Running WOT

[trejac]

I searched for a thread ont he subject but could not find anything.

I've been reading allot lately trying to gleam pearls of wisdom from the experienced boaters and I see allot of people talking about running wide open throttle. I read something in this forum last year about running too many RPMs for your boat. It had to do with prop pitch and redline for your motor. I thionkg mine is about 4300-4600 (4.3 merc)
My boat is tuned up and ready to run however since reading the article last year I've been afraid to let her run wide open. I can run at 4100 RPM and still have some to go. Is everyone else taking risk or am I being too consertive?

I would love to trim it out and see what it will do!!!!!!

 

[RWilson2526]

Re: Running WOT

Let her rip!!!!....I think you are being a little conservative...to let you know if you have the right prop your boat should run within a range of RPM at WOT...that is with the lever pressed all the way forward....you should know this information. Next time out....let her rip...trim it out and see where the RPM's are....if you approach 5000 that is too much and back it down....running a little too high for a few seconds is not going to blow your motor. not sure what the WOT rpm range is for your boat....looked up for new 4.3 mercruisers and they stated 4400 to 4800.

Get on out there and report back how you did.

 

[grahamh]

Re: Running WOT

As long as the RPM is in the acceptable range at WOT you're fine. I've heard it can be hard on the engine if you cruise at WOT for long periods of time, but I never do that anyway.

 

[Bondo]

Re: Running WOT

Ayuh,... Ya gotta hammer it to WOT once,+ awhile, to see if it's up to Snuff...

I cruise in the 3200/ 3800rpm range...

 

[apaseman]

Re: Running WOT

How does one figure out the WOT range for their motor?

Mine is a '87 175HP Mariner.

 

[Philster]

Re: Running WOT

Can you run at WOT? Yes. Should you? YES.

Can you leave it there and run it like that over and over for long periods of time? Well, not really. You can do anything you want,, but it's not advised. Bearings tend to build up more heat than the oil can take over stretches of time at WOT. "periods of time" is the operative phrase.

But if you don't trim it out and push her, you don't know if you are set up right, which means for all you know, at 4100 RPM you could be lugging the engine every single time you cruise, which is about 10,000 times worse than running at a 4600 RPM redline for a minute.

And I ain't kidding. Make sure she hits redline or damn close. So, trim it up/out. If she can't get there, you might be overpropped, putting a tremendous amount of stress on the internals of the engine.

 

[91capri2050]

Re: Running WOT

My 20 ft bayliner with the 4.3 runs 4900 rpm WOT and trimmed out with a 21 pitch prop. The redline on the factory tach is 4400, but ive read it can be 4800. Which is it? Should i move to a 22 or 23 pitch prop?

 

[Philster]

Re: Running WOT

I've read 4400. You are underpropped if 4400 is correct. It'd take a 23 to knock it down.

There is no justification for 'it can be 4800', because the lower the engine redlines by design, the happier you should be. Why run millions of revolutions of wear over the years that is not needed? Power is down in the RPM range, so use it down there!

 

[mern]

Re: Running WOT

My Merc 150 black max outboard pulls about 56-5700 rpm trimmed out at WOT. So should I not operate it in this range for the 5-7 minute trips i've been routinely doing? Obviously, I know to not run WFO all day, but never thought any damage would be done with a less than 10 min trip, at which point i'm usually tired of the wind and the noise anyway. Thanks

 

[rrkyle]

Re: Running WOT

This has me a little concerned also because my 70 hp mercury is wideopen around 5800 also. I dont run around all day at WOT though but the tach goes all the way to like 8000. I think that might give me some problems haha.

I had always thought outboards were designed to run WOT? I dont mean all day but especially on the smaller motors like 15 and 20hp. If your not at WOT with them your not goin anywhere.

And i do see those guys with the 150+ motors running all over the lake at WOT.

 

[180shabah]

Re: Running WOT

How does one figure out the WOT range for their motor?

Mine is a '87 175HP Mariner.

Refer to your service manual, or ask in the mariner OB forum, then get your self a service manual.

My Merc 150 black max outboard pulls about 56-5700 rpm trimmed out at WOT. So should I not operate it in this range for the 5-7 minute trips i've been routinely doing? Obviously, I know to not run WFO all day, but never thought any damage would be done with a less than 10 min trip, at which point i'm usually tired of the wind and the noise anyway. Thanks

Do you drive your truck at 5k for ten minutes or longer?

Will it blow apart, no it shouldn't, but you are taking time away from motor life rapidly.

 

[mern]

Re: Running WOT

Yea, i usually start my boat, give her a min or so to warm up while stowing stuff that may blow away, seating passengers, and in one motion advance to full throttle, play my way to wherever i;m going and shut her down. No my truck is a diesel, so anything over 3200 would shred it. However, my Ducati sportbike would swear 5K was idle, damn thing doesn't even run smoothly/pull hard until 5k with extended periods of much higher rpm. And its a relatively low-reving motorcycle. Just trying to figure where my boat fits in between these two extremes.

 

[RWilson2526]

Re: Running WOT

My Merc 150 black max outboard pulls about 56-5700 rpm trimmed out at WOT. So should I not operate it in this range for the 5-7 minute trips i've been routinely doing? Obviously, I know to not run WFO all day, but never thought any damage would be done with a less than 10 min trip, at which point i'm usually tired of the wind and the noise anyway. Thanks

outboard wot rpms are usually in the mid 5Ks so it sounds like you are right on.... I think things got a little muddled here with prop talk but I think the general consensus is its just fine to run at wot whenever you like for as long as you like....just dont do it all the time everytime....like you said with the wind and the noise and the water you usually cant do it that long anyway.

 

[apaseman]

Re: Running WOT

ok, my service manual states 5300-5800. So, if my motor seems to redline around 5000, is this a problem? Will running my motor around 4800 for most the time be a problem?

 

[ovrrdrive]

Re: Running WOT

I redline my optimax 150 for about a minute or two on every trip on the way back in just before the no wake zone. It blows out any junk in there and it's my chance to check to make sure the engine is running right. I wouldn't run an I/O as hard as I do the outboard. They're cut from different stones.

 

[jrbirdwell]

Re: Running WOT

This is my first time on this site. I need help with identifying the model of boat I recently acquired. It's a Citation, 19', V-hull, fiberglass, (1983 ?) walk-thru windshield. The engine( I believe its the original) is an Evinrude V-4 140 hp. I looked it up online and it was manufactured in 1983. This boat is a project fix-er-upper. I have very little experience with boats and any information would help considerably. It was last registered in North Carolina in 2005. The title has been lost by the owner. It has a HIN stamped on the transom. help!!!!!!!!!!!!

 

[apaseman]

Re: Running WOT

Might want to post this question in the main forum, you'll probably get better results.

 

[Summer Fun]

Re: Running WOT

I run my girls [twin 350's ] at WOT @ 4800rpm's for a least 30mins to 45 mins with NO ill affects.
They have 1600hrs on them.

 

[180shabah]

Re: Running WOT

This is my first time on this site. I need help with identifying the model of boat I recently acquired. It's a Citation, 19', V-hull, fiberglass, (1983 ?) walk-thru windshield. The engine( I believe its the original) is an Evinrude V-4 140 hp. I looked it up online and it was manufactured in 1983. This boat is a project fix-er-upper. I have very little experience with boats and any information would help considerably. It was last registered in North Carolina in 2005. The title has been lost by the owner. It has a HIN stamped on the transom. help!!!!!!!!!!!!

welcome to iboats, but you need to start your own thread - hijacking is not cool.

ok, my service manual states 5300-5800. So, if my motor seems to redline around 5000, is this a problem? Will running my motor around 4800 for most the time be a problem?

If the book states 53-5800, and you can't get there then yes you have a problem. If you are overpropped, then it is lugging at ALL rpms, not just WOT.

 

[QC]

Re: Running WOT

A couple of things:

1) The OP (trejac) was asking about a 4.3 Merc. Anything else just muddies this up and he/she has not returned . . . Some have touched on this, but I wanted to emphasize.

2) I keep seeing references to redline. This is not a redline discussion. To be precise, it is about WOT RPM range which is where you need to be to be propped correctly. Redline refers to vehicles with transmissions that can exceed safe RPM levels. WOT range is a good thing . . . Some have touched on this, but I wanted to emphasize.

3) WOT range is specific to year, make model etc. All else is speculation . . . Some have touched on this, but I wanted to emphasize.