Reverse engineer people's setups if you aren't tone deaf....

[Jcary85]

So, IDK if this actually makes mathematical sense, but it seems to check out...

If you listen to a recent video of my ski, you'll hear the motor is running at an "A" pitch for most of the time on the setup wake. An A2 is 110Hz. There are 60rpm in 1 Hz. 60x110=6600RPM. So, My motor is turning 6600RPM.

If you listen to, say lee stone's recent videos, its the same "A," so 6600RPM

If you listen to Brad turnbloom, he's around a A#, so 116hz or 6960RPM

Some BUN videos you can hear the motor starts at an A# and comes down to an A.

IDK, maybe the data is useless but its pretty interesting. You could make a handy chart and stalk the changes other people make

-Jordan

 

[DylanS]

So, IDK if this actually makes mathematical sense, but it seems to check out...

If you listen to a recent video of my ski, you'll hear the motor is running at an "A" pitch for most of the time on the setup wake. An A2 is 110Hz. There are 60rpm in 1 Hz. 60x110=6600RPM. So, My motor is turning 6600RPM.

If you listen to, say lee stone's recent videos, its the same "A," so 6600RPM

If you listen to Brad turnbloom, he's around a A#, so 116hz or 6960RPM

Some BUN videos you can hear the motor starts at an A# and comes down to an A.

IDK, maybe the data is useless but its pretty interesting. You could make a handy chart and stalk the changes other people make

-Jordan

Where is this recent video at?!? Gorgeous ski, nice work Jordan!

 

[Quinc]

bpipe and coffman exhausts make peak power around 6600-6800rpms.

 

[Big Kahuna]

Huh

 

[mthomps]

As a musician i get what you are saying, but how did you get 60rpm = 1hz? Im assuming the math knowing an A2 is 110.

How did you arrive at youre boat is tuned to an A? Hold a freakin tuner to the exhaust pipe? Lol

Not to mention its not a sign waves. Theres harmonics in there, some of which are almost as loud as the fundamental.

(For the non musicians a violin sounds like a violin and a trumpet a trumpet because the decibal leval of each harmonic in the harmonic series)

Interestimg concept but i dont know how practical ski tuning by the western music system is.

 

[Storbeck]

Probably somewhere online there is some sort of app to do an FFT on the sound and you can be even more precise.

Not sure if online video distorts things though.

I can remember reading that back in the two stroke era of moto GP engineers would bring flutes tuned to certain frequencies to the track to listen and compare what rpm competitors were achieving.

I'm surprised a freestyle ski running a laydown pipe is only hitting 6600 rpm, I would have guessed about 7500.

 

[Storbeck]

As a musician i get what you are saying, but how did you get 60rpm = 1hz? Im assuming the math knowing an A2 is 110.

How did you arrive at youre boat is tuned to an A? Hold a freakin tuner to the exhaust pipe? Lol

Not to mention its not a sign waves. Theres harmonics in there, some of which are almost as loud as the fundamental.

(For the non musicians a violin sounds like a violin and a trumpet a trumpet because the decibal leval of each harmonic in the harmonic series)

Interestimg concept but i dont know how practical ski tuning by the western music system is.

60 revolutions per minute X 1 minute/60 seconds = 1 revolution per second.

 

[Jcary85]

So here’s the conversion.

I just listened to the pitch of the ski, remembered it and blew the pitch on a pitch pipe (I have a very good ear).

 

[Jcary85]

Probably somewhere online there is some sort of app to do an FFT on the sound and you can be even more precise.

Not sure if online video distorts things though.

I can remember reading that back in the two stroke era of moto GP engineers would bring flutes tuned to certain frequencies to the track to listen and compare what rpm competitors were achieving.

I'm surprised a freestyle ski running a laydown pipe is only hitting 6600 rpm, I would have guessed about 7500.

The low rpm surprised me a bit but it makes sense. There are some pros turning more like 7500 rpm. It’s interesting to go listen and compare.

 

[Storbeck]

The low rpm surprised me a bit but it makes sense. There are some pros turning more like 7500 rpm. It’s interesting to go listen and compare.

Are you talking 16mm stroker 1200's? I know nothing about those but I suppose it does make some sense that a huge long stroke motor would be reving less than a smaller motor.

Have you checked any 900's?

 

[Storbeck]

Maybe set your rev limiter to just above what you figure you're hitting based on the "note" and see if you hit it. (assuming you have it way higher right now)

 

[Jcary85]

Maybe set your rev limiter to just above what you figure you're hitting based on the "note" and see if you hit it. (assuming you have it way higher right now)

Are you talking 16mm stroker 1200's? I know nothing about those but I suppose it does make some sense that a huge long stroke motor would be reving less than a smaller motor.

Have you checked any 900's?

They are all over the place. Just listened to a 900 comp ski and it’s at G# or 6180

 

[DylanS]

I’ll hopefully have my ski at blue marsh this weekend if you want to figure out the note a motor makes when it explodes

 

[Jcary85]

I’ll hopefully have my ski at blue marsh this weekend if you want to figure out the note a motor makes when it explodes

Haha I’m down for a blue marsh day. Post in phreaks. Maybe we can get a group

 

[hornedogg79]

You really are a jet ski nerd! Reminded of the time Jimmy Martin learned about bluegrass music theory. This video should clear up the music side of things for you BK. Pythagoras set it all up.