nitro vs electric

[ernest2]

if i am to compare a os .21 nitro engine into an 540 electric motor, how many electric motors with 7.2 volts each will it be compared to the nitro engine? what i mean is that a boat is powered by a .21 engine, will it takes just 1 540 size motor with 7.2 volts to make it go as fast as the nitro or will it take 2 of the 540 with 7.2v to make it go as quick.

thanks!

ernest

 

[Eric Perez]

if i am to compare a os .21 nitro engine into an 540 electric motor, how many electric motors with 7.2 volts each will it be compared to the nitro engine?  what i mean is that a boat is powered by a .21 engine, will it takes just 1 540 size motor with 7.2 volts to make it go as fast as the nitro or will it take 2 of the 540 with 7.2v to make it go as quick.thanks!

ernest

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As far as power output then letts look at the Watts. A racing 540 setup will suck about 40A out of a 6-cell 7.2 battery. Watts = Volts X Amps , Lets assume the pack can supply 40Amps at 7.2 volts, the battery motor combo would be pumping out 288 Watts of power. The 540 motor is only like 70% efficient at these power levels.

A typical .21 size engine will be able to deliver about 2HP, 1HP=745Watts. Do the math, it will take a lot of 6-cells packs and 540 motors to equal the power output of a .21 engine.

To increase the power of eletrical systems and improve the efficiency it is best to increase the voltage and get motors that can handle the higher volts. Current 540 motors are rather small and getting the heat out of the motors is the limiting factor in getting more out of them. The higher capacity batteries are already proving that heat is what's holding back rc car motor performance.

 

[Propjockey]

Nowhere close. A 540 can on 6 cells is about equivalent to a .049 glow engine with a bit more torque.

You may be better off asking on the electric forum, but I'm thinking to get close to a .21 nitro you would need a 700+ on 12 cells.

 

[Paul Pachmayer]

Hi Ernest,

Eric is right. With an 05 brushed motor you wouldn't be able to do it. On 6 cells you'd be hard pressed to keep up with a 21 with a good set-up rigger with brushless power. For a comparable 21 size hull in electrics 18 cells and 1 brushless motor would do the trick easily.

Paul.

 

[ClayGlover]

Hi Ernest,
Eric is right.  With an 05 brushed motor you wouldn't be able to do it.  On 6 cells you'd be hard pressed to keep up with a 21 with a good set-up rigger with brushless power.  For a comparable 21 size hull in electrics 18 cells and 1 brushless motor would do the trick easily.

Paul.

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Hi Paul. How much does 18 "good" cells and a brushless motor/controller setup cost (roughly)? thanks

 

[Paul Pachmayer]

Hi Clay,

How much does 18 "good" cells and a brushless motor/controller setup cost

Motor and controller about 280.00 and cells roughly 144.00. Actually 18 cells in a sport hydro would smoke a .21 sport boat, maybe not the best comparison. The boats are roughly the same size though, the one I run is 32" long.

Paul.

 

[LOU]

Our 18 cell Sport Hydros were getting close to the Sport 40 times for 4 laps.

Pete

 

[ernest2]

thanks for those infos. i guess 2 540 size motors wont beat a .21 therefore.

thanks a lot

 

[Tofastformellow]

if you used a hacker brushless with a gear drive you would be on the right track.

Jason