If your motor gets Maximum TRQ. @ 4800rpms and Max HP @ 5900 my Question is how many rpms are needed over the 4800 to be safe?? In other words could you prop it at say 5200 and be ok?

5900 That's Where Your Max Hp Is

I read somewhere that a boat that is slightly over propped is the fastest. I would think that 5600 would be safe if you were trying to have a good cruise and good top speed. Over prop too much on a high perf. boat and you will run into problems with detonation, poor fuel milage, sluggish performance.

prop it for 6000 to be fastest.... 1200 over peak tq is rule of thumb...better to "spin them, than lug them"....

It will depend on how flat the torque curve and HP are above 4800rpms. If you're only gaining 20 hp by spinning it 500 rpms faster, then its not worth it.

You will possibly cause detonation if you run so much prop it onlt turns 5200,I would prop it to turn 5900 on a warm day and run slightly over when everything is perfect,Smitty

Prop it as close as possible to the builders desired WOT rpm without constantly going over it.. I prefer to keep my units propped so that we are about 100rpm below desired wot rpm. This way if conditions are ideal & temps are low the boat could hit the DWOT without going way the hell over & when you are running the resto of the time you are not lugging the engine hard. Jamie / Lakeside


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