stunthanger.com
Engine basics => Engine set up tips => Topic started by: Matt Colan on July 17, 2009, 04:40:36 PM
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I've been thinking about this, a PA motor has a really small venturi, which has the motor make less power. If for some freak reason, the header or the pipe came off the motor, how much more power would that motor make. I'd guess they have a ton of reserve power, and I ask this because I think it is just something I'd like to know.
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I can't state this with authority, Matt, but if you removed the header and/or pipe from a properly set up PA (without changing fuel or prop), I suspect that power would drop rather dramatically.
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I can't state this with authority, Matt, but if you removed the header and/or pipe from a properly set up PA (without changing fuel or prop), I suspect that power would drop rather dramatically.
The power would drop???? On a side exhaust motor, if you took the muffler off, the motor gets more power. I asked because those motors do make a lot of power and rev high. We've had the prop get spun off a PA 51 and that motor SCREAMED! Lucky grandpa stuck his finger in the venturi to shut it off.
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I've been thinking about this, a PA motor has a really small venturi, which has the motor make less power. If for some freak reason, the header or the pipe came off the motor, how much more power would that motor make. I'd guess they have a ton of reserve power, and I ask this because I think it is just something I'd like to know.
If its set up properly, what normally happens is that when the pipe falls off, the power increases slightly. But it's not dramatic. Almost all 40-90-size stunt motors, in flight, are putting out somewhere around 1/2 a HP, no matter what the displacement.
But, no holds barred A 40VF could probably put out about 1.5 hp, and a 90 maybe 3-3.5 or so.
Brett
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I've been thinking about this, a PA motor has a really small venturi, which has the motor make less power. If for some freak reason, the header or the pipe came off the motor, how much more power would that motor make. I'd guess they have a ton of reserve power, and I ask this because I think it is just something I'd like to know.
Hi Matt
If you blow a coupler or eject a pipe out the back, not much of anything happens except noise on most ships, you may see a very small increase or decrease in power.
There are a couple of people running near peaked and will loose power, but 98% of them just loose the regulation and hold back in the high winds. Power output on the setup I am running is about 3 to 4 times what I am using in level flight , the engine will put out close to those numbers, so we have a LOT of reserve that just resides somewhere there and never get used to its fullest.
Randy
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This is all the exact opposite of what I expected, I would expect if somehow the pipe blew off the motor would make a lot more power.
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This is all the exact opposite of what I expected, I would expect if somehow the pipe blew off the motor would make a lot more power.
Hi Matt
That would happen if we used the pipe ,peaked and tuned for max boost and RPMS like speed flyers would , Most just use it to regulate speed in high winds. There are many other benefits, some use it as a quiet muffler, some use it to keep the oil off of their ships,etc
Randy