Jet ski dyno

[FX1 696]

I remember reading a few years ago, people discussing on this forum whether a jetski dyno was possible, how it would be done etc. I just came across a video on TikTok, photos attached where you could theoretically attach a strap to the rear of ski, pulling against some spring or resistance anchored to the garage wall? Couldn’t that be used to measure the power of a ski?

 

[WFO Speedracer]

Yes and no, I have yet to see one of those test tanks that you can run a ski in and it not cavitate like crazy, the more HP the ski has the worse it gets .

At any rate you would be measuring thrust not horsepower with any setup like that.

 

[joeschuit]

I've thought about some simple sensors in the reduction nozzle that would measure pressure and speed of flow. An indirect way of measuring horsepower, but more importantly being able to play with the engine and see real changes to the output.

 

[kevbo]

The pump can usually load the engine if you tie the ski to a trailer and sink it up to the hood seal. This is a great way to initially set the main jet/top screw with a tachometer. I have a thrust meter mounted to the front of a trailer. It works up to a certain amount of power then thrust will go flat as rpm rises. I can usually get around 700 pounds from a 144 pump. A powerful engine will make more thrust when the ski is moving.

 

[Quinc]

someone recently posted a picture of the Factory pipe dyno setup on one of the fb pages.

 

[Storbeck]

I have messed around with this sort of thing a little and was getting significantly different rpm and pipe temp compared to normal use.

 

[WFO Speedracer]

We ran a few skis in one of those tanks when I went to MMI for the Thunderjet school some 30 years ago, somewhere I have thrust numbers on some of the skis that were run in the tank , the problem with the tank setups is always the baffling in the tank , it is very hard to direct the water coming out of the jet so it does not cause cavitation , you want a circular flow pattern which is very hard to achieve , like I said the more HP the worse it gets .

 

[fastgtfairlane]

The only benefit I could see to that would be engine break in and carb tuning the off idle circuit. Probably wouldn't be very accurate for wot testing from cavitation. I will strap my ski to a trailer and back into the water to dial in the low speed and off idle circuits before riding when I'm tuning carbs.

 

[fx1mark]

Erickson machine has a video of his dyno. He hasn't posted any videos of it actually being used though.

 

[97superjet]

Erickson machine has a video of his dyno. He hasn't posted any videos of it actually being used though.

I was randomly thinking about this the other day, he said he was going to dyno a bunch of things and then never did...weak

 

[waxhead]

I was randomly thinking about this the other day, he said he was going to dyno a bunch of things and then never did...weak

He’s supposed to have dynoed our pipe too—yet for a YouTube channel, it’s strange there’s no dyno sheet, no video, not even a photo. Starting to wonder if it ever happened at all...

 

[Big Kahuna]

He’s supposed to have dynoed our pipe too—yet for a YouTube channel, it’s strange there’s no dyno sheet, no video, not even a photo. Starting to wonder if it ever happened at all...

Thats kinda the MO................

 

[WFO Speedracer]

Kinda like Service master , like it never even happened.

 

[97superjet]

He’s supposed to have dynoed our pipe too—yet for a YouTube channel, it’s strange there’s no dyno sheet, no video, not even a photo. Starting to wonder if it ever happened at all...

All dynos are a little different, so even if he just tested a few pipes with the same motor or whatever we would at least have a baseline idea..

 

[WFO Speedracer]