Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

what size pulley should iput on 305cc engine there is a 51/2'' pulley on blower .it is a 36' cut blower for a lawn mower but i am modifying to go on atv .its a single stage so i want to get most power i can out of it.any help would be appreciated thanks..

checked my rpm on engine today it is at 3640 rpm.would it be safe to turn it up,iread on here someone had turned up to 4500 with no problem.

Most OPE four stroke engines are designed to run at 3600 rpm.  You could spin it at 4500 but who knows what effects it will have?   I have no reservations spinning up two cycle engines.  Not sure I'd want to be spinning an OPE four stroke engine too high.   Go-cart racers do it all the time but they also rebuild their engines every so often. 

I had 4 stroke Honda 160cc engine running above 4000 RPM and it didn't feel right.  The noise was quite loud with the existing muffler.  The vibration was unbearable without some kind of isolation engine mounts from the chassis.

Increasing the RPM isn't really going to accomplish much.  On OPE engines an increase in RPM at the high end won't do anything to increase the torque. It fact it will probably drop, the higher you rev the
engine.  So the auger may spin faster, until you put a snow load on them. There is no short cut to take if your you don't have enough HP to run a blower.  And that is the problem you have. 
A 10HP engine simply isn't large enough to power a 36" blower. 

If there was a way around that problem with gearing someone would already be doing it.  Blower augers (single stage) and blower impellers
(2 stage)  need the right mixture of power and RPM to operate well.

There is no replacement for displacement when it comes to torque.

borat wrote:

Reminds me of an old hot rodder's saying "There's no substitute for cubic horsepower" :)

ok good to know for sure  tks for all the info you guys were a great help.