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170 RPM

Posted: Tue Mar 25, 2008 12:55 am
by rosbullterier
I think I am correct that the Century runs up to 3800 to 4000 RPM, but what about the 170? Overevving seems to be its downfall and I would like to experiment with other ratio gearboxes and props. ( after the new bronze end cap is fitted) . . .

Posted: Tue Mar 25, 2008 10:47 am
by charlesp
Hopefully the other Charles will be reading this forum from down under. We are most definitely straying into territory that he has made his very own...

Posted: Tue Mar 25, 2008 6:58 pm
by Charles uk
What you can rev it up to depends on the condition of your 170.

With my race 170 I throttled back at Easter, if the revs exceeded 6500 , as I needed to finish, if I wanted to finish first,

With an ok 170 on the back of a 12 foot plus non racing hull I would guess 4000 to 4500 revs should be good.

If it won't do that, it sounds ready for the skip or a good once over.

With a bronze end cap it would all depend on the quality of the engineering.

Posted: Tue Mar 25, 2008 10:44 pm
by rosbullterier
Thank you Charles - don't forget I shall have your revcounter attached. Although modifying the engine to improve performance is beyond my remit (or capability) I would like to check how propellors pitch will affect the revs and therefore wanted to know where to start from. I'm using a 1:2.5 gearbox. The bronze bigend cap will hopefully be as well ventilated to the petroil as the original.