Lycoming/Sensenich performance expectations.....?

flyboy1963 · #1 01-30-2009, 12:36 PM

Please relocate this thread if/as required.

My 2006 Rv-9a has been happily flying for 2 years; just about 6 months with me, so I'm just feeling out the performance.

Max static rpm is about 2100. WOT at 6000' gets about 2400 rpm.
The engine is a healthy low - compression 0-320- A3A (originally) with the fine pitch Sensenich 70-77. New carb installed by AME/builder. ( not me)

seems it should turn up a bit more. Performance is fine, but makes me think I am only getting 120 hp.
Yes, I have waxed the blades also, which was good for an additional 7 rpm!

any input appreciated.

Radomir · #2 01-30-2009, 01:22 PM

That's way low RPM at WOT... you sure your tach reads correct? If it is correct... something else's going on.. got all fairings on?

szicree · #3 01-30-2009, 01:30 PM

Are you sure the cable/quadrant is actually giving WOT?

flyboy1963 · #4 01-30-2009, 02:20 PM

thanks guys,
yes, at first annual prop was balanced and tach was right on.
Had my boy 'exercise' the controls at the last annual, and i saw that throttle and mixture moved from stop to stop.
all fairings were on, leaned for max rpm etc.

.....could it be 'cause the canopy was open?

but seriously, it acts like the prop has too much pitch, except for the lack of 200 kts cruise!

647jc · #5 01-30-2009, 02:53 PM

Either your engine is quite anemic or you really don't have a 70CM()S9-0-77 prop as you stated. The 77 pitch prop would be a climb prop for a 150 hp 0-320 and the performance you are describing sounds more like a cruise prop, perhaps a 70CM()S9-0-80 (recommended for 150 hp) or even greater pitch, maybe a 70CM()S9-0-81.

I have an RV-9A, 160 hp engine with a standard 70CM()S9-0-79 prop and typically see 2250 rpm static. I can also redline the prop (2600 rpm) up to 8500 msl. I would think you would see similar performance / rpm with a 70CM()S9-0-78 prop and even higher rpms with a 77 pitch prop.

Geico266 · #6 01-30-2009, 02:57 PM

Perry, you got both mags on?

flyboy1963 · #7 01-30-2009, 03:22 PM

[quote=647jc;294574]Either your engine is quite anemic or you really don't have a 70CM()S9-0-77 prop as you stated.

Rats, off comes the spinner again...but I'm SURE I looked right at the stamp a couple months ago!...although, I guess there's always 'Friday' jobs at the factory, eh?

....or I'd better check and see if I really have an 0-235!?!?!

647jc · #8 01-30-2009, 03:44 PM

Your prop may have also been 're-pitched' but still has the 77 stamp on it.

rvbuilder2002 · #9 01-30-2009, 05:20 PM

I agree with previous posts.

1. Either your tach. is reading incorrectly (you said it was already verified)

2. For some reason the engine isn't producing full rated power (could be incorrect ignition timing, engine assembled with cam timing incorrect, etc.)

3. The prop isn't really the pitch that you think it is.

gasman · #10 01-30-2009, 09:28 PM

It might be time to install a manifold pressure gauge..............