1.25 Ratio or 1.5
#1
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From: Charlotte, NC
Back in 2005 I put a nice well built 540 into my 2001 Velocity 260. Nothing major motor wise. Mild cam, 9:0 comp. Dyno right @ 620 hp.. Running good for 5+ summers now. Only issue has been with idle in gear. Livable. but not as "good" as one would hope. Nickerson has worked on the carb several times. Motor runs great.
So.. fast forward to 2009.. Got some good size flakes in the drive oil the drive oil when changed close to end of summer.. Decided to live with it and take a look this winter. Just opened the drive today.. Seems as if I took out a lower gear. Almost an entire tooth missing. explains the flakes right? So.. upon further inspection seems as if I have been running a 1.25 ratio drive. NOT a 1.5.. guess that also explains the problem of never being able to spin the prop past 5K (more or less).. got a 5 blade hydro on it.. I just thought i was over propped even though my motor "should" spin that prop OK on that hull..
Question.. What should I do? go with 1.25 ration again? 1.36? or 1.5? could the 1.25 ratio be an issue at idle? too much load on the motor when shifted into gear? Will I need to go bigger on prop if I switch to a standard 1.5 lower gear set? What is the appropriate setup for this motor and hull? XR drive if that means anything..
thanks
John
So.. fast forward to 2009.. Got some good size flakes in the drive oil the drive oil when changed close to end of summer.. Decided to live with it and take a look this winter. Just opened the drive today.. Seems as if I took out a lower gear. Almost an entire tooth missing. explains the flakes right? So.. upon further inspection seems as if I have been running a 1.25 ratio drive. NOT a 1.5.. guess that also explains the problem of never being able to spin the prop past 5K (more or less).. got a 5 blade hydro on it.. I just thought i was over propped even though my motor "should" spin that prop OK on that hull..
Question.. What should I do? go with 1.25 ration again? 1.36? or 1.5? could the 1.25 ratio be an issue at idle? too much load on the motor when shifted into gear? Will I need to go bigger on prop if I switch to a standard 1.5 lower gear set? What is the appropriate setup for this motor and hull? XR drive if that means anything..
thanks
John
#2
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Joined: Mar 2009
Posts: 1,758
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From: OFallon,Mo.
Back in 2005 I put a nice well built 540 into my 2001 Velocity 260. Nothing major motor wise. Mild cam, 9:0 comp. Dyno right @ 620 hp.. Running good for 5+ summers now. Only issue has been with idle in gear. Livable. but not as "good" as one would hope. Nickerson has worked on the carb several times. Motor runs great.
So.. fast forward to 2009.. Got some good size flakes in the drive oil the drive oil when changed close to end of summer.. Decided to live with it and take a look this winter. Just opened the drive today.. Seems as if I took out a lower gear. Almost an entire tooth missing. explains the flakes right? So.. upon further inspection seems as if I have been running a 1.25 ratio drive. NOT a 1.5.. guess that also explains the problem of never being able to spin the prop past 5K (more or less).. got a 5 blade hydro on it.. I just thought i was over propped even though my motor "should" spin that prop OK on that hull..
Question.. What should I do? go with 1.25 ration again? 1.36? or 1.5? could the 1.25 ratio be an issue at idle? too much load on the motor when shifted into gear? Will I need to go bigger on prop if I switch to a standard 1.5 lower gear set? What is the appropriate setup for this motor and hull? XR drive if that means anything..
thanks
John
So.. fast forward to 2009.. Got some good size flakes in the drive oil the drive oil when changed close to end of summer.. Decided to live with it and take a look this winter. Just opened the drive today.. Seems as if I took out a lower gear. Almost an entire tooth missing. explains the flakes right? So.. upon further inspection seems as if I have been running a 1.25 ratio drive. NOT a 1.5.. guess that also explains the problem of never being able to spin the prop past 5K (more or less).. got a 5 blade hydro on it.. I just thought i was over propped even though my motor "should" spin that prop OK on that hull..
Question.. What should I do? go with 1.25 ration again? 1.36? or 1.5? could the 1.25 ratio be an issue at idle? too much load on the motor when shifted into gear? Will I need to go bigger on prop if I switch to a standard 1.5 lower gear set? What is the appropriate setup for this motor and hull? XR drive if that means anything..
thanks
John
Last edited by picklenjim; 03-05-2010 at 12:50 AM.
#6
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From: Charlotte, NC
Being a single engine I would go with the 1.5 gears. Then I would get rid of the 5 blade ( you never mentioned the pitch) and go to either a 25P 4 blade or 27P 3 blade. If RPM's go over 5800 at WOT then I would go up 1 size at a time on the pitch . Just curious what pitch is that 5 blade? Combination of the high gear and 5 blades is probably responsible for your idle issue and low WOT rpm's. That motor should spin at least 5600 rpm.
How much RPM will I pick up going from 1.25 to a 1.5 ratio?? Right now I can spin the prop about 5k or so.. Also will my in gear idle quality be a bit better with the 1.5? How about coming out of the hole?
#7
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From: OFallon,Mo.
My current prop is a 26 inch Hydro P5.. Lab work done by Mike at Hall's propeller..
How much RPM will I pick up going from 1.25 to a 1.5 ratio?? Right now I can spin the prop about 5k or so.. Also will my in gear idle quality be a bit better with the 1.5? How about coming out of the hole?
How much RPM will I pick up going from 1.25 to a 1.5 ratio?? Right now I can spin the prop about 5k or so.. Also will my in gear idle quality be a bit better with the 1.5? How about coming out of the hole?
Last edited by picklenjim; 03-05-2010 at 10:34 AM.
#8
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From: Charlotte, NC
Thanks pick.. Seems 1.5 is what most drives are.. Untill you run out of prop pitch is what I hear.. That is not going to be the case with me.. I have plenty of $$ invested into the p5, so I would like to make that work.. Ran great last year.. just ran into a wall at 5k.. I would think a switch from 1.25 to 1.5 would get me about 600 RPMS.. the in gear idle and the hole shot are a bit more important then every last RPM and top speed
#9
Thanks pick.. Seems 1.5 is what most drives are.. Untill you run out of prop pitch is what I hear.. That is not going to be the case with me.. I have plenty of $$ invested into the p5, so I would like to make that work.. Ran great last year.. just ran into a wall at 5k.. I would think a switch from 1.25 to 1.5 would get me about 600 RPMS.. the in gear idle and the hole shot are a bit more important then every last RPM and top speed




