Porsche Enthusiasts Club Forum
http://forums.tipec.net/

Exhaust note
http://forums.tipec.net/viewtopic.php?f=25&t=22621		 Page 1 of 4
Author:  Andy S [ Thu May 18, 2017 6:16 pm ]
Post subject:  Exhaust note
I have a 944 S2 Cabriolet and it has a stainless steel back box. Not sure if it's the baffles inside or a heat shield, but it makes an awful rattling sound at about 3000 rpm.

To be frank the car never sounds that good, regardless of the rattling exhaust. Does anyone have suggestions on how to improve the exhaust note?

My other car is a Stag so this one has a lot to live up to.

Andy S
Author:  MichaelW944 [ Thu May 18, 2017 6:27 pm ]
Post subject:  Re: Exhaust note
Are you sure the rattling exhaust isn't the brake disc covers rattling on the back of the brake discs? Mine was.
Author:  Andy S [ Thu May 18, 2017 6:38 pm ]
Post subject:  Re: Exhaust note
Interesting idea. Can't be certain, worth a look. Could explain the rattle at a specific rpm, rather than all the time. When home I will give them a jiggle. I presume best fixed with an angle grinder?
Author:  A.N. [ Thu May 18, 2017 6:46 pm ]
Post subject:  Re: Exhaust note
I have the same between 2 & 3k rpm. I'm presumption ng its the heafshield above the cat. Need to get undernearh :|
Author:  Andy S [ Thu May 18, 2017 7:02 pm ]
Post subject:  Re: Exhaust note
I have a large bill on file just before i bought the car showing this being fixed at a "Specialist". Exhaust still rattles. I will ask Precision Porsche on Monday if they know what the source is. If I was the previous owner I would have taken the car back to the "Specialist" and had a moan, but then I don't know what it sounded like before.

Can they be made to sound more sporty?
Author:  MichaelW944 [ Thu May 18, 2017 7:09 pm ]
Post subject:  Re: Exhaust note
Get the wheels off at the back and wiggle the covers at the back of the brake discs. There are 3 bolts that hold them on and if 1 or 2 have rusted around and released from the plate then it will rattle like crazy.
Author:  Andy S [ Thu May 18, 2017 8:04 pm ]
Post subject:  Re: Exhaust note
Thanks Michael,

I will and I'll let you know what happens.

Andy.
Author:  JasonGibson [ Thu May 18, 2017 8:05 pm ]
Post subject:  Re: Exhaust note
the 16v engines don't have a nice note to start with, although not too bad at full chat.
I have a 3.0 and a 2.5, have always been disappointed in the 3.0 sound..

As for the rattling, it could even be the tailpipe, pop into any place that does exhaust fabrication and they will be able to fix whatever is wrong
Author:  Andy S [ Thu May 18, 2017 9:28 pm ]
Post subject:  Re: Exhaust note
Thanks Jason,

I'm determined to rid the car of this annoying rattle. Then figure out how to make it sound less like a transit. I know a guy in Brighton that built me a custom stainless steel exhaust for one of my other cars. I think I'll have a chat with him and see what he can do.

It always seems worse in an open top car. Shame as the rest of the car has exceeded my expectations. It feels very period and the scuttle shake reminds me that I'm in an eighties car. Being black the wife thinks I should fit a red light in the nose so it looks like KITT from Night Rider. Personally I feel like I'm playing Chase HQ.

The thing that impresses me most is the handling. The 944 S2 turbo and 968 coupes must be a dream to drive.

Andy S.
Author:  GlennS [ Fri May 19, 2017 6:20 am ]
Post subject:  Re: Exhaust note
Three possibilities. I've had two bouts of the dreaded "3,000rpm rattle" :lol: 3,000rpm seems to be a resonant frequency for the exhausts on these cars.

The first was caused by a loose heat shield.

The second was caused by the 02 sensor working loose and rattling around in its socket in the exhaust. Annoyingly, you could tighten it up and it would be fine for a while, then take the car for a "spirited" drive and it would work loose. Eventually sorted by a quick dab with the welder.

Another possibility is a worn engine mount. This can alter the angle at which the exhaust sits, causing it to come into contact with heat shields at certain RPM.
Author:  Andy S [ Fri May 19, 2017 8:35 pm ]
Post subject:  Re: Exhaust note
Thanks Glen,

I suppose I'll start with the easy ones and then ask the garage to take a look.

Andy S
Author:  Endoman [ Sat May 20, 2017 12:51 am ]
Post subject:  Re: Exhaust note
A baffle in the intermediate silencer/resonance chamber was loose once, replaced with Promax one and Dansk rear pipe. Rear heat shield also rattled cured with a big washer. As said it doesn't sound very sporty until you wind it up. Not many 4 pots sound good some terrible. Used to like the old MGB burble and the induction roar of twin Webers on the Escort Twin-cams. Strangley the Alfa Mito has quite a nice exhaust note. It does sound better with the Promax middle box over the original but it will never have the great note of my 993 with Fabspeed x-pipes, decat sport silencers and wide oval tail pipes a mate with almost identical Cargraphic setup has a totally different exhaust note.
Author:  Andy S [ Sat May 20, 2017 3:18 pm ]
Post subject:  Re: Exhaust note
Typical, raining today so no looking under the car.

Driving to Brooklands tomorrow. So unlikely to look then either.

Even more annoying somebody has dented and scraped the front wing and bumper where it's been parked outside and I've been away all week.
Author:  Andy S [ Tue May 23, 2017 4:54 pm ]
Post subject:  Re: Exhaust note
Rattle turns out to be from badly designed/fitted non back exhaust. Fixed with a couple of welds. Will be added to the list of parts to replace in the future.

Andy S
Author:  MichaelW944 [ Tue May 23, 2017 5:04 pm ]
Post subject:  Re: Exhaust note
Have you managed to sort the body damage? A dansk backbox is the closest to the OE one if you need to replace. I'm very pleased with the front box on mine.
Page 1 of 4 All times are UTC [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/