Spec Electric 7.5 Nitro Replacement

[HTV Boats]

Fabian,

Not familiar with your particular hull. One thing you need to do is read as much as you can on FE sites like Offshorelectrics or http://www.rumrunnerracing.com/ As for motors a 4074 is 40mm diameter and 72mm long. 4082 is same diameter and 82mm long. Max watttage on these are 2600 & 3500 respectively and not sure about efficiency percentage. An Aquacraft (p-spec) motor is 36mm diameter and 63mm long. Not sure of wattage.

You also seem concerned about run time which for the race guys means just enough for 6 laps and a little mill time. Load and potential higher speed will only reduce run time. 5000mah seems to be a common battery size here and with something like the limited Aquacraft setup your looking at 3 minutes with a conservative prop. More motor & prop and less time period. You might want to consider just purchasing a complete UL-1 hydro to start as it will be plug & play and is designed for noobies. Capable of 50mph and will give you more run time.

Going to a 4S or 6S setup maty not be give run times over 3 minutes. What Lohring and a few others here are looking for is a racing replacement for our nitro .45 engines utilizing existing proven hulls and props. Races are generally over in under two minutes.The spec equipment though not bulletproof or foolproof are very well matched and engineered. Stepping up from there is a total crapshoot but not impossible using common sense. The 200a Swordfish will definately work on a 6S. Going to motors over 2 watts and proping for speed and you are not in the bulletproof range anymore. Propload is the key to speed and failure, get greedy and going over the edge comes fast. Lots of us including myself are learning as we go. Listen to what has worked for others and expand a little from there.

Mic

 

[Fabian Hill]

Is my hull ok weight wise ? not too heavy ?

ok so my choice so far would be the recommended one from HTV : 4074/2000kv motor and Swordfish 200a

Or I would like to try something maybe you guys haven't tried yet so I can provide some input to this thread and so was thinking maybe going with :

4082/1450kv

or

4082/1600kv motor and Swordfish 200a

or

4082/2200kv

What do you think ?

 

[Kris Flynn]

2.5Kg's is heavy for 4S, I would go for a lower reving motor (1450Kv or even 1200Kv), 6s and a Turnigy 180 Speedy. This will get you going and having plenty of fun.

I think your hull will not handle speeds above 50 in much other than perfect water conditions.

 

[Fabian Hill]

ok thanks Kris,

Would I still be better off going the swordfish 200a esc for future upgrades to motor and possibly hull down the track ?

Is it a better esc isn't it ? more solid ?

Since the price difference between turnigy 180 and swordfish 200A seems minimal I would still like to go the better unit.

do you guys use that lcd esc programer for the swordfish or the usb ? which is better in your eyes

Let's say I go the 1450Kv Am I better of with the 4082

 

[Fabian Hill]

Hey Kris, pending your reply I'm ordering everything else today apart from batterys , what prop would you recommend to try first with a hull that weight ?

cheers

Fabian

 

[Fabian Hill]

Well I think maybe I asked too many questions, as this thread has died by the looks.

I received the lawless lower today ; )

Ordered the conversion plate

I found scorpion 4025 1100KV at hobbyking for $134 " pretty good price for that engine " so have ordered that. Anyone tried ceramic bearings in these yet ?

Now I hope I haven't stuffed up here but I went for the swordfish 200A esc with the LCD programmer, just looks like has more functions and settings to play with.

Anyone care to suggest a couple of props as a starting point for me and what sort of batterys would suit and also what sort of servos to you guys run for steering ?

 

[HTV Boats]

Fabian,

I can give my opinion on a couple things here. First the 1100kv is a safe staring point and should be able to pull decent props. Bear in mind a small change in prop may put you over the edge real quick. Running my .45 size tunnel on 4S and a 2200kv motor it ran fine with a M445 and radared at 54mph. Stepping up to an M545 the contoller and battery heated up significantly.That was just a pitch change and diameter change like a 447 would be much stiffer. Without a data logger I usually run 2-3 hard laps and bring it in immediately and check temperatures batt and ESC.

As for ceramic bearings why? For the cost and trouble you won't improve a cheap motor. Just spend another $70 and get A Nue. You may want to spend the $$ and experiment with a 1250KV also to see what changes. Will be much more than a bearing change. Under 40000rpm it's insignificant.

For props it depends on your hull and what works on it. For tunnels the X series Octura seems to work well on many different setups. Work your way up from a 445 and theoretically up to an X450 might work. 447 and 448 inbetween. I am not sure if diameter or pitch increases heat more but my experience is diameter kills power first.

I have the Swordfish and the digital programer works well. Actually default settings are fine. I like the Auto mode for timming as it keeps me safe since I don't actually know each manufacturers recomendation and advancing timming could lead to burning things up prematurely.

Servos? I have run some .45's on 130oz 3305 Futabas and 645 Hitecs but they are marginal. An 805mg Hitec if you have room should steer well at 300oz. I guess anyting in the 200oz+ range will be fine. My favorite is a 5301 Futaba but they don't offer them anymore.

Batteries? Read all you can on Offshorelectrics or Rumrunners forums. After 10 hours there make a choice. Ecomomy go with Turnigy or Zippy which I have had good results with. Top shelf is Hyperion but pricey. I have heard some good things about Gens Ace. Ordered some this week and and waiting for delivery. I am staying in the 5000-5800ma range with single packs due to space restrictipons in my radio box. Good enough for heat racing but not capable of much over 3 minute runs. Lipo bags for charging are cheap and I store my lipo's in a household strong box. Was designed to keep documents safe to 3500 degrees in a fire and hope it works from the inside out as well?

http://www.hobbypartz.com/gensace6s30c.html

Hope this helps and keep asking. Generally threads die when no one has any better information. Good thing here is there are many ways to get similar results. At the end of the day it is setup and prop prop prop prop!!!!

Mic

 

[Fabian Hill]

Thanks HTV,

Getting close to having everything ready for build just going to set it up and get it running probably order batterys last as I'm hoping price might drop a bit, and also can spend some more time reading up on them.

I think I read this thread about 20 times it's a lot of info for a newb .... lol

Spotted a ceramic bearing kit for $30 but like you say may as well spend a bit more and just upgrade motor down the track.

I use to use hitec in my old tunnel with k&B 7.5 a long time ago, sounds like they are still the thing to go for then, do you run the servos / receiver of your main battery pack or a separate one ?

gen ace is $35 shipping alone to get 1 here which is way overpriced as far as shipping goes, will keep an eye out local see if they pop up somewhere.

Right going prop hunting ! lol

Fabs

 

[lohring]

As I said in the beginning, our goal was to duplicate 7.5 nitro performance without using high cost equipment. We've more than succeeded and are running some old Leecraft XT-460s at at least the same speeds as they went with nitro engines. We are even running the same 1450 props. The steering servo is also the same old Hitec 750MG 1/4 scale servo. We ran those because the control arm spline strips before the gears. The forces from flipping are lots more than normal steering force and a plastic servo arm makes a good "fuse". Newer digital servos would be better, but I'm cheap and ran what I had. One thing I like about the new speed controls is the BEC circuit. I don't know about the Swordfish, but the Hobby King 180 works with 6S lipos. It makes the setup simple since you don't need a receiver battery. The one thing we found is you need to run the prop shallower than with nitro. Otherwise, the torque pushes the sponson in and trips the boat. Good luck with your build.

Lohring Miller

 

[HTV Boats]

Most of the reading I have done on FE sites the concensus is BEC's are not reliable on 6S. But it does seem the T-180 guys are using it on 6s successfully. I have not gone above 4s on my swordfish yet but will try without a separate reciever battery to start with. All new ground for a lot of us here and good to hear what actually works rather than opinions from someone secomdhand. Thats what I hope this threads discussion will bring about. Like Lohring I use the cheapest plastic standard servo horns as a fuse. Never had one break while running without a severe blowover. Do look for metal gears though. I like the 1/4 scale due to just bigger geartrains.

Hobbypartz.com has free shipping lower 48 and have Gens.

Mic

Lohring I hope there is still enough equipment out there to keep .45 nitro tunnels alive but with not a lot of time running FE I guess this is the future of more than just tunnels. At the FE Nats here in Florida watching the tunnels run was neat and also the whine of the motors reminded me in a distant way of the pitch of a full size 2.5 liter Merc. A unique sound now we just need to spray burnt Klotz oil in the air and everone will be happy.

 

[Fabian Hill]

Just thought I would let you guys know first not sure if interested but the link below will get you a scorpion motor from hobbyking it's the 4025 1100 for $114

http://www.hobbyking.com/buddy.asp?code=6D574F7E-FD4A-4003-BEB8-EAB35C44EE75

8mm gold bullet connectors

http://www.hobbyking.com/buddy.asp?code=0EB1F90A-8F06-40BC-BC1D-15C4F36BF2BE

Thanks for info Mic, hey by the way I'm in Australia.

 

[Fabian Hill]

octura x series has 2 and 3 blade props , can you use 3 blades on electric ? or is 2 better ?

 

[HTV Boats]

Fabian,

Not sure how far you are from Kris Flynn but he surely is closer to you for hands on help. Now for props I look at the 2 vs 3 blade as this. Same pitch and diameter the 3 should load more. Some find handling differences but I feel every prop has a different sweet spot for shaft height and angle. There are simply not as many 3 blade options under 50mm diameter. If I stay with an X series 2 blade between 45-50 mm we have M detoungued X's and X's in 445,545,645 447 547 448 548 648 450 and probably a few more I don't have. In 3 blades the choice is 447 or 450. 2 or 3 blade properlty set up either may be the best for a particular boat. But when I stay in the 45-48mm two blade range I have a variety with similar lift and handling properties so I don't need to go up and down or in and out nearly as much to test with. Makes setup much easier with closer pitch and diameters not needing as wide a range of possible adjustments. If your prop box resourses are limited stay with known props. Being you are going 6S with 1100KV my opinion that X447/2 X448/2 would be safe and X450 or 1450 could work well also. On my nitro .45's I rarley go over 48mm diameter but have several 50+mm props cut down a bit. This all depends on what your hull works with too. If I only could choose 2 props it would be an x448 and X450 with 1100KV 6S. That also would be a safe choice as you may be able to pull more pitch. Remember going off the deep end in FE is not a gradual slide at some point heat becomes a cliff.

JMO

Mic

 

[Fabian Hill]

Thanks Mic, I got a x447 / 2 coming and another smaller prop as well just a cheapy to try see what happens will get more down the track was just to have at least one or 2 props to try once it's built.

I got the hi jack mount / prop shaft / flex shaft in the mail today and the electric converter plate yesterday so I should be able to start drilling holes and mounting stuff on the w/end.

Will read this thread another 10 times on the w/end though lol.

thanks everyone for your input, and I hope I don't burnout the swordfish 200...

Cheers

Fabs

 

[HTV Boats]

There are two similar threads here on IW concerning "P-Q" tunnels and this one is more geared twords the replacement of 7.5's and I feel like a few of us on the east coast like Lohring are looking for a FE class above the P-spec or limited one that is established. That and staying cost effective to draw new people to the class. Aptly put the $60 motor is the equalizing "fuse" in P-spec. A few of us have talked here and feel Open FE at Charleston and STORM races will draw a P-Q field. I do not see anyone building an 8S-10S tunnel in the near future. That said is just P vs Q combined any advantage for a Q? Not if a motor or battery fuse is applied. I am not sure what might work there either. What would make a 4S-5S-6S level. 6000ma 4S, 5500ma 5S,5000ma 6s? Or just 4S and 5S only. This is for 6 laps heat racing not SAW speeds. I just threw those numbers out for an examle as battery weight would determine energy availiable also. A 6S could not use a hot motor or big prop without going through his availiable power very quickly. Or just leave it unlimited and get some experience with a class letting people know restrictions after going to be reviewed on maybe a 2 year basis. The other issue with rules is simply inspections do not happen at the end of the race day at local races as officials barely get races run and hand out trophies. We used to have a local class up north that worked well using a simple baby scale. You made a minumum weight right after retrieval and alowwing water to be drained if you placed. Too light and DQ. Simple to enforce every heat as your competition will be right there watching the scale, to police everything. HP is easy to limit with weight. 8 lbs 4S, 9 lbs 5S, 10 lbs 6S? Again just throwing out numbers to start convesation. If its not easy to enforce it won't work. ROAR has done pretty well with "approved" motors and a list of motors and controllers that meet certain cost limits is worth looking into.

Mic

 

[Fabian Hill]

Didn't end up having a lot of time to put into my boat for a while but finally did a test run the other day with that old castrol hull and was very pleased with first run, I've now sold that hull and finishing off a vision 40 that will have the same powerplant, lawless 7.5 lower with scorpion hk4025-1100 prop was x447.on 6s and swordfish 200A

A big thank to everyone in this thread that helped me out with information tips ect.

 

[hugh hargett]

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.innov8tiv...products_id=569

Turnigy 180 amp speed control http://www.hobbyking...?idProduct=8937

6S 5000 40 or 45C batteries http://www.hobbyking...idProduct=14616

Hyperformance 7.5 outboard conversion kit http://hyperprod.biz...ersion_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

Lohring i got someone that can upgrade the scorpions with water cooling direcly on the windings,replace the bearing with mil spec bearings and rewind it will mill spec wire (300 C) pm me.

 

[hugh hargett]

I think a turnigy 1400 kv t600 4030 will work too for a little less money. and it will def pull a 1450

 

[hugh hargett]

Didn't end up having a lot of time to put into my boat for a while but finally did a test run the other day with that old castrol hull and was very pleased with first run, I've now sold that hull and finishing off a vision 40 that will have the same powerplant, lawless 7.5 lower with scorpion hk4025-1100 prop was x447.on 6s and swordfish 200A

A big thank to everyone in this thread that helped me out with information tips ect.

http://www.youtube.com/watch?v=dsbx4qH985M

fabian the driving style youre using is not very the best way to keep the amps down on off on off gunning does nothing but throw surge after surge on the esc be smooth with the throttle get on top and stay there If you really like to punch it like that I suggest an external cap bank just to be safe and give you that punch your looking for.

 

[lohring]

At this point I'm not sure the outboards need any extra cooling. After all, the motor is connected to a big, water cooled heat sink (the lower unit) and gets spray plus air ovet it. The above Q power plant is now installed in a Mutt II sport 40. The motor is still exposed but is now under a cowel. That's the same setup I ran on my Scorpion powered 1/8 scale boat. If the current is kept to a reasonable level, heating shouldn't be a problem. We'll see how that works.

The Scorpion motors have been getting more expensive. I would be interested in how some of the other 1000 to 1200 KV outrunners are doing. The other problem with the Scorpions is that they are conservatively rated. Both of these mean they might not make the best "fuse".

Lohring Miller