flyboy1963

flyboy1963

Well Known Member
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.
 
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?
 
performance???

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!
 
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.
 
Last edited:
647jc said:
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!?!?!
Click to expand...
 
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.
 
flyboy1963 said:
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! :)
Click to expand...
Something seems to be amiss somewhere. At 6000 ft, full throttle, how much EGT rise can you get when you pull the mixture back from full rich?

Do you have a fuel flow indicator? If so, and if you have it well calibrated, it might help shed some light here. What is the fuel flow at 6000 ft, full throttle?

Where did the engine come from?
 
You've verified the tach is correct so figure out if the prop is pitched correctly before you do anything else. If you find that it has been repitched and there are no logbook entries for it or if you don't have a log book for the prop get rid of it as you don't know who did it or how it was done. Don
 
flyboy1963 said:
Max static rpm is about 2100. WOT at 6000' gets about 2400 rpm. The engine is a healthy low - compression 0-320- A3A (originally)
Click to expand...
Do you know the engine is healthy? I suspect you are not producing rated power. I had the same prop as you on a 2500hr O-320-Exx on a 6A and it would pull 2500+ at 6000' and give 2150 to 70 static. Perhaps you have a cam lobe spalling? Have you checked the filter last time you changed the oil? Do you have CHTs & EGTs on all cylinders? I believe there is a procedure to check the valve lift (check cam lobe size) without taking a pot off - ask a local A&P.

Start saving for a overhaul perhaps?

Pete
 
LYC/Sen perf.

thanks for all the tips guys.....looks like I've opened a can of worms, eh?

Prop is brand-new from Sensenich. I'll have to go flying to check the MP and EGT rise as suggested. No other fancy instrumentation available.

Still I'm pretty happy with how it climbs and runs.....just would be nice to know if there's more performance to be had.
 
Perry,

There is definitely more performance to be had :), just depends how much you want to pay! Seriously, it might be worth logging some prformance numbers and weather conditions, such as rate of climb & rpm after take off and then cruise speed and rpm, just to make sure there is no gradual degradation.

Another thought is that if you have Slick mags that haven't been opened up for >500 hours, it might be worth getting them checked over, it could be worth 30 to 50 rpm static.

Pete
 
Lyc/Sens perf.

Good point. I have great faith that the AME who built my plane had everything setup correctly, but that's not to say that things aren't aging gradually. The mags are original Bendix, and are no doubt 'getting tired'.....so before I even open them, I'll buy a new Slick Left one, new harness, and plan to add an electronic Right mag.
 
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