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stephenh

Noise from an XI

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stephenh

I seem to remember that someone was looking at possibly getting an improved, and possibly re-packable, silencer made for the XI? I can't see a thread however, so maybe this was mentioned within a build thread? Somewhere I've got a cheap sound meter, but I'm not sure how accurate it is, and it isn't very easy to check a car single handed! I might bring it with me to Stoneleigh, always assuming that the weather report stays ok. 

I think Simon has or had a subsidiary silencer in front of the Westfield polished one? I would prefer to stick with a single one if possible. Has anyone talked to Wunoff (or one of the other  manufacturers) about this, and if so with what result?

I don't plan on doing any competition, but I don't want to end up getting chucked off at a trackday, if in fact it is too loud. 

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jonjh1964

Stephen,

Happy for you to measure mine if it makes it, it's currently on axle stands after a radiator failure - I'm driving up to Moss in Bristol 1st thing tomorrow to pick up a new one.

Tricia, who officially 'owns' the Eleven is keen to do track days, so having an exhaust that were confident will pass will be a relief, it measured 102dB at 4,500 rpm on the IVA, passing at 3/4 of 5,000 rpm.

See you on Sunday,

Jon

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Simon Marks - North Oxfordshire AO

Hi, Stephen,

I'll bring my (MSA calibrated) sound meter with me to Stoneleigh over the weekend and give yours a test, if you like.  Please give me a call on (07880) 405148 when you arrive and we can test it when it is nice and warm - much better for the engine than stone cold, first thing in a morning at the event.

I'm hoping to fit a new (Westfield) silencer to mine before towing it up to Stoneleigh tomorrow.  I'll try to get a test done on that so we could, potentially, evaluate the effect of my extra silencer (and silenced floor below the carburettor).

Simon

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stephenh

Thanks Simon, that sounds like a plan.:t-up:

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stephenh

Well, 106 dBs at 4,500 rpm is just too much!

I spoke to the chaps at Custom Chrome, who had a stand at the show, and one of them came over to the marquee and had a look at my car. He seemed quite happy that he could sort it out and get it down to 102 or less which should be fine for most "noisey" trackdays, at a relatively modest cost. So I've got to ring him after the bank holiday and get it booked in for about a month's time. They are quite booked up with work at the moment. He reckons he could do it in a morning, while I wait.:t-up:

I will report further when I have more news on this as I know others have the same problem.

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jonjh1964

Stephen,

I saw your car looking very smart in the marque but didn't see you, I parked on/near the Westfield Avenue both days and managed to catch up with Simon, I believe there were 4 x Elevens on the Westfield areas over the weekend.

My car is now has close to 700 miles under it's belt and I have a plan for bonnet ducting after 2 x 150 miles in the mid 20s DegC, I'm also interested in your new exhaust as I'd like to do some track days in the eleven at some point - I'd target 99dB to give more options.

Jon

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stephenh

My car is going to Custom Chrome on 30th. May, for them to see what they can do to make it slightly less noisey. They say they will do it while I wait, as long as I don't mind waiting for the afternoon. I'll report back with results, and cost, after the visit.

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Simon Marks - North Oxfordshire AO

Hi, Stephen,

I'll look forward to reading the outcome.

Simon

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stephenh

Well, I had a rather wet drive to Custom Chrome in Nuneaton yesterday. How is it that the weather seems to know when I'm committed to driving out in my car with no roof, and make sure it rains that day, after weeks of fine weather?

Anyway, I have a slim but very long silencer now on the car, manufactured and fitted whilst I waited. It looks neat, and although it still makes plenty of noise, it seems to me, subjectively, that it isn't so loud when I open the throttle wide, and/or let it rev a bit. Also, in particular, it has lost the loud raspey noise when it revs on full or fairly wide throttle, so much more pleasant.:t-up:

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Dave Eastwood (Gadgetman) - Club Secretary

:d pictures or it didn’t happen! ;)

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stephenh

Oh ok, if I must. Not a lot to see, but you will see that it is a small diameter box, to fit in the available space, but twice as long as the standard silencer supplied as part of the kit. The inner (perforated) pipe is in 2 parts, part of it is a conventional perforated pipe which any of us who have repacked a silencer or have watched it done will have seen. The other part is (so they tell me) like a cheese grater (so like miniature scoops) with the scoops following a spiral form, around the inner tube. This sets up a spiral pattern in the gases, which they (Custom Chrome that is) say dissipates the sound better. 

It all looks a bit grubby from the drive home, on wet major roads.

IMGP6108.JPG

IMGP6109.JPG

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jonjh1964

Stephen,

Looks very nice, how much noise reduction?

Jon

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stephenh

Not sure yet, Jon, because we forgot to do a "before" reading on their equipment, so not much point in doing an "after", and it will get quieter over the first two or three runs. It certainly sounds much less sharp when giving it the beans.

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