TGNY Posted May 26, 2015 Report Share Posted May 26, 2015 About to order a new exhaust system for my TR4A. There are two options available, the single muffler that goes crosswise to the chassis or the two inline mufflers. Is there any preference of one system over the other? Quote Link to post Share on other sites
stuart Posted May 26, 2015 Report Share Posted May 26, 2015 Personally I prefer the single inline large bore one. Stuart. Quote Link to post Share on other sites
Fireman049 Posted May 26, 2015 Report Share Posted May 26, 2015 Hi TGNY ~ I would definitely go for the twin box set-up ~ far less resistance, or back pressure. Regards ~ Tom. Quote Link to post Share on other sites
BrianC Posted May 27, 2015 Report Share Posted May 27, 2015 I'm sure I read some discussion on this (a long, long time ago), which suggested that although the later twin-box system was quieter and, in theory, more efficient in terms of power, the single box system preferred by Stuart was in practice actually better for performance. No idea about the cross-box except that I don't like them aesthetically. Quote Link to post Share on other sites
tim hunt Posted May 27, 2015 Report Share Posted May 27, 2015 It was actually the earlier 4As that were fitted with a rear silencer, 'Y' piece and twin rear boxes. the "more efficient" cross box single rear silencer was fitted as from July 1966 at chassis CT/CTC70000. I also prefer the straight through large bore system, mine is Phoenix stainless. I'm no exhaust expert but can't see how turning the gases twice in succession through a right angle can be more efficient. Tim Quote Link to post Share on other sites
peejay4A Posted May 27, 2015 Report Share Posted May 27, 2015 I found the right balance of nice sound and aesthetic appeal (for me) to be the twin box rear section but without the front box. Quote Link to post Share on other sites
TGNY Posted May 28, 2015 Author Report Share Posted May 28, 2015 It was actually the earlier 4As that were fitted with a rear silencer, 'Y' piece and twin rear boxes. the "more efficient" cross box single rear silencer was fitted as from July 1966 at chassis CT/CTC70000. I also prefer the straight through large bore system, mine is Phoenix stainless. I'm no exhaust expert but can't see how turning the gases twice in succession through a right angle can be more efficient. Tim Yes that was my thought also, that there would be more resistance do to the 90 degree turns. Quote Link to post Share on other sites
nickphuket Posted May 29, 2015 Report Share Posted May 29, 2015 Think it may have to do with back pressure. Too much not good, not enough not good. There will be an optimal back pressure in a tr engine that will help with scavenging In the cchambers. And the exhaust. Quote Link to post Share on other sites
Geko Posted May 29, 2015 Report Share Posted May 29, 2015 with the crossbox you don't get annoyed by the exhaust fumes blowing back in the cockpit due to depression Quote Link to post Share on other sites
peejay4A Posted May 29, 2015 Report Share Posted May 29, 2015 (edited) ...which I've found not to be a problem on the 4A unlike the TR6 with it's Kamm tail. Edited May 29, 2015 by peejay4A Quote Link to post Share on other sites
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