What does derated mean? Does it have more than 200 HP but only puts out 200 HP? What are the advantages of it being derated?
It means that the IO-360-ES engine is rated to put out 210HP at 2800 RPM in other applications but in the SR-20 it is certified at a maximum of 200HP at 2700 RPM.
Benefits:
Quieter
No HP endorsement required
Engine (theoretically) lasts longer
In reply to:
What does derated mean? Does it have more than 200 HP but only puts out 200 HP? What are the advantages of it being derated?
W.B…
The “standard” IO360ES is designed to provide 210 HP, as far as I know, at 2800 RPM. I believe that by governing the prop to 2700 RPM, the power is limited to 200 HP.
As for advantages, I’m not sure. Perhaps it gives the engine an easier (and quieter) life, but I suspect the answer has more to do with the fact that if it were 201 HP, you’d shut out the pilots who don’t have a High Performance endorsement.
- Mike.
Wild Bill: I think Mike may have misspoken about the 200 HP and High Performance endorsement. I think that 200 HP is the threshold not “over 200 HP.” If I am mistaken, I am sure that another member will post the appropriate regs.
Good luck with the wild west shows.
When I go to full power (takeoff) I notice that my engine RPM is around 2770. I usually pull the throttle back until I am in the Green. Is this normal? Is the derating supposed to be an RPM limit?
In reply to:
Wild Bill: I think Mike may have misspoken about the 200 HP and High Performance endorsement. I think that 200 HP is the threshold not “over 200 HP.” If I am mistaken, I am sure that another member will post the appropriate regs.
Good luck with the wild west shows.
Marty,
Mike is correct.
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Marty, Mike is correct.
Damn! Again #$%#? I oughta be right just once! [:(]Mea Culpa.
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When I go to full power (takeoff) I notice that my engine RPM is around 2770. I usually pull the throttle back until I am in the Green. Is this normal? Is the derating supposed to be an RPM limit?
Seems a little high. Most people are happy, I think, if they get 2710 or even 2720, that
being slightly better than 2680. 2770 is outside normal service parameters and you
should really have that looked at. What do you get in cruise, same thing?
You might want to consider, before reducing power on takeoff, that all the performance measures for the plane on takeoff are done at full power. Taking off with less than full power is not normally recommended for any plane I’ve been familiar with (I think a P-51 is launched with less than full power, but only because the extreme torque of the Merlin could flip the airplane).
In my Pitts S2C, takeoff RPM is always redlined. (AEIO540). That is considered normal. I usually reduce RPM and throttle between 500 and 1000 feet, while starting to lower the nose.
If the book or the factory says your RPM is within normal parameters, I’d say, “Hey…enjoy that extra takeoff power!”
I would have my prop governor tweaked down a bit if I were you. My full power RPM after annual somehow dropped to about 2650. I had it tweaked up and now I get 2700-2740. I reduce power to 2700 after 500-1000 ft of climb, just to stay in specs, but 40 extra RPM for a minute or so can’t be much of a problem. 2770 might be a little extreme. It should mean you are getting about 207 HP initially.
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I would have my prop governor tweaked down a bit if I were you.
I’d agree. At 2700rpm the tips of your prop are going supersonic; going faster is just going to increase noise as the supersonic region propagates but not deliver much more power. Also I’d guess the 2700rpm limitation is a prop or governor limitation since the engine can handle it fine. You probably don’t want to find out which.