Post #26
I expect inside the silencer is not too different- however it will be inferior and louder as it does not have the ribbing to reduce resonance of the genuine part.
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displaying posts 26 to 32 of 32
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| Author | Subject: Bosal as good as PSA? |
 dented_vts
Regular  Location: london Registered: 23 Feb 2010 Posts: 440 Status: Offline |
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 Posted 27th Aug 2010 at 23:01
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dented_vts
Regular Location: london Registered: 23 Feb 2010 Posts: 440 Status: Offline |
Post #27
Dan 86- i'm thinking more old school race car scenario. On this design things are a bit different, so the length of the pipe to where it expands to accommodate the CAT is a tuned length part of the "manifold" as its a productionised 4 into 1 that is in 2 parts. CAT's do funny things to the system . It used to be that it was to the first silencer, not collector as i said before, that was the critical part, but CATS have changed things. Stick one in a system and you can need a bigger bore tailpipe section for max power. So take one out and the opposite would be true. Was interesting to see in some race classes where they had to use CATS. If the length of the pipes there made a difference all performance systems would give less power, but people say some have been shown to increase power- Miles on here got about 10bhp more at the wheels form his standard car i heard than other standard cars at a rolling road day with just one of his own exhaust systems fitted. |
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Posted 27th Aug 2010 at 23:36
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dan86
Senior User  Location: Bideford Registered: 10 May 2009 Posts: 548 Status: Offline |
Post #28
dented_vts- I fitted a 2 ½ inch bore straight through ashley competition exhaust to my 1.9 gti 205 which made my ears bleed as well as half of the local population, so i replaced it with a genuine pug one.I always got the impression that it was more powerful with the smaller bore pug one. The 205 non cat exhaust system was very simple- just a centre box and a cylindrical backbox with two baffle plates. Just goes to show that shiney stainless and 4" tailpipes don't necessarily mean a power hike. Thank you for taking the time out to explain the phrase tuned length. I feel a bit embarrassed for loosely using it in the wrong way. I take it then that the tuned length is from the manifold to the first expansion point (cat or silencer). In the case of the 205 gti, the cast mani had siamesed ports to the olive joint (4-2) then the down pipe was two halves welded together to create two pipes running side by side up to the centre box (2-1) then simple straight tubing for the rest (4-2-1 system). That shows to me that peugeot had put a lot of effort into the first section of system -AKA Tuned length. Maybe a non genuine centre section/backbox would be just as good as £333 worth of aluminised french scaffold tube? ________________________________________ |
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Posted 28th Aug 2010 at 02:26
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dan86
Senior User Location: Bideford Registered: 10 May 2009 Posts: 548 Status: Offline |
Post #29
I wouldn't bent the hangers on the car for the simple fact that the paint may crack near to the welds and create a nesting place for rust bugs. Plus the hangers on the car should be perfectly alligned from the factory. I bought a genuine pug system for my GTI6 and it fitted "like a golf". perfect! I was pleased and surprised.________________________________________ |
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Posted 28th Aug 2010 at 02:35
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dented_vts
Regular Location: london Registered: 23 Feb 2010 Posts: 440 Status: Offline |
Post #30
dan86 wrote: dented_vts- I fitted a 2 ½ inch bore straight through ashley competition exhaust to my 1.9 gti 205 which made my ears bleed as well as half of the local population, so i replaced it with a genuine pug one.I always got the impression that it was more powerful with the smaller bore pug one. The 205 non cat exhaust system was very simple- just a centre box and a cylindrical backbox with two baffle plates. Just goes to show that shiney stainless and 4" tailpipes don't necessarily mean a power hike. Thank you for taking the time out to explain the phrase tuned length. I feel a bit embarrassed for loosely using it in the wrong way. I take it then that the tuned length is from the manifold to the first expansion point (cat or silencer). In the case of the 205 gti, the cast mani had siamesed ports to the olive joint (4-2) then the down pipe was two halves welded together to create two pipes running side by side up to the centre box (2-1) then simple straight tubing for the rest (4-2-1 system). That shows to me that peugeot had put a lot of effort into the first section of system -AKA Tuned length. Maybe a non genuine centre section/backbox would be just as good as £333 worth of aluminised french scaffold tube? I dont doubt what i have is worse than the genuine thing but i just want it to fit not vibrate the car and not blow! But retail price of back box is 297 and centre pipe 144!!! I had a mk.2 Jetta 16v- that too had a productionised 421 system but 4 silencers. The 306 has 2 hence the serious back box. 421favours midrange, whereas a 4 to 1 favours top end- however when you take into account cams and the rest of the engine things get more complicated. Check out the manifolds on Nascar cars where its all about top end power. Exhaust systems are mad things to try and understand, all about pulses, the speed of sound loads of stuff. There was a proper test in one of the magazines years ago where they tested a brand new 205 gti system against a number of after-market "performance" systems- the best of which made 2bhp less than the PSA original. Bare in mind this was with a bog standard engine and the results may well have been different with a modified engine. Can photocopy a chapter out a book on exhausts if your interested! Also check if your library has any tuning books by Dave Vizard- his a - series engine book is amazing! You may be right that the lengths of the tail pipe section makes a difference, but that's not my understanding at the minute. I would be interested to see which silencers Miles uses and wish i had tried to persuade him to make one up for a Xsara. |
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Posted 28th Aug 2010 at 02:39
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dented_vts
Regular Location: london Registered: 23 Feb 2010 Posts: 440 Status: Offline |
Post #31
dan86 wrote: I wouldn't bent the hangers on the car for the simple fact that the paint may crack near to the welds and create a nesting place for rust bugs. Plus the hangers on the car should be perfectly alligned from the factory. I bought a genuine pug system for my GTI6 and it fitted "like a golf". perfect! I was pleased and surprised. I thought about ordering the 306 system but the hangers are all in different places and the tail pipe is shorter. Although my Jetta never handled as well as a 309 the exhaust caused me no problems in four years! |
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Posted 28th Aug 2010 at 02:42
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chas
Seasoned Pro  Location: Warwickshire Registered: 31 Oct 2007 Posts: 1,468 Status: Offline |
Post #32
That cat looks like a pattern cat.When I had one fitted (a EuroCat) it never stopped blowing. With a genuine Pug Cat on, the exhaust system no longer was near the ground, and it never leaked from there again  .________________________________________ Ex Owner of 2000 Phase 3 306 GTi 6 China Blue - You shall be missed1974 Triumph Stag 1989 Peugeot 205 GTi 1.6 2003 Alfa Romeo 147 JTD Lusso 2005 Mondeo Ghia X 3.0 Estate LPG |
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Posted 10th Sep 2010 at 03:57
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