[QUOTE=JammedStab;9739292]Speaking about getting a higher rpm on a free turbine engine prior to introducing fuel, I was told once that if you left the propeller tied in place during the start(we used to tie them down on the Twin Otter to keep them from rotating in a strong wind while shut down), you could get an extra 1 or 2% rpm. Never tried it of course, has anybody else.
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Never tried this for cold starts as I almost never flew anywhere seriously cold but >20 years ago we tried this "for sport" on ferry flights when we had to start the engines without a marshaller and the copilot would stand outside and check the area.
It was no problem holding the prop of even the (then) strongest PT6 variant with one hand but once you let go of it you probably would not have been able to catch even the next blade, so swift and strong was the acceleration.
As for the OP, good luck with your swift Piper and should you ever need to trade up a PC-12 would probably be a good choice
As for the hand cranking, the one who recommended it probably had Garret engines in mind which
AFAIK sometimes required hand cranking after shutdown to prevent bending.
There are CF34 engines with FADEC that will not even turn on fuel before the ITT has dropped to a certain value but they are bleed started and can run the starter for 2 minutes which is probably too much for most electric starters.