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About engine RPM, deck blade tip speed and Kohler:
Kohler labeling a twin 18 with a so called 'quiet operation' as a 16QS and not indicating that it actually is an 18 is strange, particularly when they also show a 16QS as a single cylinder engine, not the first odd thing that Kohler has done however!
Most engines are factory setup to run at high idle around 3,200 to 3,400 RPM although the specs may show 3,600 RPM. Engine RPM can be adjusted to 3,600 RPM on all engines and I have readjusted many to 3,600 RPM high idle. This increases the blade tip speed on the mower deck somewhat. The pump manufacturers specify a maximum RPM of 3,600 and a risk of cavitation if 3,600 is exceeded. Cavitation is when air bubbles are created in the pump that is turning too fast. Air caused by cavitation will reduce performance of the hydraulic system.
Generally, Case and Ingersoll mower deck blade tip speed is low relative to current industry standards. Current standards are approximately 18,000 FPM where the Case Ingersoll decks are approximately 12,000 to 13,000 FPM, feet per minute.
Case Ingersoll mower decks J44, J46 thru N44 and N46 deck blade tip speed can be increased by replacing the deck drive pulley (the upper pulley on the center spindle) with one for a J40-N40 pulley. The J46 thru N46 decks will gain the most increase in blade tip speed, J44 thru N44, not so much.
The same thought holds with Ingersoll RM44 and RM48 decks as a center spindle shaft from an RM40 deck can be installed in RM44 and RM48 decks to increase blade tip speed.
In both situations, there is no need to change V belt size as the tensioner is able to adjust.
So, bottom line, engine RPM up to 3,600 and deck drive pulley changes will increase the blade tip speeds by about 2,500 FPM! Having done this to many machines including my own, the performance is greatly improved!:cool:
 
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