[QUOTE=wh500special;6365204]I think for most of Evinrude's - and everybody else's too - normal computer-controlled engines that you should expect they produce their rated power plus or minus some small tolerance. Output would be easy to control and is directly proportional to fuel flow.
You wouldn't think they'd want to risk customer dissatisfaction with a slug, and they don't want to create higher emissions than they promise the EPA. So I would think a 75 hp rated engine would pretty much nail 75 actual horsepower most of the time.
Apparently manufacturers are allowed a +/- 10% variance on their outputs. Evinrude capitalizes on this with their various High Output ("HO") series motors. They have the computer set the output to coincide with the max allowable, so in your case your 60 HP is probably delivering 66 hp max. Bobby's 90 HO should be delivering 99 hp.
Often the advantage to Evinrude's HO series is that the motor has a comparatively higher displacement than a non-HO motor of the same rating. This will translate to increased torque output which, of course, will get a heavier boat on plane more easily. That would be the case with your 60 HO versus the standard 60.
The relationship I have seen for how increased horsepower affects the top speed of a planing hull is to divide the higher horsepower by the lower horsepower, take the square root, then multiply that result by the top speed achieved with the lower horsepower. You can, of course, go the other way and see the effect a lower horsepower would have on the same hull.
1 and 2 are subscripts for the two HP cases.
So in your case, assuming you have 66 HP from your current engine and 75 from the new, you'd see a mph increase of 6.6%. So if you're getting 30 mph now, you'll get 32 mph with the larger engine. If you get lucky and get a thundering 82.5 hp version of the 75hp, you can expect a 12% gain...33.5 mph. Unless you do all your running around at full blast, you might never feel the benefits of the higher horsepower.
Or - much more succinctly - what DW said.
Whether these modest speed increase are worth it to you is your decision. Chances are that acceleration and planing ability will be pretty similar for both the 60 HO and 75 (same displacement motor). They both weigh the same, so it comes down to preference and cost.
wh500special. Thank you soooo much for the excellent explanation. After reading what you wrote I fully understand now. God Bless and take care . Tight Lines :)
[QUOTE=Bobby Winds;6365186]Hey.........isn't this your boat and motor . . . .[/QUOTE]
Lol looks like fun but that pics has been a bit played out
Nice reply special. :rockit::bowdown:
[QUOTE=Hartly;6364934]Guys is this a true statement that the Evinrude Etec 75hp actually puts out 83HP ? If so how much difference will i see upgrading from an Evinrude Etec 60HO?[/QUOTE]
No ! it does not 80 may be? but 83 would be breaking the law ratings are allowed to go + - 10% 75x1.1=82.5 no motor company is going to risk government fines and liabilities by giving you too much Hp and a posible safety isue
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