Exhaust silencer

[Jean-Paul Reckinger]

Hello all,

my GTD with 302 Ford engine is way too loud for passing the SVA test
(+-100 dB)

does anybody know where I can buy a (larger ) silencer ?

Thanks JP

[Mike Pass]

Try :-

Mick Sollis at Southern GT
Southern GT - Manufacturer of the new Southern GT40 Replica-55b8cde9a418003849039ae65c8c99a0
Tel: +44 1489 789143
Email enquiries @southerngt.co.uk

Frank Catt at Wealden Engineering
Wealden Engineering Development
Tel: +44 1323 843839

Cheers
Mike

[andy loveday]

Hi JP,

Under the new IVA its 99dba, Andy

[Brett James-McCall]

JP,
I still beleive that the test is done at 2/3 of max engine revs. So in theory, if you are running a 6AL, couldn't you just put in a lower rev cut-off.....

Brett

[Simon]

brett, what a naughty idea!

[Dave Collins]

Hi,

I hae been talking to JP Exhausts in Macclesfield about exhaust boxes for my car to meet the 99dba requirement. They have done systems for several GT40's and seem very knowledgeable.

Stainless Steel Exhausts, Manifolds, Car Exhausts Systems - JP Exhausts Ltd, Cheshire, UK

Dave

[RichardH]

Can someone put me right here - I have heard from somewhere that Stainless steel wasn't a good idea for exhausts because of the thermo-dynamic cycling at the manifold causing stress fractures and possible failure. Obviously further down the exhaust, where the temperatures arent so extreme its OK.
Is this rubbish or correct?

[Molleur]

not quite rubbish. A very thin wall tubing may cause stress cracks/cracking, however, 16 gauge (US) or thicker material should not have these problems

[Andy Sheldon]

A customer called today to inform me about his SVA test.

The engine is a Ford 347 stroker running quad 48 IDFs.

Our standard 1 3/4" bore system tested at 96 dB.

Andy

[Lynn Erickson]

Originally Posted by RichardH

Can someone put me right here - I have heard from somewhere that Stainless steel wasn't a good idea for exhausts because of the thermo-dynamic cycling at the manifold causing stress fractures and possible failure. Obviously further down the exhaust, where the temperatures arent so extreme its OK.
Is this rubbish or correct?

this has been a problem on some automotive exhaust systems. many are made of type 304 stainless and do not hold up to the extreme temps on some engines. the type 304 stainless gets brittle after a few heat cycles. when the system is made of type 321 stainless, which contains titanium the system will last a considerable time longer. most all aircraft exhaust are made of type 321 and are .035" wall thickness. this makes a very light exhaust system that will hold for a long time. the auto systems are commonly made of 304 .065" ( 16 gauge ) wall thickness and this is done to make the system last longer ( and it is half the price ) but is twice as heavy as they need to be. the type 321 can save about 25 lbs on a set of V8 headers. A system made of the type 321 stainless will cost you a lot more because the material is more expensive and the labor is higher because the harder, thinner material is more difficult to work with and weld properly.

[Molleur]

Perfectly stated Lynn...
Type 316 is not too bad to work with and the properties are much better than the Type 304.

[Lynn Erickson]

Originally Posted by molleur

Perfectly stated Lynn...
Type 316 is not too bad to work with and the properties are much better than the Type 304.

316 is a bit better than the 304 but the cost is about the same as the type 321, so for the money I would go with the 321. 321 is an alloy made for exhausts, 316 is the same as 304 but with more Chromium and nickel but does not contain any Titanium which is the alloying element that makes 321 good for an exhaust header. they all cut and weld about the same but the when using the thin .035" wall tubing the fits need to be very precise to weld it properly.