SR20 vs SR22 exhaust

In article , xyzzy wrote:
Ben Jackson wrote:
I'm not sure I'd ever seen an SR20 before today, and boy does it have
obnoxious exhausts. Are all Cirrus planes like that and I've just missed
it?

According to this admittedly very anti-Cirrus website, an SR22 is seven
times louder than a C-182:

I'm not talking about sound, I'm talking about the pipes. They stuck
about 2' out of the bottom of the cowling on the SR20 I saw. Like giant
fangs... I see now that those are only on the SR20 -- the SR22 has much
shorter pipes.

--
Ben Jackson

http://www.ben.com/

I'm not talking about sound, I'm talking about the pipes. They stuck
about 2' out of the bottom of the cowling on the SR20 I saw. Like giant
fangs... I see now that those are only on the SR20 -- the SR22 has much
shorter pipes.

Yep, they're ugly -- but I assume they are "tuned" exhausts...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:

Yep, they're ugly -- but I assume they are "tuned" exhausts...

Well, it may not equate, but the tuning on automotive systems is done in the header.
The length and bends of the pipes from the heads to the collectors is important, but
the length of the exhaust pipes is not.

George Patterson
If you don't tell lies, you never have to remember what you said.

Yep, they're ugly -- but I assume they are "tuned" exhausts...

Well, it may not equate, but the tuning on automotive systems is done in
the header.
The length and bends of the pipes from the heads to the collectors is
important, but
the length of the exhaust pipes is not.

Hmmm. I thought that new "performance exhaust" system for Cherokees and
Skyhawks had to be "x" number of inches (feet?) long in order to "tune" the
exhaust, in order to increase horsepower "x" percent?

Isn't that why those things are so big, honkin' ugly, hanging out the bottom
of the plane?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:
Yep, they're ugly -- but I assume they are "tuned" exhausts...

Well, it may not equate, but the tuning on automotive systems is done in

the header.

The length and bends of the pipes from the heads to the collectors is

important, but

the length of the exhaust pipes is not.


Hmmm. I thought that new "performance exhaust" system for Cherokees and
Skyhawks had to be "x" number of inches (feet?) long in order to "tune" the
exhaust, in order to increase horsepower "x" percent?

Isn't that why those things are so big, honkin' ugly, hanging out the bottom
of the plane?

Could be a marketing thing. People don't like to spend money on things that
can't be seen.

Dave
Remove SHIRT to reply directly.

On Wed, 28 Apr 2004 13:49:41 +0000, Jay Honeck wrote:

Yep, they're ugly -- but I assume they are "tuned" exhausts...

Well, it may not equate, but the tuning on automotive systems is done in
the header.
The length and bends of the pipes from the heads to the collectors is
important, but
the length of the exhaust pipes is not.

Hmmm. I thought that new "performance exhaust" system for Cherokees and
Skyhawks had to be "x" number of inches (feet?) long in order to "tune" the
exhaust, in order to increase horsepower "x" percent?

Isn't that why those things are so big, honkin' ugly, hanging out the bottom
of the plane?

Well, I can't speak specifically to planes in this regard, but for
some other engines, that's the difference between turned exhaust and a
tuned pipe. The idea is that the pipe is used to improve scavenging
capabilities of the engine. Tuned pipes can often be used in
conjunction with performance headers (tuned exhaust) to improve
overall performance of the engine. The length and size of the pipe
directly relates to the targeted RPM range at which the improved behavior
is desired.

Headers are normally used to improve the ability of the engine to get
exhaust out of the engine. Likewise, pipes are normally used to effect
the scavenging abilities (helping to suck exhaust out of the engine). As
you can see, the two can be considered complimentary.

Granted, I don't normally associate pipes with 4-cycle engines. That
ignored, the length of the pipe, especially with performance headers can
also effect the backpressure on the engine. Too little backpressure can
lead to poor performance, just like too much can. AFAIK, it's not
uncommon to add a longer exhaust pipe to slightly increase backpressure to
compliment a performance header.

Jay Honeck wrote:

Hmmm. I thought that new "performance exhaust" system for Cherokees and
Skyhawks had to be "x" number of inches (feet?) long in order to "tune" the
exhaust, in order to increase horsepower "x" percent?

Tuned headers work by the fact that, if you take tubes that are between 32" and 36"
long and hook one end of each to the exhaust port of the engine and the other end to
a collector tube, the flow of the exhaust from the first cylinder to fire will help
pull the exhaust out of the second cylinder to fire. I was told that the length of
the exhaust system after the collector doesn't matter. You can reduce the length of
the tubes in the header by adding bends; conversely, if you have to bend the tubes
for clearance reasons, you have to reduce the length. This is why most automotive
tuned headers look like pretzels.

George Patterson
If you don't tell lies, you never have to remember what you said.

Ben Jackson wrote:

: I'm not talking about sound, I'm talking about the pipes. They stuck
: about 2' out of the bottom of the cowling on the SR20 I saw. Like giant
: fangs... I see now that those are only on the SR20 -- the SR22 has much
: shorter pipes.

The Mooney Ovation has the same long "tailpipes". I think it is to relocate
the boomy exhaust further from the floor where you put your feet. The Mooney
201 has the exhaust end right under the co-pilot's feet, and the noise and
vibration in tune with the engine is very impressive in the co-pilot's seat.
I find that without noise-cancelling headsets the noise is very tiring after
only an hour or two.
--
Aaron Coolidge (N9376J)