How to compare gasengine size to outrunner ?
 

I'm going to put a outrunner in my hpi baja ss. but i don't know how big a outrunner are that are equal to a 26cc gas engine ?

What is the rated HP on the Baja engine? For a ballpark figure take that a multiply it by 750. Since 1 HP = 750 W, that will give you the sustained wattage (~5 seconds) you would want from an electric setup to achieve the same performance. So if it's 3 HP, then 3 * 750 = 2250- meaning the system should be capable of sustained bursts to 2250 W.

This is just a guide. Personally, I'd want a system capable of 4000 W in a vehicle as heavy as the Baja. But see what the stock engine is rated for and that will give you an idea. What voltage do you plan on running? 10s LiPo sounds like a good starting point. I'm sure someone here has experience with converting the Baja so they can chime in as well.

but you need a motor with enough bottomend grunt to make an effechent set-up not just topend watt's :) i i meen you can pull lot's of watt's from a neu 1515 motor but i don't think the can power a heavy car like the baja ! Then they woud pull amp's like a big cigarette lighter :)

Well, if the motor can handle the power, then the rest is gearing. If you have limited gearing choices you need to find a motor in a certain kV range. Outrunners have plenty of torque, and happen to be in the same speed range as gas engines.

Would a kb45 xl motor with 800kv be enough ? I i drop the gearing from stock 17/57 down to 60/14t ? and run it on 8-10 lipos ?

or how about this motor ? if i put the piniongear on the gearbox shaft and the spur on the motorshaft to compensate for the low rpm and torque ? it's supose to be equal to a 30cc + nitro engine ! and it's lite ! i think my baja will weigh aboud 4 pound less than with yhe gas engine :)but it will go sooo mutch faster :)

If you don't have money for a Neu 1515 or 1521 go with a Medusa 70-80mm motor they are 100x better than Feigao and only about 150

very funny man ! They woud burn ! this is a 1/5 scale buggy not an 1/8 !!!

Which motor?

Neu 1512 and Medusa 60mm are for 1/8 buggy even some truggies, 1515 is for MT's and some truggy setups and will be just fine on a 1/5 2wd buggy with the right motor and voltage, though the 1521 would be better. The 70mm medusa is too small sorry, but the 80mm should be fine.

Neu
1515 - 1500/2700watts 30sec
1521 - 1700/3000watts 30sec

Medusa
70mm - 1100/?30sec
80mm - 1300/?30sec

My vote is for the 1521 1y w/ 6s lipo, that would be more than enough, if he was to use a 1515 or medusa 80mm he would need low kv and HIGH voltage 10s-12s range and a very expensive ESC to meet the demands.

I can safely say that a 1521 will not be too happy trying to move a 20+ lb vehicle at 40+ mph.

That only depend on the gearing and general terrain. Gear it for 25 mph instead of 40 and it would survive just fine. Remember that some kid jeep can bear said child with 2 550 brushed can...

For such a big vehicule if you are dead set on an outrunner then maybe A60-L?

http://www.aero-model.com/motordetai...es=A60&style=L

ops sorry ! http://http://www.hobbycity.com/hobb...nner_(Eq:5240)


The model namefor this motor is :HXT63-74

hmm that 1521 will generate at least as much HP as that gas motor can. Is he doing something different with the transmission? After looking at the gearing and what not you would really need at least 8s to run 40+ properly w/o heat issues iMO (6s maybe 32-35). That is with a 19t pinion on the 1y or change up accordingly if using a different motor. there is always a 1527 or the 21xx's if you are really crazy :)

Hmm id bet a dual 1515 1y config on 5s x2 (dual mmm's) would do the trick too.. seems like there is plenty of room :)

you can't compare motors based on bhp ! i meen a .21 nitro engine can put out about 3bhp but they don't have the tq of an scooter 3bhp engine !

i whan't to use an outrunner becasue thet are very cheap (65$ for a .200 size outrunner ) Compared to a lennher or neu for about 500-900$ :)

When in doubt, 1527. :mdr: Oh and your link doesn't work because you have an extra "http" at the beginning. That motor should do OK though. They say 8s LiPo max so I'd be careful if you expect to run it on 10s.

Differential Ratio: 1
Transmission Ratio: 8.382
Other Ratio: 1
Spur Tooth Count: 57
Pinion Tooth Count: 26
Total Voltage: 22.2
Motor KV: 1577
Tire Diameter (inches): 6.88
Tire Ballooning (inches): .5
Motor Current Draw: 80
Motor coil Ω: 0.008
Spur/Pinion Ratio: 2.19 : 1
Total Ratio: 18.37592 : 1
Tire Circumference (inches): 24.76 inches (628.8 mm)
Total Motor Speed: 34000.12 RPM
Vehicle Speed: 43.38 mph (69.68 km/h)
Estimated Adjusted Speed: 41 mph (66 km/h) - 6% loss
Effective KV Value: 1531.54
KT constant: 0.86 oz-in/A
Motor Torque: 0.36 ft-lbs
Final Torque: 6.57 ft-lbs
Final Power: 1776 watts (2.4 HP)



Differential Ratio: 1
Transmission Ratio: 8.382
Other Ratio: 1
Spur Tooth Count: 57
Pinion Tooth Count: 20
Total Voltage: 29.6
Motor KV: 1577
Tire Diameter (inches): 6.88
Tire Ballooning (inches): .5
Motor Current Draw: 80
Motor coil Ω: 0.008
Spur/Pinion Ratio: 2.85 : 1
Total Ratio: 23.8887 : 1
Tire Circumference (inches): 24.76 inches (628.8 mm)
Total Motor Speed: 45669.92 RPM
Vehicle Speed: 44.82 mph (71.99 km/h)
Estimated Adjusted Speed: 42 mph (68 km/h) - 6% loss
Effective KV Value: 1542.9
KT constant: 0.86 oz-in/A
Motor Torque: 0.36 ft-lbs
Final Torque: 8.54 ft-lbs
Final Power: 2368 watts (3.2 HP)

Differential Ratio: 1
Transmission Ratio: 8.382
Other Ratio: 1
Spur Tooth Count: 57
Pinion Tooth Count: 26
Total Voltage: 22.2
Motor KV: 1500
Tire Diameter (inches): 6.88
Tire Ballooning (inches): .5
Motor Current Draw: 80
Motor coil Ω: 0
Spur/Pinion Ratio: 2.19 : 1
Total Ratio: 18.37592 : 1
Tire Circumference (inches): 24.76 inches (628.8 mm)
Total Motor Speed: 33300 RPM
Vehicle Speed: 42.48 mph (68.24 km/h)
Estimated Adjusted Speed: 40 mph (64 km/h) - 6% loss
Effective KV Value: 1500
KT constant: 0.9 oz-in/A
Motor Torque: 0.38 ft-lbs
Final Torque: 6.9 ft-lbs
Final Power: 1776 watts (2.4 HP)


Differential Ratio: 1
Transmission Ratio: 8.382
Other Ratio: 1
Spur Tooth Count: 57
Pinion Tooth Count: 25
Total Voltage: 29.6
Motor KV: 1250
Tire Diameter (inches): 6.88
Tire Ballooning (inches): .5
Motor Current Draw: 80
Motor coil Ω: 0
Spur/Pinion Ratio: 2.28 : 1
Total Ratio: 19.11096 : 1
Tire Circumference (inches): 24.76 inches (628.8 mm)
Total Motor Speed: 37000 RPM
Vehicle Speed: 45.39 mph (72.91 km/h)
Estimated Adjusted Speed: 43 mph (69 km/h) - 6% loss
Effective KV Value: 1250
KT constant: 1.08 oz-in/A
Motor Torque: 0.45 ft-lbs
Final Torque: 8.62 ft-lbs
Final Power: 2368 watts (3.2 HP)

I'd definitely go 8s with the 1521/1y. Lots more torque at the wheels with that gearing. Speedy, those motors are nice and they will get the job done, but they are $65 for a reason. If they get pushed too hard they pop, fizz, etc. You should save your money and get better stuff because you'll be happier in the end. On the other hand, try the outrunner. If it blows up then w/e- it was cheap! :yes:

Pimp

I second that. I tried the 1521 and it struggled to push my 22lb 2WD car. I think the 1527 will be ok. I have a Lehner 2280 and it shifted the FG brushless car ok. The Lehner 2250 which is the same size as the 1521 Neu had to work hard. As the Lehner 2280 is the same size as the Neu 1527 and the 1527 is muti pole motor it should have the torque to propel the car from standstill and still be geared for 50mph on 10S

Mohan

woud a kb45 xl motor make it ?i'd like the same preformance like the baja has with the stock 26cc engine !

Hobbycity sell a 100A hv esc for up to 12s lipo for like 120$ do you guy's think it woud work ?

I don't think the KB45 would be enough if some are saying that the 1521 wouldn't cut it. The Sentilon HV controllers are very nice though. That would be my choice for an "inexpensive" controller. You might want to consider the CC HV110 as well.

My point exactly! You need a motor with plenty of torque to get a heavy vehicle rolling. A smaller motor geared down may do it, but will not be optimum.

Peoples tried to rationalize why electric motors were so overwhelming in comparison to an nitro engine. The truth is that hp is still 750 watts no matter how you look and that torque should affect acceleration but for top speed that main culprit should be real hp and gearing.

The reason you can't it's because nitro engine in reality don't reach anywhere near the claimed hp. A 4 hp motors might in reality put 1.7-1.8 hp on a dyno!

Once you will have paid for a controller able to run realibly your motors and the batts, 500$ motors won't look so expansive.

The issue here is not having enough power or not as even an Feigao XL could push around a Baja5b around at 40-45 mph.

The issue is : "Will it cook doing it?"

Yes, a Kb45 will be able to push around a Baja 5b at 40+ mph but not for long(Read less than a run).

You are trying to push something that is twice as heavy as a e-maxx so i figure that a motor twice as massive than a neu 1515, lehner 1950, hacker b50/c50 or plettenberg big maxximum should do.

I would look at:
Neu 1527 or 2215
Lehner 2280 (2250 a bit on the tight side)
Hacker A60-L
Plettenberg Bolido

Also once you will have paid the battery and the controller to push around a Baja 5b, 300 to 500$ for an high-end brushless motors will look trivial.

For the neu 1521, i believe that it might work but it won't let you enough head room. Meaning you might be able to run on a cool day and cook it on another...

600+ grams brushless motors is a good beginnings for a 1/5 scale. High end brushless motors can sustain about double the power of cheaper one without cooking because they generate half as much heat by hp as they are twice as much efficients(90% vs 80% [Yes 10% is a world of diffrence!].

For the controller, it handle about as much power than a MMM (12s 100 amps is as much power than a 6s 200 amps controller).

Beside it's probably a "cheap" brand so i don't think that it would cut it.

1/5 conversion and cheap don't go hand in hand. Hell it's hard even for an 1/8...

Oppressor, the Sentilon line of controllers are probably better quality than everything else on the Hobby City site. I have used one of those 100A controllers and it was great! As long as the truck is reasonably geared there will be no issues with cogging. They have a large heatsink as well, but mine never got much above ambient. I was using it in my Ofna GTP on 6s with a Neu 1515/1y geared for about 76mph (using mechanical brakes of course). I could light up all 4 tires (foams) at will. :smile:

That's good but it doesn't change the fact that 12s and 100 amp seem too little to me for an 1/5 and 40+ mph...

Well, then I guess an HV110 is in order. :smile: But I don't think he wants to spend that much....

I liked reading this info but was a little tough to follow.
I'm just trying to learn about high power brushless for a 1/5 build I'm starting at the bottom low budget at till I can afford it

Thank you for this subject

Keep us informed and the outcome

OPpressor has nailed it on the head. 1/5 conversion and "budget" do not really go hand in hand. If you want to do the conversion right and actually SAVE yourself a lot of time and money then do it right the first time and use quality parts all the way around. That means something like the Neu 2215 or a Bolido and a MGM esc and ThunderPower Lipos. Those 3 items will put you in the $1500-$1800 range combined. Or you can cut corners and spend $500 and then have to come back and spend the $1800 anyway in a months time. Just my humble opinion. Plus, if you do it right you will be way pleased. Save up and buy one part at a time or something. Then build the baddest Baja anyone has seen. :yipi:

I agree. Better to do it right the first time than to do it twice.

A smaller motor can push it, but as others say, it will get too hot too fast. For something that large, you need torque - and that requires a large motor. I too would look at the 1527 at a minimum, but the 2215 probably would be more optimum.

Once you get your motor choice squared away, use high voltage to keep current levels manageable. Even on 10s, I would expect large current spikes on startup simply because of the size/weight. For something like this, I would like a 200A ESC @ 10s (or 12s), otherwise the ESC will be working hard IMO. I don't think the Sentilon will like this setup unless you can have someone parallel 2 or 3 of the FET boards, but then you are at ~$300. At that point, might as well get an MGM or something. Contact Castle - they might have a recommendation for you (they have a large HV/200A ESC in their special projects page). They may be able to custom build you a super-HV110 by adding one or two more FET PCBs, but that will cost more.

No matter what, pushing a 25lb vehicle to 40mph speeds is not gonna be cheap.

Here is a thread you might to check out if you really want to know what you are getting into: http://www.hpibajaforum.com/forum/sh...ad.php?t=13998

He could use a Jeti SPIN200? I do have 3 of them :lol:.