scsmith
Well Known Member
Larry DeCamp's recent thread about finding intake leaks contained an interesting reference provided by Kyle Boatright on exhaust system performance, written by the CAFE foundation:
http://acversailles.free.fr/documen...ur/Echappement/Aircraft_exhaust_system_IV.pdf
I don't see a date anywhere, I don't know how long ago this was printed in Sport Aviation.
I found this article very informative, but I think there is an error in the discussion of cross-over exhaust systems. The author states that cylinders #1 and #2 fire 180 degrees apart, and similarly cylinders 3 and 4. Thus he describes a crossover system that connects the exhaust headers from cylinders 1 and 2, etc.
However, using Lycoming cylinder numbering convention, the firing order is 1,3,2,4 and so cylinders #1 and #2 fire 360 degrees apart, not 180 degrees. Same for 3 and 4.
I am trying to recall how my Vetterman cross-over works without going out to pull my cowl. I think it does connect cylinders 1,2 and then 3,4. This would mean that the pipe lengths would have to be adjusted to provide some beneficial scavenging with 360 degree delay. But it does mean that the benefit would be symmetrical, i.e. the benefit from #1 reflected wave helps #2 in the same way that #2 helps #1.
If the cross-over worked with 180 degree delay, then it would not be symmetrical -- For example if you connected #1 and #3, you would have 180 degree delay for #3, but then 540 degree delay for #1 after that.
Anyone with more in-depth understanding of crossover exhaust systems care to comment?
Also, am I the only one that gets a blank page with nothing but a /**/ in the upper left corner when I try to go to vettermanexhaust.com?
http://acversailles.free.fr/documen...ur/Echappement/Aircraft_exhaust_system_IV.pdf
I don't see a date anywhere, I don't know how long ago this was printed in Sport Aviation.
I found this article very informative, but I think there is an error in the discussion of cross-over exhaust systems. The author states that cylinders #1 and #2 fire 180 degrees apart, and similarly cylinders 3 and 4. Thus he describes a crossover system that connects the exhaust headers from cylinders 1 and 2, etc.
However, using Lycoming cylinder numbering convention, the firing order is 1,3,2,4 and so cylinders #1 and #2 fire 360 degrees apart, not 180 degrees. Same for 3 and 4.
I am trying to recall how my Vetterman cross-over works without going out to pull my cowl. I think it does connect cylinders 1,2 and then 3,4. This would mean that the pipe lengths would have to be adjusted to provide some beneficial scavenging with 360 degree delay. But it does mean that the benefit would be symmetrical, i.e. the benefit from #1 reflected wave helps #2 in the same way that #2 helps #1.
If the cross-over worked with 180 degree delay, then it would not be symmetrical -- For example if you connected #1 and #3, you would have 180 degree delay for #3, but then 540 degree delay for #1 after that.
Anyone with more in-depth understanding of crossover exhaust systems care to comment?
Also, am I the only one that gets a blank page with nothing but a /**/ in the upper left corner when I try to go to vettermanexhaust.com?
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