I’m trying to figure out which engine is best to run a pump I’m looking at the Honda GX630 GX660 and GX690 they list different horsepower but the torque and RPM are the same. I’m not a very educated person but this doesn’t make sense to me.
Carburetor size.
I guess I just need to hit the I believe button but when they list the torque and RPM’s the same it doesn’t make sense.
Thanks for the reply I love watching the progress on your build.
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You’re welcome! It’s been discussed here before if you search for it, there’s more detail on the other thread.
Specifications usually only list the max torque@rpm. The power is a function of the “amount of torque” available during the rpm range - usually referred to as the "area under the (torque) curve.
If both engines are limited to 2500rpm, then they may very well produce the same amount of HP, but gx690 produces more torque after 2500rpm than gx630 does.
One of these days I’m gonna slap on a 690 carb and see if my surface cleaner flies over my head.
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Thanks for the help.
If it does at least you don’t have to worrying about striping. 
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I thought about @dcbrock today when testing my SC’s on the driveway and I didn’t see any striping.
Aww, you were thinking of me? I’m touched!
Yeah I often wonder why it stripes so bad. Wish you could get it corrected. Less work, less stress.
Don’t I know it. I can only dream of going back and forth in a straight line like the video and not have to go over it again. Maybe when I figure out how to add hot water.
Have you greased rotor swivel?
It’s also a different cam usually as well . And sometimes the thickness of the cylinder and head gasket. I few thousands of an inch can make a big difference
