BimmerFest BMW Forum banner
1 - 8 of 8 Posts

·
Rambling Wreck
Joined
·
2,073 Posts
Discussion Starter · #1 · (Edited)
I finally got around to installing the Stebel Nautilus horn that's been sitting on my workbench for almost a year. The following describes how I installed the horn and modified my existing horn wiring to suit. As always, if you want to install this stuff some other way, have at it. I will not be responsible for any injury, damage, or other loss caused by your actions.

I bought the Compact horn from Griot's Garage. Even though there's actually a fair amount of space behind the front bumper, I chose the Compact model to conserve weight and have a good selection of mounting options.

The kit from Griot's includes the horn, a nut and bolt for mounting, and an optional fitting for attachment of an air tube. If you're mounting the horn in a particularly dirty or wet environment, you can attach the fitting to the horn's air inlet and route a tube from the horn to a cleaner place. I didn't use the fitting. Also included, but not pictured, is an inline fuse holder that I didn't use.

The instructions state to mount the horn cylinder within 25 degrees of vertical, in a location that's protected from road spray and dust. The horn has some weight to it, so it needs to be bolted to something solid. After poking around the front bumper, I found an existing ~5/16" diameter hole in the front bumper carrier (the structural part of the front bumper cover) that would enable me to install an L-bracket to locate the horn above and outboard of the passenger side fog light. I found a corner bracket and Grade 8 5/16" nuts and bolts at the local hardware store. To avoid galvanic corrosion due to contact between the aluminum bumper carrier and the zinc-plated bracket, I made a spacer out of some ABS plastic. Tape or sheet rubber might also work.

If you're thinking about attaching the factory horn wires to this horn, forget it. According to Stebel, this sucker draws 18 amps. That's way too much for those wimpy 18-gauge wires to handle. The Griot's instructions recommend 12-gauge wire for both power and ground. I used the larger 10-gauge wire I had on hand. I ran the factory driver's side horn wire to a SPST 40-amp relay, then ran the 10-gauge wire from the relay output terminal to the horn positive terminal. I grounded the horn at the factory ground location just behind the parking light. The hot wire to the relay comes from the positive battery terminal in the engine compartment, and it has a 20-amp fuse inline. With the Stebel horn mounted on the passenger side of the bumper carrier and the horn relay located in the empty compartment behind the passenger strut tower, the length of 10-gauge wire to the new horn is kept to a minimum.

I kept the Fiamm Freeway Blaster horns I posted about earlier in this thread. Since the Stebel horn has higher-pitched low and high tones, my intention is to use the Freeway Blasters as more civilized "toot-toot" horns when the situation calls for something less abrasive than the Stebel horn - for example, at a stop light when Soccer Mom, absorbed in her text message, doesn't notice that the light's gone green.

I added a second SPST relay for the Freeway Blasters. This relay has dual 87 output terminals, one for each horn. I ran a 14-gauge wire (16-gauge would probably be fine) from the relay to each horn. The horns remain grounded as they were through the factory horn connectors, but the power wire on the driver's side is heat-shrink capped and tied back because it's no longer needed. The relay trigger is a momentary rocker switch in the cabin that's inline with a switched power source. The hot wire to this relay has a 15-amp inline fuse.

The results? Much better than when I replaced my stock horns with the Freeway Blasters two years ago. The Freeway Blasters are good, inexpensive stock replacements, but when mounted in the same location as the car's original horns, they gave me absolutely no gains in terms of loudness. This time, with the hood closed and the decibel meter located about two feet in front of the grills, the Freeway Blasters measured 104 dB, and the Stebel horn measured 110dB. This difference doesn't seem like much until you realize that the decibel scale is a logarithmic scale. If my calculations are correct, 110 dB is actually four times more intense than 104 dB. I'm very pleased with the results.

Here are the manufacturers' specifications for the horns I now have installed:

Fiamm Freeway Blasters (2)

http://www.fiammamerica.com/
  • Low tone: 405 Hz
  • High tone: 485 Hz
  • Current draw: 5 amps each
  • Decibel rating: 130 dB at 4"
Stebel Nautilus Compact (1)

http://www.stebel.it/
  • Low tone: 530 Hz
  • High tone: 680 Hz
  • Current draw: 18 amps
  • Decibel rating: 139 dB at 4"
 

Attachments

·
Rambling Wreck
Joined
·
2,073 Posts
Discussion Starter · #2 ·
I used my multimeter tonight to measure the current draw of the horns.

  • Freeway Blasters: Approximately 7 amps (3.5 amps each)
  • Stebel Nautilus: Approximately 19.5 to 20 amps

I have read that others have blown a 20-amp fuse with the Stebel horn, so I bumped its fuse up to 25 amps. Some vendors actually recommend a 30-amp fuse.
 

·
Rambling Wreck
Joined
·
2,073 Posts
Discussion Starter · #5 · (Edited)
install some real horns! Like my train horns 156 real dBs
Well, now I know that it is technically feasible to mount a train horn in an E46...but the horn looks like it would block much of the air flow to the radiator. As failure-prone as our cars' cooling systems are, I would be hesitant to stress the system like that. Have you noticed any increase in coolant temperatures with the train horn installed?

The horn also looks pretty heavy. Did you have to modify the bumper carrier to fit it?

To each his own. I think that most DIYers will find that aftermarket horns like the Stebel horn are an inexpensive ($40) and less labor-intensive way to make themselves more noticeable to idiot drivers with a lower risk of violating local noise ordinances. Respectfully submitted...

Make a sound clip!
Who? Me or bimmerguy055? (I think I already know the answer.)
 

·
Registered
Joined
·
122 Posts
horn test



The horn location does not seam to restrict air flow, nor did the temps go up. some times the horns acts like a heat sink when idling (since its touching the radiator) . I'm guessing, I'm one of the 1st to put such a horn in a bmw? :clap:

I did have to trim away at the bracket that holds the grill. currently I'm making a low profile black mesh that will replace the original vertical grill. It was worth the time and $ to do such a thing, most cali drivers don't use turn signals and cut others off, therefor it becomes useful having authority when pushing my horn.

Unfortunately the sound clip can not reproduce the raw power. people that are 10-15 ft away from the car, have there lose clothing shake. I did a short sound distance test and it took 15 seconds to reach 3 miles! that's crazy
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top