It's all about ground speed. I run a 6' 3pt blower on my
L4200 (37 PTO HP). I was running it on my driveway - WFO in 4th gear up a 10-15% grade while blowing 20+ inches of snow, which was WAY too fast. My tractor or blower never missed a beat, but after the 500' climb at the top of my drive, I looked down and sparks were shooting out of my engine compartment - not like a few sparks, but a shower - like what you see flying off of a 9" grinder. It stopped after a minute or two and all was fine - I figured that I worked the engine hard enough to ignite carbon deposits in the head and exhaust. Scared the crap out of me, but was probably good for the engine.