Dyno Sheets

WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
If you click on the yellow box that saus only $119.00 per month it takes you to the prices page $4995.00 gets you the dyno and the adaptorsare $800.00 to $1000.00 a piece.
 
crammit442

crammit442

makin' legs
Location
here
SuperJETT said:
Something else about dynos with skis, because most of our engines use wet exhaust, it's next to impossible to get the water pressure to reflect what you'd see in a ski.

Dynos are for bragging rights or serious testing/tuning IMO, nothing else.
Click to expand...


Or a sales tool.........
 
W

waxhead

wannabe backflipper
Location
gold coast
SuperJETT said:
Something else about dynos with skis, because most of our engines use wet exhaust, it's next to impossible to get the water pressure to reflect what you'd see in a ski.

Dynos are for bragging rights or serious testing/tuning IMO, nothing else.
Click to expand...

Thank you some one who understands

our exhausts use water ethier for injection or stinger ,to modify back pressure
there is no way to simulate pump pressure at the exhaust

as its not constant
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Royal Flush said:
So, you going to buy one, wedoseadoo?!? :poke:
Click to expand...

Probably not I could go to the lake water test and be back before you could get that damn thing hooked up,besides all these couch riders need to know is what the dreamometer says and will it go faster if I stretch out like Superman.
 
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Mouthfulloflake

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
for comparison purposes, why not just test them on the water, with some sort of a harness, pulling on a scale to measure thrust?

you could likely figure mathmatically the effeciency of the pump, temp and water density, and get pretty close to HP, BUT HP numbers dont matter as much as thrust does, I would think.

HP numbers plotted along a RPM scale would be good to know, but again, not as useful as THRUST plotted along the RPM output.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Why not rig up a special trailer for that purpose with the thrust gauge attached and a safety harness so it can't get loose.
 
E

egbrig

Testing with the boat hooked to a "thrust guage " would only test the efficiency of the pump matched to the engine, not the tourque of the engine. A dyno is a device used to test one setup against another. Dyno's can be made to say what the user wants just like those who through out HP numbers and have to ask questions of how the engine works.
 
Mouthfulloflake

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
right

but that is more important than HP numbers.

who do you know that runs a PV lamey bigbore stroker with a stock impeller?

pump power is what maters.

its the reason cars do dyno runs on the rear tires for real life workable numbers.

engine numbers without the drivetrain are great to talk about, great to compare side by side. but the actual thrust is what makes you move, and is more important than any " printed sheet dyno nymbers"

In my opinon of course.
who knows the basic volumetric efficiency of the different yamaha based 2 stroke twins? ( 61x vs 62t)

I would like to see and play with those numbers...






egbrig said:
Testing with the boat hooked to a "thrust guage " would only test the efficiency of the pump matched to the engine, not the tourque of the engine. A dyno is a device used to test one setup against another. Dyno's can be made to say what the user wants just like those who through out HP numbers and have to ask questions of how the engine works.
Click to expand...
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
egbrig said:
Testing with the boat hooked to a "thrust guage " would only test the efficiency of the pump matched to the engine, not the tourque of the engine. A dyno is a device used to test one setup against another. Dyno's can be made to say what the user wants just like those who through out HP numbers and have to ask questions of how the engine works.
Click to expand...

Isn't that exactly the point ? thrust numbers do not lie.
 
K

kawi66

I think we are arguing and agreeing and don't realize it. Yes, total thurst plotted on a graph would be a great assest maybe more so than a dyno sheet. But tourque must be put to the water and this is done with a pump, impeller, nozzle combo, just like some guy who tells you that his 427 make 600hp and he runs 14's in the quarter. He might be making the power but its not getting to the ground. The engines power is the engines power. Thrust is the process of turning that power into hopefully forward motion (for us).

egbrig
 
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Mouthfulloflake

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
In my opinon:

an engine only dyno would be good for builders to test timing/porting, and ignition setups, side by side.
I would think a good flow bench would be helpful for case porting, and intake mods as well.

a thrust test on the water would be the way to fine tune, or dial in a complete engine/pump hull package.
 
E

egbrig

How many of you actually race? How many of you have used a dyno to test a 2stroke watercraft engine? Not always does a dyno power translate to the water. Those who have will say that they have made mods which translate into more tourque but it doesn't react the same in hull, on the water. Racing gives side by side visual as to who is making power and putting it to the water. There are many factors that come into play when an engine sits in a high humidity, high air temp compartment. How does the humidity affect the sonic wave in the pipe along with the combustion process? A dyno is test and tune tool. BTW a flow bench can show an improvement but a dyno will show if it works and a water test will prove it.
 
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