yakfish

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I know I'm not the only one on here who tries to make my cars go faster and faster. And there is no such thing as too much speed! There is a similar thread in the nitro on-road section that was great help to me back when I was building my Big Block NTC3! This thread is all about SPEED!!!![>:]

So if you are building something fast show it off here! If you have questions about motors, gearing, tires or whatever ask them here. Lets see your pics and vids of speed runs. This will not be model specific just anything 1/18 scale that is fast. I guess 1/16 will be allowed as well. Some of the mini revo guys think their cars are fast![X(]

So lets get this thread going! How fast can you go?

Here is my brushless RC18T. Its not anything special yet I have only clocked it doing about 60 MPH so far. But I have a few new brushless systems on the way that should make it a real screamer. They should be here on Tuesday.

jermpool

Short video of my mini dt. Not sure how fast it was.

[youtube]http://www.youtube.com/watch?v=PyOWileZexY[/youtube]



It has a Castle Creations Mamba Micro Pro with a 5400kv motor, Since the video I have added a dual disc slipper and aluminum turnbuckles for some strength. Upgraded steering servo with a Hitec 82-mg with slight grinding to the chassis. And I use a 1050 mah 2s lipo. I run 12/80 gearing for normal driving but have a 16 pinion for more speed. Next upgrade I would like to ad metal transmission gears.

flipside7

yakfish

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nice truck jermpool.
I just came across these metal tranny gears on ebay. I don't know what they normally go for but this seems like a pretty descent price for them.
http://cgi.ebay.com/Losi-LOSB1065-Me...item5ae1df7274

RCJuice

This is a cool thread!! Some of you may have seen my recent questions about a micro setup for a high speed car.  Having done a lot of nitro high speed projects in the past, I thought it time to get into a 1/18th high speed setup.  After some advice from guys here on the baord I decided to build a Vendetta.  This will be my first electric car but it should be fun.  I ordered a brand new Vendetta SC that I will be working with, and I've already got sealed bearings, CVD's and ball diffs with metal gears coming for it. I'm now debating between a Mamba setup or a Tekin Mini Rage setup (I'm leaning towards the Mini Rage as it can run 4S).
Also, any recommendations on body, wheel/tire, width setup for this project?  Obviously an open wheel car isn't the best for a high speed project, but I like the liked the length of the SC chassis.  Should I swap over the suspension pieces from a TC version, or do I want the width for stability?
Are there any bigger bodies that will cover the wheels? Maybe a 1/10th pan car body or something?
My favorite basher is my MT2 that I have all set up for on road use, so I am also building a brushless, high speed pass MT2.  I'm addicted to the high speed thing!

yakfish

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Keep us posted on the vendetta build. I am looking forward to seeing how it does on 4s!! I have just modified my battery tray to fit dual 2s batts so all I need now is to put together a series connector and I will have 4s. I actually have enough room now to fit a 3s and a 2s in series but I think I will just try the dual 2s lipos first to see how hot everything gets.

I have some extra 1/10 touring bodies but they are way too big to put on an 1/18. I had thought about mounting one on my 18T but it would just look dumb. I am trying to find a better body for more down force for my speed runs. but I really haven't had any issues yet.

FloridaDude

I had a RC18t with a Mamba 6800kv w/ the micro pro esc and 3s lipo, did 60 until the whole thing caught on fire

yakfish

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My order from hobbypartz just came in today! I bought an ezrun A3 combo with the 7800kv motor, a Tacon 7800kv motor and one of the toro micro brushless sytems. I am very curious to see how the toro micro system works. I tried to find some info on it but nobody knew much if anything about it. I was able to get it mounted in one of my other rc18t chassis and got the deans connectors soldered onto both of the new ESCs befor I needed to leave for work. I will get it programed in the morning and take it for a test run to see how it works.

I will also drop in the new tacon motor into my speed car. I have some tall gearing for it I was able to hit 60 mph with the 4120 kv motor so it should be interesting to see what I can get to with this 7800kv motor with the same gearing. but I will need to keep my eye on the temps I suspect it will get pretty warm with that gearing setup.

I have to say I am very impressed with hobbypartz.com so far. I placed my order just 5 days ago and for $75 shipped I got 2 brushless combos plus an extra motor! they sent me a SHIPPING confirmation email with a couple hours of placing the order too. if these sytems turn out to be any good I will be even more impressed. not bad considering a new castle system would set me back more than $100.

If I have time tomarrow before work I will post up some pics of everything put together and maybe a vid or two of some speed runs.

hyperscorpic

The mini rage and mambe are 180 sized motors. These are too small for the detta and will run hot. Go for 380 sized motors instead. A few good ones are the ammo (cheapest option), the medusa V2 (very hard to find now), and the neu (the best motor money can buy). I've personally used all 3 motors, and I prefer the meduas for bashing. Its more controllable. The neu is a monster and I can still wheelie at 90% throttle (a complete backflip landing on the roof of the detta and sliding on the roof for meters).

If you're going for neu, be prepared to upgrade ur drivetrain (steel gears + ball diffs is a must). Also, go for a 1/10 sized ESC or bigger. I'm running the side winder 1/10 esc in my detta, and the neu is able to draw up enough amps to heat up the esc to 60+ degC, so you'll most likely overheat the mini rage esc if you pair it with a neu. The medusa only managed to warm the ESC. Despite the neu being a shorter can, it is still able to produce a lot more torque than the medusa motor. And since you're getting the SC, you will have more room for a longer neu motor. This will mean a torquey motor, and you can gear much higher. Do make sure your lipos can supply the amount of power the neu needs thou.

Foxy

I have an Xray M18T pro which is currently geared for about 45mph, because I like to get at least one battery through it before I have to wait for it to cool.

It currently sports a Team Orion Vortex micro speed control and motor combo at 7500kv and runs on 3S 1600mAh packs for about 20-30 minutes. Gearing is stock steel spur (I forget how many teeth) and a 10t pinion. It's quite ridiculously fast. I also have the foam monster truck tires for later speed runs, which will push the speed up about another 10% due to the increased diameter. The motor finishes a battery at about 170*F, so if I gear down (for more speed) I'm going to have quite a bit more downtime (waiting for cooling).

I'm still waiting for a body. When that arrives I will post pics and vid.

yakfish

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I messed around a bit today with these new brushless setups. I'm not too impressed with them so far. All were run on 3s.

Actually the Toro Micro system with a 5200kv motor seems to be pretty descent as long as I don't gear it too high. The ESC feels real cheap but it programs easily. I ran it with 60/15 gearing and it did pretty well although it wasn't what I would call fast only about 35-40mph I did run it with my taller pinion (60/26) and there was alot of cogging and it got hot quick so I can't run those gears with that system but for a lower gear set it should be a good little setup. Not too bad for $29!

The Ezrun A3 combo with the 7800kv motor I haven't had much chance to run yet but I did run it with the 60/23 gear set and it got hot real quick so it won't be much good for high speed either.

Then I ran the new 7800kv Tacon motor and it must have been a bad motor. It cooked itself almost as soon as I started to run it with a load. It did just fine with the wheels off the ground and looked like it would be great for some speed runs but when I set it down for a run it took off then bogged real bad and started to smoke. I only got about 30 feet away with it. I took the motor out of the truck and spun it by hand and it was relatively hard to turn the shaft. I might call hobby partz about this one and try out their customer service.

So unfortunantly no good speed runs today. I need to find a motor with more torque than these have and just gear it higher. I want to break the 80+ MPH mark with one of these trucks. I know the chassis is capable of more speed and anyone can hit 65 with it. I want to go faster!

Another side note. The can size of these 7800kv motors is short compared to the 4120kv tacon I already have. It is longer and seems to be able to handle taller geaing better than these higher rpm motors.

Foxy

Yeh, longer cans will be better for what you want to do. But I'm not sure what you're expecting from these motors. Anything that will approach 60mph plus, will not do more than two maybe three passes before you have to wait for it to cool. It's the nature of the beast. High speed needs high power, high power makes lots of heat. Therefore, very high speed=very hot motors. It really is that simple. To be honest though, I'm surprised the toro 5200 on 3s was getting too hot on 15/60 gearing, that sounds about right if you ask me for a decent amount of bashing time at medium speeds.

What kind of temps are we talking about? I let mine get to 175 before I stop and let it cool. Of course geared for 45mph-ish, that takes a while, but the Orion combo I use is known for it's quality, so that may have something to do with it.

Hate to say it, but see my sig...if you are serious about mad speed, you would be well advised, to at least get a top of the range motor. I'm pretty sure these cheap motors really have 2S and not much more than pottering about outside the house in mind. Asking a 1/18th to do that kind of speed is asking a lot of some very small electronics. The faster you go, the more heat you create exponentially. In other words, at 60 mph, maybe you get 10 passes, at 70 you may get 6, at 80, you'd probably only get 1. Think of it in full scale car terms. You need at least 500hp to do 200mph, but you need at least DOUBLE that to do 250mph.

yakfish

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the temp with the toro running 15/60 gearing were pretty good it was when I put the 26/60 gearing in that it got hot.I don't have batteries in my temp gun rggtnnow so i don'tknow the exact emps but ggoing by how hotitfelI would say around 200 deges. I know what t heat should feel like from checking my nitro engines and these didn't seem quite as hot as when they would run around 250

Foxy

Get your temp gun working, as the difference between 180 and 200 is motor death. The resin that holds the internals of the motor together will start to disintegrate at 190ish. And remember, 180 external temperature of the can is about 200 internally. Try to keep them under 180, this is important. If it was 200, then that is surprisingly hot. Did you at least get a full battery through it before temps got that high? As I mentioned, my Orion is getting up to about 175 before I stop, but that is after a full battery, sometimes a battery and a half (45 mins) depending on ambient temperature (which is generally over 100 degrees at the moment, it's been hot this summer). My motor is a 7500 and I'm running 10/46, but the Xray's gear ratio is 2.5, where I believe the RC18T is 2.0?

Setting the rear ball diff a bit looser (to act as a slipper) can help temps a bit too.

yakfish

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http://www.hobbypartz.com/96m30-car-2848-4300.html
Can anyone give me a reason why this motor would not work in my 18t? I know it is designed for 1/10 but after looking at the dimensions it will fit the space i have for it. It actually isn't much larger around than the stock brushed 370 motors these trucks came with stock. I am thinking with a 1/10 motor I will have to try much harder to over load it! I can use this motor and toss in some 33/54 gearing (after market delrin spur and mini revo pinion) and get some descent speeds out of it. This setup gives me a theoretical top speed of 86.092MPH which is closer to where I want to try and be. Any thoughts?

Foxy

That looks like it should work. Even if the screw holes don't line up you could make your own with some careful drill and tap work. I would suggest that with the gearing you're proposing, it'll pull bursts of 50A on startup. As long as your ESC and batteries can deliver, that may be a good way to go.

RCJuice

Allright guys, after reading these last posts I feel like a complete newb.  I'm still picking my setup for my Vendetta speed project.  I was thinking about going with the Tekin Mini Rage which can handle 4S, and the Tekin 6900KV motor.  If the KV rating converts into RPM's per volt, then wouldn't I want the highest KV rating possible (assuming that it works with my battery/ESC)?
I see the above mentioned Tacon motor is a 4300KV motor.  Is this enough for what I am trying to do? Being a nitro only guy I don't know about the gear ratios on these things, maybe I'm crazy with my plan.  I know that the "bigger is better" theory doesn't always apply, but as long as the motor doesn't overheat and the ESC can take it wouldn't I want to go with the highest KV possible?

yakfish

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what if I just setup the ESC with a lower "punch" setting. That would be less strain on the ESC and battery right? I have the hobbywing 25 amp ESC that is supposed to be for 1/18 scale so I was looking at the ESC's they have for 1/10 and it looks like the one I have is used for 1/10 purposes as well just with an extra fan mounted on top.



I am still a newb too. but it seems that the higher kv rated motors just don't have the torque nessasary to to get up to these high speeds. I have melted two 7800kv motors in the last 2 days. if you don't have your car yet, once you get it you will be able to see how much room you have for different gear combos.

RCJuice

Thanks for the quick reply Yakfish.  What ESC are you running in your build?  I have also been doing a lot of reading on the Ammo 28-35 series of motors (the 3900 and the 5100), do you know anything about these? Everything I read looks good.

yakfish

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I have heard good thing about the ammo brushless sytem but i have never use one so I don't have any experience with it.

Also I ment to post this earlier. this is th gearing calculator that I use. I downloaded it and saved it on my desktop. really easy to use. the rc18 has a 2.5:1 ratio
http://www.rctek.com/miscellaneous/i....html#download

RCJuice

Excellent, thanks again.  Do you know if the Vendetta also has a 2.5:1 ratio?
Also, I have noticed that airplace ESC's are much cheaper than car specific ones. Is this because of the bigger amont of settings available on car ESC's?  Would an airplane one work on a high speed pass only car? Will I have brakes? How do I calculate how many amps my ESC needs to be capable of handling?
Sorry for all the questions but I cna't get enough of this stuff.

hands without shadows

Airplane ESC's have no brakes or reverse and are typically rated for far less amps than car controllers. You could use one in a car. I would read the specs on car ESCs and use their amp ratings if shopping for one.

yakfish

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http://www.voodoorc.com/vendetta-sc
This page says it has a 2.53:1 ratio

Foxy

Guys, let me stress again, if you want to do crazy speed runs, you are going to be pushing the limits of the electronics. Every dollar put into your motor and ESC will be worth it. If you are serious about achieving those speeds you are going to need the best products there are on the market in terms of ESC, motor and batteries. It's that simple. Even my quite expensive Orion Vortex system is prone to high heat at 7500 on 3s and has to be constantly monitored, and I'm not even doing speed runs, I'm quite high geared.

Having done some testing myself lately, I would say 6000kv is probably about optimal in a micro motor on 3s, as a balance of rpm, torque and heat. I can't speak about the larger cans as I haven't tried them.

Above all though, see my signature below. Then refer to another great RC adage. "Speed costs. How fast do you want to go? "

Yakfish, I may have missed that you are using a 25A speed control in an earlier post, but now you've brought it to my attention, I can tell you that it will be tough to hit 80mph with only 25A. You need to be looking at a 40A at least now (minimum!), especially if you have your eye on that slightly bigger motor.

RCJuice

Foxy, thank you for your input. Could you give me a couple suggestions on ESC's to look at seeing as how I am new to the electric scene (I'd prefer 4S capability)? I fully agree with the money spent being worth it on the electrinics and am not afraid of spending some coin, I just need alittel guidance.

Also, do you know how to figure out the necessary amp rating of the ESC I will be using? Is it based off of the mah of the battery pack(s) I'll be using?