Cruising RPM's

[Steve W.]

I normally cruise my old tired "evindude" at about 3500 rpm's.

I was doing some searching and found that most everyone cruises their 2-strokes at or above the 4000 mark.

Would everyone agree that that's a good place to run?

[warthog5]

On my little 162 Scout w/ C-90 Yamaha. I cruise it at 3800RPM. this gives me a 26MPH speed.

[mako224]

35oo seems a little low to me. My rig the slowest I can cruise without lugging is 38oo. 4ooo is perfect. 45oo all the time or higher and your shortening the life of your motor by running too hard.

[Steve W.]

Keep the answer's coming.

Mako224,

It's defenitely not lugging at that speed. I am well on a plane and making 18-19 kts. Maybe I'm a little lighter or something.

[Mr. P-Reaux]

What's the HP rating of the "evindude"?

4000RPM probably won't hurt it. If you have a temp gauge, keep an eye on it. If it raises temperature significantly, back off. Also listen to it; if it is sounding like it is struggling, again, back off.

I cruise my 4-stroke Mercruiser I/O @ 3800. These can't turn up nearly as many RPM's as a 2-stroke outboard. However, you are being good to your engine: it WILL treat you well when the time comes![]

-Pat.

[Steve W.]

Cyclops,

See signature for hp.

I guess I will keep running it the way I have been, knowing that if I need the extra speed, I can use it without hurting the motor.

[Alcedo]

The engine is suppose to run at a certain RPM at WOT..........as long as you are in this range......where ever you run it it will be fine......I am not saying run it WOT all the time.......

Mine gets the best gas milage and runs best at cruise of 4500 RPM.

[Steve W.]

Alcedo,

Good point

I really ought to get some sort of flow sensor on there, that would probably be a better indicator of where to run it.

[Alcedo]

Just to fuel the subject, I had a 78 22B, 1988 Rude 225, she loved 3800 RPM @ 28 MPH........it was propped right, 5600 RPM @ 40 MPH was WOT with a 14 1/4 X 19 Ballistic, I tryed a 21 but only got 5000 RPM, not enough azz. I don't understand why she was so much slower than the 21B I have now.......I just toss it up to hull design. I really feel the cruise sweet spot for OMC big block (200 HP +) loopers is between 4 and 5 K RPM. They just seem to breath better there. The '88 OMC 225 is not the same engine as a '92, somewhere in there they went from 2.7 L to 3.0 L.

It's really a big crap shoot, trying to get everything right......hitting the WOT manufactor's RPM limits is a must though.....or bad things will happen.

[Steve W.]

I am pretty sure that I am propped right, but I have never really left it at WOT very long to make sure that it wasn't exceeding it.

I think this weekend, I might spend some time and calibrate my new tach and at the same time check WOT rpm.

[Empress III]

I have always been told that 2 stroke engines were designed to run continuously at the higher end of the rev. range. Every boat is different, but a correctly proped 2 stroke o/b should cruise in the 4,000-5,000 range. One can usually hear when the engine is in its comfort zone. I cruise around 4,200-4,300 @ 29 knots.

[mubikS]

quote:

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Originally posted by Steve W.


I am well on a plane and making 18-19 kts.

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Yowzaz. I can't even slow down to that speed and stay on plane... but I'm a sailor first and this is my first boat (so what do I know, right?[:x)]). I struggle to stay on plane at 20mph. I cruise at 30 (~4000rpm) and slow-cruise (when it's rough) at 25 (~3500).

[Sailor]

According to my Navman fuel flow gauge, 4k rpm's is the most efficient speed for my boat. When I drop down to 3200 - 3400 which is nice leisurely pace, I go from 3 nmpg to about 2.2 nmpg.

[Bungo Pete]

I crank the old 200 Mariner between 3800 and 4200 rpm, depending upon sea conditions. 4000 seems about right, and we're good for about 28 knots. WOT is somewhere over 5000. I very rarely open her up that much except when it is dead flat calm (which ain't often [:u]). Each time I have done it, it has only been for a couple of minutes; not because I fear any problem, it is just that I don't see any upside.

BTW, have any of you guys had experience with doel fins. I understand that you can stay on plane at a lower speed with them. Any comments will be appreciated.

[Shagndj]

My Johnson 225 hates anything from 2000 to 3700. Trolling speeds are great as well as Idle. Anything from 3800 up and she loves it. When I had the old Evinrude 200 on her, the cruise speed was a little lower, but the engine didn't sound so darn rough in the 2000 to 3700 range. Don't run at that speed often, but sometimes need it for a rough inlet.