prop question...

[FrenchPhil]

Most of the speed records in your category were done with semi-cleavers, so I'd try a 10ish x16 & take it from there.

[FOGO]

Hi Mate,
I have a Thundercat with a Mercury 40HP (3 cyl, 698 cc. Tohatsu made it in Japan for Mercury)
I use a Yamaha SS 10.25" x 15" propeller standard and hit 80 Km/h (48.45 miles) at 6600 RPM.

I like to BUY a 10" x 18" "Chopper" style prop, but our rules says Exhaust Through 3 blade prop.
Any one Knows if sombady builds Choppers with Exhaust Through propellers???

Regards,

FOGO

[serious3]

well i've a tiny tach in my hand and my gps is fixed so all i need now is a bit of weather trhis weekend and ill post up revs and speeds etc!

[serious3]

so i went out this evening and at a gps reading of 46mph i'm doing 6450 rpm.......
how long is the motor gonna last revving it that hard??

[JohnsonM50]

I'm not familiar with your motor so don't know.. Generally tho an engine will do better running sweet at a higher R level than straining & pounding under load at a lower rpm. Trick is what the manufacture recommendation is & why. The particular motor I experiment with can handle over 1500 R's more than spec & be fine, I don't expect 20 years out of them & would likely rebuild within 5 anyway. Good Luck

[serious3]

i think wot for the 6e9 is 5500 rpm, i havent touched the std timing settings yet either,all i'm doing is running a little more oil than normal and trying to not hold full throttle for extended periods.

[fs5]

thats not bad at all mate! 6450rpm is getting out out there a bit ,for a stock motor.i'd fit some fibre reeds reving it that hard.other then that it "should" handle it ,depending on how the previuos owners looked after it.
i'd definately be saving for one of rons choppers .they excellarate pretty good with the exhaust mod and hold half decent through the turns compared to cleavers.
do they run the same 1.83 gear ratio as the old 30 yam/mariner?