[ROVERNET - UK] exhaust and back pressure

Gundry, Kenneth KG at dolby.com
Wed Aug 11 21:51:46 BST 2004

Dear Peter,

Thank you for that suggestion.  I hadn't thought of a constriction that might have developed; I was merely wondering whether the muffler (see, I am bi-lingual) was unsuitable.  Actually I don't think it is very likely that it has fallen apart inside, in that my cousin installed it only a few years ago, since when the car has not done more than a few thousand miles, if that, and has not been exposed to the elements.  The outside of the exhaust system is not seriously rusty.  However, I have no idea of the source or construction of the muffler, or how my cousin chose it, so I really have no idea whether it was suitable.  I doubt if what he replaced was the original, in fact, I'm sure not, so he didn't have anything authentic to match.  

Anyway I am still interested in whether there is any objection to or possible damage from disconnecting the exhaust pipe from the manifold (temporarily, of course) to see whether a reduction in back-pressure increases the power output.  If disconnecting it makes no appreciable difference, then clearly there is no point dismantling it.  

It occurs to me alternatively that disconnecting the exhaust pipe and somehow measuring the pressure required to force air through it might tell me something, except that I really have no idea what the figures ought to be.  Presumably the actual exhaust gas flow rate is related to the engine displacement and speed.  I suppose there is some standard form of measurement for the obstruction to flow and for the sound-reducing properties of mufflers.  Does anyone know how the performance is specified?

Ken G, 1925 Rover 16/50 (San Francisco)

-----Original Message-----
From: rovernet-bounces at lyris.ccdata.com
[mailto:rovernet-bounces at lyris.ccdata.com]On Behalf Of
sspmilr at netzero.net
Sent: Wednesday, August 11, 2004 9:42 AM
To: rovernet at lyris.ccdata.com
Subject: Re: [ROVERNET - UK] exhaust and back pressure

Hi Ken G:

Your muffler may have rusted to the point where there is
bits and pieces restricting the exhaust flow.  Take the
exhaust appart as best you can, put a cardboard box on
the floor with a flat piece of wood in the box.  Bounce
the exhaust pipe on the wood, as well as tapping the
exhaust with a rubber mallet.  This should dislodge any
bits and pieces from the system.

Hope this helps.

Peter Miller
Port Orchard, Wa.
Formally of South San Francisco.

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