas22Step Well-Known Member

    Me too, but I am still looking for a place on which to bolt my add-on, Chinese-made, Clarity foldable wings and empennage first ...
  19. RichL

    RichL Member

    I did something similar and installed a pair of these air horns:
    Used the OEM horn mounting points with some custom brackets, 2x relays, 2x fuses, etc... - same as Ken but doubled up and removed both OEM horns.

    Comes in handy as I live in the Toronto area - home of North America's worst daily commute. Had one unit that lasted 8 years in a RAV4 but had a pair fail after 3 years in my wife's SUV - it was exposed to the elements as it was installed just behind the grill. I find air horns need be blasted weekly to keep the air pump from seizing up.
    KentuckyKen likes this.
  20. David in TN

    David in TN Well-Known Member

    Not only have I previously stayed at a Holiday Inn Express, but one of my jobs (that I've been doing for over 30 years...) is that of an Audio Engineer.

    Sound levels are logarithmic. Every 10db increase in sound level doubles the sound.

    80db is twice as loud as 70db.
    120db is twice as loud as 110db. etc....

    Actual 150db -- that's the same level as a jet fighter taking off.

  21. David Towle

    David Towle Active Member

    That's not fully correct. A 10 dB increase results in a PERCEIVED doubling of the sound. A 10 dB increase is actually a ten times increase in sound power. 3dB is an actual doubling of sound power. (I looked it up to be sure.) Nice chart though.
  22. jorgie393

    jorgie393 Well-Known Member

    To make the numbers even more subjective: dB depends on distance from the source. And there is no agreed on standard distance AFAIK, and it often is not reported. It is sometimes 1m; sometimes the usual position of the typical listener from the typical source; sometimes a specific listener from a specific source.

    Or (and call me a cynic) whatever distance will produce an impressive dB number for sales purposes. So I would take horn dB with a grain of salt.

    I think we can all agree though:

    1) Clarity OEM horn goes “peep-peep” and is disappointing
    2) Louder horns are available, and are more fun....and probably safer
    3) Of the louder horns, air horns are REALLY loud
    4) If you put an air horn in your ear, it will be REALLY REALLY loud, maybe even as loud as a jet engine (from farther away)

    I upgraded to a louder horn myself, sort of wish I had an air horn :)

    Sent from my iPhone using Inside EVs
    KentuckyKen likes this.
  23. 2002

    2002 Well-Known Member

    Actually it's perfectly correct in the context of this discussion which is solely about perceived sound. Nice physics lesson though.

    For our next question, if a tree falls in the forest and no one is around .....
    MPower likes this.

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