Outrunners...... are they worth messing with?

[don ferrette]

Ok here's the deal - got a 41" cat hull coming my way that was originally set up for twin nitro (.67/.80) and I'm thinking of re-doing it as FE twin. Up until now I've used nothing but water cooled inrunners (NEU typically) but am curious about experimenting with a pair of outrunners. Since this type of hull is so wide open inside I'm thinking outrunners may survive ok which would simplify the plumbing for water cooling. so is this a viable line of thought here? Input and outrunner motor suggestions welcome.

[SweetAccord]

Outrunners are typically lower amp draw for the same KV/diameter of an inrunner and for the same KV/diameter of an inrunner provider more torque.

[Fluid]

I have run half a dozen outrunners in boats, all quality motors in single sport applications. They have been reliable as long as the amps are kept down, they will not tolerate what a Neu 1527 will. The real problem is electrical, the large Scorpion 4035 motor coils start to become saturated above ~100 amps - loading the motor more just generates more heat. I found this out myself, and was subsequently told why by the main US distributor.

That said, the 40-series Scorpions will spin a big prop, larger than you might guess from their light weight. Running on 8S or 10S and 100 amps each, a twin would have plenty of power and should survive fine with all that internal air volume.

Edit: the biggest issue may be finding a large motor with enough Kv. Scorpion's 4035 used to be offered with a 800 Kv option, but it is discontinued. Most 700-helicopter-sized outrunners have max Kvs of 600.




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[axel]

I have run half a dozen outrunners in boats, all quality motors in single sport applications. They have been reliable as long as the amps are kept down, they will not tolerate what a Neu 1527 will. The real problem is electrical, the large Scorpion 4035 motor coils start to become saturated above ~100 amps - loading the motor more just generates more heat. I found this out myself, and was subsequently told why by the main US distributor.

That said, the 40-series Scorpions will spin a big prop, larger than you might guess from their light weight. Running on 8S or 10S and 100 amps each, a twin would have plenty of power and should survive fine with all that internal air volume.

Edit: the biggest issue may be finding a large motor with enough Kv. Scorpion's 4035 used to be offered with a 800 Kv option, but it is discontinued. Most 700-helicopter-sized outrunners have max Kvs of 600.




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Just for your notice - time changes

http://www.mhz-powerboats.com/E---Motoren/Scorpion-Motoren/MHZ---Scorpion-Motor-HK-4035-1600.html

or a number bigger

http://www.mhz-powerboats.com/E---Motoren/Scorpion-Motoren/MHZ---Scorpion-Motor-HK-5035-760.html

Axel

[Fluid]

Of course we are aware of those - they have been around for years - but at $500 for each of those you could almost buy two Neu motors with more power. Plus they are massive overkill in a 1.04 meter hull. I doubt the OP is interested....but I could be wrong.


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[photohoward1]

We have all tried outrunners in our boats....Why do you think we run innrunners? IMO they are powerful but run really hot....My experience too is that they are hard on controllers. All those poles to keep timed.

[don ferrette]

Thanks guys, guess I'll keep doin' the inrunners. Since this is going to be a fun boat any thoughts on motor options besides NEU if I wanted to save some $$. Also trying to decide on power, thinking 8S but wondering if a pair of 6S motors might be an option without being too hard on stuff.

[Fluid]

I and a few other experienced FE guys have found the HET motors to be close to Neu effiency at lower cost. They are EDF motors so are designed for high amp use. The only problem is limited Kv, but the 700-98 780 on 10S or the 700-83 1445 on 6s are options which can give great results for less cost than the Neus. I have had great results with the latter with great power and relatively low temps. It is a 39 mm motor not a 40 mm motor, but slightly larger O-rings will make normal cooling jackets fit fine.






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[photohoward1]

Inn runners there are great choice for affordable motors. Check here on offshore...Leopards or TP are great.....