WOT Questions

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wolfnnj
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WOT Questions

Post by wolfnnj »

Hi all
I pulled up a lobster pot late last year and destroyed my tranny (PV31 V-drive) prior to the lobster pot everytime i got the rpm to 4000 the damper plate blew a spring into the bellhousing causing chaos. I had to pull the engine last year and replace a damper plate 3 times. I put the boat up for sale after the second time it happened. My engine 350 260hp crusader wot is 4800-5000 the max on the pv31 v-drive is 4000 rpm at 225 hp. taking all of that into account I had a very used bell-housing that never sat right, I have replaced it with a new one, the pv31 is 100% rebuilt like butter, the engine starts on a half of a turn. The boat goes 23mph @3900 rpm with full fuel and load honestly never better. BUT depending on the sea conditions and the curent through the inlets & being a single screw I have to really lay into the throttle to keep control somtimes. I am kinda affraid to run it WOT or over 4000 in fear of something like the damper plate thing happening.

Can I go over 4000? is it safe?

Wolf
1971 f-26 express
1971 F-26 w/ 350 Crusader and Paragon PV-31 V-drive.
1968 MFG Westfield w/ Evinrude 50
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prowlersfish
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Re: WOT Questions

Post by prowlersfish »

IMO yes its safe . Most marine gears now are rated using torque . My gear for example is rated for 350 hp at 2800 rpm but rated for 525 @ 4200 rpm . A big difference in HP but not in torque . Its the torque that breaks things not the HP or rpm (within reason ) your gears are rated just on hp and really you have increased the HP and not that much increases in torque


This is why IMO your ok .
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mikeandanne
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Re: WOT Questions

Post by mikeandanne »

Judging by your explanation, that old bell housing was probably putting the damper ,trans combo off center which would do just what you said IMO.....hopefully when you installed the new one the locating pins on the engine block are good ?? If they are you should be good to go....Mike
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k9th
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Re: WOT Questions

Post by k9th »

From a purely engineering standpoint, Torque, HP, and RPM are all inter-related and cannot be dis-associated or considered independently of one another. The formula for calculating any of the three is as follows:

T = (HP * K)/RPM where T = Torque, HP = Horsepower, RPM = Revolutions/Minute, and K = a constant that determines whether the torque is expressed in lbs-ft, lbs-in, etc. The value of K for Lbs-Ft (what most people call foot-pounds) is 5,252. The value of K for Lbs-in (what most people call inch-pounds) is 63,025

In the above example that Paul gave, T = (350 * 5252)/2800 = 656.5 Lbs-ft of Torque
In the second example that he gave, T = (525 * 5252)/4200 = 656.5 Lbs-Ft of Torque

Since the three are always inter-related and dependent upon each other's value, if there is a failure, each must be considered equally as the possible culprit.

Basically, HP, by definition, is a unit of work and 1 HP = 550 Ft-Lbs/sec. That means that to simulate 1 HP a person would have to lift a 550 Lb weight vertically 1 foot every second.

Additionally, gear design, if done in accordance with AGMA standards, is done by HP since it is a unit of work. Obviously, torque can be calculated by adding the RPM range where the gear will operate, and therefore both HP and Torque are used to specify the gear. All gear design that I am aware of sizes the Pinion gear to carry the needed load with the desired safety factor since the Pinion is the smallest and will see the highest load in the system.
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captainmaniac
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Re: WOT Questions

Post by captainmaniac »

IMO, if the v-drive is only rated for 4000RPM, then pushing it 25% beyond that just doesn't sound like a good idea. If the v-drive can't handle the revs coming out of the engine, something has to give...

Your comment re having to really lay into the throttle because of inlet and sea conditions -- I understand having to goose the throttle on occasion. But if you need WOT to deal with the inlet, you probably shouldn't be going out! Normally in bad sea conditions (head, beam, or following seas) you need to run slower to run safer, reduce pounding, reduce launching off waves, have better control in beam seas, and sit lower in the water to reduce surfing in following seas. So not understanding why you would need WOT for seas? There is something about your situation I am not understanding, and must be missing, because it sounds to me like you might just be pushing it too hard.
wolfnnj
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Re: WOT Questions

Post by wolfnnj »

Capt. M
My year f-26 is known for nose dives hard to port in three different sea situations and I'll explain what your missing here

In a strong under tow ( if I am following a twin screw too closely as well) my bow digs in when on plane and goes hard to port. This is not a situation where I need wot I just have to trim all the way up and slow down.

In a following sea I have two options 1 to out run the waves on plane fast or 2 trawl. if my trim tabs are down I'm nose diving to port with every passing wave on plane and holding on to the steering wheel for dear life as my steering is a chain going to a shaft pushing a rack. I sometimes have to go over 4000 to out run being tossed around. You would then say just go slow but if it's choppy I can't control it at slow speeds as it doesn't hold its path very well in chop no matter what the trim or rpm.

Going out an inlet while the tide is going out fast I have to power between swells with trim all the way up if a roller hits me astern my bow goes violently to port. This is an occasion where I have to goose it to keep in between swells.

Every boat has its quirks this one is not exception to the rule.
1971 F-26 w/ 350 Crusader and Paragon PV-31 V-drive.
1968 MFG Westfield w/ Evinrude 50
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prowlersfish
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Re: WOT Questions

Post by prowlersfish »

Where did you get the ratings of your gear ? 225hp@4000 is the rating of your old engine , rarely are the gears rated the same. The ratings I came up with on similar paragons was 277 @ 4400 . At the time that was pretty much the limit on rpm for stock engines . Again torque is the issue . Rpm not so much , again within reason .
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The Dog House
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Re: WOT Questions

Post by The Dog House »

According to the TMI Transmission catalog, the PV31 is rated for 260 hp @ 4000 rpm. The horsepower isn't the issue, but I'm not sure if the V drive could handle rpms higher than 4000.
1993 Sea Ray 200 Overnighter OB with 1993 Mercury 150 hp Outboard
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prowlersfish
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Re: WOT Questions

Post by prowlersfish »

I would contact one the places that deal with the paragons . And see what they say about the rpm . If they are truly limited on rpm .
Boating is good for the soul
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Life is to short for a ugly boat :D
wolfnnj
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Re: WOT Questions

Post by wolfnnj »

@dog house
Have you ever run your boat over 4K or do you have the 318 still?
1971 F-26 w/ 350 Crusader and Paragon PV-31 V-drive.
1968 MFG Westfield w/ Evinrude 50
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The Dog House
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Re: WOT Questions

Post by The Dog House »

wolfnnj wrote:@dog house
Have you ever run your boat over 4K or do you have the 318 still?
I still have the Chrysler 318 in my boat. The highest rpm I've run is 3600. At 3000 rpm my V drive temperature is between 160F and 180F. Maximum temperature is 210F, but recommended temperature is < 180F. My main concern about running at higher rpms would be the temperature of the V drive. Higher rpms will generate higher heat but will you have the cooling capacity to keep the temperatures down? If you plan on running at higher rpms continuously, then consider increasing your cooling capacity somehow.
1993 Sea Ray 200 Overnighter OB with 1993 Mercury 150 hp Outboard
1979 Starcraft 14' Rowboat with 2011 Mercury 9.9 hp Outboard
Former boat: 1971 Trojan F26
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prowlersfish
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Re: WOT Questions

Post by prowlersfish »

Some thing to think about
With increased rpm you get increased water flow so that helps with the cooling . Load on the gears will increase heat . If your not able to make your rated RPM by Some a overload like being over propped you could be adding stress and load ( and heat ) to the complete drive train . Just food for thought :mrgreen:
Boating is good for the soul
77/78 TROJAN F36 Conv.
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Life is to short for a ugly boat :D
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The Dog House
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Re: WOT Questions

Post by The Dog House »

prowlersfish wrote:Some thing to think about
With increased rpm you get increased water flow so that helps with the cooling . Load on the gears will increase heat . If your not able to make your rated RPM by Some a overload like being over propped you could be adding stress and load ( and heat ) to the complete drive train . Just food for thought :mrgreen:
I could get to 4000 rpm if I used full throttle. At 3600 rpm I still have a lot of throttle travel left. I just don't need to go to 4000 rpm to get on plane and I don't believe in taking a 44 year old engine to WOT. I know others disagree, but I believe there is a greater chance of something breaking at 4000 rpm than at 3500 rpm. Your philosophies may vary. :mrgreen:
1993 Sea Ray 200 Overnighter OB with 1993 Mercury 150 hp Outboard
1979 Starcraft 14' Rowboat with 2011 Mercury 9.9 hp Outboard
Former boat: 1971 Trojan F26
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captainmaniac
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Re: WOT Questions

Post by captainmaniac »

I don't tend to boat in areas with currents and undertow, so have to give you that one. Paul (Prowlersfish) - and others more local to you - can probably give more focused advice re handling i those conditions. Having said that, I operated a single engine 28' Trojan for over 20 years, so I do have a bit of experience with single engine Trojans too. Main message is : don't write me off -- just trying to help.

It seems strange to me that you always dive to port - I would think you would dive to port or starboard depending on what side following seas or waves are coming from. If you always go to port, do you have one lazy trim tab (likely starboard side) that stays down and forces the port bow down? There is nothing fundamental about Trojans that make them always dive to to port.

In any kind of following sea, you should always be trimmed up. Keep the bow up, so that if you do catch a wave, you are not dooming yourself when you are pushed into the preceeding one. When you say "if I am following a twin screw too closely as well" - got nothing to do with it being a twin or single... if you are riding anybody's wake and surfing off of it, it is the same as just surfing regular waves. Your bow is not going to dig in unless you are trimmed too far down. Trim up in following seas, and down in head seas.

Outrunning a following sea is one way of dealing with it, but if you are at WOT and the waves are big enough you will just launch off of them. If you are getting air or pounding, you need to slow down as the boat and its passengers can only take so much. Whether you try to outrun or slow down so you don't surf, keep the tabs up. Your steering is actually the best setup IMO... same as my father had on his '69. No chance of a leak, and 100% reliability between wheel position and rudder position.

Handling decisions in regular wave patterns vs totally choppy conditions are different, so depends on what you are really dealing with. If it is a total chop, then tab position and throttle will probably need to be adjusted constantly. Regular wave patterns may need some adjustment, but for the most part you can set tabs and just run with that.

One last comment : if you need to run at WOT to keep control given the sea conditions, should you be going out? It's called 'pleasure boating' for a reason. If lives are at stake, it's not pleasure!
wolfnnj
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Re: WOT Questions

Post by wolfnnj »

I probably won't be happy until I break it again lol
I replaced my engine with a 350 instead of a 318 with no impact at all on speed or performance. I don't produce 260 hp until 4800 I can't get to my peak hp since I can't get the Rpms up there. So I increased my ponys with no use of them.
Seems kinda fruitless
1971 F-26 w/ 350 Crusader and Paragon PV-31 V-drive.
1968 MFG Westfield w/ Evinrude 50
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