Following on from Toprivetguns posting re: BEC noise reduction I am off to Lydden Hill this morning where they are going to do a noise test for me on my MK Indyblade. I run an early Fireblade engine through a Fireblade silencer but I have got a horrible feeling it's going to be too noisy. As it's a bike track day it will be interesting to see what the Fireblade Bikes sound like.

The reason for this posting is that I have seen Decibal Killers advertised but still cannot understand how they are fitted. The end of my exhaust has very short offset tail pipe with a rolled end. Therefore, do you have to remove the end plate and insert the new baffled section in, I also assume that you can then also fill the silencer with some acoustic packing. The adverts for these devices say no drilling or cutting but I can't see how, as anyone got any pics of them fitted, thanks.

They are not designed for Bike silencers.

I had to remove the end cap, remove the centre baffle tube, drill and tap an M4 hole to hold it in place. They are designed to simply slide into your standard bike silencer, however most 7 style cars have your 90 degree end pipe, hence why it's not a simple fit.

U2U your email address and I can send pictures.

[Edited on 10/7/16 by Toprivetguns]

This is also an interesting read.

http://www.piteraq.dk/flight/muffler.html

My bike, fireblade had an open can, it was very noisy along with all the other noisy bikes when it went around Lydden.

I did I see someone knocking noise off the back of a skyline a few months ago, all they did Was to cut a circular disc a little bit wider than the diameter of the outlet then suspended it with a couple of simple brackets 1" for the outlet, an external baffle which took the edge off the noise.

On my car the stand between the engine and the outlet knocked off 4db, lots of engine noise transmitted by a 7 with all the rattly panels.

Hi my Blackbird tested 90db at Lydden but they seem a bit more relaxed about noise, the testing guy only wanted me to hold it at 4000rpm lol.
But it was markably quiter than a lot of other Cec there.
There was a turbo mk2 escort that sounded like the devil was trying to escape lol
I've got a Caterham Airbox, sound insulated bonnet, repacked acustafil silencer.

https://youtu.be/pvu39L8UAvk

It's interesting to see the variations in noise between different installations.

I've got a 954 blade, open filter and 5 or 6" diameter can (ie: not massive) and I seem to test between 96 and 99dB at 3/4 revs (depending on exactly how close to 3/4 we get...)

I've mainly been on the MSE airfield days but had a day at Castle Combe with no problems last year.

Thanks toprivetgun but it's now sorted, when I got to Lydden Hill I couldn't believe it I ran the engine at 4000 rpm and it registered 94db. I thought it sounded so loud that we retested it and again 94db. So problem solved, thanks for replies.

Good stuff !