smart51
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| posted on 11/3/06 at 10:59 AM |
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MNR can vs R1 can
Last week I had the exhaust noise measured on my car at 107.9 dB at 9000 RPM. Too loud for a track day. I bit of silicon here and there plus some
bonnet sealing foam tape reduced that to 106.7 dB. Lifting the bonnet off altogether only raised it to 108.9
I replaced my MNR stainless straight through silencer with an R1 can today. It is noticably quieter but it messed up the midrange fueling. I leaned
off the needles by 1 groove which mostly sorted it. It is now slightly hesitant at full throttle.
The noise went down to 101.6 dB. At 10000 RPM it was 102.4 on both the exhaust and non-exhaust sides of the car.
The noise went down to 100.6 dB. Interestingly it was 97.6 dB on the other side of the car but at 10000 RPM it was 102.4 dB on either side.
Now the down side. Whilst the power delivery is smoother from 4000 - 5000, that is because it no longer jumps up at 5000 It now just rises smoothly
but not as far). It feels slower all all engine speeds from 5000 up. I guess that's why I had to tweak the fueling.
What I want is something half way between the two, slightly more punch than the R1 can with only slightly more noise. any ideas? how I can get the
MNR can to be quiter?
I measured from the same place on the non-exhaust side of the car just for fun
8000 RPM 97.6 dB
9000 RPM 97.6 dB
10000 RPM 102.4
[Edited on 14-3-2006 by smart51]
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Avoneer
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| posted on 11/3/06 at 12:26 PM |
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Hi,
See my other link here:
http://www.locostbuilders.co.uk/viewthread.php?tid=40421
I'm after the same solution and within a few months, should have tested my Supertrapp, R1 and Yoshi can (which looks like it will be the best
in-betweeny).
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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smart51
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| posted on 11/3/06 at 01:54 PM |
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118 dB. How? Are you using a silencer?
What have you done so far? I assume you've checked for air leaks. What can are you using?
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Avoneer
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| posted on 11/3/06 at 02:25 PM |
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Yeah, you might need one of those huge 7" x 30" numebrs Chris.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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mad-butcher
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| posted on 12/3/06 at 10:52 AM |
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I run a blade with an MK silencer on. must be about 106 db fortunatley Aintree is the only trackday that doesn't check noise level but they will
pull you off if they think it is to loud which gives you a bit of leaway, the likes of donnington, oulton park if it ain't right you've
waisted your money. A local bike racer said to me find out what the bike racers are running and use the same as the ACU have very strict noise levels
at race meetings
tony
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Coose
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| posted on 13/3/06 at 10:23 AM |
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The ACU regs give a calculation for noise test engine speed based on the stroke of the motor. Would you believe I had my '06 ACU rule book here
with me last week?
Normally, you're looking at about half max rpm with the meter 1 metre away from the end of the chimberley. The ACU limit at that is
105.something db (my TZ250 is bang-on the limit!!!  ), but track day organisers don't seem to like this level....
[Edited on 13/3/06 by Coose]
Spin 'er off Well...
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mad-butcher
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| posted on 13/3/06 at 06:35 PM |
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TZ250 now that takes me back I was racing a TD1C when they first came out difference in speed was mind blowing, saw the light at the end of the tunnel
and swapped over to racing sidecars
Tony
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Coose
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| posted on 14/3/06 at 11:34 AM |
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Ah, now this is a '94 v-twin...... 
[img][/img]
Spin 'er off Well...
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ChrisGamlin
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| posted on 14/3/06 at 02:51 PM |
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If you get it properly rolling roaded you'll most likely gain virtually all the lost power anyway, Richard Miles ran a standard R1 can on his R1
Striker and got some very healthy power figures and mine gave a reasonable RR figure whilst using someone else's engine map (ie mine hasnt yet
been fully set up) so it can't be that restrictive.
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