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Old 03-08-2018, 06:34 PM
Phenomflyer237 Phenomflyer237 is offline
 
Join Date: Oct 2017
Location: Sarasota Florida
Posts: 13
Default Prop RPM and MP

I had posted a previous post about my plane not reaching max rated RPM on a 0320 160HP. It would only do 2300WOT. After flying the plane some and installing fine wire plugs- now I get just bumping 2600RPM at WOT around 2000ft MSL in FL.
The prop is 70CMCM6S16-0-78

when I run WOT my prop is just shy of 2600RPM and MP is just shy of 27", IAS is 166kts.
is this dangerous to push the engine that hard? does it indicate over propping or under propping?

for normal cruise i run2350RPM and noticed still running 26.5mp leaned 50ROP i am at 8.7gph running 145Kts indicated does this power setting seem normal

Thanks for any help!
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  #2  
Old 03-08-2018, 08:02 PM
moosepileit moosepileit is offline
 
Join Date: Dec 2010
Location: Floyds Knobs, IN
Posts: 308
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Welcome back, I recall posting in your earlier thread:

http://www.vansairforce.com/communit...d.php?t=155633


"2600RPM at WOT around 2000ft MSL in FL. The prop is 70CMCM6S16-0-78"

What fuel flow above?

What is your static rpm? About 2350?

I have a -6, I believe you have a 6A. Mine is an O-320-e2d, 9:1, carb, vetterman crossovers, fixed timing mags at 25 degrees and same prop in 79" pitch. WOT std day 2000' msl I flow over 13gph. If you have fuel injection I assume you can save over 1 gph at same rpm and fuel flow as my carb. I static about 2320rpm. I can go well over 2600 rpm WOT at 79" pitch down low, is your tach accurate? A $10 RC handheld tach can check it inflight flying into the sun.


"when I run WOT my prop is just shy of 2600RPM and MP is just shy of 27", IAS is 166kts.
is this dangerous to push the engine that hard? does it indicate over propping or under propping?""

What fuel flow?

Sounds ok , but I think most look at 65% power, near WOT, up in the 6500-9500' for fixed pitch prop tweaks, IF they have enough static rpm and runway performance.

Folks will accept 2200 static to have more TAS at high altitude with our fixed pitch props

"for normal cruise i run 2350RPM and noticed still running 26.5mp leaned 50ROP i am at 8.7gph running 145Kts indicated does this power setting seem normal"

What altitude above? If your tach, fuel flow, ASI and MAP are accurate, 2000' msl, which is a guestimate from your MAP..

http://www.vansairforce.com/communit...hp?t-8037.html

Using about 15, 14.9 for 8.5:1 CR and 15.4 for 9:1 CR x fuel flow of 8.7, that's about 80% of 160hp power at 130 hp. Since you are 50 ROP it sounds like you have enough carb jet or fuel flow available. I assume normal CHTs and EGTs.

Your airspeed may read high or tach low.
Assuming a 90% efficient prop, 2350 rpm and 78 inch pitch yields 136 knots.

Not an engineer, throw darts!
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RV-6 N91GG, bought from builder.
O-320, slider, carb, mags, FP

Last edited by moosepileit : 03-08-2018 at 08:22 PM.
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