Does anyone have Full HP and Torque Info on outboards over 150 HP

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Seahorse5, do you still think that there are no scientific methods in my procedures? I am doing research on boats, motors and props to try and find an easier way to find a BETTER prop for a boat and the owners intended uses than he has now, with the very limited information given by the owner.
If he wants the BEST prop it will ALWAYS require testing a decent number of props until he finds the best one, and then if he wants more he can spend the money to have the prop labbed for his particular circumstances. My research is NOT for these people, it is for the people walking in here with limited knowledge and limited information. I am just here to facilitate a quicker and easier way to do this.
I am not here to have arguments or to be dismissed as foolish. I am just trying to learn more than I now know, and Dale says you have a lot of knowledge, and I believe what Dale says, the same way I believe what Kenny says. I am on a mission, that is the best way I can describe it, in my quest for more knowledge and to try and find easier ways for people to find a better prop for their boat.
I do appreciate dialogue and constructive criticism, that is how we all learn more than we know now. When I find that my theories or concepts are wrong I am very happy to acknowledge to everyone that I was mistaken in my beliefs, see the following.

http://forums.iboats.com/showthread.php?t=371668

So, if you have the time to look at my spreadsheet and tell me where I have made errors, or where I might be able to improve it with more information I would appreciate it very much. Knowledge and new theories are normally found by standing on the shoulders of men who have much more knowledge than the man who actually presents the new theory or hypothesis.


H

 

[seahorse5]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Sorry to say but there probably isn't any way to look at a chart and pick the best prop first time out. Too many variables, boat designs, engine characteristics, and customer expectations. The boat companies are also a wealth of information as they may test a multitude of props from different manufacturers.

Every outboard company already has put a lot of work into not only designing props but testing them with different boat and engine configurations. Each one also puts out a rigging booklet with recommendations as a starting point to start choosing the correct prop for the application. They also publish this info online and in booklet forms.

Any experienced dealer can also access the factory info to help a customer.

Any propping is trial and error and the same boat and motor may need a different prop depending on how the customer wants to use the boat.

I think you are putting a lot of effort into something that may not be practical for all purposes, may not be accurate for different conditions, and could lead someone down the wrong path thinking that the chart is a bible.

If you market your chart as a starting point, you have to assume that the prospect will understand spreadsheets and how to interpret them. If that is the case, the outboard manufacturer charts are handier and simpler.

Remember that props are designed for nominal speed ranges, then for boat applications.

I'll be out of internet access for the rest of the month so I may not be able to watch this thread very often.

 

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Seahorse5, I thank you very much for your time and thoughts. This spread sheet is not for public use, it is only for me to try and assimilate more information about the interactions between boats, motors and props.
I have about 45 spreadsheets already, this is only one of them. I find it helps me to understand what is going on with the whole interactions of the props and motors when I chart the numbers. By charting I am able to see things that I normally don't see when I just look at data or read the performance data on a particular prop with a particular boat and motor, and I thank you very much for taking the time to look over my work.

EVERY prop is a compromise in one way or another, it just depends on the needs of the user which prop is better suited for their needs and expectations.

And I also have my own boat company here with test results on different props with different boats and the results, Kenny and Dale are HERE. LOL

I also want to thank you for that reminder that props ARE designed for nominal speed ranges first.

H

 

[QC]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Hey Chuck, I actually agree with most of your post, but . . .

First off all that matters is torque, HP is a mathematical function of rpm and torque and really doesn't tell you anything other than it makes a certain amount of torque at a specific rpm.

. . . I always comment on this as it messes with people's heads. If you are going to pick one or the other to concentrate on, which is a mistake, the one that ultimately matters is clearly horsepower. It is what you pay for, and it is what fuel use results in. I always suggest if all that matters is torque, then just buy some oars. You can make a lot of torque just with your arms. Problem is that you can't make much horsepower, so you're not gonna go anywhere in much of a hurry.

To add to the confusion the point of maximum torque production does not occur at the point of maximum HP.

And this may help clarify my point. If all that matters is torque, then why run the engine anywhere but at peak torque RPM?

Based on the rest of your post, I actually think you understand this issue well, but I am on a personal crusade to end the "all that matter's is torque" mantra. It perpetuates the confusion and causes many a well intentioned marine consumer to chase torque specs when most manufacturers don't publish them (see post #1). Annnnnnnd, ultimately the reason they don't is that compared to wheeled vehicles, when it comes to marine engines torque is less critical (with the exception of hole shot or a marginally powered combo). Just look at the prop load curves that hw has prepared. The gap between power required and power available at less than full engine speed is evident.

With all of that said, without torque you ain't goin' nowhere, so maybe the best thing to glean from this is we shouldn't spend much time trying to separate torque and horsepower from each other . . . One begets the other when we add our other friend RPM

 

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Chuck, of course QC is right about HP.

In general a propeller is a variable load on the motor that changes efficiency at speed

You are 100% right in this statement as that is exactly what is happening with a prop on a motor.

really what you need to know are the load/efficiency of the different props as it relates to their advertised pitch.

And if I understand correctly what you mean by this statement I agree with you 100% as well. Pitch is not as important as the blade geometry. A manufacturers pitch rating is usually only relative to that particular model of prop. A prime example is a 17" pitch Yamaha Painted Steel prop on an 18' outboard Dory that turns 5,750 RPM at 37 MPH was changed to a Performance Series 16" pitch and the result was that the Performance Series could only turn 5,050 RPM at 31.5 MPH. clearly the Performance prop had way too much and the wrong blade geometry for this particular boat and motor, YET they said it was a 16" pitch prop and most people would think that they would gain some RPM at least.
I have found in my experiences that Blade Geometry can and usually does have more control over RPM and speed than pitch, if you pick the wrong geometry for your boat.

Before any study can be done to relate props to motor ratings you need to test the props to find out how their shape relates to drag and efficiency at specific rpm. In summary what you really need to know is not the torque curve of the output device but the nature and relationship of the load to rpm which is strictly a function of propeller design. You will never be able to graph or understand how to answer any of the above questions without knowing prop data.

Thanks to Kenny I have over 54 different SS props from different manufacturers and about 40 different models in different pitches and with different known loads, with the same boat and motor, that I have been able to chart already, so I have a pretty good database of props already, but I am shortly going to have a whole lot more props of the newest models that I can make comparisons with, thanks to Kenny.
In my opinion, the most important thing to know first is what blade geometry is best suited for what particular hull form and then you can look at the pitch of the prop.


H

 

[4JawChuck]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

I won't go into the HP - torque debate because its a dead horse thats been beaten to death a million times over. Manufacturers like to advertise their HP ratings because the public is used to that kind of advertisement but those who race or stress their engines in any kind of motorsports know that its torque that makes the goods move.

Something that hasn't been mentioned yet that is actually far more important than HP is transient throttle response, its that intangible seat of the pants feel when you put your foot in it or slam the throttle lever forward. You can't read it on a dyno except by timing rpm change related to load but you can say torque is the largest single determining factor in its relationship to engine response. In some forms of racing transient response is tuned for along with torque, nobody tunes a race engine for HP output...its simply a mathematical relationship between rpm and torque output which is easy to graph alongside torque which indicates work accomplished.

Much of the research in prop design and testing has to include variable pitch on high end SS props, much of the efficiency gain at higher speeds is a result of the higher loads these kinds of props put on the prime mover which also allows higher speeds due to it being more efficient at higher speeds.

Of course everything is a tradeoff and a heavy cruiser IB may not be happy with progressive rake three blade props meant for light fast boats, I think most people get confused with prop selection because they fall in love with the idea of a "fast" SS prop only to find out later they would have been better served with a straight pitch prop in AL for their intended usage pattern.

If your interested I assist modding a forum on the web where this debate is frequently discussed (same user name), we have 50K members and some of them run some serious hardware. You can always ask engine questions there and get some educated answers from guys who run the dynos and race the hardware.

http://www.hotrodders.com/forum/engine/

These guys know a thing or two about prop selection and two stroke power also.

http://forums.screamandfly.com/forums/index.php?

 

[QC]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Something that hasn't been mentioned yet that is actually far more important than HP is transient throttle response,

Chuck, Chuck, Chuck,

You are making a big mistake here. You are evaluating specific engine attributes as if all applications are equal. They are not. What you say is a nice to have for a car, but it is not more important than horsepower. Stuff may start going with torque, and stuff may increase it's rate of going more rapidly with good transient response, but stuff will not stay going without horsepower. Period, end of story, PLEASE!

I keep this up because people leave these discussions and say, "Hmmmmmm, I better build my engine for transient load response, because that is "more important than horsepower". These attributes are way cool, and they are especially cool in specific applications, but transient response is less important in even a heavy-duty truck engine than a sports coupe. Drivers like it, but owners pay for, buy fuel for, pay their bills with horsepower . . .

those who race or stress their engines in any kind of motorsports know that its torque that makes the goods move.

Kinda, but you have qualified this semi-correctly "those who race [and] motorpsorts". But we aren't talking about that Oh, and BTW "goods"
are "move(d)" by horsepower!!

You can increase torque all day long at low engine RPM and it will not make a boat go faster if horsepower is not increased. Of course it does result in a horsepower increase, but not necessarily where it counts for a boat, at rated RPM. Give me a tranny (possibly with OD) and we can discuss it, but not with a single gear . . . Another way to look at it is if I had a single speed application that required 1000 horsepower and I had a turbine rated at 20,000 RPM I could get the job done with 262 lb/ft torque, however a 2000 lb/ft peak torque 15 liter diesel rated at 1800 RPM would simply not work, and I have sold the latter for the last 30 years. It's what I do for a living

Wheeled applications, fixed load applications and propellers are not the same thing.

 

[RotaryRacer]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Lets get back to the basics.

Power = Rate at which WORK is performed.
P = Work / time

Work = The amount of energy transferred by a FORCE acting through a distance.
W = Force * displacement

Force = An influence which causes a free massive body to undergo an acceleration.
F = mass * acceleration


What HSW is trying to do is figure out a way to mathematically determine what prop would work better given a small variable set. He is assuming that he already has performance data for a given boat with a given motor and a given prop. He then wants to take this data and determine if there is a better prop available to better suit the needs of the boat's owner.

Better for a given owner could be one of several things:

Economy: Do the most work with the least energy.

Speed: Put as much power to the water as possible.

Hole Shot: Transmit the most force possible to water so as to accelerate up to speed as quickly as possible.

 

[4JawChuck]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Lets get back to the basics.

Power = Rate at which WORK is performed.
P = Work / time.

Thank you!

 

[RotaryRacer]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

I'm surprised this dicussion hasn't gone further.

Where is everyone?

 

[QC]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Personally I didn't want to continue the appearance of an argument. I will say that Chuck's quotation of the formula you posted seems to validate the ultimate role that horsepower holds . . . Annnnd, despite my comments, for most people the problem starts when we try to decouple torque and horsepower. Yes, I know that sounds like a contradiction, but it is the "this is more important than that" thing that requires a clear explanation of both. Ultimately, without torque there is no horsepower, without horsepower there is no speed.

 

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Rotary, I am sorry I haven't been here much, I am reading a lot of material on fluids and steadily filling out spreadsheets with new information to see where it leads me. But what you described is exactly what I am trying to accomplish, and it may never happen, but I am not going to stop until I prove to myself I can't do it. I realize that the numbers will never be a way to find the perfect prop, but I do believe that they can lead me to some new formulas to better be able to find a prop very close.


H

 

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

These charts show some interesting information in my opinion, the first one compares prop slip with the True effective prop pitch of this prop.
What this means is that if the prop had NO prop slip this is exactly how much pitch this prop has at these RPM. By using these charts it is easy to see the relationship between what is called Effective prop pitch of this particular prop with this boat, motor and prop at this boat weight. By looking at the effective pitch we get an idea of where this prop starts producing the real pitch that it is capable of on this boat.
The next chart compares the prop slip of this prop on this boat and how it affects the speed of the boat. It should be different for every prop tried on this boat, but sometimes you will see two props that even show a different pitch from each other can be very close when you compare the effective prop pith.

The next chart compares this same prop with the amount of acceleration that it produces at different speeds and RPM. It also plots where the acceleration is the strongest and when it peaks and starts falling lower and lower. We can see that at about 3,500 RPM the acceleration starts failing.

The first chart shows the relationship of theoretical speed and real speed achieved with this prop and how they start getting closer together the higher the RPM turned, and this is the way it should be with most props. I run analysis like this at times to prove to people that the hub in their prop is slipping, in fact I just did that the other day for a gentleman.
The second one shows the motor HP at WOT at all RPM and how much HP it produces at those RPM while the prop curve shows the large difference in prop HP needed with the throttle pulled back starting at 3,250 RPM and just pushed far enough for cruising speed at each RPM level, instead of the HP that is there that could be used if needed. This comes in very handy for people who want to pull skiers or tubes. If you will notice before 3,250RPM the throttle is at WOT to get to planing speed and the HP used by the prop is the same as the motor HP available from the motor.

The first hart shows the thrust curve available from this motor at WOT and at just cruising speeds the same way the other charts showed the differences between WOT and cruising speeds. We are still using full HP to get to plane and then throttling back for cruising thrust, and you can see the difference in HP required between WOT and cruising throttle.
The second hart shows the extra HP available for acceleration at any RPM level after planing speed has been reached. This is how much HP is available at any RPM level while cruising to attain faster speeds and acceleration.

The next two charts show Torque, HP, Thrust and MPH in a comparative analysis of each other and their relationships.
The first one shows all of the relationships between motor Torque, HP and Thrust from the motor at WOT and cruising speeds. The numbers are there so you an easily see the relationships between HP, Torque and Thrust at any RPM. With this prop on this boat and motor this is the results obtained at all RPM levels.
The second hart shows what is happening to Torque, HP and MPH at all RPM levels. With all of these plots it is very easy to see their relationship to the speed the boat is attaining and how much HP, Torque and thrust is needed to attain these speeds at these RPM.

This chart shows how much gas is being consumed at all speeds of the boat. From the chart we can see that the best MPG are attained between 23 to about 30 MPH, but even at 36 MPH the gas mileage is still very good in my opinion.

Hopefully these charts give people a better view of what is happening with a boat, motor and prop when it is being used and all of the interactions and comparisons of the different numbers for each between all three of them at different RPM levels and speed.



H

 

[4JawChuck]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Pretty charts.

 

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Thank you chuck, I am hoping by looking at these that we can derive more information for our discussions.


H

 

[4JawChuck]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

You noticed that thrust follows the torque curve.

 

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Chuck, you are 100% RIGHT, and Torque is not even part of the equation for thrust.
That is what I mean about the charts show us information we would NOT see by looking at the raw numbers.



H

 

[4JawChuck]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

How you figure? Torque is multiplied through the gearcase and transmitted through the prop as thrust in the water.

Did you also notice HP has no relationship to thrust at the prop shaft, its almost an inverse relationship as rpm goes up beyond the torque peak. Engines are tuned on the dyno by attempting to increase the area under the torque curve not peak HP. Many people look at the peak HP numbers for bragging rights but the reality is, its the torque area that gives the best performance...even if the peak HP is lower which it often is.

There are applications where having the torque peak at high rpm is the goal but the load has to be light or the vehicle will not have decent performance, race boats running surface piercing props tuned for high top speed numbers would be one example but even in those applications the engine is tuned for torque under the curve since this determines thrust thoughout the rpm range which is what moves the boat. I have built many engines that varied on the dyno by up to 50HP at the flywheel, the tune always chosen gave the highest torque area which usually gave the lowest HP number because it gives the best performance no matter how you want to measure that performance whether its with a stopwatch in a timed distance or a top speed number.

HP is a convenient measuring stick for the average person looking to rig his boat since this is how the hulls are rated and it is helpful in determining top speed, however you can see a prime mover with a larger displacement would produce more thrust/torque throughout the rpm range giving better performance even if the peak HP figure was identical to a lower displacement motor...the top speed will likely be higher particularly with a heavier load.

I hope I have explained how torque area is the goal in every application, where that torque is made determines the peak HP but not real world performance...the HP figure is incidental to the engine designer/builder not the goal hence the term "there is no replacement for displacement". A HP figure without an associated rpm figure to go with it is a useless measurement since it tells you nothing about the torque characteristics of the prime mover.

Hopefully I have explained this in the most uncontroversial manner possible as that is my intent.

 

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Chuck, what I meant was, the "equation" that shows how much thrust is produced at the prop actually uses HP, Prop Slip and Speed with a constant. and doesn't use torque as a variable in it. I wasn't saying that Torque wasn't proportional to Thrust, I just meant it wasn't biased by torque in the equation.

I need to take some time to read and digest what you are saying, and then I want to talk some more. My knowledge of motors is NOWHERE near as much as yours, or for that matter MOST people in here, so it takes me awhile to fully comprehend what is going on. My knowledge is in props.

And I DO appreciate your keeping this discussion at a level where it is civil and based on scientific principles and not confrontational, as we all learn more with honest level headed criticism and knowledge, and you did a superb job.



H

 

[hwsiii]

Re: Does anyone have Full HP and Torque Info on outboards over 150 HP

Chuck, I redid the chart and made it easier to read hopefully. The numbers are proportional on each side if you will notice, I used a factor of 6 to fit the thrust in where you can see it easily and compare it to HP and Torque.

HP Torque and Thrust Chart

H