WOT 80/20 Rule ???

K

K Hultgre

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Was reading a thread that got me to thinkin. What is the recommended WOT duration (time) for a std. engine? 80% cruise and 20% WOT ??
 
Bondo

Bondo

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Re: WOT 80/20 Rule ???

Let me Answer your Question,<br />With a Question......<br /><br />How Long Will You Hold the Pedal to the Metal inYour Car ?????????????<br /><br />Remember, That's a Car Motor in your boat......
 
K

K Hultgre

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Re: WOT 80/20 Rule ???

to answer a ? with a ?. I thought they were designed to run that way?<br /><br />Ditto on the "All Day" but the shore keeps getting in my way. :eek:
 
Bondo

Bondo

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Re: WOT 80/20 Rule ???

OK, Well,<br />Look at it this way.....<br />A SBC, or 4.3, or 3.0, or Whatever engine you want to use,<br />Should run Atleast 1500/2000hrs, Before a Rebuild.......<br /> If you Don't Abuse it..... <br />I've put Over 600hrs on the 4.3 I built 4 yrs ago, at Idle, to 3500rpms... Occasional Bursts to 4600rpms.....<br />I plan on getting to the Higher side or Beyond the above mention hour limit........<br /><br />For you Fellas who wish to run WOT, I think you'll be hard pressed to get to the 200hrs mark.....<br /><br />So, I guess it all comes down to just What You Want out of Your Boat......<br /><br />FYI, <br />Diesels are built to run at or just under their Governed WOT......<br />2-strokes are built to run Very Near their WOT......(they Have to, to build any Power)<br />Gas motors are Not built to run WOT, All Day Long.........<br /><br />Good Luck.....<br />Your Going to Need It...
 
D

Doug Durako

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Re: WOT 80/20 Rule ???

As I've said before, many boats are underpowered.<br /><br />Get a small boat with a v8 and you can get anywhere you want to fast. At 3800 rpm I am zipping right along in the upper 40mph range.<br /><br />Most passengers freak at about 55 mph anyway.<br /><br />I've got two friends with Fountain boats (one 35-footer and one 42-footer) with twin 502s and their wives/girlfriends rarely let them punch it with passengares aboard. They usually cruise at about 45---half throttle---and even then they are burning about 13 gallons of gas an hour.<br /><br />Of coures, when someone roars by them, they don't have to sit still and take it.
 
Bondo

Bondo

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Re: WOT 80/20 Rule ???

Yep,<br />I Just Hate Boats with Too Much HorsePower.... :rolleyes:
 
D

Doug Durako

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Re: WOT 80/20 Rule ???

Hay, Bondo----most of our "governors" are not in the engine compartment, they are sitting in the passenger seat next to us.<br /><br />Unless we are talking about one of the "sausage festival" boats running with 4 dudes because they've scared the girls off.<br /><br />Once you find a woman who can handle the speed, you have another problem because there is ALWAYS someone with a bigger, faster boat . . . .
 
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Squirterguy

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Re: WOT 80/20 Rule ???

A lot of that WOT time depends on just how close your max RPM is to the max DESIGNED RPM of the engine as well. In my case, a balanced 454 Chevy was designed with a maximum safe sustained RPM of 7,200 without grenading the crankshaft. (Here's "too much HP") haha My '78 Taylor SS spins 330 HP out of that very 454 at 5000 RPM. The Berkley 12JF jet pump and "A" impeller devour those 330 HP at about 4800 to 4900 RPM (maybe 5000 on a cool morning). If I am running flat out, I am only running about 70% of the designed stress on the motor. SHe has only about 200 hours on it since dad (his boat new) only went boating a couple times a year for many years. Lugging a motor with too much prop load to allow the right RPM is just as detrimental as too little prop and an excessively high RPM. Lots of trade-offs to balance and figure. Wish it was as simple as a number. :)
 
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BRIAN03

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Re: WOT 80/20 Rule ???

The 80/20 rule. I learned it from the diesel engine manufactures. They call it a duty cycle. The duty cycle is how much load you put on the connecting rods in the engine. Example Volvo-Penta diesels have 4 duty cycles. Pleasure 400 hours or less per year. light commerical 600 hours per year. Commerical 1000 hours per year. Heavy commerical runs 24/7 never shuts down. Each engine is the same cid. but they pull the fuel back to take load of the engine.The same engine has 4 hp ratings 240hp. down to 160hp. The reason behind it is. The engine will reach a longevity curve of 6000 hours. Now a gas marine engine 4 stroke has a (expected) life cycle of 2000 hours. The engine will live if properly propped for 2000 hours if the duty cycle(or load on the connecting rods is 80/20. If you run the engine at wot if will fail at 400 hours. The theory is to put the load on the engine so that it MAY reach a life cycle of 2000 hours of service. When you have exceeded the life cycle there will be a conn. rod hanging out the side of the block. If its less than 2000 hours you know the 80/20 rule wasnt followed. I have always said an engine has so many TURNS in it. You can take them all at once or take them over a long period of time.
 
POINTER94

POINTER94

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Re: WOT 80/20 Rule ???

Hey bondo,<br /><br />My dad has 3200hrs on his 76' ford 302, 175hp with the 76 OMC outdrive on a 22" carver cabin cruiser. Now for the unfair part. I feels tired to me but it runs like a watch. I am pushing him to rebuild it and see what he can do to boost the hp. It was underpowered out of the box.<br /><br />Can it be upgraded from its 175hp rating with a carb and what about turning it into a stroker? Should he stick to the: if it aint broke don't fix it rule? Ballpark figure to do this.<br /><br />We hate the outdrive but it has actually held up well. I am told that it can be converted to a Volvo outdrive. Is this true?<br /><br />My advise was to get a new boat but nobody is listening.<br /><br />Thanks
 
Bondo

Bondo

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Re: WOT 80/20 Rule ???

POINTER94,<br />A Compression,+ Leak-down Test will give you the Answer on the Condition of Dad's Motor.....<br />Boomyal can give you the answers on the Stroker Mods.... He's doing one Now......<br />As for the Outdrive ??? I Think it's Too Old to Easily Up-grade to Anything...... I Think only the Late-Model OMCs are convertable to Volvo.....<br />I Do Know, a 351w is a direct swap for the 302..... Much Easier than a Stroker....<br />BTW, I Don't Do OMCs...<br />I Only Know Enough about them, to Avoid Them.....<br />Working on OMC/Merc swap #4 at the moment....<br />1 ChrisCraft Lancer...<br />2 Highliner 222s<br />And My Old Town Atlantis......<br />All Now sporting Merc Alpha1s.......<br />Chevy Power, Of Course...!!!! :D
 
Boomyal

Boomyal

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Re: WOT 80/20 Rule ???

Don't let Bondo bully you POINTER94. ;) I don't care what they say. You just can't beat a 302 Ford in a marine engine. However, that being said, you can improve them without unduly stressing them. You just don't want to do it with the valvetrain. As always, there is no substitute for CUBES. Take a look at this site:<br />This is where I'm going. I'm upgrading my perfectly good running (2000 hr, 29 y/o) 2 bbl 190 hp 302 OMC.(running synthetic oil of course)<br /><br /> http://www.fordmuscle.com/archives/2003/09/stroker/index.shtml <br /><br /> http://www.speedomotive.com/ford_302_to_331_stroke_crank_kit.htm <br /><br />If you have room {height and width) and can stand about 80 extra lbs, a 351W swap would work and probably be a little cheaper (for stock). <br /><br />The one place I do agree with Bondo is that your electric shift outdrive is eh eh a little marginal. But do not dispair. The latter cable shift 800 will bolt right up. and they have no bellows to blow holes in. :p I can give you a name of a guy in the biz, in AZ, that will use nothing but.
 
Bondo

Bondo

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Re: WOT 80/20 Rule ???

Boomyal,<br />Why Aren't You Doing the 351w Swap ???<br />
As always, there is no substitute for CUBES.
Click to expand...
Never mind, I Just found the Computer thread... :D
 
S

Squirterguy

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Re: WOT 80/20 Rule ???

Bondo & Boomyal are right ... There IS no replacement for displacement.<br /><br />I'll be the first to say I don't know much about I/O drives but I'd hesitate to upgrade power very much on a stock outdrive, especially an older one with an unknown cieling. I'd do the 351 swap likely but I'd also look for a drive unit to be certain I wouldn't wreck the old one.
 
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BRIAN03

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Re: WOT 80/20 Rule ???

I had a 7.3 powerstroke in a 1999 F-350. In 80,000 miles I pounded the main bearings out of the engine. The truck is rated to haul 10,000 lbs. and I hauled 20,000 lbs. behind it everyday of its life. I exceeded the duty cycle of the engine. I've herd of 400,000 miles on a powerstroke. I got 100,000 and had to put a set of bearings in it. Main bearing were down to copper. Less load on the conn. rods and the engine would have lasted alot longer. I changed the oil and filter every 3,000 miles.
 
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