Today's Message Index:
----------------------
1. 05:29 AM - Exhaust pipes. (Gene Smith)
2. 05:50 AM - Re: Exhaust pipes. (Archie)
3. 06:02 AM - Re: Exhaust pipes. (Hans Teijgeler)
4. 06:43 AM - Re: Exhaust pipes. (n801bh@netzero.com)
5. 08:04 AM - Re: Exhaust pipes. (DOUGPFLYRV@aol.com)
6. 10:30 AM - Re: Exhaust pipes. (Tedd McHenry)
Message 1
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--> Engines-List message posted by: "Gene Smith" <esmith6@satx.rr.com>
I need new exhaust pipes for my RV-4...Would someone please educate me on the difference
between "straight pipes" and "cross-overs." Fuel consumption obviously
is a big concern now, and noise levels near a small community could develop
into a problem...Specifically, do "straights" enable more power from the engine,
and less fuel consumption?..Seems I read somewhere that "tuned" exhausts
were the way to go...What is the advantage and disadvantage of each?..The engine
is a Lycoming 0-320 E2A, modified to 160 HP..........Thanks..........CHEERS!!!!..........Gene
Smith.
Message 2
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| Subject: | Re: Exhaust pipes. |
--> Engines-List message posted by: "Archie" <archie97@earthlink.net>
The advantage of "straight" pipes is simplicity and cost.
The disadvantage is that hp is not maximized by exhaust.
Tuned exhausts may cost a bit more due to their complexity. (if done
correctly),
and will take advantage of pulses complementing each other, (in many
instances
requiring a crossover), with each tube being equal length taking advantage
of
resonant frequency.
Archie
----- Original Message -----
From: "Gene Smith" <esmith6@satx.rr.com>
Subject: Engines-List: Exhaust pipes.
> --> Engines-List message posted by: "Gene Smith" <esmith6@satx.rr.com>
>
> I need new exhaust pipes for my RV-4...Would someone please educate me on
> the difference between "straight pipes" and "cross-overs." Fuel
> consumption obviously is a big concern now, and noise levels near a small
> community could develop into a problem...Specifically, do "straights"
> enable more power from the engine, and less fuel consumption?..Seems I
> read somewhere that "tuned" exhausts were the way to go...What is the
> advantage and disadvantage of each?..The engine is a Lycoming 0-320 E2A,
> modified to 160 HP..........Thanks..........CHEERS!!!!..........Gene
> Smith.
>
>
>
Message 3
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| Subject: | Re: Exhaust pipes. |
(not processed: message from valid local sender)
--> Engines-List message posted by: "Hans Teijgeler" <hans@jodel.com>
Gene,
The idea behind tuned exhausts is that the shock wave that travels up and
down your exhaust system will actually help to suck exhaust gasses out of
your cylinders, giving you a few hp, or saving you a few ounces of fuel per
hour.
That's the smallest nut shell that I could find.
The catches?
1) This scavenging effect will only work for ONE rpm, or at least a fairly
narrow rpm band
2) Which rpm band this is depends on a number of factors: Pipe length,
exhaust gas temperature, rough edges and steps in your exhaust pipes
(anything that might bounce off the shock wave)
3) Because of this, tuning is a bit of a black art, with ballpark values
available, but empirical fine-tuning being required
4) It requires all exhaust pipes to be equal length
5) This makes for more complex exhaust systems
6) And heavier
7) And a smoother running engine (ever so slightly) - all cylinders being
able to deliver the same power
Have a look at http://www.jodel.com/index.asp?p=exhaust&engines for an
article on my site. Although the site is on Jodel aircraft, the tuning
applies to all piston aircraft.
Making your aircraft more silent is always a good idea. In the US, you are
still far removed from the everyday situation that we have here in Europe,
but you're heading in this direction too: Airports being closed for weeks on
end because the "noise quotum" has been used up, noisy aircraft not being
allowed to take off during noise sensitive hours, big $$$ landing feed for
all but the most silent aircraft, etc. In the aviation community, we've had
our head up our behinds for far too long. It's never too early to try to be
a good neighbour.
Just my 2 cents,
Hans
-----Original Message-----
From: "Gene Smith" <esmith6@satx.rr.com>
Subject: Engines-List: Exhaust pipes.
> --> Engines-List message posted by: "Gene Smith" <esmith6@satx.rr.com>
>
> I need new exhaust pipes for my RV-4...Would someone please educate me
> on the difference between "straight pipes" and "cross-overs." Fuel
> consumption obviously is a big concern now, and noise levels near a
> small community could develop into a problem...Specifically, do
> "straights" enable more power from the engine, and less fuel
> consumption?..Seems I read somewhere that "tuned" exhausts were the way
> to go...What is the advantage and disadvantage of each?..The engine is
> a Lycoming 0-320 E2A, modified to 160
> HP..........Thanks..........CHEERS!!!!..........Gene Smith.
>
>
>
>
>
>
Gene,
The idea behind tuned exhausts is that the shock wave that travels up
and down your exhaust system will actually help to suck exhaust gasses out
of your cylinders, giving you a few hp, or saving you a few ounces of fuel
per hour.
That's the smallest nut shell that I could find.
The catches?
1) This scavenging effect will only work for ONE rpm, or at least a
fairly narrow rpm band
2) Which rpm band this is depends on a number of factors: Pipe length,
exhaust gas temperature, rough edges and steps in your exhaust pipes
(anything that might bounce off the shock wave)
3) Because of this, tuning is a bit of a black art, with ballpark
values available, but empirical fine-tuning being required
4) It requires all exhaust pipes to be equal length
5) This makes for more complex exhaust systems
6) And heavier
7) And a smoother running engine (ever so slightly) - all
cylinders being able to deliver the same power
Have a look at <A
">
http://www.jodel.com/index.asp?p=exhaustenginesfor an article
on my site. Although the site is on Jodel aircraft, the tuning applies to
all piston aircraft.
Making your aircraft more silent is always a good idea. In the US, you
are still far removed from the everyday situation that we have here in
Europe, but you're heading in this direction too: Airports being closed for
weeks on end because the "noise quotum" has been used up, noisy aircraft not
being allowed to take off during noise sensitive hours, big $$$ landing feed
for all but the most silent aircraft, etc. In the aviation community, we've
had our head up our behinds for far too long. It's never too early to try to
be a good neighbour.
Just my 2 cents,
Hans
-----Original Message-----
From: "Gene Smith"
esmith6@satx.rr.com
engines-list@matronics.com, RV4-list@matronics.com
Mon, 5 Sep 2005 07:29:59 -0500
Subject: Engines-List: Exhaust pipes.
-- Engines-List message posted by: "Gene Smith"
esmith6@satx.rr.com
I need new exhaust pipes for my
RV-4...Would someone please educate me
on the difference between
"straight pipes" and "cross-overs." Fuel
consumption obviously
is a big concern now, and noise levels near a
small community could
develop into a problem...Specifically, do
"straights" enable more
power from the engine, and less fuel
consumption?..Seems I read
somewhere that "tuned" exhausts were the way
to go...What is the
advantage and disadvantage of each?..The engine is
a Lycoming 0-320
E2A, modified to 160
HP..........Thanks..........CHEERS!!!!..........Gene Smith.
-
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Message 4
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| Subject: | Re: Exhaust pipes. |
--> Engines-List message posted by: "n801bh@netzero.com" <n801bh@netzero.com>
The advantage of "straight" pipes is simplicity and cost.
The disadvantage is that hp is not maximized by exhaust.
Tuned exhausts may cost a bit more due to their complexity. (if done
correctly),
and will take advantage of pulses complementing each other, (in many
instances
requiring a crossover), with each tube being equal length taking advantage
of
resonant frequency.
Archie
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
Archie explained this concept very clearly. I hope there is a few manufacturers
making tuned pipes for experimentals though. Surely they will be priced logically.
A local guy with a Cessna 172 wanted to improve his fuel burn so he priced
a set for his bird. Powerflow, who makes a good set of pipes quoted him 4,900.00
and he bought them. It will take 80 years for a pay back on fuel savings,
If I would have known there was a huge margin for bending up pipes I would
have gone into the business years ago !!!!!!!!!
Ben Haas
N801BH
www.haaspowerair.com
The advantage of "straight" pipes is simplicity and cost.
The disadvantage is that hp is not maximized by exhaust.
Tuned exhausts may cost a bit more due to their complexity. (if done
correctly),
and will take advantage of pulses complementing each other, (in many
instances
requiring a crossover), with each tube being equal length taking advantage
of
resonant frequency.
Archie
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
Archie explained this concept very clearly. I hope there is a few manufacturers
making tuned pipes for experimentals though. Surely they will be priced logically.
A local guy with a Cessna 172 wanted to improve his fuel burn so he priced
a set for his bird. Powerflow, who makes a good set of pipes quoted him 4,900.00
and he bought them. It will take 80 years for a pay back on fuel savings,
If I would have known there was a huge margin for bending up pipes I would have
gone into the business years ago !!!!!!!!!
BenHaas
N801BH
www.haaspowerair.com
Message 5
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| Subject: | Re: Exhaust pipes. |
--> Engines-List message posted by: DOUGPFLYRV@aol.com
In a message dated 9/5/2005 8:45:38 A.M. Central Daylight Time,
n801bh@netzero.com writes:
Engines-List message posted by: "n801bh@netzero.com" <n801bh@netzero.com>
The advantage of "straight" pipes is simplicity and cost.
The disadvantage is that hp is not maximized by exhaust.
Tuned exhausts may cost a bit more due to their complexity. (if done
correctly),
and will take advantage of pulses complementing each other, (in many
instances
requiring a crossover), with each tube being equal length taking advantage
of
resonant frequency.
Archie
//////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////
Archie explained this concept very clearly. I hope there is a few
manufacturers making tuned pipes for experimentals though. Surely they will be
priced
logically. A local guy with a Cessna 172 wanted to improve his fuel burn so
he priced a set for his bird. Powerflow, who makes a good set of pipes quoted
him 4,900.00 and he bought them. It will take 80 years for a pay back on
fuel savings, If I would have known there was a huge margin for bending up
pipes I would have gone into the business years ago !!!!!!!!!
Ben Haas
N801BH
www.haaspowerair.com
I talked to Aircraft Exhaust Technologies (I think that is correct) at OSH.
They had tuned exhaust for RV's except the 'A' models. Think it was about
$1100.00.
Doug Preston
RV7 147 hrs.
Message 6
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| Subject: | Re: Exhaust pipes. |
--> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
Gene:
You can buy a Vetterman crossover exhaust for an RV through Van's.
http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1125941155-374-657&browse=engines&product=vetterman-exhausts
Prices are under a thousand dollars. Customer satisfaction seems to be high,
from what I've heard.
I've never bought from Vetterman, but I had a long conversation on the phone
with Mr. Vetterman and he sounds like a good person to do business with. He
also seems to know what he's doing.
Tedd McHenry
Surrey, BC, Canada
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