70" stepped V,single brushless or gas?

[FastVee]

So my question is are there any motors that would push this about 50+ mph ,with esc that wont break the bank? -RELIABLE PARTS!

The gas parts I am thinking would cost about 600$ (Full mod tiger king 28.5cc ,pipe etc, )-drive&hardware,batteries cost will add to that ,so if motor and esc would cost the same or less I am going to think about it.

Thinking 8-10s 2-4p to get atleast 15min run times.


This will be my first big single build(would do twins but wifey wants another kid so budget build again I guess lol) and if going gas my first gasser also on water.

The hull I found from the iiibay, hull looks a lot like the mhz xxx 71" if that helps, no pics yet still on the way here.

I just saw the Proteus X520 3D 730KV/1280KV ,said to work 1.5-2m long boat, looks a bit small imo? http://www.skyrc.com/index.php?route...product_id=140

-Pate

[Roy Van De Sande]

Big hull to build up with a single motor... I would go for the new TP5870 series. They can deliver 9kw constant power and 15kw burst.
Kv wise, I would chose the 490kv motor and run it on 14s 3p. You will need the high voltage to keep the amps under controle, otherwise you won't find an esc that can handle your setup. For the esc you can look at the swordfish 300A 15s esc's.
Either way, the gas setup will be much much cheaper than a brushless setup. The batteries alone will cost a fortune.
Runtime will be in the 5-7min range, I don't know much brushless boats with a runtime of 15min.

Another option is this Lehner in Wye mode: http://forums.offshoreelectrics.com/...ha-Motor-Mount
With this motor you can run 2 esc's. For example, 2x swordfish 300A esc on 12s2p each. This way the esc's wont suffer that much from the high amps of the single motor setup.

[Doby]

Go Gas.

[grsboats]

15min run time...no way ! A Fe set up for this boat will be much higher than a Gas.....A Lerhner 3080 is what you will need for this size boat..go to their site and take a look to their prices.....I second Gas.

[Fluid]

The axiom of FE is: fast, cheap, reliable, choose any two. A 70" Mono is in no way a $600 budget build anyway. As recommended above, better to go gas.



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[FastVee]

Gas it is then. Just the thought of my 58 and 50" boats I build using about 400 worth of electrics each are solid and fast made me believe I can do this ...-it is "only" 12 more inches to the 58 apache... oh wel thanks guys and will do this one with an engine.

-Pate

[boredom.is.me]

Now get off our forum with your fuel powered abomination!!!

[NativePaul]

Is a single 28.5cc engine enough for a 70" boat? I don't know much about gas boats, but all the <30cc class boats I have seen were a lot smaller than that.

[FastVee]

Paul, I have been thinking about that also, but same size Expresscraft apache moves with a single stock 26cc in the 40´s what I have read.I have no idea does these boats compare but lenght is the same.

My other option is rcmk k600 twin, but it weights twice as much as the tk engine.

I will check with the sellers again what they think is enough but I was promised 60+ mph with the k600 and 40+ with tk when I asked these q´s earlier. I may get the D.Marles tiger king if he says it hauls a## with that. (It is 7.8hp, dyno numbers)

-Pate

[grsboats]

Pate I also run Gas (only riggers) and can say if your boat is light a good 29,5 will do the job...Zenoah released their new 32cc that also can be a good option modified...about speed I have no experience with mono's but a stepped one will help for sure.Gill

[Peter A]

The zenoah 32cc should be ok for what you want to do, and they can be modded for more power. It should get you to the 50 mph goal without too much trouble, it will just be a matter of the right prop. Also with a boat that size the weight of a twin would not be an issue. The bigger problem with twins is tuning the two cylinders equally and that may require some experienced help.

[FastVee]

Thanks guys! I will do some searching.

The zen 320 would be great but I have read the engine will only last few tanks. Some issue with con rod bearings? -shame ,that would have been great price really...

[Peter A]

The Zenoah 320 will go more than a few tanks. You need plenty of oil. We run 80ml per litre, which is close to 12:1, and many are running endurance races which can go for an hour at a time. And use a good quality two stroke racing oil, not cheap lawnmower stuff.