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Thread: Exhaust system for O-320 Pacer experimental...Which setup?

  1. #1
    cook11's Avatar
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    Default Exhaust system for O-320 Pacer experimental...Which setup?

    With the availability of various experimental exhaust system setups available today which one will have the greatest performance value? Carb and cabin heat are of course a requirement too.

    1) 4-1
    2) Crossover
    3) 4 pipe

  2. #2
    Pacerfgoe's Avatar
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    Default Re: Exhaust system for O-320 Pacer experimental...Which setup?

    I think the 4 into 1 is probably the best for getting the most out of your engine. That said, it likely isn't the lightest weight option, and also presents problems if a muffler is involved.
    I found a really good video that demonstrates the benefits of 4 into one.

    https://www.youtube.com/watch?v=NekTRPx68zs

  3. #3
    cook11's Avatar
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    Default Re: Exhaust system for O-320 Pacer experimental...Which setup?

    That's what I assumed but there seems to be some conflicting opinions on various other forums.

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    Administrator Steve Pierce's Avatar
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    Default Re: Exhaust system for O-320 Pacer experimental...Which setup?

    Larry Vetterman says the pulses in a crossover system help scavenge exhaust resulting in more power. Vetterman made his name building RV exhaust systems. Jared from Canada started a thread here and installed a Vetterman system on his Owner Maintenance Pacer.
    http://www.shortwingpipers.org/forum...terman-Exhaust

    http://www.shortwingpipers.org/forum...exhaust-system

  5. #5
    cook11's Avatar
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    Default Re: Exhaust system for O-320 Pacer experimental...Which setup?

    Thanks for the links Steve. I have a hard time understanding why a crossover would have the best scavenging when the exhaust pipe lengths are drastically different? I keep thinking that the 4-1 would have the best scavenging due to the pipes being "relatively" equal in length and combined within a collector. The Sky Dynamics systems certainly look attractive.

    http://www.skydynamics.com/index.php...xhaust-systems

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    Administrator Steve Pierce's Avatar
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    Default Re: Exhaust system for O-320 Pacer experimental...Which setup?

    The way it was explained to me the pulse from one cylinder helps scavenge the other cylinder. I did put the Sky Dynamics 6 into one system on Mike Goulian's Red Bull air racer after the Ft. Worth race several years ago. It looks pretty much like the four into one used on the Carbon Cub as well.

  7. #7
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    Default Re: Exhaust system for O-320 Pacer experimental...Which setup?

    Quote Originally Posted by cook11 View Post
    Thanks for the links Steve. I have a hard time understanding why a crossover would have the best scavenging when the exhaust pipe lengths are drastically different? I keep thinking that the 4-1 would have the best scavenging due to the pipes being "relatively" equal in length and combined within a collector. The Sky Dynamics systems certainly look attractive.

    http://www.skydynamics.com/index.php...xhaust-systems
    Exhaust with equal length primary, and same number and angle bends in it in theory is the best performing. Primary pipe diameter and length a contributing factors to performance. This type of header will give the widest rpm range. A system with unequal length primary tubes may "scavenge" but will typically be at certain rpm where the pulses are perfectly timed. A tri Y collector may work well on aircraft but they are heavier and take up more space. I have found them to produce more torque. Stock Piper is a POS, but it produces great cabin heat. Larger secondary pipe leaving muffler would help. No flame tube as some Comanche mufflers would also.

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