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Author: Subject: R1 engine/exhaust and noise restrictions
timmyb

posted on 12/9/06 at 05:28 PM Reply With Quote
R1 engine/exhaust and noise restrictions

Hi guys,

"Tried" to have my first track outing in the MK Indy on Saturday at Castle Combe, but I was a league over the 100dB noise limit they impose. Mine came out at 115dB @ 7000rpm (2004 R1 engine) - what exhaust box do you guys running a similar setup use to get under 100dB????

Tim





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posted on 12/9/06 at 08:30 PM Reply With Quote
this the new r1 or the last of the old ones?

things you could try, non straight through exhaust (a chamber at the front with a partial baffle in it before the main tube/wadding part of the exhaust)
sealed air box might also help as induction noise may be increasing it a bit too.

if it is the newer engine then make sure its a trackday without the drive by sensors as you mighr get it to pass a static at 7000rpm but it wont pass at 11000+ where all the fun happens.

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smart51

posted on 12/9/06 at 09:00 PM Reply With Quote
I have a 6" x 26" straight through can on my 98 R1. It measures 101 dB at 8800 RPM on my uncalibrated meter. on a 2004 R1, 3/4 of max revs is 10300 RPM so for track days that will be really loud.
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dave-69isit

posted on 12/9/06 at 09:02 PM Reply With Quote
hijack

colin has your cabel came yet
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DIY Si

posted on 12/9/06 at 11:33 PM Reply With Quote
It should be 3/4 of max power revs, or so I've been told in the past. May differ from place to place though.





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TimC

posted on 13/9/06 at 05:47 AM Reply With Quote
Talk to Simpson Exhausts. They do a pretty gigantic box which a lot of the Westfield guys/gals are using to get noise down.

I'll probably be going the same route with mine.






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907

posted on 13/9/06 at 07:34 AM Reply With Quote
Food for Thought

Just a couple of points which may or may not be worth thinking about.

In my experiments with exhausts over the years I have found that the length of a can has more effect than the diameter.

For example, if you had a 125mm dia can 500mm long, and you fit a 150 x 500 you reduce the sound by say 1 dBa.
If a 125 x 600 can is fitted sound is reduced by say 4 dBa.
(assuming same design and materials are used)

To sum up, longer is better than fatter.



The other thing I notice is that bikes have enclosed engines, and within the bodywork are various bits
of stuck on foam or ally foil clad padding, partly to direct air flow, but also to absorb sound.

If I owned a BEC I would be looking at this as a partial solution.
Cover the inside of the side panels, bonnet, maybe fit a thin ally under-tray and clad this also.
Perhaps a layer of thin sponge behind air intake grills and outlet vents would help.

I think for very little cost a lot could be learned.

Sound reduction for no power loss IMHO is worth looking into.

atb
Paul G






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timmyb

posted on 13/9/06 at 08:46 AM Reply With Quote
Cheers for the replies.

It's one of the last fuel injection models before the big changes. It confused me for a while - they seem to use almost the same castings on the 2003/2004 throttle bodies as they do the carbs from the same/previous years! The exhaust box that's on at present came with the car when I bought it, so I'll look into what exactly it is and put the info on here. I'm certain it'll be an MK supplied variant though.

I couldn't believe the figure that came out when the test was conducted though! My engine's running the standard air box, so I'm confident that minimal nopise is passing over from that area too.

I did notice that the BEC's that did manage to pass the test and get onto track were running monsterous silencers. Unfortunately, I never managed to find any of the owners near their cars to talk to them about it!

Where can I get in touch with Simpson Exhausts?

Many thanks once more,

Tim





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TimC

posted on 13/9/06 at 09:09 AM Reply With Quote
Google is your friend....

http://www.simpsonraceexhausts.com/






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zxrlocost

posted on 13/9/06 at 11:27 AM Reply With Quote
my r1 can was around 97db
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timmyb

posted on 13/9/06 at 12:47 PM Reply With Quote
Cheers Tim, you're too good to me





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amalyos

posted on 13/9/06 at 01:29 PM Reply With Quote
I looked at turning the airbox around, but the spacing on the carbs are not equal, so it wasn't possible. I ended up making my own intake, and got 95db at SVA using a 30" can from MNR.
Are the injection intakes equally spaced?

Steve. Rescued attachment Airbox.JPG
Rescued attachment Airbox.JPG

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