Primary muffler on a non cat car
03-24-2003, 05:58 AM
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Primary muffler on a non cat car
I have a RHD 88 951 that came from the factory without a catalytic converter, I think this is called a ROW (rest of the world) model.
In place of the cat is a cylinderical primary muffler. Question is after 15 years of use what sort of condition are the internals in. Has anyone on the list removed one and perhaps opened it up and had a look.
The reason I ask is I've just had my rear muffler replaced. The previous muffler was non porsche and a a free flow design (straight thru with a perforated pipe) the silencing was fine, but on shining a torch into the muffler I noticed the perforated pipe had developed a wavy sort of ripple on one side. The new muffler is a lot smaller in volume and quite a bit louder ( but still quite mellow) and lo and behold boost starts to build about 200 rpm earlier and on a slightly smaller throttle opening ( I have an lbe fitted). So the old muffler must have ben more restrictive, although I would never had thought so.
Could there be some benefit in repacing the primary muffler if it's internals were past there
best. By the looks of it a typical cylinderical straight thru resonator would fit. I wouldn't want just a pipe as it is already on the boarder of being too loud for my personal taste.
In place of the cat is a cylinderical primary muffler. Question is after 15 years of use what sort of condition are the internals in. Has anyone on the list removed one and perhaps opened it up and had a look.
The reason I ask is I've just had my rear muffler replaced. The previous muffler was non porsche and a a free flow design (straight thru with a perforated pipe) the silencing was fine, but on shining a torch into the muffler I noticed the perforated pipe had developed a wavy sort of ripple on one side. The new muffler is a lot smaller in volume and quite a bit louder ( but still quite mellow) and lo and behold boost starts to build about 200 rpm earlier and on a slightly smaller throttle opening ( I have an lbe fitted). So the old muffler must have ben more restrictive, although I would never had thought so.
Could there be some benefit in repacing the primary muffler if it's internals were past there
best. By the looks of it a typical cylinderical straight thru resonator would fit. I wouldn't want just a pipe as it is already on the boarder of being too loud for my personal taste.
03-25-2003, 03:01 AM
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Well, the pipe in question, if it is just like a US car, only with a resonator instead of a cat, is called the downpipe and it does have an outer and an inner wall. If you boost is real slow to build, it could be the inner wall is colaped. It does happen, but not something to panic over unless your car builds boost abnormally slow. It's hard to tell as you can not look strait thorough it when it's out of the car or in it for that matter.
As far as the perf. pipe, I cannot say. Cats get clogged all the time.
As far as the perf. pipe, I cannot say. Cats get clogged all the time.
03-25-2003, 03:32 AM
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Thanks Matt, just to clarify my downpipe ends in a flange. The next section looks like what everyone on the list calls a test pipe. ie it has a matching flange and in my case instead of being just a straight pipe there is a cylinderical muffler as well. We would cut out the muffler and weld in a new stainless steel resonator (I think most of them are quite a bit shorter than the stock muffler). I presume that after the flange it would be a single walled pipe?, is that correct as I would hate to cut the old one out to be confronted by a double walled pipe.