The 3d printed way is how I understood it.
Only way to do it the other way is by rebuilding the board, or remounting the jet box.
We have already made a design for the 3d printed way incase the other impellers do not work.
That’s great, please share some pictures! 
Time for a small update.
Finally we managed to get some more testing done with our DIY jet board.
The ESC’s in this run are set to 70% power output.
We still have some cavitation problems, but only in rough conditions.
Another small issue is with the BMS FET’s heating up too much, however this should be an easy fix.
Or… See the longer version here:
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Beautiful, congrats, I like the carbon look!
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Thank you. It was a great learning experience.
From designing the board, shaping it, and glassing it.
One thing I really love now is working with composite materials!
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80mm m.k. jet
Esc 400a
13s8p battery 60amp bms
Sss 360kv motor
Board weight 23kg
Rider weight 80kg
7mph roughly
You guys are definitely missing something. Both top brands jet boards I have in mind are in the range of 7.5k - 9k rpm with 100-110mm diameter impeller and they have around 100kg+ thrust. I tried to hold the board still, impossible with that much thrust.
The motors you guys are using don’t have enough torque for this application. I can tell you guys you would need at least 15Nm of torque with the above rpm to get the impeller pushing 100kg…
Sure, lightweight riders might be able to push the board to 40kmh with half the torque, but the calculations I posted above are proven in the field…
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Sounds to me that you need more RPM’s
Maybe a 600kv motor will fix this.
We tested two 360kv motors in our board, and this was not getting the RPM’s we wanted.
We are now back to the two 600kv motors, and getting around 50KG of thrust (jets are only 53mm.)
(feels like way more when holding the board by hand.!)
RPM’s we are doing are now around the 15.000.
Pulling amps when running W.O.T. is around 300 amp total!
Do you have some more info about the “80mm m.k. jet”??
Rpm motor depends on the rider weight. You might fly at 40kmh while heavier riders won’t with the same setup.
I would consider using a torqstar motor at 8500rpm and a 110mm jet.
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looks nice. If you can, try a bigger (KV’s) motor.
You will need to change the ESC too. a 60 amp BMS will not handle a bigger motor.
Is the flier 400a esc not enough power?
I got full throttle and it didn’t trip bms? Only time I’ve had issues with it tripping bms was when I try to make it to go 100% from 0 with smaller battery
My misstake.
You mentioned “13s8p battery 60amp bms”
I was thinking that your BMS was 60amps 
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What bms would you recommend ?
Would a 180kv 80mm motor be better?
I dont believe the impeller in this jet is efficient
@JZILVIA 360kv on 13s so around 18000 rpm , on your video it doesn’t sound it is running at that speed
The problem is with your esc you cannot see the rpm , or what is left of it and I think the water intake has too much angle compared to what is on the market
Proven built : sss motor 56mm with 50-55mm impeller , you need 2-3 of them
80mm impeller with a 80mm outrunner or 100mm inrunner
For the kv calculation, speed desired knowing impeller have a ratio of 1or 1.2 ( diameter vs pitch and pitch x rpm= speed or pressure …)
Voltage drop of the battery , you can take 3,6v as a average
Rpm drop of the motor under load : you can take - 40%
So on a 13s battery with a sss 56mm 360kv you should take a impeller of 52mm to :
13x3,6 x360 x60% = 10000rpm
Which is not enough for it and why 600kv is better
Now with 80mm : a 300-360kv outrunner 80mm should do the job but they are hard to find
Esurfboard are nice but price vs fun is not so good , you take a large board ( inflatable) with a 63mm outrunner and a good prop , for 1/4 of the price you have more fun
Nice car 
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Alexandre nails it every time.
83100 water cooled is a good start for 70~80mm 3-4 bladed impeller.
There’s a Chinese MHZ 7455 Scorpion clone, I think its goes by the model “9096” on Alibaba, if you’re looking for a powerful outrunner it should be in the 2.2~2.5kg range.
Chris Green’s early jet design:
Thanks for the info ^^^.
So basically I would need to ether up the motor to a rare 80mm or down size the jet to a 53?
1x53mm jet is unlikely to push a 3m board with total weight around 100kg and the rear of the board isn’t really wide enough to house 2 jets.
Think I will likely up the motor size and see what it can do
The jet lift is maybe only 10mm
@Alexandre thanks the car has been a restoration project since 2016 but it’s at a point I’m happy to just drive it and has now freed up enough time for me to play jet boards 
Yes it would perform a lot better , just need cooling , need to be mounted on a big plate that will hold it and cooling it
Watercooling will go on the plate
Some 80100 are watercooled , you may want to ask APS for it with 350kv
Tp100 looks exciting in 540kv