The weak standard horn on the Elise can be replaced with a more powerful set of twin air-horns if desired. Make a real presence on the road!
Luckily the Elise is already fitted with a relay on the horn circuit, so the original horn can be swapped out with relative ease. This job is a bit fiddly, but is not particularly difficult. You'll need to set aside an hour or so for the work.
Before you start, it's best to remove the horn fuse from the fuse box. It's a 7.5A fuse, located in slot 10.
1. Raise the car
on the driver's side jacking point. Use a small piece of wood to spread the
2. Remove the front undertray. This is the small one at the very front of the car. If it's not been removed before, it may be stuck with a little corrosion - give it a helping hand with a hammer. The tray should slide forward then you can pull it out. You need to remove this to access the horn fittings under the car.
3. Turn the steering wheel full-lock to the right to give access to the wheel arch liner.
4. Pull the wheel-arch liner back and tuck it behind the road wheel.
5. Disconnect the two wires from the horn.
6. Working in the wheel arch, use a rachet to undo the horn retaining bolt. Get ready to catch the horn once unscrewed!
7. First fit the compressor unit. Plug the wires in from the original horn - black to negative (-) and purple/green to positive (+). You can use the original horn hole to mount the compressor to the front crash structure. Bolt it on and tighten.
8. Now fit the air tubes onto the unit. These should be kept as short as possible for reliable performance. Plug the other air tubes onto the air horns.
9. Find a suitable location for the air horns. Space is tight behind the wheel arch, so this may be tricky! I wedged the horns against the front clam/crash structure for ease, but it's probably wiser to bolt them onto the frame if possible.
10. Before putting the car back together, test that the horn functions correctly. The original 7.5A fuse will most likely not be enough to power the compressor. I changed it for a 25A blade fuse.
11. Tuck in the wheel-arch liner, refit the undertray, and remove the jack and you're all done! Now that sounds like a proper sports car!!
The location of the horn fuse in slot 10. This picture shows the 7.5A fuse replaced with the 25A fuse.
Air horn and compressor placement.