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E225 rpm restrictions

I'm brand new to ABS and soon to be a c35 owner. I'm sure the subject has been discussed before but I'm unclear as to why the rpm restriction is needed. I read about vibration and CHT issues. I also read about the improved internal balancing in the e225 8 motors and that the lower end is very robust and durable.
Is it damaging to run at 24 Square for instance . I'd very much like to find out the bottom line on this subject. Thank you.

Model: Bonanza C35
Posted 11/15/2021 - 6 months ago
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The Type Certificate Data Sheet (TCDS) shows the following for the E185-8 engine

Takeoff (one minute) 2600 RPM (205 HP)
For all other operations 2300 RPM (185 HP)

This is what is approved unless you have the E185-11 which was installed in S/N D-5122 and up
It allows the 2600 RPM for 5 minutes, all other limitations remain the same.

Bob Ripley
ABS Technical Advisor

Posted 11/15/2021 - 6 months ago
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I have the e225-8 motor.

Posted 11/15/2021 - 6 months ago
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The C-35's airplanes left the factory with an E 185-11 engine. The A-777 TC is somewhat misleading in listing reference to Continental's engine specification (E-246). Those engine specifications are for any E series engine installed in any machine EXCEPT the 1947 through 1956 V tailed Bonanzas. All of the E engines (185-1 through 225-8) are limited to 1 minute of takeoff RPM and then must be reduced to the listed maximum operating range. For the 185-1 or -8 engine that would be 2050 RPM while the 185-11 or 225-8 would be 2300 RPM. Since the airplanes have been in service for 55+ years many have had allowable substitute E engines installed per item 111(d) of the A-777 TC. But in all cases if any E series engine is installed in a V tailed Bonanza the takeoff RPM is limited to 1 minute. I believe the primary reason the 185 -1 and -8 engines have the lower RPM operating range of RPM is due to those engines originally having two 6th order torsional dampers on the crankshaft while the 185 -11 and the 225-8 have one 6th and one 5th order damper.

Regards, Lew Gage

Posted 11/15/2021 - 6 months ago
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Is it damaging to run above 2300 rpm?

Posted 11/15/2021 - 6 months ago
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2300 RPM is a LIMIT. Just as the IAS has a limit and the several other listed limits in the POH are good and sound advice.

Regards, Lew Gage

Posted 11/15/2021 - 6 months ago
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I very much appreciate your input in fact I just ordered your book.

Posted 11/15/2021 - 6 months ago
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E225 rpm restrictions