I only remember seeing one set of pictures of your latest manifold (actually, you were showing the pictures of the crack in your intake plenum) and I was wondering about this stuff at that time but didn't bring up the subject of intake maniflod length. What is the diamenter of the sceet tubing that runs from your throttle body to your plenum? If the tubing is not considerably larger, imagine what the intake pulses 'see' when the TB is wide open. In other words, the motor may be functioning at WOT as if the intake tubes are VERY long which will keep the motor from turning high RPM. The opposite problem of this is an intake that has short tubes for high RPM but the prop load keeps the motor from ever reaching the area of the power curve where the motor can function in the designed power band. When I calculated this length (and I don't remember what temp I used) I came up with something like 12" for 7500 rpm. I think I have the calcs at work if anyone is interested. Ed, how about a sanity check.
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Always a sucker for a function or an equal sign. AM going out to put on gearbox tomorrow. Bad week, nothing like disasters just everything from two cars that failed inspection, tires, mufflers. Program set back and to top it off the IRS sent this old retired guy a letter telling him since he's not working and having withholdings from salary - they expect him to make estimated payments each quarter ARgggg!.
Sure glad we have this group - keeps me on the right side of the line.
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
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Sent: Saturday, August 21, 2004 10:21 PM
Subject: [FlyRotary] Re: EM-2 MAP readings
But - by personal experience, the wraparound manifold you have should
work well with the <=7K steady state area you plan to operate in.
-Mike
Thanks for the additional comments Mike, and also Ed. I knew a little math would draw him into the conversation :-)
Cheers,
Rusty