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Author: Subject: DB killer
smart51

posted on 13/3/06 at 01:52 PM Reply With Quote
DB killer

I need to lose 2 dB from my exhaust noise to get into a track day, which has been covered elsewhere. There are some DB killers for sale on eBay fairly cheaply. Much cheaper than a replacement can anyway.

They are perforated tubes that you bolt into the end of your silencer. If I buy one and cut it down little by little until I'm just under the max noise level, am I likely to lose much power? also, is it likely to mess up my fuelling? 2dB(A) is not a lot to lose but I don't know how good / bad this type of DB killer is.

http://cgi.ebay.co.uk/ROAD-RACE-DECIBEL-db-KILLER-REDUCER-REMOVABLE-BAFFLE_W0QQitemZ8045614555QQcategoryZ25623QQssPageNameZWDVWQQrdZ1QQcmdZViewItem[pg =58992]

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JoelP

posted on 13/3/06 at 02:14 PM Reply With Quote
recently someone said that some trackdays dont let you fix noise problems once you've been black flagged. Think it was donnington.
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smart51

posted on 13/3/06 at 02:58 PM Reply With Quote
I'd only fit it for a track day. If it was well under when the noise was measured then I'd take it out. and have them remeasure the noise before the day started.

I don't know how much noise they tend to lose as is. I'd hope that if they normally lose 10 dB and I cut it down to lose 2, then I wouldn't lose too much power either.

Has anyone any experiance with these? How much noise can you hope to kill?

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trikerneil

posted on 13/3/06 at 04:25 PM Reply With Quote
They choked my Harley to death in straight through pipes even when cut right down.

Use as last resort





ACE Cafe - Just say No.

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Jon Ison

posted on 13/3/06 at 05:04 PM Reply With Quote
I know Ive said this a thousand times before but.........

Why not get an exhaust on that meets the requirements in the 1st place, get the engine ignition and fueling set up too suit it and then forget it ? You may lose a few bhp up the rev range (count them on one hand) but you will get them back lower down the rev range anyhow and it will be more drivable too.

Fitting a DB killer will mess up all your fueling and general clean crisp running of the engine, (and lose more bhp than a quieter set up) Would you tie an athletes shoe laces together for a race and then undo them again for the walk home ?

Its the best advice I can give, the choice is yours.






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Winston Todge

posted on 13/3/06 at 06:44 PM Reply With Quote
Hey Smart,

Just thought I'd say that Marc popped one of these in his exhaust at Donnington because they failed the noise test... Hence Ian on all fours!



Marc said that the R1 felt a little flat but I can personally vouch that it still went like poo off a digging implement...

Maybe phone Marc for his opinion? It certainly quietened it down a lot! And they didn't get black flagged at any point...

Chris.






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Wadders

posted on 13/3/06 at 06:57 PM Reply With Quote
Once tried one of those, killed the performance
and the engine got extremely hot, quietest was a standard can off a gsxr 750 which i used for sva, performance was pretty good too, but the can weighed a ton. as Jon said best to get a system built to your requirements.
saying that i have a standard R1 carbon can waiting to be fitted and tested, cheap light and hopefully quiet.

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smart51

posted on 13/3/06 at 07:08 PM Reply With Quote
Quotes for a larger can are 250 - 300 so far. I could just dump the can that I have and shell out the cash. I'd rather look at the other options first.

10 for a DB killer for one track day a year and take it out afterwards is the cheapest option. I have heard conflicting reports and was just asking more widely for opinions.

An R1 can off eBay will cost 50. The one I have borrowed kills the noise and kills the power. A 10 dB killer does the same for a fraction of the cost and is more easily removable.

Someone at work today said that if ali cans are quieter than stainless steel, try wrapping exhaust tape round the can. It might be worth 1/2dB on a track day. If I can loose the noise cheaply without losing too much power then thats the way I'll go.

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dave r

posted on 13/3/06 at 08:25 PM Reply With Quote
i made something similar for sva day
didnt notice it strangling the engine (pinto) but then i didnt boot it (much)

will look it out and post a picture

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MrSandMan

posted on 13/3/06 at 08:58 PM Reply With Quote
I have the same problem!!

I spoke to the guy who runs Custom Chrome in Nuneaton. He can build a silencer to beat 98db for around 180.00

If my carbon can fails this is where I will be going. He already supplies at least on Seven manufacturer.

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smart51

posted on 13/3/06 at 09:41 PM Reply With Quote
The same guy who recommended the exhaust tape also recommended custom chrome. Maybe I should give them a ring.
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907

posted on 13/3/06 at 11:00 PM Reply With Quote
quote:
Originally posted by smart51


Someone at work today said that if ali cans are quieter than stainless steel, try wrapping exhaust tape round the can. It might be worth 1/2dB on a track day. If I can loose the noise cheaply without losing too much power then thats the way I'll go.






That's the trouble with stainless. Being smooth it reflects sound.

IMHO mild steel is better for internals.
When it gets a good thick layer of rust on it, it seems quieter.


Just an idea, probably crap, but I wonder if the inside of the body could be lined?

Silencer bandage springs to mind.

Paul G





Member of the Suttol Owners Club, the MX5 Owners Club and the BMMC

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stevebubs

posted on 13/3/06 at 11:14 PM Reply With Quote
quote:
Originally posted by smart51
Quotes for a larger can are 250 - 300 so far. I could just dump the can that I have and shell out the cash. I'd rather look at the other options first.

10 for a DB killer for one track day a year and take it out afterwards is the cheapest option. I have heard conflicting reports and was just asking more widely for opinions.

An R1 can off eBay will cost 50. The one I have borrowed kills the noise and kills the power. A 10 dB killer does the same for a fraction of the cost and is more easily removable.

Someone at work today said that if ali cans are quieter than stainless steel, try wrapping exhaust tape round the can. It might be worth 1/2dB on a track day. If I can loose the noise cheaply without losing too much power then thats the way I'll go.


May be worth giving The Kit Car Workshop (aka Fisher Sports Cars now) a ring.

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smart51

posted on 15/3/06 at 09:05 PM Reply With Quote
Are Fisher sports cars on holiday? I've been trying to ring them for a couple of days without answer.
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