115 db problem

[BlueNGT]

Late last year a couple of friends (RIVIERAM002) and I went to Oulton Park to try and get an afternoon on the track. Steve's car was measured at 106db which hopefully is sorted now. However the 2 964 Clubsports were way over...mine was measured at 115db's[] which clearly means I didnt get on!![]

What exhaust set-up is everybody else running to get under the 105 db's?

 

[jason]

115 holy scmloley! I was 109 and thought i was going to struggle getting down to 105.

Have you checked to see if there is actually any exhaust at all on your car????

 

[BlueNGT]

Thats is a common question....but yes it does have an exhaust, obviously it isnt there to quieten the car at the moment!!

Sounds FANTASTIC though, just a tad restricting on track entry.

 

[rskiwi]

A 964 rs has 3 noise restrictors; 1 The Cat, 2 Rear silencer, 3 off side Wing silencer.
With all of these fitted you should be well under 105db.
I have had cat removed, replaced rear silencer with "cup pipe" and left the wing silencer. Got on at Bedford no problem but it was 2 years ago.
If you retain the Rear Silencer and remove the wing silencer and replace it with a G pipe it is very loud and IMO sounds awful.
A nicer sound but still loud is a Fuchs pipe, Scart make these as well. I have the Fuchs and it is about 2ft long and is fixed to the bar that the wing silencer bolts to. Too loud for long journeys! I have tried it without rear silencer and Fuchs and the noise was incredible must be 120db Plus!
Jeff

 

[Tony]

Currently running without cat, with cup pipe and with final silencer, with this setup I was spot on 105db at oulton in november. Will be replacing cup pipe with silencer this year, mainly because I want to run in std class at sprints & hillclimbs.
Checking noise with static tests is always going to give some variation due to surroundings, operator and how honest the driver is about revs! Add to that that silencer becomes less efficient as it gets older, variations in engines and lord knows what else and your only going to be able to get it approximately right.

Tony

 

[BlueNGT]

So, Cat bypass - Cup pipe and the secondary should get it down to 105 db?

I currently have Cat Bypass, Primary silencer and G-pipe = 115db at 5,200 ish revs (no doubt the primary baffles are shot to pieces by now).

Oh yeah...I dont run the engine tray and have an open airbox too!

 

[jason]

ORIGINAL: BlueNGT

So, Cat bypass - Cup pipe and the secondary.

I dont run the engine tray and have an open airbox too

Above is exactly what I had and was 109 static.

As Tony says varies from car to car but I had to swap cup pipe for standard to get to 104 and a bit

 

[Tony]

configs the same, no undertray, drilled airbox.
G-pipes probably contributing most to the 115, but still expect variations.

Tony

 

[BlueNGT]

Intersting post over on Pistonheads regarding reducing noise on a 964...

http://www.pistonheads.com/gassing/topic.asp?t=359516&f=48&h=0

 

[Jamie Summers]

I've got one on order and should have it ready to fit at Bedford next weekend. I will get a before and after noise reading on the day, but have no reason to doubt the claims made about its effectiveness. I have seen the prototype and it's a very nicely put together bit of equipment. I'll report back in due course .........

Jamie

 

[RSGulp]

Jamie,
How much is the MHP exhaust solution? And when you report back with your noise readings from Bedford can you give details of your set-up.
Many thanks.

 

[carreraboy]

The 964RS Clubsport Exhaust came standard with rear Cup Pipe unlike Lightweight, should be 105db...have you modified your exhaust?

 

[Jamie Summers]

ORIGINAL: Rich Claridge

Jamie,
How much is the MHP exhaust solution? And when you report back with your noise readings from Bedford can you give details of your set-up.
Many thanks.

Rich,
Not exactly sure what the price will be, but somewhere around the £200 mark I think. My set up is as follows - De-cat, Cup pipe, running 9m Motec with a custom air intake. According to the previous owner it reads 108db static !!!! I'll obviously be able to confirm that on the day, but if I can get down to 102 - 103db static then I should be absolutely fine on any driveby test (given experience of my previous 964 C2 which read 105db static). My car has been black flagged at Bedford several times before (under previous ownership), so if I can get through the day without a black flag then I think that will be a great success !!!!

Jamie

 

[RSGulp]

Jamie,
Do you have the standard secondary silencer or G-pipe?

 

[Jamie Summers]

ORIGINAL: Rich Claridge

Jamie,
Do you have the standard secondary silencer or G-pipe?

Rich,
Still have the standard secondary. I honestly don't know of anyone who runs with de-cat, cup pipe and G-pipe. It would be far too noisy to be comfortable let alone ever get onto a track !

Jamie

 

[RSGulp]

ORIGINAL: Jamie Summers

I honestly don't know of anyone who runs with de-cat, cup pipe and G-pipe. It would be far too noisy to be comfortable let alone ever get onto a track !

You do now..!
My car has cat-bypass, cargraphic virtually straight-through rear box and G-pipe.
And yes, it's fairly loud! But in a deep burbling way rather than 'noise' (if that makes sense).

I plan to replace the secondary silencer just for the track, and also get a blanking cap made to seal the left-side exhaust outlet (Cargraphic's advice - and again just for the track).

I'll be very interested in your before and after decibel readings.

 

[Jamie Summers]

Have a look back at the Pistonheads thread - now with added pictures !!!

Jamie

 

[lowndes]

Apologies in advance if this is too far from the OP. Are there any tracks at which a 964rs with standard factory exhaust would not pass the noise test? The reason for asking is that I intend to make some bookings in the next few days and would like to avoid obvious problems.

 

[Laurence Gibbs]

Goodwood i think can be difficult and any tracks with low static noise limits. Standard exhaust set up is circa 102-104 dbs(static, so usually ok for drive by) i beleive.

 

[Jamie Summers]

Quick update on the exhaust tips (copy of my post on Pistonheads)


Thanks to Will I was able to try out the new exhaust tip at Bedford yesterday.

On the initial static test my car measured 108db (exactly what I expected it would) using the factory tip. I then fitted the silencer tip and had the car re-tested, this time it measured 105db. Clearly this wasn't quite as big a reduction as Will experienced on his own car, however it is extremely difficult to hold a steady 4,500rpm in my car and I think that the second reading spiked at closer to 5,000rpm. Nevertheless this is still a significant reduction, and even at 105db will allow the car to get onto pretty much every track, which it would not have done before.

The most significant effect was, however, on the all-important drive-by test. My car has consistantly failed the drive-by test at Bedford to the point where the previous owner stopped even bothering to go there any more. The drive-by limit is 87.5db, and on two runs my car measured 83.1db and 83.8db.

Bedford have instigated a new noise test procedure whereby if your car fails the static test then you have to hand over the keys to one of Bedford's instructors and they conduct the drive-by test i.e. gone are the days when you can just hope to get by by short-shifting at the microphones. If you don't get past the drive-by test with an instructor driving then it's game over before you've even started, you just won't be let on track at all.

Having passed the test my red sticker was swapped for a green one and I was able to drive all day flat-out, not having to worry about tripping the noise meters.

In short the tip does exactly what it is meant to, it reduced the noise to a level that allowed me on circuit and meant I could give it full beans all day. There was no discernable loss of power and the tip took no more than five minutes to fit.

When you consider that these tips cost about the same as a track-day I think it's a bit of a no-brainer......

Jamie