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Kevin (mcdo)
Kevin
Ding Ding Ding. You win the brass ring.........
......
Laws of physics are rather constant. Your observations are correct.
given fuel flow = given hp (less losses / frictional and less wasted fuel)
peak hp = peak egt = best efficiency = A Constant.
from this point you back off and increase fuel flow (waste fuel) to save engines. 50 rop / 100 rop/ full throttle. your choice in between. Above 70% we agree there is not much choice due to detonation potential. Below 65% we have all the choices including running at peak or lean of peak.
Bottom line > the intercoolers do exactly what you say. they cool the incoming air or change the density depending on airspeed, altitude, OAT, and intercooler efficiency. They do not defy the rules of physics!
I consider intercoolers were another "carnie" thing that does add performance under certain conditions, mostly under full power climb or hot and heavy departures, even then, they are not as efficient due to lack of increased air flow due to lack forward speed. They sure help when OAT is ISA +++++
So why would anyone reduce the mp on takeoff as it has been suggested? 100 % power is 100% power with 37 inches! The engine doesn't care about outside temp, just over or under boost and FUEL FLOW. Riley gives you the MINIMIM FF for a given RPM (2800) and they suggest reducing the mp after a given altitude ( based on book fuel flows). So much fuel gives you so much fire.
Assuming you had a switch to turn the intercoolers on and off you should see the engine running hotter OR your ROP value (drop) has changed due to improvement in air/fuel mixture (oxygen).
In either case, regardless of intercoolers or NOT, your HP should be calculated at a given book fuel flow and RPM, then MP becomes the variable. If you set your engines to PEAK then richen the mixture does not give you more horsepower. It is a "throw the fuel overboard lever" that contributes to fuel cooling. Therefore, yell if I am wrong, but the true measurement of hp is at the peak lean. Read the fuel flow and work backwards with given rpm. Voila...... hp! You have set the proper stoimetric power for the given conditions (atmospheric, with or without intercoolers).
What we are trying to do is save our engines by setting the proper mixture level.
Mike is correct. 32" and 2400 and burn 13.5 gph/side. Look at the POH for 32/2400 and the difference between POH value and the 13.5 is fuel cooling or the amount of fuel sacrificed to save the engines.
I think this hocus pokus came from Riley and American Intercoolers trying to sell intercoolers------- any people bought it , hook line and sinker!
Want more horsepower then go to IO-540s or burn more fuel.
Sorry to disagree with you Skyking.
Bob
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