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Posting a reply to: Re: Suzuki or OptiMax???

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[QUOTE]tcbetka - 6/29/2007  10:42 AM

I do NOT believe this "guest" who claims to be a mechanic.

If the manufacturer of an outboard engine (water-cooled, I might add) advises that the maximum safe operating range is 5500-6400 RPM, for example, then you should be able to run it to 6400 without difficulty. If we were talking about air-cooled engines like an aircraft engine, then that might be another story--simply due to improper cooling. But the engine guys that work on my Verado implore me to run it near WOT...which by the way is only about 6200 RPM on my boat.

These engines are designed and built to run within the specifications established by the manufacturer. So as long as you have adequate cooling (easily verifiable by a water pressure gauge), you are good to go--according to everyone I have spoken to. And besides; most of the time the engine is propped in such a way that you won't be able to even *reach* the top of the power range at WOT.

Here's another way of looking at it... If you look at the power curve of a Honda 200, it is rated to make 200 horsepower at 5500 RPM; however the operating range is 5000-6000 RPM. When I ran one the thing was propped so that it would only turn about 5750 at WOT--simply because there wasn't a prop in the size I needed to get the little extra to get to 6000 RPM. But when I talked to the Honda rep he told me not to worry about it as that particular model engine didn't make much additional power until it went well over 6000 RPM--in other words, outside of the normal operating range specified by Honda; a range where you would never want to run it.

Now contrast this with the Honda 225. Even though it makes its max 225hp turning 5500 RPM, that engine's power curve shows that it continues to make more horsepower all the way up through 6000 RPM. So it should be obvious that a guy would want to turn that engine as close to 6000 RPM as possible. Indeed, the Honda rep (Pete Sullivan, as I recall) confirmed this to me.

Do not confuse WOT with maximum *POSSIBLE* RPM...the two are not the same. I would check the owners manual, but if there aren't any restrictions imposed by the manufacturer in terms of maximum power settings for certain time periods (there aren't for my Verado, after the first 10 hours of use), then run it WOT.

TB[/QUOTE]

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tcbetka

Posted 6/29/2007 10:42 AM (#262890 - in reply to #262878)
Subject: Re: Suzuki or OptiMax???

Location: Green Bay, WI

I do NOT believe this "guest" who claims to be a mechanic.

If the manufacturer of an outboard engine (water-cooled, I might add) advises that the maximum safe operating range is 5500-6400 RPM, for example, then you should be able to run it to 6400 without difficulty. If we were talking about air-cooled engines like an aircraft engine, then that might be another story--simply due to improper cooling. But the engine guys that work on my Verado implore me to run it near WOT...which by the way is only about 6200 RPM on my boat.

These engines are designed and built to run within the specifications established by the manufacturer. So as long as you have adequate cooling (easily verifiable by a water pressure gauge), you are good to go--according to everyone I have spoken to. And besides; most of the time the engine is propped in such a way that you won't be able to even *reach* the top of the power range at WOT.

Here's another way of looking at it... If you look at the power curve of a Honda 200, it is rated to make 200 horsepower at 5500 RPM; however the operating range is 5000-6000 RPM. When I ran one the thing was propped so that it would only turn about 5750 at WOT--simply because there wasn't a prop in the size I needed to get the little extra to get to 6000 RPM. But when I talked to the Honda rep he told me not to worry about it as that particular model engine didn't make much additional power until it went well over 6000 RPM--in other words, outside of the normal operating range specified by Honda; a range where you would never want to run it.

Now contrast this with the Honda 225. Even though it makes its max 225hp turning 5500 RPM, that engine's power curve shows that it continues to make more horsepower all the way up through 6000 RPM. So it should be obvious that a guy would want to turn that engine as close to 6000 RPM as possible. Indeed, the Honda rep (Pete Sullivan, as I recall) confirmed this to me.

Do not confuse WOT with maximum *POSSIBLE* RPM...the two are not the same. I would check the owners manual, but if there aren't any restrictions imposed by the manufacturer in terms of maximum power settings for certain time periods (there aren't for my Verado, after the first 10 hours of use), then run it WOT.

TB