November 19, 2012 at 4:38 pm #83948
Is anybody familiar with the outlawaircraft “Speed Increase STC”? Their website does not give much detail but it sounds like they are just running the engines at higher power settings…anyone have this STC installed?November 19, 2012 at 6:59 pm #97129
I think the Outlaw STC was before Lean of Peak operation became understood. I think it was 27″ and 15gph per side.
I have been operating my engines LOP for some 300 hours now and most of that is at 30 inches, 2400 rpm, and typically 13.5 gph. I think that you need 2 things for LOP. GAMI injectors and an engine analyzer, and I would say you should attend the “Advance Pilot’s Course” at GAMI, Ada, OK.
You need to understand the “red box” that it is essential to operate outside of or you will over heat the engines. I came away with a great deal of information but 2 pieces are critical. Run a turbocharged engine at full rich or 50 to 70F LOP, as determined by peak TIT, and turbo charged engines should be run hard for efficiency.
If you are interested I can give you my SOP direct rather than bore everyone else. I would add that my oil analysis and compressions show no adverse effects for LOP. My left engine has 400 hours on it and the right 1600.
John HodgsonNovember 20, 2012 at 10:55 pm #97138rtoweParticipantquote TJOHNSONJR:
We have the STC and yes, they are running higher power settings along with a marked up manifold pressure gauge to 27″ in the green and amended power setting charts in the performance part of the POH. I still only run 24″/2200@24gph(total)@100ROP unless we have a lot of spare AMU’s and we need to get somewhere fast… 8)November 20, 2012 at 11:28 pm #97139quote RTOWE:
Just out of curiosity, what performance are people getting with their 303’s? (no, I’m not looking to get rid of the 421!)
RobertNovember 21, 2012 at 12:05 am #97140quote JHODGSON:
I agree with the GAMIjectors, and some form of instruction from someone who understands how these engines operate. The APS courses in Ada are good, but I disagree with a few things they state. Yes, they are correct that you can run engines harder for more efficiency, but there is a limit to what you can do and still expect the engines to last a long time. The SR22 Turbos are evidence of this – people run them at 30″ and 2500 RPM with 8.5:1 compression, and their owners are seeing top overhauls required every 600 hours despite excellent cooling. These engines just don’t last that long that way. 90+% power is not a cruise point, except on very low power engines. For those who wish to go as fast as they can, of course, that’s their prerogative. However, I find most people don’t really care about that extra 5 kts and would rather get a bit better reliability. Also, while the engines are more efficient at a higher power setting, that doesn’t mean the aircraft is. Horsepower to go a given speed is still a function of speed^3, meaning that even a small increase in speed requires a substantial increase in power typically. The dynamics are more complex with airplanes, but more speed still means more power provided you’re not on the back side of the power curve.
When I teach people how to operate their engines, we typically start off by figuring out what their speed needs are, and then start operating their engines to find a point that provides good temperatures, good speeds, and will also provide good longevity. Since people are often times operating their planes with arcane power settings that are very poor, we typically come up with a solution that ends up going faster with lower fuel burn.November 21, 2012 at 1:43 am #97143rtoweParticipantquote RCJOHNSON:
Ok, on average, we can carry full fuel@153gal and have 600lbs of payload and do 170KTAS averaging 32gph(1sthr),24gph each hour after so, time wise, that’s 6 hrs total flight time(no reserves)@100ROP. All that doing the above stated performance@ 8-10,000′. Or, you can carry 900lbs payload and fly 3hrs plus reserve which is more typical and about a 500-550 mile range. Or, you can haul ass at 190KTAS, at the same altitude and get there in 2 1/2hrs plus reserves but, you will only get 450-500 mile range. 8)
I would guess that Bob T can provide some more accurate data as much as he flies… ❓
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