Specs say WOT is 4,400 - 4,800 RPM. While running around at wot all the time is not recommended, there is nothing wrong with winding it up every once in awhile to see what she'll do. Just watch the tach, and pull back if it looks to be edging above 4,800. With your boat/motor setup I would suspect WOT will put you in the low 40s for mph.

 

I run my boat up to WOT twice a season for just a couple minutes - typically after I add fresh fuel in the spring/summer and then toward the end of the season. Then at WOT I watch the RPM's to see if my engines are synced and then I watch that the oil pressure is holding. Last season - I never opened the boat up. But - my boats have always needed to be between 3200 and 3600 rpm's minimum to stay on plane. I try to keep the boat running at around 75% of WOT for cruising on plane, when getting on plane - the engines will hit about 4000 rpm's and then I pull back to about 3650 to 3750 rpms - my boat runs WOT at 5000 RPMs. Then when I idle around - I like to be at about 1600 rpm's. When I owned my 2 previous boats WOT was around 4400 rpms and I would cruise at 3200 rpm's. I opened the smaller boats up a few more (5) times a season - but still not for a long duration. I also watch the temp gauge and water pressure gauge. I can display all of my gauges on my GPS.

 

When you open it up trim it out as far as you can before it ventilates. Watch your gauges max rpm for 5.0mpi is 5000 rpm. When I plane off I often will go wide open to jump on plane then back off to 3000 rpm.

 

When you open it up trim it out as far as you can before it ventilates.

You really meant to say....... Cavitation. :grin:

 

I thought a blowout was what happens when you get the mechanics bill. Requires changing the drawers? And sometimes makes you palpitate.

Good input folks. I just didn't want to introduce too much excessive wear or tear if winding it up. The 4800rpm is a good guide. What would happen if you just hammer down and left it.... would you over rev and blow something or is the engine/rpm regulated in some way? Not that I'm trying to be a racer, inquiring minds just wonder.

 

I don't know about 2004 models but my 2010 4.3mpi has an overspeed limiter which will not allow the engine to rev past 4950 rpm's. At that point you can feel the engine hesitate and an alarm sounds. On the 5.0mpi this may happen at a higher rpm as the engine is rated at 4600-5000 instead of 4400-4800.

 

You may never hit the rev limiter. The main thing as you put the hammer down is to watch the gauges and see how your boat reacts. Every boat is different and going full throttle for a period of time is not going to hurt anything as long as oil/water pressure are OK and you don;t over rev the motor. My last boat (bought new) had a 200HP outboard and after 12 years and probably 1400+ hours it ran like new. Nothing other than normal service was done to it and I ran it full throttle and trimmed up probably 50% of the time.

 

Don't know if this belongs here or Gas/Engine. Don't see this specific question on search. Wondering if I'm OK to open up the engine to see what it will do.

Wow, I full throttled my boat on the first two trips out to see how it did and felt to me, and to show off to my passengers. :smt001

Guys have already told you what to look for. Have fun! I don't go past crusing RPM's much really (3600rpm) as I hate to actually see the fuel gauge moving downward that fast, but this past weekend I went up to 4200rpm for a few minutes to get ahead of a boat that was parallel to me for several miles and the river was beginning to pinch in. It was fun as he was in a smaller bowrider and I disappeared in front of him. :smt001 Engines purred like a young kitten...

 

I second Gunns statement. I forgot to add that in our boats we don't run full throttle too much because it hurts to actually watch the speedo go to 48MPH and actually seeing the fuel gauge moving towards empty.

 

so which guage wins the race ???

 

My days boat when he had it a 1986 Arrow Glass Bow Rider with an OMC 135 had a rev limiter. Besides, you would more than likely float the valves before you did damage.

 

My days boat when he had it a 1986 Arrow Glass Bow Rider with an OMC 135 had a rev limiter. Besides, you would more than likely float the valves before you did damage.

float the valve???

 

45-48 depending on weight and sea conditions.

 

I must definetly have something wrong! My boat won't plane loaded without full tabs, everyone elses will....my boat tops out about 42, and that's with a bottom with no bottom paint and looks like new, and everyone has more topend:huh: You have me curious now:smt101:smt021

Edit: I should add that she runs perfectly when she runs!

 

I have a problem getting on plane too with a full laod of full, water, heavy passengers and full coolers. I notice when I hammer down that the port motor lags behind by 300-500 rpms until it hits around 3200rpm's and then it catches up. I'm sure this is hindering the planning but I'm not going to do a tune up until next year when I replace the risers and manifolds.

 

Hate to keep up the hijack...lol My port is the same, it has a new tune up!!

 

I use tabs to get on plane and then retract them almost all the way and trim my drives. I find bringing up the tabs will increase my speed by about two miles per hour with the same throttle settings. My boat takes a while to plane with a full fuel load, full water and six or more adults plus gear and provisions. I don't firewall the throttles at all, I just advance them to about 3200 and drop the tabs and wait a few seconds and she will pop up and then I can adjust the trim.

 

i was told by the mechanic at my marina that running WOT is good in small doses, especially after being off for a while, It helps the engine survive the crappy ethanol we have to use

 

I run mine at WOT in short doses to make sure they both run up to the same RPM and oil/temp stays steady. Full load on mine with drives and tabs trimmed up is 44mph on a calm day. It's fun to watch boats who think you are a slow cruiser just get smaller in your wake... When I repowered I expected a bit more out of the top end but ended up with better low end and can cruise at 28-30mph at about 300-400 less RPM than before so not too bad.

 

On a somewhat related topic, at times I tend to have a bit of weight (although not over the posted capacity) on the boat between people, fuel, water, coolers...etc and my boat sometimes struggles to get on plane right away. I can tell in the first 3 seconds if she is going to stuggle or get right up. My question is how long is it ok to let her "struggle" while at WOT? I tend to leave it at WOT until I feel her starting to get up but sometimes it takes a little while. Am I doing any damage or is it ok for a reasonable amount of time until she gets going?

BTW - I have a Mercruiser 5.7, 265HP I/O

 

On the days you struggle to plane out have you run to max speed to see your max rpm's? I know you don't take your friends out and just run full blast all the time but the numbers will tell you how much your lugging the engine. If it's safe to do so try and see if you are in the wot powerband for your engine. If not then you may be causing damage to the engine.

 

I tend to run the boat at WOT once or twice a season... Always at least once at the beginning of the year to be sure the engine makes the spec'd rpm and runs smoothly. I watch the water temp, tach, and speedometer gauges pretty closely when I do. Otherwise, I may goose it if I'm trying to outrun a rainstorm and get back to the dock if I'm nearby.

When I ran smaller boats, I ran WOT much more frequently for short bursts (maybe a minute), as it cost less to do so. In addition to the good advice already given, with outdrives I would be careful to tweak the drive trim before getting to 100% throttle to avoid ventilation and bumping the rev limiter. Also, I don't run outdrives at WOT if there's a chance of "catching air" for safety reasons, and to preserve the gears in the drive...

 

How many gallons per mile do you get running wide open?

 

It's not a bad idea to open it up once or twice a season like Terminaldegree said. It will tell you a lot about your engine and prop health.

 

Hi blaster,

I'm not sure what my gph/speed are at WOT; if conditions are good next week, I'll give it a shot and report back with the results... I'll take a wild guess now: maybe 30 gph per engine and top speed in the high 30's (but it'll make a glorious noise like a speedboat)!

 

Well, through 4 boats, which have never had an issue, we do it probably more frequently than most. But then I've never had a boat that'll go much above maximum rated RPM either. With the 300 DA, which is actually our fastest boat top end boat yet by 3mph, we probably do it once per weekend but usually not for really long times. But we'll run a 40-42mph for extended periods. The issue with wide open is that it's a diminishing returns issue. But it is fun to go fast now and then. If anything, I suspect you may have to worry about canvas more than motors. I think there's a recommended maximum speed for various canvas configurations but don't recall where I read it.

 

I always use the tabs to get on plane. I was told by a long time mechanic that the Alphas were "bullet proof" but why add the extra stress on the outdrives while getting on plane. The tabs take a few seconds to lower and raise so I always use them. While on plane (and less than 2' waves) I rasie the tabs and trim up to 2-3 at the max. I will usually gain a couple miles per hour while increasing my mpg. I'm not able to boat this Saturday but hopefully on Sunday. If so I will run WOT again to see what the GPS says. Last time out I hit 48 but depending on water conditions 46 is average.

 

A few longish trips at WOT will completely cure you as your wallet melts in your pants. I tend to go WOT maybe once or twice a season just because I can.