Tank testing 3hp

[kyron4]

Is it normal when "tank testing" a 3hp in a 35 gal. drum as the motor runs WOT for it to sound like it revs slightly high then a bit lower and back up again due to all the water sloshing around in a small area ? Not real noticable but not a smooth purr like on open water. Also after running about 5-10 minutes the water had a thin film of oil on top , is this normal from exhuast ? I was running a rich mix to test about 18:1-Thanks

 

[steelespike]

Re: Tank testing 3hp

Yes in a tank test the motor may surge slightly do to water turbulance and/or exhaust getting ingested best way to tune and test is on a boat on the water.
It is normal to have a pretty nasty residue on the water in a test tank.