Spec Electric 7.5 Nitro Replacement

We are looking for a low cost replacement for 7.5 nitro engines. The first test was on Leecraft XT-460 tunnels. After some trials with inexpensive motors that didn't hold up we settled on:

Scorpion HK 4025 1100 KV motor http://www.innov8tivedesigns.com/product_info.php?cPath=21_25_68&products_id=569

Turnigy 180 amp speed control http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=8937

6S 5000 40 or 45C batteries http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=14616

Hyperformance 7.5 outboard conversion kit http://hyperprod.bizhosting.com/7_5_electric_outboard_conversion_kit.html

That power plant costs around $400 with the motor at $160. Still, the cost is in line with nitro power heads. We used an old K&B lower unit. The performance of Brian's boat is better than a mod engine powered XT-460 with both electric and nitro boats running an Octura 1450 prop. You just need to run the prop a lot shallower than with a nitro engine. Bigger props torque the sponson into the water, flipping the boat. Outrunner motors worried us since they aren't as easy to water cool as inrunners, but that doesn't seem to be a problem with outboards. The next test will be an inboard setup in a Sport 40.

Lohring Miller

Hey Lohring,

That is great news! I am getting the spark to finish my 6S Vision!

Cheers

Kris

did you make the motor adapter yourself?

Very nice! Any video of test runs?

Much like Lohring a few of us here are working 45 size FE's. The P-Spec seems to have power to put it into a mod 21 class so going to a straight "P" on 4s or "Q" on 6s should definately require a 45 size hull. Batteries like Hobby Kings we have been using seem to work well but I can see some Grimracers and Hyperions in the future.

So far a P-spec on my hull only yielded about 45mpn and this hull now has a 1400 KV leopard 4074 (under $100) waiting on a 150A Etti/Navy controller thats rated for 7s which I hope will hold the 6s 40c 5000ma and 30c 8000ma Turnigeys I have. Hoping to turn 45X68 GrimRacer,47X60 ABC's and X447-448 which work well on our 45's. May also try a 4082 1500kv Leopard. Have a 4082 2200KV leopard that will be a 4s setup that will definately run on the Shaman. Going with Leopards as they cost under $100 and are availiable in several KV ratings. Can always upgrade to NUe's and Castle 240's. At this point trying to keep costs down to try different aproaches. I see Lohring is going with 1100KV probably needed to turn 50mm diameter props. My understanding is diameter will create heat more than pitch. For a 45 equivalent setup we have props and hulls that should work just need to find what works bulletproof.

That said the Aquacraft 60amp controller and 1800 or 2000 KV motors are matched very wellfor 4s. On a Vision it runs much faster than an OS and will give a good mod a run any day. For an under $200 powerplant replacing a stock OS powerhead you will get hooked on the power. The cost of batteries compared to fuel and glow plugs will be your choice.

In rigging a few FE Tunnels I like the batteries as far back against the transom as possible. Makes it easierr to control CG. Just my opinion.

Hope we get some more feedback here from others and as I test on thje water I will update. New ground here.

Mic

obrien said:

did you make the motor adapter yourself?

Click to expand...

Here are the adapter kits: http://hyperprod.bizhosting.com/7_5_electric_outboard_conversion_kit.html

That outboard cowling looks very trick. I like the rest as well, lol. Very nice looking boats Mic.

In the Leecraft you need to put the batteries into the front section of the hull. I've tried to keep the same cg as the nitro boats and we always needed lead on the sponsons. I think the electrics have an advantage because the weight is concentrated centrally in the batteries. Weight at the ends of the hull encourages porpoising.

Our P spec boats have gotten a lot faster. The VS-1 hull is a little too small now so the Top Speed II seems about right. Brian Buaas ran his TS 2 over 70 mph with a full P setup. The P spec boats are more reasonable, but are still as fast as 3.5 mod tunnels. The way to keep electrics inexpensive is to limit currents. The spec boats run at around 100 amps with spikes to 150 amps. Low cost motors and controllers can stand this. For more power in spec classes, you add voltage. As a comparison, we tested two P monos. Their Castle ICE controllers recorded over 200 amps during steady running with spikes to 300 amps. Brian locked up a motor and the ICE controller survived. They cost money, but the ICE controllers are very tough. So is my Neu motor that also survived the testing.

Lohring Miller

I am still undecided on weather or not I will build a p-tunnel, but I do plan on building a q tunnel. I have had alot of fun with my p-spec vision. Its a fun class that is great for getting started. I can only imagine how much fun tunnel racing is going to be once we have a few more boats out there to race.

As soon as Fred Howe gets his shop back up and running (tornados) and he gets a chance to ship the Lawless parts I need, I'll be building a Warhead 2 with a Lawless 7.5 lower to run with Lohring and Brian and whoever else wants to join in the fun... This boat will also double as a P-OPC hull when the opportunity arrises.

Which is the better lower to use in the 7.5 size ? bullet / K & B / lawless / r k carbon ?

Is there no gear driven lowers at all ? would have thought that would be more efficient than flex cable ?

Where should I look for a second hand unit or well priced new stuff ?

So far I'm tempted to go bullet drive since hyperformance seems to have the whole package.

Does it make a big difference which one I use ?

With : the Scorpion HK 4025 1100 KV motor. Would there be a huge decrease in power going for Scorpion HK-4015-1450KV Brushless Outrunner Motor ? http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=17398

I notice on your setup Lohring you don't have water cooling on this motor is that right ?

Will be following this thread closely as I have a hull sitting there and just getting back into the hobby with already a few other projects under way.

Cheers

Fabian

Fabian, I would recomend going with the K&B 45 or Lawless 45 OB lowers for a 6S setup. The OS and smaller cable limits prop diameter and overall strenght for the power availiable.

Jay and I got a chance yesterday to run my 45 hull with a 4074/1400kv Leopard and Turnigy 5000ma 6S batteries and an ETTI 150A controller. Ran a Grimracer 45X68 prop and a stiffer 47mm ABC from Sholund. Don't have a course set up in the canal behind my house so just have to give you "butt dyno" readings. The boat liked the GR prop and ran fast enough to blow over which in my hull usually means well into the 50's. Adjusted driving into the wind and I would say performance is on par with a mod 40 boat. I would have no problem running this setup in mod 40 or Open tunnel. What we don't have on top end would be made up in and off the corners. This boat gets there quick. I chose the motor which is rated at 1500w to not overload the controller and give a decent run time. I figure 2-3 minutes depending on prop load which should cover a 6 lap + one penalty in a heat race. The next step would be a 4082/1500kv motor at 2000w. Going to eat a little more power but faster. I like the 1100-1500kv range which should adapt to 45-50mm props we already have in our boxes. Whats the magic #'s. Testing and racing will figure this out as this is all new ground here. Going to be many aproaches that work. From my research reading and talking to FE racers a 6S needs a decent contoller. I chose the ETTI 150 no/bec as it is rated for 7S. General opinion is a 6S max controller is marginal. If you stay with smaller props and motors the under $100 controlers will live. Getting over 2000w and 448 ton 450 props will yeild HP and need $250+ controllers in my opinion. That said a 1515 2y/1400kv Neu and a 240 Castle are not going to break the budget that a mod nitro motor and pipe cost. Going to get interesting. I also feel a full "P" 14,8v setup might work just as well in a .45 size tunnel. Little less weight but capable of 60+ mph in a not too heavy hull. Power and reliability are opposed here. Hope a few more will try it out.

Mic

PS. The ETTI is only transmitter programable and difficult to set. I think a Swordfish 200 or T-180 would work well but not bulletproof to overloading. Too much watts or props will kill them.

Hey Mic, As I said on the phone, I am REALLY glad you and Jay are getting into the FE, as it will only be for the good of the Sport/hobby.

Now, start saving the pennies to donate to my cause of getting over there in the next year or 2 LOL

OK, now i have to decide, run K&B or spend some time and Mod my perfectly good Lawless 7.5

Kris

The issue with lower cost motors is durability. The Leopard motor current ratings depend on KV and are listed here:

http://www.leopardhobby.com/product/product_veiws.asp?id=1251&functionID=01020201

http://www.leopardhobby.com/product/product_veiws.asp?id=1417&functionID=01020201

The higher KV motors look OK, but you will need to run smaller props than we are. We were trying to run the nitro motor props at a similar rpm. The only way to know is to test. However, Brian Buaas locked up his Leopard in a full P setup. I'm sure he was pulling well over the rated amps. So far the Scorpion motors have been very dependable. The real issue is how to write rules that limit the current. Either the motor or the speed control can be the fuse, but motor failure often takes out the speed control as well unless it has a substantially higher current rating. We shoot for 100 to 150 amps to keep the costs low. Unlimited classes can easily run twice that current.

Lohring Miller

In selecting a motor I hoped to stay in the 24000 to 28000 working rpm range with a 1400kv motor on 6S (22V). 31000 without a load before batteries drop off. The same hull with a Nelson at 26000 rpm and an X450 (cut to 48mm) clocked 58mph though the SAW traps at the Internats.

So far turning a GR 45X68 which the boat handled well and yesterday a straight X447 which brought the speed up. Side by side it walked all over our P-OPC. Probably 6-8 mph faster. Batteries came in at 109 degrees similar to the controller. Need to get to a course and get lap times. 55+ Mph should be within capabilities.

I like anyone figured a 4082 would be better but wanted to stay conservative and the 4074 is a handfull already. I would go with a 1250KV 4082 if we need more power. Should sustain the 47-48mm props we have. But it might need a 240A controller to live. The Scorpions specs look interesting and they are shorter which keeps there weight lower which is a plus for handling. I agree amp draw will be a key factor. As for prop diameters it will depend on the hulls liking for deep or sky high prop settings. We just need to keep testing and share info.

Mic

Thanks HTV boats "Mic"

Here's what's on it's way so far :

7.5 size lawless lower

Hi jack mount

flex and prop shaft

Missing:

What do I need to mount a brushless motor to a lawless lower ? will that converter on this page work from perfomance website ?

Brushless motor trying to decide which way to go

esc depends on engine and battery

Lot's of good info on this page , thanks heaps guys, keep it coming please.

Hey Mic what is a " full "P" 14,8v setup " ?

The hull I have is not the latest I will post a pic so maybe someone can tell what it is and will weigh it see if it's worth going FE with it otherwise might try and throw a zenoah in it see what happens lol

thanks again everyone for all the info.

Fabian,

I ran a Zenoah/gas tunnel and believe me the 8 pounds of motor and lower with pipe and servo costs near $1200 alone and finding a hull that works will put you over 2 grand and I like my simple P-spec Aquacraft motor and controller on a 21 tunnel much better at a fraction of the cost.

When I say full "P" I refer to any motor/controller using 14.8V (4S) Limited or spec "P" refers to class rule limitations. Basically an Aquacraft UL-1 or Proboat 4S powertrain. I put my P spec motor on my .45 hull and it ran pretty good up to maybe 42mph. Going to a unregualed motor controller on 14.8v lipo we up it to the 50 mph range. 200amp Swordfish and leopard 2200kv motor with a 45X68 Grimracer prop. No heat issue as controller at 110 degrees after the run. M445 should work also. I think 2000KV would allow less heat with the same props. An M545 brought the controller up to 160 degrees. This is again P not Q. Just a little simpler with existing equipment in my box. You do not need to go off the deep end with FE motors. Performance from my 4074 and 4082 leopards make plenty of power. Enough that I need to adjust for handling already. These are $100 motors at Offshorelectrics.

As for an adapter Hyperformance makes a bolt on setup

http://hyperprod.bizhosting.com/7_5_electric_outboard_conversion_kit.html

Very nice quality and not expensive.

My advice would be a 4074/2000kv motor and Swordfish 200a controller with a GR 44X66 or M445 to start on 14.8v and your under $250 before batteries. You can work up from there but this should put a .45 size hull into the 50mph range without smoking everything. These parts are availiable and you can always move up in power. The Swordfish I feel is easier to program than the ETTI 150 and may work on 5S-6S with not to large wattage motors.

http://www.offshoreelectrics.com/proddetail.php?prod=leo-4074&cat=148

I only know what has worked for me so if this is sending someone down an incorrect road anyone with more experience please jump in and help out some FE rookies.

Mic

Thanks Mic,

I've just read this whole thread again and I'd like to put a couple of simple question to you ?

If I want to run 6s battery with the 200A swordfish what motor would you recommend to try to get between 50 to 60mph ? and what do you think the runtime would be ?

If I go as you suggest with the 4074/2000kv and swordfish 200 and run 4s I should do 50mph , what would the runtime be on this roughly ?

and also when you say : You can work up from there , do you mean work up bigger motor or bigger batteries ?

I'd just like to get the best bang for buck including a bit of run time as well, I know all this is new and just looking for some simple clues, because after reading the whole thread I think I'm just even more confused now ... : ) lol

Not much price difference between 4074 and 4082 what do these model numbers mean ? is that the efficiency is it ?

thank you

Fabian " FE noob "

What Hull have you got Fabian, we can give you something that will go these speeds, but you hull may not be up to it.

Ok so here it is ...

be easy on me please ... lol

86cm L x 36cm W

weighs in at 2.5kg on my fish scales I don't think they are real acurate if anything may be a bit lighter.



can anyone help me with this total noob question ... ? " see post below "

http://www.intlwaters.com/index.php?showtopic=46431

thank you

Fabian