Why don't I ever see dyno's?

[WB1994]

I think its pretty obvious that it would need to be a third party testing everything on one setup with all variables as close to the same. other than that its just a tuning tool.

 

[kevbo]

Pump load squares with rpm. Piped two strokes struggle with this because of their narrow power range so concessions must be made. Few customers can understand why a 100hp engine can make more thrust than a 120 hp unit.

 

[Ratking]

There was a claim that there is a disconnect between dyno numbers and real world performance due to driveline variables and therefore dyno numbers are somewhat irrelevant.

I understand that, but how does the need for different pumps for different motors void the fact that a dyno reading tells how a motor behaves?

Am I missing a important factor? If I had two motors with the same torque curves. How would the two motors behave differently? And if one motor has more torque low down it is more suitable for freestyle, how can that not help a buyer deciding?

 

[Ratking]

Pump load squares with rpm. Piped two strokes struggle with this because of their narrow power range so concessions must be made. Few customers can understand why a 100hp engine can make more thrust than a 120 hp unit.

Do you have more info about this? I am in the process of making some custom stuff and need to calculate torque requirements for the pump

 

[Big Kahuna]

I understand that, but how does the need for different pumps for different motors void the fact that a dyno reading tells how a motor behaves?

Am I missing a important factor? If I had two motors with the same torque curves. How would the two motors behave differently? And if one motor has more torque low down it is more suitable for freestyle, how can that not help a buyer deciding?

If you had 2 motors with the same torque curve. Then both would theoretically be the same, one would not have more torque than the other.

 

[masterblaster]

So the guys that race jet boats with engines and pumps are also wasting there time with dyno tuning?

A better thing to look for would be thrust. That would measure the pump as well.

http://www.dynomitedynamometer.com/pwc-dyno/pwc-dyno.htm

that's a diff way of doing it that would be fast way of dynoing a lot of skis quick at a ride without pulling motors. it tests with drivetrain loss factored in through coupler and shaft but does not factor using pump thrust

 

[kevbo]

Still some work to be done with sizing pumps to the application. It's a tough sell because it requires major modifications. I haven't met many skiers that would take on that project.

 

[Vumad]

I say flatwater Friday this year has a step up limbo competition like the
Xgames.

Cheaper than a dyno, will draw a crowd, may the best setup win.

 

[xzibit a]

Holy crap, i started a wicked tangent.

I wasn't saying the motors shouldn't be tested, i was simply implying the numbers are meaningless. In the automotive scene i see people travel around and use different dynos to find the one their car makes the biggest numbers on for bragging rights . Ive seen it range up to 50HP. And thats using the same correction factors!!

Point being, If Xscream says their 1200RR makes 200HP on their dyno, and the guys at blowsion run their own test and it only dynos at 160, who looks bad? the manufacture or course, their engines aren't up to advertised specs. Now lets say I but that motor and put it in my mostly stock SJ with a 144mm pump with a worn out impeller. Its not going to make the same power even if i run everything to exact specs as xscream says to and I'm going to be pissed and go online and bash scream because their motor doesn't make the power it should.

Here is one fact that is indisputable. The only number that a dyno can give you that is of any value is a DELTA from your baseline. in other word, how much have the changes you have made increased/decreased since the previous pull.

Second fact. Someone mention "street tuning" isn't a thing, It is very much a thing and infact every tuner i know that tunes car, will street tune the car after dyno tuning it. The dyno shows you full load WOT runs only. how often do most street cars run under those circumstances? So they use street tuning and data logging to make sure that the fueling and timing are spot on while crusing around town and during part throttle accelerations. Some don't have access to a dyno and have to do drag runs on the highway while data logging as the only means of tuning. Which do you think is a better tune? Clearly one is "safer," more convenient and legal, but do you think its optimized for the conditions the car will be run in? Or do you think tuning it while driving in the exact same manner your going to be using it will be better?

Racers could easily use a dyno to dial their setup fairly close. they would still have to tune it for water temps and conditions and other factors as well but they are doing mostly WOT runs . Freeride and freestyle boats have to be tuned by riding. Your doing full throttle hits for a second maybe more, then its hitting the rev limiter, closed throttle, then landing and going back to WOT. No dyno can ever reproduce those load simulations therefore is of no value to a tuner.

Finding someone to "tune" your ski for the way you ride could gain you so much more power than just guessing and assuming since it feels pretty good then it must be tuned right.

Dyno's are a very powerful development tool. Yes, they are wildly used in marketing efforts too, but you have to take all of those published power number's with a grain of salt.

Very well said. Ever notice that Car manufacturers use engine hp numbers instead or wheel hp numbers???? a 400hp mustang will sell better than a 340hp mustang........

 

[Big Kahuna]

Holy crap, i started a wicked tangent.

I wasn't saying the motors shouldn't be tested, i was simply implying the numbers are meaningless. In the automotive scene i see people travel around and use different dynos to find the one their car makes the biggest numbers on for bragging rights . Ive seen it range up to 50HP. And thats using the same correction factors!!

Point being, If Xscream says their 1200RR makes 200HP on their dyno, and the guys at blowsion run their own test and it only dynos at 160, who looks bad? the manufacture or course, their engines aren't up to advertised specs. Now lets say I but that motor and put it in my mostly stock SJ with a 144mm pump with a worn out impeller. Its not going to make the same power even if i run everything to exact specs as xscream says to and I'm going to be pissed and go online and bash scream because their motor doesn't make the power it should.

Here is one fact that is indisputable. The only number that a dyno can give you that is of any value is a DELTA from your baseline. in other word, how much have the changes you have made increased/decreased since the previous pull.

Second fact. Someone mention "street tuning" isn't a thing, It is very much a thing and infact every tuner i know that tunes car, will street tune the car after dyno tuning it. The dyno shows you full load WOT runs only. how often do most street cars run under those circumstances? So they use street tuning and data logging to make sure that the fueling and timing are spot on while crusing around town and during part throttle accelerations. Some don't have access to a dyno and have to do drag runs on the highway while data logging as the only means of tuning. Which do you think is a better tune? Clearly one is "safer," more convenient and legal, but do you think its optimized for the conditions the car will be run in? Or do you think tuning it while driving in the exact same manner your going to be using it will be better?

Racers could easily use a dyno to dial their setup fairly close. they would still have to tune it for water temps and conditions and other factors as well but they are doing mostly WOT runs . Freeride and freestyle boats have to be tuned by riding. Your doing full throttle hits for a second maybe more, then its hitting the rev limiter, closed throttle, then landing and going back to WOT. No dyno can ever reproduce those load simulations therefore is of no value to a tuner.

Finding someone to "tune" your ski for the way you ride could gain you so much more power than just guessing and assuming since it feels pretty good then it must be tuned right.


Very well said. Ever notice that Car manufacturers use engine hp numbers instead or wheel hp numbers???? a 400hp mustang will sell better than a 340hp mustang........

Best response yet. You have to ride your ski, set up your driveline for your ski and tune it. Tuning = carb adjustments, timing (static and curves), pump size and prop pitch, water flow at the pipe and temp control, engine compression determination so the fuel you run is optimized. HP numbers is just a number that at the end of the day does not mean jack. It's the street tuning that matters. One of the strongest hitting SJ'S I ever rode had an 84mm big bore with enhancer, head, b pipe and oem 38's. Wamilton set it up. It is all about the package. There are skis with 900cc motors that are out performing 1100-1200 cc motors because their package is set up right and the best combo of parts even though on a dyno it might be 15 HP less. This is our real world, not a fantasy world where we are efficiently using all of our power.

 

[DAG]

What’s the downside to have more information about a motor? A engine builder said he would volunteer his equipment and time to gather the data. He just needs motors.

If you don’t think the data is useful then don’t read the data, simple as that. Don’t prevent other people from learning because you don’t agree or you don’t understand. Let them do it. Why does it affect you so strongly you wouldn’t let other people try?

 

[Vumad]

What’s the downside to have more information about a motor?

The price tag to the consumer.

Either you pay more for the motor as the company invests in pointless research, or you get information from enthusiest. Weve read enough non sense over the years to not trust much we read. An example is having conversations with someone about how we think our machine is tuned like poop, and they give you information about their machine being tuned awesome. Then you ride each other machines, and you find the perfectly tuned machine is worse than yours and the guy who thouht his machine was tuned perfect realizes he has a piece of crap.

Now you get dyno numbers from that and say brand x is better than brand y so you buy brand x because thee are some dyno numbers from some guy who had a bad setup of a better motor and dynoed it against someone who had a good setup of a lesser motor. I dont feel like thees a winner there.

 

[WB1994]

You would first have to run all motors with all the variables the same . Then if brand x says thier motor runs best with certain parts retest with thier suggestions and give all brands the option of suggesting setup. But its one third party with one machine then take all info with a grain of salt and go buy the blingiest motor with colored fuel lines.

 

[xzibit a]

What’s the downside to have more information about a motor? A engine builder said he would volunteer his equipment and time to gather the data. He just needs motors.

If you don’t think the data is useful then don’t read the data, simple as that. Don’t prevent other people from learning because you don’t agree or you don’t understand. Let them do it. Why does it affect you so strongly you wouldn’t let other people try?

I don't think you understood my response. I never said don't do it. I simply answered the original question with my opinion, " why don't we see dyno sheets"

My point is, the data would be so inconsistent that it wouldn't help at all really. Infact all it would do is create expectations that will likely not be fulfilled. That's why I gave you the example of the Xscream motor( I have nothing against xscream nor do I work with or for them, they are just popular).

 

[Dartman]

i think dynos can give some useful info in developing a engine setup
ultimately on water performance tuning is the way to go
look at xscream engines winning almost every flatwater competition around the world and owning the podium in the top 3 most of the time

 

[Lumpy]

If you ask me..... what difference would dyno charts make other than the fact that average joe consumer gets off on that kind of stuff? In my opinion if the owner of any given engine is happy with the performance of their machine as whole, who gives a damn how many horsepower it has. I know I enjoy my ski every time I ride it. Might have 60 hp, might have 130 hp. Doesn't matter either way because every time I pull the throttle it puts a smile on my face.

 

[Quinc]

Be nice to know if your engine makes X amount of power then you need Y pump setup. Instead of buy a mag pump and hooker..

 

[Lumpy]

That's getting to be the problem with america. Everyone wants to take the easiest way out. Instead of learning about tuning a ski, people just want it handed to them. What fun is that?

 

[xzibit a]

Be nice to know if your engine makes X amount of power then you need Y pump setup. Instead of buy a mag pump and hooker..

That would be awesome, but our hobby isn't anywhere near that simple. I have 2 skis that have the same motor with the same parts pump props and everything. carbs pipes and ignition are the same but they don't feel the same. ones a SN and the other is a RN( same bottom deck right???). Why? they are even tuned the exact same, screws and all????

 

[Quinc]

That's getting to be the problem with america. Everyone wants to take the easiest way out. Instead of learning about tuning a ski, people just want it handed to them. What fun is that?

I don't mind tuning and enjoy trying to squeeze every last pony out of my engine. What i don't want to do is buy or pay to have my impeller re-pitched a dozen times. Should be if your machine's torque/hp curve is "between this and this" you are best with this pump/impeller/cone setup for X riding style. Also be interesting to know what the difference is between all of the different reed options.