Hobby king HK Genesis upgrade

[Bagoboy]

Hi guys I am new to the forum.I like the Hobby King HK Genesis but I am looking to upgrade with Tunigy electrics, because of pricing and performance. I want to attain speeds of over 75mph with this hull as I have seen on youtube. I am looking at Tunigy xk3674-1400kv motor and Hobby KIng 90A boat ESC 4ASBEC.I have seen that combo run but it looks closer to 50mph.I need advice on a Tunigy motor and ESC that can give me 75mph plus because i have seen guys running 40 size leopard motor in this hull and attaining 80mph thx.

 

[lohring]

For starters I would use at least the Turnigy Marine 120 ESC. It's a tough but inexpensive unit with a 240 amp burst amp capability. The Turnigy Marine 180 is also a good ESC if it's available. .Also, Hobby King recommends a 2075 KV motor. That would give you around 25,000 rpm under load with a 4S pack. A 100 mm pitch propeller would give you about 75 mph. On 6S you would need about a 67 mm pitch prop.

Lohring Miller

PS I just checked the specs on the above ESCs. The new ones have an even higher burst capability.

 

[Bagoboy]

Thx national racer i need your help on this also. I am also looking at Turnigy xk 4082-1450kv Brushless inrunner and the Hobby king YEP 120A HV Marine brushless speed control on 7s lipos. What do you think of that combination. I need to know if the stock shaft can handle that speed and i also read that i have to fiber glass the inside of the hull to handle such speed, what prop to use for this setup i also need help on fiber glassing your, thoughts please.

 

[lohring]

I'm mostly familiar with the Neu motors. A table of recommendations is also on the Castle site. I've chosen slightly different winds for approximately 2075 Kv. A 1527 1D with a Kv of 2300 would be about right for over 6S. The 1524 1D at 2550 Kv should be OK for 6S and below. Motors with similar dimensions and weights should have similar characteristics. The 1527 is rated for around 200 amps on 6S while the 1521 is rated for about 180 amps on 6S. You could run slightly lower Kv ratings but would need more pitch.

The standard way to estimate loaded rpm is to take 80% of the Kv times the nominal volts. The amperage is the motors rating in watts divided by the nominal volts. A lithium polymer battery's nominal voltage is 3.7 times the number of cells. A pitch versus speed calculator can be found on line at Marks Marine. I usually guess at around 20% slip for rough calculations of speed.

Lohring Miller