Is the maximum power the Merlin 61 reciprocating engine occuring at its maximum RPM? Looking at the stats breakdown on Wikipedia here for the Merlin 61 series reciprocating engines used in Spitfire planes, I noticed that maximum horsepower is given at approximately 3000 RPM. But AirPages has what looks like a manual here that lists the maximum RPM as 3000.

Are they simply stating that the same thing: that torque starts to fall off at 3000 RPM? Or are they saying that the engine is just physically incapably of spinning faster than 3000 RPM (seems unlikely)?

In the case of the first one, what is the (approximate) redline for one of these engines?
Power output of a reciprocating engine goes up with speed, and yes, maximum power is reached at maximum RPM. Considering the size and age of the Merlin 61 (27 liters displacement) it had a rather high maximum speed. Some contemporary engines ran even slower:


Daimler-Benz 601E: 2700 RPM for take-off, 2326 RPM continuous power
Daimler-Benz 605A: 2800 RPM for take-off, 2300 RPM continuous power
Allison V-1710-A: 2800 RPM
Klimov VK-107: 3200 RPM for take-off, 2800 RPM continuous power
Jumo 213A: 3250 RPM for take-off, 2900 RPM continuous power


Note that the considerably smaller GA engines still only allow a maximum speed of 2700 RPM. The smaller the engine becomes, the higher the maximum RPM will be. Model engines for RC racing easily top 50.000 RPM.

Age is also a factor. Modern engines run much faster, and the early rotary engines of WW I would run 1350 RPM, max. The radial engine of the Boeing Stearman which I once flew was limited at 1700 RPM, requiring me to throttle back when accelerating for a loop-the-loop so I would not overspeed the engine in the dive.