RSX 310 4s setup help

[Troy1957]

Looking for 4s setup for rsx310 for six lap races.
Just running in local club and I want to go as fast as possible. ML boatworks rsx310 31 in.

Thanks Troy

[Bande1]

https://www.tppowerusa.com/index.php?route=product/product&path=20_71_144&product_id=465

[Troy1957]

So what esc and prop would pair with all that kv?

[tbonemcniel]

https://www.tppowerusa.com/index.php...product_id=465

That is an incorrect motor choice on two counts. It's not quite rated powerful enough for modern P Sport Hydro racers, and the kv is much too high. He'll end up with a tiny prop that is physically too small for the boat in order to try and keep the current at reasonable level.

My own P Sport Hydro, is powered by motor of unknown wind as I bought it used. I know it tests out at 2456kv on my tester. Paired with a Castle X8S ESC converted to water cooled, and two 4S 4000 batteries in parallel, it runs over 70 mph in the straights in a 6 lap race. It averages 2900W continuous power and 4600W peak (average of 9 race datalogs).

Either of these would work well, depending on how much room for you have for motor length.

https://www.tppowerusa.com/index.php?route=product/product&path=20_71_140&product_id=216

https://www.tppowerusa.com/index.php?route=product/product&path=20_71_140&product_id=317

Paired with a converted Castle X8S https://stumpfabrication.com/product...a8693e9c&_ss=r

[tbonemcniel]

So what esc and prop would pair with all that kv?

Something tiny that would work horribly on a 31" hydro. Like an Octura M435. A 35mm prop is not appropriate for that size boat. Better suited to the 42-48mm range IMO.

[Troy1957]

Thank you for the response. That setup will work in that boat. Question is how do you convert that esc to water cooled....

[Troy1957]

Thank you for the response. That setup will work in that boat. Question is how do you convert that esc to water cooled..

[Bande1]

That is an incorrect motor choice on two counts. It's not quite rated powerful enough for modern P Sport Hydro racers, and the kv is much too high. He'll end up with a tiny prop that is physically too small for the boat in order to try and keep the current at reasonable level.

My own P Sport Hydro, is powered by motor of unknown wind as I bought it used. I know it tests out at 2456kv on my tester. Paired with a Castle X8S ESC converted to water cooled, and two 4S 4000 batteries in parallel, it runs over 70 mph in the straights in a 6 lap race. It averages 2900W continuous power and 4600W peak (average of 9 race datalogs).

Either of these would work well, depending on how much room for you have for motor length.

https://www.tppowerusa.com/index.php?route=product/product&path=20_71_140&product_id=216

https://www.tppowerusa.com/index.php?route=product/product&path=20_71_140&product_id=317

Paired with a converted Castle X8S https://stumpfabrication.com/product...a8693e9c&_ss=r

the can is 36mm x 84mm quite a bit larger than typical P class 37mm x 60mm.

[Bande1]

Thank you for the response. That setup will work in that boat. Question is how do you convert that esc to water cooled..

water cooled esc's are readily available. what's your budget? If you dont want to spend a bunch run an OSE raider 150a with a rocket RC motor. a $110 combo that will be pretty decent. 2600kv - 3200kv range. The one I linked earlier was me being cheeky. You also need to know any club rules. they can limit motor size so take that into consideration. 3660 usually.

basically what you do when sizing a motor is a balancing act between a good prop size and RPM. if you go lower RPM/KV you go bigger prop. higher rpm smaller prop. You cant go too small or too large of a prop for the boat.

Go to the speed calculator and punch in different motors and props and see what you can roughly expect in speed.

[Troy1957]

Budget not really a problem. I'll look at these

[tbonemcniel]

Thank you for the response. That setup will work in that boat. Question is how do you convert that esc to water cooled..

The link I posted, is to that ESC already converted to water cooled by Stump Fab. Or, you can buy the ESC separate, the cooling plate from Stump Fab, and do the conversion yourself to save a few dollars. Stump Fab has instructions for how to do it.

[tbonemcniel]

the can is 36mm x 84mm quite a bit larger than typical P class 37mm x 60mm.

The motor size restriction is for P-Limited, not P, or often called full P. In a full P, one could run twin 56mm motors if they so desired. All of my P boats are 40mm cans.

[tbonemcniel]

water cooled esc's are readily available. what's your budget? If you dont want to spend a bunch run an OSE raider 150a with a rocket RC motor. a $110 combo that will be pretty decent. 2600kv - 3200kv range. The one I linked earlier was me being cheeky. You also need to know any club rules. they can limit motor size so take that into consideration. 3660 usually.

basically what you do when sizing a motor is a balancing act between a good prop size and RPM. if you go lower RPM/KV you go bigger prop. higher rpm smaller prop. You cant go too small or too large of a prop for the boat.

Go to the speed calculator and punch in different motors and props and see what you can roughly expect in speed.

You certainly can go too small or large of a diameter prop. Too small of a prop for a given hull will cavitate to no end, have trouble getting on plane, and generally be less efficient. Too large of a prop for a given hull can allow the prop to drive the boat rather than propel and lift it. A 35mm prop on a 31" hydro would be inappropriate, and result in poor driving characteristics. As would a 55mm prop on the same hull, but with wildly different issues.

One should first select a diameter range suited to the size hull you're running. For this boat, as above, I would recommend between 42-48mm, 45mm being the average. Taking a middle of the road pitch ratio, say 1.5, and a target mph of say 65 mph, working backwards, taking into account efficiencies and prop slippage, that calculates to a 2400kv motor. Propping all the way down to a 42mm with 1.4 ratio would theoretically go 57 mph, and propping all the way up to a 48mm 1.7 ratio would theoretically go 79 mph. Somewhere in between those two extremes of the range is the right prop for the boat in racing conditions, depending on how the boat handles, turns, it's top speed, etc.

[Bande1]

You certainly can go too small or large of a diameter prop. Too small of a prop for a given hull will cavitate to no end, have trouble getting on plane, and generally be less efficient. Too large of a prop for a given hull can allow the prop to drive the boat rather than propel and lift it. A 35mm prop on a 31" hydro would be inappropriate, and result in poor driving characteristics. As would a 55mm prop on the same hull, but with wildly different issues.

One should first select a diameter range suited to the size hull you're running. For this boat, as above, I would recommend between 42-48mm, 45mm being the average. Taking a middle of the road pitch ratio, say 1.5, and a target mph of say 65 mph, working backwards, taking into account efficiencies and prop slippage, that calculates to a 2400kv motor. Propping all the way down to a 42mm with 1.4 ratio would theoretically go 57 mph, and propping all the way up to a 48mm 1.7 ratio would theoretically go 79 mph. Somewhere in between those two extremes of the range is the right prop for the boat in racing conditions, depending on how the boat handles, turns, it's top speed, etc.

what I said.

[Troy1957]

On our pond 65 mph will be good if I can do that constantly 70 on straight away would be awesome