14.2 second 1/3 mile? (oval)
 

So there's a 1/3 mile oval track about 25min from my house called Lake Geneva Raceway.. ie. http://www.lakegenevaraceway.com/

They've been open for 44 years, but this is the last year. The track will be torn down and houses will be built. I've gone to this track almost every saturday night since I can remember. My dad used to race there as well.

The racetrack decided to try and break the track record which was a 14.9. this past saturday, they had an outlaw sprint run a 14.3 second lap. If I calculated it right, that's ~80mph consistant.. right?

My dad knows the track owners from his racing days, and will talk to them about me running an rc to try and set the record. I think a car that can hit 90mph on the straights w/ a decent it doesn't scrub to much on the corners will easily take the record. I've been looking at a few options, but am not sure which route to take..

something like a 1/8 scale converted to nitro, would greatly improve handling.. I even thought about the SuperRS4, but the belt design worries me, and will limit motor choice without designing/machining alot of complex parts. larger scale also means not just weight, but mass. i'll need to be able to go around the corners at near full speed. the track is banked, but not nearly as much as say a super speedway.

so far, my plan is to go with a TC3 ; again, i've run lots of power through the tc3 before, and had to put alot of money into making it more durable, but I usually bashed it harder than any other rc I've owned. For this attempt, I'd have to be very easy on the throttle, and make sure the car's dialed..

I've got a Mtroniks Monster controller and a feigao 380c-6l that I'll be selling, and buying a Quark 125b. throw in my 540c-9l and 16 cell, and I should have enough power to obtain the record. my worry is handling. I havn't found a decent "large" scale onroad electric, or nitro that can easily be converted to electric.. other than Rotary Rocket's Landmax, but I'm not sure about the weight, especially of the tires. and since i'm not very knowledgable w/ larger scale vehicles, i'm not even sure what body styles would be available.

please, let me hear your opinions. anyone have experience running on a 1:1scale 1/3 mile pavement track? or anything similar? anyone get a 1/8 scale past 80mph before?

also, does any one know if the emoli cells will astroflight 109d's?

didn't know if i should post this here, or the brushless forum.:dft001:

Have you though about lipo? It would be lighter for a run like this.

Hey DualBL (just remembered that's you). It's Nick, right? I'm the same guy as tcolesen over on RCZ.

The Emoli cells will charge up on AF109s. But, the most you can get out of Emolis in a burst is about 60amps, at which point their voltage does not hold too well. Even at 45amps their voltage isn't all that great, but anything under that is fine.

BTW, how'd your last project vehicle come out (was it the MT2?)?

How about converting a Kyosho Evolva 2005 into brushless?
These are 4wd pan cars which 1/8 with the lightest drive train in its class.
A 1940/6 with 5-6 lipos will surely make it fly.
If you are going to attend this project, it will be one of a kind.

I think you need way more power than 16 cells to reach the 80mph. But you won't reach a record with an 80 mph car.. this is an average, so you need to peak to a higher speed as well. Lets say it takes you 2 seconds to get to that speed. meaning less time to do the 1/3rd mile.


you say 14.2 in 1/3rd of a mile, so 42. equals 1 mile. 3600 seconds equals 1 hour, so 3600/42.6=84.5 mph. (again, average)

you are going to need a lot more cells and a perfect flat road to keep it going straight.

I don't want to burst you bubble in what way ever, but i think you need at least an 8S flightpower 3700 pack. They stay above 3.1V@50C discharge peak. which means that one single cell can deliver 573W. So 8 of them can do 8X573W peak. that is a rough 4500 watts of energy. that's more like it, but still i think it will be very hard to get the speed record done.

that in combination with an MGM 24160 would be a nice combo and a 9L won't pull that sled a 2240 would be a nice motor to use.

The problem is, you don't only need speed, but you have got limited time getting to that speed! and that is the reason why you need all that power!

coolhand country, I have indeed thought about lipo.. I own two AF 109d chargers w/ a psu, and have three 2s1p polyquest packs, but have never used them. I'm planning on trying the 16 sub-c's, and if it's too much weight, or not enough voltage, I'll look further into lipo/liion/ect.

tcolesen, thanks for the info.. still not sure on what batts would be best.. but I first have to figure out what vehicle to run, and get it configured, then i can change out batteries/motor later.
the MT2 project is still sitting here.. Andrew at CFR cut me out some test pieces to make sure the critical measurements were on.. they weren't, but only the rear diff didn't line up w/ the center brace. I designed a very small simple part to connect the two, and the design is now finished. the reason it's still sitting, is $. I got quoted ~$300, which isn't bad, but enough for me hold off on that project right now. in the meantime, I had bought a Academy SB Sport V2 4wd buggy to race with. I put the 380c-6l and 8 cells in it, and didn't even get through practice before both front and rear diffs were gone. It's now going to be sold. I went ahead and bought one of Andrew's $25 motor mounts, so I can run the MT2 at least with the stock chassis in the meantime, but have to find all the random parts for it that became scattered around my room during the design phaze :P

captain harlock, I've actually designed a 1/8 nitro converted to electric, but lost my work on that hard drive.. the problem, is I don't own a 1/8 onroad, and I've never even seen one assembled up close. I used the hi-res renders of a Serpent car.. the driveline on these cars are alot more complex than say a 1/10tc.. i guess i could buy/build one, and then get the measurements i need to design a feasable motor mount and chassis..

Serum, I know you know alot more about brushless than I do, but I'm not sure about your power recomendation. I've hit 75mph with a tc3 running a Basic5300 on 12 "sport stick pack" cells, and it was controllable even topped out in a parking lot.. on a prepped and banked track, I don't doubt i would be able to run 70mph around the track w/ the setup i had, and that included 6 of the cells being simply ziptied to the rear bumper. I think a 540c-9L on 16 cells won't have a problem supplying the power. I'm not sure if your familiar w/ Cliff Lett? http://www.rccaraction.com/articles/need_speed.asp His tc3 setup was 14 2400mah subc cells, and a custom brushed motor w/ a 12t armature and stronger magnets.. he hit 96.4mph. I don't see why a 540 9L on 16 cells couldn't run equal to that. I would only run this for about a minute or two at a time, I can and will overgear it. I don't need a tried and true power house, I only need ~1 minute of full power. also, multiple laps can be run, and i don't need to worry about accelleration, as i can be rolling accross the line at 90mph when the clock starts. the way they had the sprint run, he did three warm up laps to get heat in the tires, and get the motor up to temp, then did two "fast laps". first being 14.90 and the second being the new record at 14.3. I'm not saying your wrong, as you said "and that is the reason why you need all that power!", you'd be correct if I had to start from a stand still.

Well, a TC3 is a very good chassis for high speeds or any other 4wd shaft driven touring car. The market is full of them.
Also, there was a person who used a Hacker master controller with a 1920/5 motor and 12 nimh cells and he was able to easily hit 86mph.
With 4s lipos and let's say a 1930/5, you can reach the 90s in an instant.

I really didn't knew it was a rolling start.

I would think a motor with more Kv would be better at top speed. Something like a 7XL, or even just a 7L (dont they have 6XLs?).

Anyways, that, combined with two 3s lipo's (or a 2s and 3s for a total of 5, if the controller doesnt take 6s). That should be well enough to set a record I would think.

Actually, yes, there are 6XL's.

Your best bet would be a converted 1/8 onroad car, such as a Mugen or a Serpent. Keep the 2-speed. Even the nitros can do up to 80mph. Those cars just stick to the track.
I would look into a Serpent.

Left Mugen, right Serpent. And they are huge, 8th scale.

Is there a real reason to use all wheel drive for this? Quick cornering is really not a concern in this application - your only turning left.

Also, you could put more of the batts to the left hand side of the car to improve the centripital forces during cornering, but you'd also have to comp your steering for getting down the straight. How much straight is there on that track? Enough to worry about?

Your going to want really slow steering response - a slight over steer at 90 will spell certain death!

You MAY want to be particulary careful with your aero control at that speed. I'd put adjustable screws at your body attach points to be able to screw your body up/down.

I think this is very interesting (I'm a huge NASCAR fan). I look forward to seeing your results.

Make sure you get this run on video when you make your attempt at the record. I'm sure we all whould love to see it.

what about a nitro 4 tech 3.3?

bp, i think the 9l is a low enough turn. i don't want to run a 10s lipo pack, but at the same time, i don't know if a lower turn motor would have enough torque.. I think a 9L geared right will be just fine.. if it's not.. lower turn, is always a possibility. I'm going w/ what i have right now, as I don't have an unlimited bank to buy multiple motors, ect.

dafni, I'm thinking about it.. seriously..

jt, the reason for 4wd is stability. I've run rwd above 50mph before, and it was alot more nerve racking than a 4wd at the same speeds. I've got a XS3, so exponential steering throttle, ect is possible, and will be used. I've also got a few ideas as far as aero goes.. a full left side wall is what i'm planning at the moment.. similar to to sprints, but I've seen it work wonderfully on 1:1 cars.. when this project gets further under way, I'll explain it better.

jhautz, video is obvious :)

mike, I'm familiar w/ a nitro 4tech, but what's the 3.3?

It's got the new TRX 3.3 engine. 70+ stock I believe. With a pipe, port/polishing, modified crank, ect. It could possible break 85.

RC-Monster Forums > Support Forums > General Electric

lol.. I've never run nitro in my life, and i don't think i want to start by trying 90mph... btw, your not by any chance the same person as "pedeforever" from maxxtraxx are you?

then how are you going to handle brushlesss man:026: bl is wayy crazyer

Nope, not me. I'm squeeforever there to :p. Yea, if you were to attempt this, I think nitro might be easier.

it's not that i can't drive a nitro car.. i've driven friends' ntc3, rc10gt, tmaxx, and xxx-nts' before.. it's the fact i know next to NOTHING about nitro, and don't plan on ever running nitro.. I've got a few years of brushless experience, and like experimenting w/ bl power more than learning nitro from scratch.

Yea. Only thing is cost with the brushless...

In the long run its way cheaper than nitro.

A4DTM, 1/8 scale on road machines are your ultimate choice.
Either Mugen MRX-4, the Serpent or the Evolva2005( best of the three) would fly over 100mph using nitro .21-.28 engines. With a Lehner 1940/6-7 motor and 6-8 lipos the car will cry.

ok, I got most of my stuff up for sale, but it needs to go fast, because I found out Saturday that October 1st is the last day an attempt can be made.. there's no for sale forum here, but pm me if anyones interested in:

Academy SB Sport V2

Two Reedy Quasar Pro Chargers

Two Reedy Pulse R Modifieds (10t and 11t)

Novak EVX

Traxxas Sledgehammer(?)
Tamiya Grasshopper
Kyosho or Traxxas 2wd truck or buggy (the Traxxas Ruslter's steering bellcranks fit it, but I was told Traxxas and Kyosho had VERY similar parts, so it could be either brand.)

Ofna Hyper7pro Needs few parts to become a roller. ie. front universal, servo tray, diff cases, any nitro specific parts)

Bolink 1/8 scale Corvette Stingray body


as far as vehicle, I've decided to go with an XR8. http://www.rctech.net/forum/showthre...9&page=1&pp=30
rc union has them for $288. http://www.rc-union.com/product_info...oducts_id=6087

what batteries would you guys recomend for around 20 volts? I'm guessing I'll need around at least 60amps continuous? motor's a 9L. The batts need to be compatible with Astroflight 109d's, and I also don't know much about balancing.. someone direct me towards a proven setup. thanks.

PM me for prices.

You kinda have to choose between 5s Lipo and 6s. That's 18.5v vs. 22.2v. 5s Lipo would be easier to do since there are more (cheaper) 5s balancers out there. Here's a balancer I just ordered last night:
http://home.comcast.net/~truerc/Charge/chargers.htm (Smart Balancer and Guard 505). At $30 that can do 5s Lipo with a 300ma drain rate, it's a steal. However, you can only charge at up to 3amps when the balancer is connected to the charger, so charging at a higher rate will need to be done with the charger hooked up to the battery, and the balancer hooked up to the taps on the battery.

True RC has some batteries that would be possible choices (and they're really inexpensive). Look here:
http://home.comcast.net/~truerc/custompack.htm
The last battery on the page would work well for you. The weight of that battery is about 200grams less than 16 NiMh cells. Although it says that the batteries aren't in stock, they have the cells, so you might just need to email them about making the 5s 8000mah pack.

make sure to get alot of downforce on that car or at that speed the car will fly i recamend a pancar body with a wing fited on the front so it wont flip and reduce the rotating mass as much as posible to keep your hopes up here is a vid http://www.radiocontrolzone.com/cars/video.asp it is at the bottom of the page don't make his mistake and not have enough downforce in the front and gut that thing down take off anything u don't need like the bumper and roll bar upgrade the bearings put on lipos to save more wait and bring extra parts incase it crashes

http://img126.imageshack.us/img126/4760/xr81yy.jpg
http://img146.imageshack.us/img146/9999/xr82tk.jpg

hopefully it'll be here by saturday/monday at the latest.

I've been wondering what happened to that MT2 project! The design was awesome! Shame on you for not updating the threads to tell us that you put it on hold. :019: j/k It's a shame that truck never got built. It would have been sweet.

well time for the bad news... i talked w/ the track owner saturday night, and he said that the driver must be in the car.. so that ruins that plan.. the cars in transit to me, and I'm still gonna convert it, and we'll see when it's done if he'll let me run it on the track on a day it's closed or something, just for kicks.

i talked w/ the track owner saturday night, and he said that the driver must be in the car.. so that ruins that plan.. the cars in transit to me, and I'm still gonna convert it, and we'll see when it's done if he'll let me run it on the track on a day it's closed or something, just for kicks.

but now two dilemas. 1, where/how to mount batteries. and 2, what do you guys think about the mechanical brake?

http://img150.imageshack.us/img150/6793/img0562dp7.jpg
http://img150.imageshack.us/img150/5279/img0557wo3.jpg
http://img153.imageshack.us/img153/985/img0556ud6.jpg

there's not much space between where the motor would sit, and the mid belt pulley. about 4" max. I'd have to stack the cells or make one big "brick"..
I'm was planning on the TrueRC 18.5V 5S2P 8000mAh packs that but they're mm suggested, but they're 5.7" in length.
what are your guys ideas to re-arange the chassis to hold the pack.. or other battery options? I think it would be possible to move the motor above the spur shaft, but I'm not sure if a body would even fit then.. and i'd rather have a REAL low cg.

the second problem, the motor hits the mechanical brake. I was hoping to keep the mechanical brake to keep stress off the controller. I'm not sure how the dia of the 540c compares to other motors in this range, and may want to try a different motor in the future.. pletty big maxx, or lehner 19xx's? larger or smaller in dia?
i havn't tried to figure it out yet, but w/ my 14t, there's quite a big gap. it looks like 17/18t would be needed to touch the spur gear. I'm not sure if that'll be to high of a gear ratio.

i'll start planning/designing tommorow night. thanks for any suggestion.

If your going for speed runs, Id dump the mechanical brake and save the weight of the servo and the mechanism. Your not gonna be beaking that much anyway so it probably wouldnt add much load to the controller. you just have to make sure the tranny doesnt have a 1 way in it somwhere that would prevent using the electronic brakes.

The wanderer motors of the same size and wind are smaller in diameter. The same internals, without cooling fins around the can. I dont know about the others.

Have you considered the emoli cells. They would make a nice compact brick and save a ton of weight over sub c's. But the lightest option would still be to find a lipo pack that would fit. Its gonna be hard to find them much shorter though if you want larger capacity cells.

hmm just thought of something. what about two 5s1p packs, one on each side.. the problem I see with that, is that the drive belt isn't in the center, and that would push the weight way to the outside.. almost to the full width of the car..
then again, they are alot lighter.. but then i could mount the rest of the elctronics realy low on the chassis in the center.

the front has a one way in it..
i'm not familiar w/ nitro, oneways, and or 1/8 onroad drivetrains.. the rear doesn't seem like a differential. if I hold the center drive train, and spin one tire, it's very tight, but opposite wheel doesn't move..
it all seems very weird to me, having so many drivetrain changes i'm not used to at once. how could I lock the 2speed to the smaller spur gear? it spins and does nothing.. so centrifical*?
the drivetrain also seems very tight. not sure if something's binding or not.

I bought the car as a display model, with the car, and nothing else. i don't even have an instruction manual! =\. the discount was worth it imho. I'll probably rebuild the car completely before I run it to check the drivetrain.

If you come up with a way to run the two speed. I would keep the mechanical brakes. It would requre a pinion make with two gears. I have seen a few around. You would have reverse then though. But who needs reverse if you can go 90mph forward.

I'm going to try and keep it as simple as possible.. making my own pinions doesn't follow that rule :)
also, this car has no reverse, and now that I think of it, if I don't lock the 2speed, then there's NO electronic brakes. when the spur spins in reverse, it free spins.. if I hold the spur in one location, the car will still rolls forward.. like a one-way 2speed..


question time!

I'm looking at two different batteries..

#1:
MaxAmps Lipoly 4200HV 5S2P 18.5V Pack = $184.99
* 4200mah Capacity
* 18.5 Volts
* 34mm X 98mm X 62mm
* Rated at 60 Amp Constant Discharge
* Rated at 80 Amp Burst for 10 seconds
* 495 grams
* Comes with Standard Taps
* TP Taps Optional

#2
TrueRC 5S1P 18.5V 4000mAh = $85
* 4000mAh Capacity
* 18.5 Volts
* 27mm X 145mm X 50mm
* Rated at 40 Amp Constant Discharge
* Rated at 60 Amp Burst
* 425 grams
* TP Taps Optional

I'll be running two packs in parallel, so the maxamps would be 120a/160a discharge, the truerc's would be 80a/120a discharge. the truerc's would also have lower cg, and be lighter. Do you guys think 80a constant, 120 burst would be ok? I'm thinking it would, but want your insight.

also, will the ThunderPower TP205 2s-5s balancer work with my 109d's?

if you guys think I'll be ok, I'll go ahead and get the truerc's. then I need a ubec, and li-saver.. anything else I'm missing?

very simple motor mount design completed:
http://img223.imageshack.us/img223/1...rmount1ey6.jpg
http://img223.imageshack.us/img223/2...rmount2ih6.jpg

only one other part needs to be designed for a completed conversion.. battery mounts. I've decided to make "trays" that attach to the center of the chassis under where the gas tank was, and span along the sides between the tires.. updates as I get em :)

Why not just run a TrueRC 5S2P pack? Or if you want to run 2 packs instead, a 3S2P pack and a 2S2P pack in series. Either way, its the same amount of cells.

I'm mounting the batteries on the sides of the chassis. I need the weight to be even :rolleyes: .. which brings up my next question..

which keeps seperate packs in balance w/ eachother? in series or parallel? ie, if I run these packs in paralell, can I charge them in parallel? will the balancer work like this? sorry, never used my lipos :o


edit:
looks like I'm done for the night. I'm going to try and meet up with a buddy tommorow to try and get some of it cut.
http://img224.imageshack.us/img224/8451/assem1xf3.jpg

If you have two 5S1P packs and want to run them in parallel, you should prep them first by fully balance-charging both packs individually. This means taking one pack, hooking up a balancer capable of balancing while charging (active balancer), then charging the pack fully. Repeat with the second pack.
The balancer will only work on 1P of batteries at a time. In a 2P (or more P) pack, you need two or more balancer leads (taps); one for each P.
Once both packs are fully balance-charged, you can use them in parallel in the vehicle and charge them in parallel. I would, for safety's sake, re-balance them (using the method from above) after about 5-10 charges. This is really just to make sure they stay in balance, which will help prevent damage from over-discharge or over-charging.
I actually have two new 4S1P 4000mah TrueRC 10C packs that I will be running in parallel, but it'll be a few weeks before I can get this done so I can't offer any pics or results at this point. I will balance-charge both packs fully, then wire them in parallel in the vehicle for 4S2P 8000mah. To charge them, I'll leave them in parallel and charge on my ICE at up to 8A (1C of 8000mah).

eh now that I think about it, I'll charge them seperately, but run them in parallel in the car.. so I'll be able to re-balance every charge. so can i assume 80a constant is sufficient?

80amps continuous would be enough for the batteries in that car.

*Update*

Nick is pretty busy so I thought that I would help out and update the post. The proto type pieces are going to be machined out of 6061 this week and the final pieces will be done out of 7075. This is a pretty crazy project and can't wait to see it complete.

Thanks,
-Joe