BMW Rallying Forum

In recent events we have been recorded at 100dbs at 4.5k revs, ie right on the maximum allowed. Strangely, my car is one of the quietest at events once under way according to spectators. The car seems noisier now that we have had it fitted with a custom DTA map. We have recently fitted a third box to the custom made 3 inch system, but this has probably only brought us down a db or two (so we are now at rather than slightly over 100) All the boxes are the plate type, so there are no baffles to blow out. As we only need to keep the noise down a tiny bit I was wondering whether a resonator tail pipe would make any difference? I'm keen not to increase back pressure, another thought is to fit a remote control valve in the exhaust, which I can close to get through scrutineering and reopen once competing... Any thoughts?

Chris, I bet your DTA ecu has the option to run 2 maps which are switchable

If the old map was quieter switch to that one for noise test, you could probably have it tweaked to be even quieter at the all important 4.5k

gartrac wrote:Chris, I bet your DTA ecu has the option to run 2 maps which are switchable

If the old map was quieter switch to that one for noise test, you could probably have it tweaked to be even quieter at the all important 4.5k

That's a really interesting idea, thanks. I'll see whether Martin (Mef) who supplied the system thinks it is possible

2nd that, or disconnect rev counter it'll sound quieter then!! Lol

Yes, its certainly possible to have a switch to switch between 2 maps, you will need to put a wire into pin 15 of the Sensor connector and switch it to sensor ground.

But..... looking at the settings in your map I can see that Pin 15 is already in use by the downshift paddle input so you will first have to move that to pin 29 (cam 2 hall effect input, which isnt used on your car) and change the setting in the DTASwin software to accept this....simples!

Hope this is helpful!

Cheers,

Martin

I wonder what would happen to the noise level if you used launch control and set the revs to 4500rpm? It might be noisier or possibly not! Try it!

Martin