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carlbon

Brands GP - April 23rd

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I just booked a noise test. I am going to Brands Hatch tomorrow morning and have the car measured.

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how about those merlin mufflers? or something similar? I remember a post where someone was saying that there is an outlet at Castle Combe that makes these bolt ons and they reduce 3-4dbs....

 

True or am I out of my mind?

My Merlin Muffler turned up today Teo. The guy I spoke to at Merlin said they didn't have a big effect on 911s. He warned me (and it also says in the catalogue) that it may have no effect at all !

 

If I can find my sound meter I'll do a before and after test on the Merlin.

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Next stick only to 105db events and be done with it...

That is the way to go at the mo, zero stress! I think it is quiet enough for me but I wouldn't be surprised if it measures at 104 to start with, will quieten down a bit as it carbons up, plus of course it is now repackable.

 

The pipes test at 102 on Roys 3.8 so should be fine in time.

 

Your redline is 5800 revs if anyone asks, not 7600!!

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Gary's rev limit is apparently infinite - "now unlimited revs (whoa - just keeps on pulling !)" - so 2/3 of that is ....?

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2/3 of that is ....?

3800, same as yours ;)

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My Merlin Muffler turned up today Teo. The guy I spoke to at Merlin said they didn't have a big effect on 911s. He warned me (and it also says in the catalogue) that it may have no effect at all !

 

At combe I've seen:-

 

a merlin muffler tested on a 2.4s with all stainless system exhaust system and it had no effect

 

My SC regularly test at 100db with the merlin muffler and 102-103 without, exhaust is SSI's with mild OEM 74 box

 

A 996 cup car with twin outlet and a merlin on each pass the 100db test

 

Based on observation it seems stainless systems are naturally noisy as they tend to "ring" and amplify the exhaust note, mild steel systems seems to deaden the sound and reduce noise.

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Gary's rev limit is apparently infinite - "now unlimited revs (whoa - just keeps on pulling !)" - so 2/3 of that is ....?

Haha - as I wrote that I thought 'a poke in the eye' for the first one to notice and come back with a comment - lol

 

At combe I've seen:-

 

a merlin muffler tested on a 2.4s with all stainless system exhaust system and it had no effect

 

My SC regularly test at 100db with the merlin muffler and 102-103 without, exhaust is SSI's with mild OEM 74 box

 

A 996 cup car with twin outlet and a merlin on each pass the 100db test

 

Based on observation it seems stainless systems are naturally noisy as they tend to "ring" and amplify the exhaust note, mild steel systems seems to deaden the sound and reduce noise.

Good to know Bruce. I bought it half on your earlier recommendation (your system being almost identical to mine) and half from a 'well at least it looks like I'm trying to be quiet' angle. Got Le Mans and Brands GP both at 101db, so it's just a bit of insurance really. Not even convinced I'll need it since mechanically it's very quiet since John adjusted the valve clearances. With your hand covering the exhaust you can barely hear it.

 

As for 'unlimited revs' ;), I came back in the rush hour yesterday and was bogged down in traffic almost all the way home. On a couple of short bursts it revved up to 6500 and was still pulling well :ani_clapping:

 

ps Do you stick a self-tapper through the Merlin and the clamp just for extra insurance ?

Edited by GaryH

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OK just got back from Brands Hatch for the testing...

 

105.3db @ 3,600 rpm

106db @ 4,000 rpm

 

My instrument was correct.... :angry:

 

But as I did the U turn to leave the noise testing area the guy that measuread approached my window and asked me when I was booked for the GP layout. I answered I was going to come on the 23rd. To that he replied that he was going to be doing the testing and started looking at the car again...

 

Him - "It's a lovely car.... maybe we can be a little flexible on the 23rd..." and keeps looking at me.

Me - "Thanks... flexible uh?"

Him - "Yeah... these cars are usually louder on a static reading but are just fine on the track... maybe we'll sort something out...."

Me - "So you rekcon it might pass on the 23rd?"

Him - "Yeah, I reckon it will be OK" and smiles.

 

At which point my faces lights up... I shake his hand and drive away....

 

So thanks to this great guy I'll be in the 911!!!!!

 

Still I might buy a set of Merlins... just to show I tried....

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OK just got back from Brands Hatch for the testing...

 

105.3db @ 3,600 rpm

106db @ 4,000 rpm

 

My instrument was correct.... :angry:

 

But as I did the U turn to leave the noise testing area the guy that measuread approached my window and asked me when I was booked for the GP layout. I answered I was going to come on the 23rd. To that he replied that he was going to be doing the testing and started looking at the car again...

 

Him - "It's a lovely car.... maybe we can be a little flexible on the 23rd..." and keeps looking at me.

Me - "Thanks... flexible uh?"

Him - "Yeah... these cars are usually louder on a static reading but are just fine on the track... maybe we'll sort something out...."

Me - "So you rekcon it might pass on the 23rd?"

Him - "Yeah, I reckon it will be OK" and smiles.

 

At which point my faces lights up... I shake his hand and drive away....

 

So thanks to this great guy I'll be in the 911!!!!!

 

Still I might buy a set of Merlins... just to show I tried....

 

Good times :D

 

I think showing that you have tried goes a long way. FWIW, having the Merlin cans is relatively cheap insurance. I have seen them take a 2.7RS spec motor on SSIs and single out from 109db to 105db at Goodwood. That car didn't sound all that loud but it sure tested loud. Even if they make little difference to the db meter, they sound different (anyone remember the 355 at Snet running with 2 Merlin cans in the morning and none in the afternoon?) and show that you are trying. These noise guys are, under the initial sergeant major type attitude, normally petrol heads. Give them an excuse to let you on and they normally will.

 

RB

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I'm a bit disappointed with the 106 but tbh is where I thought it might be. Can you up the packing to bring it down a touch? Or would a change of heat exchangers help I wonder?

 

I think a large part of your car's reading is a certain amount of induction noise hitting the meter too. These tests unfairly penalise our cars, they're a bugger.

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If you are getting lots of induction noise could you not make a temporary tray that covers the underside of the engine grille for the noise test? A sheet of perspex and some dynamat should kill a load of noise from the engine bay. I still recon 993 HE's and a bolt on muffler with capping options should sort you out - Chris/Tim even have a spare M&K kit ready to weld up.

 

Pleased you found a friendly tester at last - hope he is there on the day too.

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I am still wondering how Bob measured it at 102db.... :rant_yellow:

 

I have ordered some Merlins.. After the 23rd only 105db days for me...

 

I guess I can open the mufflers ups and stuff them... but since the guy gave me the green light for Brands I am not going to bother...

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Great news! Guess I should have tried that myself :rolleyes:

What, frenching the noise tester ;) ?

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I just received the Merlin mufflers. I will bolt them on tonight (if I can make it home in time) and post the results on the db difference.

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I am really puzzled....

 

Now stone cold car.... 4k rpm.... reading 102.5db without mufflers and 100.2db with the Merlin mufflers....

 

Anyway the Merlins cut at least 2.5dbs. I am bringing them to Brands. Will try without, and then mount them if I fail...

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I am really puzzled....

 

Now stone cold car.... 4k rpm.... reading 102.5db without mufflers and 100.2db with the Merlin mufflers....

 

Anyway the Merlins cut at least 2.5dbs. I am bringing them to Brands. Will try without, and then mount them if I fail...

A result anyway then Teo. Good to hear that the Merlins work. I've got one for my car. How exactly did you mount them ? Any pics ?

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My tail pipes are 2.5 inches in diameter. I ordered the ones that have a 2 5/8 diameter sleeve. I then slide them onto the tail pipes and secure them with a ring clamp (the ones with the screw that u can tighten or loose up).

 

I will take some pics tomorrow.

 

I will bring them to BH and if I pass without them you are all welcome to use them if needed and if they fit...

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I am really puzzled....

 

Now stone cold car.... 4k rpm.... reading 102.5db without mufflers and 100.2db with the Merlin mufflers....

 

Anyway the Merlins cut at least 2.5dbs. I am bringing them to Brands. Will try without, and then mount them if I fail...

Each DB is x 3 to the human ear so that drop is quite a lot,I agree with John I think it could also be induction noise,your car eally didnt sound nosiy at all to me but I suppose it what the track bods say that counts :(

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Each DB is x 3 to the human ear

I thought it was every 3db was a doubling in total volume? Or are they the same thing?

 

That is a good result on the merlins Teo, but I thought the whole point of getting the repackable exhausts was so that you could kill the volume inside the pipe rather than outside?

 

Put that debit card away for a few weeks, and wave some tools about instead, set this stuff up how you like it mate ;)

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I am surprised because with the same noise meter I measured it at 106.5db @ 4k and at Brands Hatch the noise test returned 105.3db @ 3.5k.

 

Tonight 102.5db @ 4k without the Merlins and 100.6db with the Merlins....

 

Maybe if/when the muffler gets hot it looses some of it's "muffling" properties.... That's my only explanation (tonight the car was cold as I did not drive it to work).

 

Either that or some build up inside the muffler...

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I thought it was every 3db was a doubling in total volume? Or are they the same thing?

 

That is a good result on the merlins Teo, but I thought the whole point of getting the repackable exhausts was so that you could kill the volume inside the pipe rather than outside?

 

Put that debit card away for a few weeks, and wave some tools about instead, set this stuff up how you like it mate ;)

 

 

You are funny.... :P

 

Bhe Merlins were 100 quid shipped.

 

For me to take the muffler apart I need to:

 

- find the stuff that you put into the muffler ($$$, where?)

- take the morning/afternoon off work (if everything goes ok... which it never does 1st time)

- show up at home and explain to my 2 little ones I am not there to play with them.

- as above but with wife.

 

The dude at Brands told me I was fine. The Merlins were just an insurance...

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Normally they get quieter hot and with time, due to carbon build up. My car tests 103db cold and 100db hot.

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My tail pipes are 2.5 inches in diameter. I ordered the ones that have a 2 5/8 diameter sleeve. I then slide them onto the tail pipes and secure them with a ring clamp (the ones with the screw that u can tighten or loose up).

Haha - mine are 60mm :P

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Normally they get quieter hot and with time, due to carbon build up. My car tests 103db cold and 100db hot.

 

 

That is what I thought as well.

 

I must say though that when the car is hot the exhaust starts booming a little...

 

Anyway we'll see next week. Can't wait to meet you all!

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