RPM question

dingbat

dingbat

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Nov 20, 2001
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16,420
Full throttle operating range 5000 - 6000 RPM

Prop for WOT or peak HP? There is a 500 RPM difference between the two.
 
JB

JB

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45,907
Re: RPM question

Prop for as close as you can get to 5500rpm.


Good luck. :)
 
dingbat

dingbat

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Nov 20, 2001
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Re: RPM question

Is 5450 close enough? :D

I'm running a 4 blade stainless that has reworked on to get to that RPM. The shop that did the work told me to prop to peak HP. I've since had several guys tell me that I should have propped to WOT which didn't make sense to me. Why prop on the downside of the HP curve?
 
S

steelespike

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Apr 26, 2002
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19,069
Re: RPM question

Prop not to the existing rpm but the max rated rpm.5450 is ok if you don't intend to carry a lot of additional weight.I would prop closer to the max rated rpm lightly loaded anyway.
 
JB

JB

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Re: RPM question

You won't get any closer with a "normal" load. The reason I said 5500 is so that there is room to go up to 6000 with a lighter load or down to 5000 with a heavier load.

That doesn't disagree with steelspike suggesting prop for 6000 with a light load.

I think you are okay with what you have, assuming the 5450 is with a "normal" load.
 
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Dhadley

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Feb 4, 2001
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16,978
Re: RPM question

If we're talking about the 200 looper in your signature then you want to prop as close to 5800 with a normal load as you can get. The rev limiter is at a minimum of 6200. If you use ethanol fuel you may not (easily) get there but you should be close. 5500 is actually lower than you want to be and even there we're making it harder on the motor than necessary.
 
dingbat

dingbat

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Re: RPM question

Yep, 200 Ocean Pro - 14.25 x 17" Renegade Offshore

The 5450 rpm is with 130-140 gallons of fuel. Normal load, 50-75 gallons, ~5700 @ 38.7 MPH gps

I tried a 15" prop before going 17". You would hammer it to get out of the hole and the prop would break loose. Hand to back off and let the prop get a grip. The 17" give good overal performance but limits my top end as noted.

Any suggestions? Leave it alone?
 
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