http://pages.ebay.com/link/?nav=item.view&alt=web&id=161282941044&globalID=EBAY-GB
As well when I source a new bonnet
Usual BEC problem - noise.
Going to get a new quieter exhaust, but still struggling with general engine/induction noise despite airbox.
I am thinking about lining the fibreglass bonnet of mk MK Indy with some noise reducing / fire retardant foam.
Anybody done the same? Any advice - did it make cooling an issue?
I've been quietening down my blackbird engine over the past few months, Caterham Blackbird Airbox and Acousafill in the exhaust, got it down to
93dB but was going to use this
http://pages.ebay.com/link/?nav=item.view&alt=web&id=161282941044&globalID=EBAY-GB
As well when I source a new bonnet
I'll be interested in the results if you use the sound damping sheets, as I'm also struggling with noise issues and need to get the noise
below 100Dba for Castle Combe
Cheers Iainl
IanL - good luck with Combe, is it the static limit or drive-by that is the issue?
With an airbox and a good exhaust can (by good, I mean a long wide type thing, not a bike can) you'll see 100 dB static with some certainty. My
Megabusa with a Pipercross airbox and Westfield's larger (Catalyst) can with a Merlin add-on will *just* about do the 100 dB static at Combe.
Just taking the bonnet off will exceed this.
Same at Brands, with the same result after 2 laps of drive-by, a black flag and game over. Combe's circuit recorded 106 dB.
Running at Brands was possible by dropping the RPM a tad, but Combe and (especially) Goodwood, no hope.
The GSXR1000 and R1 engine fitments were noisier, particularly the GSXR1000 on WOT.
'Adithorpe' on here has an R1 car generating incredible horsepower and doing so silently, so hopefully some help for you will be
forthcoming.
I bought an MX5....
Just turn up and give em some ear plugs!!!!, seriously, I worried about this post as I thought you meant general driving noise!
It's why you want a v4. No matter where they stand half the noise is coming out the other side 
quote:
Originally posted by IainL
I'll be interested in the results if you use the sound damping sheets, as I'm also struggling with noise issues and need to get the noise below 100Dba for Castle Combe
Cheers Iainl
I used a dense acoustic foam when I went through the SVA with my BEC, I used a foam used in the lining of ductwork and it made a massive difference to the induction noise readings. I lined the sides of the engine bay internally (stuck the body) and the underside of the bonnet, the foam is still in place now (SVA in 2009). It wasn't cheap, I think it was about £70/£80 + VAT per m - but it certainly did the job
I don't know much about BEC's, but what changes in engine application to make the BEC so much louder than the original bike? Surely Coombe
has bike trackdays as well?
I was at the bike shop on the weekend getting an MOT, and I saw a bike with a dB level stamped on the chassis plate. 84 dB...apparently similar noise
to a food blender...
I've ridden bikes for 30 years, so have a bit more knowledge than my recent foray into the kit car world.
Bike engines rev much higher than a car's engine - especially an in-line 4 cylinder. When fitted in a bike, at max revs on a Fireblade 1000cc
engine, you will be flying at 170mph+. Not too many opportunities to get up to that speed unless you are very talented and brave.
When you use the same engine in a car, which often is only geared to 120 mph and weighs over twice as much as a bike, you will be spending alot more
time in the higher rev range. So even if you can pass a static db test, the drive by at 120 mph with mx revs will probably catch you out.
Add to that the induction noise. Most people ditch the standard bike air box as it does not fit under a kit car's bonnet. If you use a foam
filter instead, the induction roar of air being sucked into the engine can break the track noise limits.
I've fitted a bespoke air box and am going to use an MK Indy exhaust, but still not sure if i can get the car down to passing a bedford 87.5db at
20M drive by.
Hence the question on adding noise reduction foam...
I've used some closed cell foam with a silver reflective outer face similar to
THIS on my Defender 90 to reduce engine noise, and it works quote well. It's a closed cell foam, reflective outer face, and
adhesive backing about 20mm thick. Unfortunately I couldn't tell you where to get it as I bought an offcut at one of the shows last year.
I used DynaMat Lite on the inside which is even better at noise reduction and thinner (complete with the reflective surface), but on the down side it
is significantly heavier and a lot more expensive.
Hope this gives you something to work with....
[Edited on 17/8/15 by Charlie_Zetec]
I'm pretty convinced that the noise produced in a BEC compared to that on a bike is partly induction roar but mostly produced by the aluminium
and grp panels acting like a sound box. Most of the exhaust systems fitted are more effective than bike cans, so the exhaust is generally not the main
perpetrator here.
To me its like a bee in a can, the vibration and noise from the engine at higher rpm's is just the right frequency to be amplified by the
surrounding grp or aluminium panels.
So a bit of experimenting with various sound deadening materials in various locations around the engine bay should reap the biggest gains (or should
that be losses).
chutley,
How did you get on lining your bonnet to reduce the noise?
I'm think of doing the same as well as the side panels, so I'm interested in seeing what you used?
Cheers
Iainl
quote:
Originally posted by IainL
chutley,
How did you get on lining your bonnet to reduce the noise?
I'm think of doing the same as well as the side panels, so I'm interested in seeing what you used?
Cheers
Iainl
Any tech sheets on the temperatures it can withstand ?
quote:
Originally posted by DRM Black7
I've been quietening down my blackbird engine over the past few months, Caterham Blackbird Airbox and Acousafill in the exhaust, got it down to 93dB but was going to use this
http://pages.ebay.com/link/?nav=item.view&alt=web&id=161282941044&globalID=EBAY-GB
As well when I source a new bonnet
I went for this in the end, good up to 200degrees
https://www.ebay.co.uk/ulk/itm/262309262075
Has made a vast difference but not the lightest material tho.
quote:
Originally posted by DRM Black7
I went for this in the end, good up to 200degrees
https://www.ebay.co.uk/ulk/itm/262309262075
Has made a vast difference
Can't post photos on here. Can put them on Facebook, I'm in most of the seven groups on there.
quote:
Originally posted by DRM Black7
Can't post photos on here. Can put them on Facebook, I'm in most of the seven groups on there.
Done