Would a wide dragster type body fit on your 1/10th? Plenty of downforce with those bodies.

It may fit. I am really happy with the lola body. I will use some fuel tubing as a shock limilter, and add some preload clips to stiffen it up. I need to find a larger area to run, as the car had more than 75 to give, just ran out of road! I have a feeling that on a calm day it should do 80.

I have not read this entire thread, but I can tell you that 6S with a 1512 will not be enough to hit 100 mph. My TC4 (126 mph) would not break 94 mph with a 1512 on 6S no matter what I tried. I went to a 1515 on 12S and BINGO, 108 mph on the first wound out run.

Also, stock bodies have major problems above 90 mph.

What you will find is 80 mph is not hard to hit with modern motors and packs. 90 is tougher to hit and requires actual engineering to achieve. 100 mph is an order of magnitude harder and requires some significant effort and aerodynamic R&D. 120 is EXTREMELY difficult to hit! That will require well over 3000 watts, and some crazy tires (Personally I like BSR radials). Oh, to break 100 you will need at least 1300 feet, 800 feet to accellerate, and 500 feet to stop. Radio range fast becomes an issue as well as line of sight.

You guys here on RC-Monster are at an advantage because you are already used to running big power systems. I am glad to know there are top speed guys here.

Matt

Mod Man is the mac daddy of high power, exotic, and wild RC related toys. :D

Take a look at his last high speed car project.

Hi Matt :)

A few pics.

Oh, top speed is crazy expensive! I bet it costs me around $20 for every full throttle run when you consider pack wear (I toast packs even on 12S), tire wear, mechanical wear overall, and the occasional encounter with nature. :mdr:

Matt

Hey Aragon! Dude, fancy seeing you here!

I am not trying to hijack this thread, though. Just very excited to see other top speed guys pushing for triple digits.

Matt

You will notice I mentioned hitting 115 on 6S in that thread. That was a reading from a VSM. Apparently I had alot of wheelspin because I finally got a radar gun and found my actual top speed on 6S was 94.

Matt

Holly #!@@!$&%!! Thats a serious speed setup you have there. Whats the top speed you have hit with that?

Where do you run that thing at those kinds of speeds. I cant find a parking lot big enough and smooth enough to do much over 70. I just run out of room. Any of the lots that are big enough arent anywhere smooth enough.

Hey Man! I am up in McHenry! You ough to swing by this summer and check things out.

I run on the street outside my neighborhood (a stone's throw from my house). The street is 1500 feet long, straight and pretty smooth.

I have seen 108 mph on the radar gun and 126 on my VSM. However, with the current setup and gearing, I have not had it full throttle. I run out of road (or nerve) at that magic 108 mph mark. Typically the Eagle Tree shows 80% throttle at 108 mph and 3600 watts. Oh, it accellerates with an innitial burst of over 2 Gs and a continuous 1.3 Gs to 100 mph. It actually accellerates like a top fueler. I cannot believe teh stock FT TC4 diffs and gears tolerate it!

It is geared at 1.9 to one. The wheels spin at nearly 40,000 RPM at full throttle!

On one run, the radar registered 108mph while the VSM registered 140 mph of wheel spin!

You gotta love brushless power!

Oh, I have a vid of it running 90 mph on you tube. You can search under "90mph RC car". The car was no where near its current setup when that was shot. But, you will see it run and you will see my street.

Matt

Dude, wow. That things got more gadgets bolted to it than a F1 car....

I read through that thread a while back. That is a crazy car. One of my favourite RC cars of all time. I couldn't find the video on youtube though. Any direct links?

http://www.youtube.com/watch?v=fphhgmQqOQ8

This is with a Hacker C40 12T on 7S, stock FT TC4 with a Stratus body. It ran 88 to 90 mph consistantly. 0 to 80 in 2 seconds.

Matt

I saw that but didn't think it was yours because of the body. You need to make a new video with the new body. Actually you probably don't cause you can only see the car in the video for a fraction of a second as it flies past.

The only parts left from the car in that video are the diffs and suspension. Every other part has been changed. Heck even the transmitter has been modded.

Matt

I am curious, why would say this when Nic Case did his 134mph run on a 1509 with 8S in a TC3?? Obviously the power from a 1512 is more then enough to hit 100!!

Nic is a good friend of mine. We have gone over this subject for many hours on the phone. He really lucked out with that setup! Even he says that. He had the sweet spot found for that motor and power system. Since then, he has not been able to duplicate that run! This year, after and entire year of R&D, his top speed was 126 mph. He went all the way up to a 1521 on 12S and still could not break that.

When we talked about S count, we both found that 6S seemed to be good for 90mph (we both went down that road), but 8S or higher was needed to break 100. Now, bear in mind, top speed is a funny thing. Nic also held (still holds?) the world record in drag racing running only 5S (I believe 114 mph in 132 feet). But, that car does not want to wind out more than the 132 feet.

This is such a funny hobby to mess with. I can tell you that a 1512 on 6S is capable of some high speeds. You may hit the perfect sweet spot. But, that is hard to do. I put hundreds of runs on my car with various setups (motors, chassis, suspension, gearing, lipos, ESCs, bodies, etc, etc, etc) and found that most changes netted a loss of speed. So, I wouls change that back and try something else. When I did make progress, it was one MPH at a time. Be prepared for ALOT of R&D.

Oh, Nic also ran his own hand made body with a super low CD for that car. That seems to be the single most important thing other than perfectly matching the motor to the pack to the gearing to the tires.

You will get there. It will take alot of time, though. That is the fun of this!

Matt

Wow, quite a few posts here while I was away!

ModMan, I'm glad you're here. This is my first foray into really high speeds, so the experiences from someone who's done it will be nice to have!

Your vehicle is probably a lot lighter than mine is going to be. The Ultra GTP is simply a 1/8 scale buggy modified for onroad use. I can see this thing weighing around 8lbs (128oz) RTR. TBH: I think 90-100mph would still be fun to see. I would like to hit really high speeds every now and then, but I will probably also be using it in parking lots and such for fun. From your thread, it looks like you need to make this specifically for high speed use only if you're really serious about it. Given that fact, I probably won't hit the high speeds I was hoping for (~130-140mph) since this will be doing double duty (playing and high speed runs). Plus, it sounds like this project will get VERY expensive VERY quickly if I try to go crazy.

After having the vehicle stripped down, I am pretty sure I will be using 10S (the most my charger is capable of), a 1515 or 1521 motor, probably the CC HV ESC, mechanical brakes, and the two speed tranny. I'll have two sets of pinion gears; one for the high speed runs, and one for more normal usage. I'll also have two bodies for the same reason. I'm thinking of making the high speed body modeled after yours, except made of 1/16-1/8" thick lexan for workability.

Anyway, I appreciate your input! Thanks!

Just the start of the pictures of this project. Not much to see here really. All I've done is strip all the nitro stuff off it and did a little modding to the brake area...

http://scriptasylum.com/forumpics/ultra_gtp_1.jpg

It all looks very good!

A couple things for you;

#1 I would just run it single speed. A 1515 or 1521 on 10S will be plenty of power to run without a two speed. Also, a two speed will tend to break the tires loose when it shifts. You will find that wheel spin management is critical with this and a two speed make wheel spin tough to control.

#2 I bet you can get your car to run solid 90 mph while geared for all around running with a 1515 on 10S. I would setup everything for 90 mph and move up from there.

Another thing to consider is, 100 mph is nearly twice as hard on the car as 85 to 90 mph. I know the numbers show that it should only add about 30% to 40% more drag. But, trust me, moving up 10mph is a huge thing. That is why I say to shoot for 90 first. If you shoot for 100 right off the bat, you are almost surely going to ruin alot of equipment and get very frustrated very quickly. However, 90 is not too hard to hit with the caliber equipment you are running and will really make you smile!

Also, most "Standard" RC tires will take 90 mph, but not 100. That is another reason to shoot for 90 first. You can move it up a bit at a time to the magin tripple digits soon enough.

Wait till you pull the trigger on that beast. It is like nothing else in the world. My top speed car is the only RC car I have (RC anything I have) that can draw this statement out of me "OK Honey, can you wait? I will be therer after this run!!"

Seriously, I cannot tell you what is was like when I got my car dialed. To give you an idea of the power, I gave it 40% throttle in front of my house as a sort of top fueller run and this is what happened; I pulled the throttle (again 40% throttle) from a dead stop. The tires (4wd) instantly broke loose and smoked (yes I said SMOKED) all the way down my street leaving long black marks down the pavement. The car accellerated like a freaking nitro burning blown funnycar. Then at about 80 mph or so, one tire shredded (Kevlar BSR radial tire). When the car came to a stop, one tires was blown, the other three were pretty worn, all the tires were too hot to touch, and there was tire dust and debris all over the inside of the body!

My wife was standing there and all she said was WOW! That thing is dangerous!

ABSOLUTELY!

My advice is GO FOR IT! Yes it is expensive (like nothing else RC you have run, no doubt). But, it is well worth it.

Matt

Here is my modded TX for top speed use. The steering throw is increaed 3X for finer control and the antenna is a 9db gain unit for longer range. I get 1500 feet out of this setup.

I do not mean to hijack this thread, though. Thsi is not my build up.

I am more than willing to answer questions, though. If you would like me to start my own thread, I will.

Matt

Thanks for the input!

I'll probably pick up the single speed eventually, but the two-speed kit is ~100 alone, so I got the RTR. It was more $$$, but I also got a body (for just playing around), servos, and radio (I won't be using an AM radio for anything BL, but maybe for something else). I figure I can get some cash back from the silly .28 engine and other nitro crap on eBay. :smile:

I already thought about the BL torque when shifting, but was hoping that if I dialed down the ESC start power (or whatever it would be called), it would help with that. It should also minimize the off-the-line power for less tire spin. Plus, I plan to use the exponential throttle function of my radio to give me a little more off-the-line control (hopefully).

I was concerned that by gearing so high, that the ESC would have trouble getting rotor position at start. Hence another reason for the 2 speed.

We'll see how things go as I build this up.

Cool!

I have never had any startup hesitation with my car. I have run both 1512 and 1515 with a HV110. No startup issues at all and that is geared at 1.9 to 1 (motor to wheel ratio). It is funny, my motor pinion is actually about 50% bigger than the spur!

Matt

Love the transmitter dude... gear reduction?.. :)

Belt drive, 16 tooth pinion, 48 tooth spur. :)

Matt

That is looking good brian. Can't wait to see the top speed figures. Mod man that radio is almost as crazy as your car.

Wow, I was just looking at an f1 car and a pan car in a magazine. I was thinking higher speeds but not this high. Probably 60-70 just for fun in a parking lot. Now I am kind of think more 85-90. I think the pan car, not sure its called that, like the robotronic scalpel was 2wd,(no go) but the f1 was awd. I also like over powered drifting. Should be cool. I like just reading the info you guys post.

In case anyone is interested: http://cgi.ebay.com/ws/eBayISAPI.dll...MESE:IT&ih=013

Your roller looks nice, Brian. Looks a lot like my X1-CR chassis. I'm wondering if I'd be able to do a direct transplant of my buggy conversion into one of these...

I am looking at the same car and the same conversion but I just want 60mph with bullet acceleration. Any suggestions?

60 mph is easy. You could go with a Neu 1512 on 5 or 6S and hit that while still being driveable. If you are planning on running off road tires you will have problems, though. Make sure they are CAed very well.

Matt

Thanks Matt,

That helps alot. I will definitly be running street tires. I am looking to power the beast with two A123 6.6 packs in series. That way I can still use my Mamba Esc. Just got to find a motor I can run. I don't like the idea of endbell popping of motors.

Manual brake with electric conversion
 

How do you retain the use of manual brakes with an electric conversion if you don't want to use the ESC brake function?

Keep the brake servo and parts, use a y cable for 2 channel radio, or hook brake to channel 3 on a 3 channel radio.

Well, I have a Neu 1515 2.5d coming! With a motor kv of 1700, 8s lipo should be a decent match for 50k motor rpm. May go with 9s for 56k rpm, dunno yet. Either way, I'm gonna need a special balancer setup - probably pick up two Commonsenserc balancer units and make a custom 12s balancer. Dual LBA10s is just too much wire for my liking.

Also got another Koolflight UBEC. Keeping the voltage under 40v lets me be able to use the UBEC, otherwise, I'd need a receiver pack or some special regulator design. Technically, I probably could get away with 10s since it's 37v nominal, 42v max, but that's too close to the max input for the UBEC.

I haven't done much progress on the project though. Cut the body out and test-fitted it. Man, that thing is HUGE! The plastic guards don't even come close to touching the sides of the body (at least 1" gap) and there is so much room in front and rear of the chassis that I could easily fit the ESC, Rx, UBEC there. Might put the ESC in back on a custom tray and the Rx/UBEC up front. That should help radio range by keeping the motor wires quite far from the antenna and other low-level signal wires.

Made some fiberglass flat pieces to re-fab the servo tray, but the fleece is a little too flexible I think. So, I'm gonna pick up some glass matting, or a denser cloth and try that. Fleece is nice for curves and such because it stretches in all directions, but not needed for this. Maybe for the battery tray...

Brian, since you're gonna run 8s and have two balancers, are you gonna charge two 4s packs in parallel? If not, I can't imagine all of the cells being in the best balance possible without getting networked balancers (like 2x LBA10).

No, in series. I'm going to take a look at the tolerances between the two and adjust the circuitry as needed. Or, maybe the main IC has some type of syncing input that I can take advantage of - that would make things easier. Either way, I'll "git 'er done". :smile:

The other option would be to just run the UBEC off the first battery pack before the series connection. The wiring would not be as clean but it is an easy way to avoid the over voltage problem.

Brian,

There are some HV BEC out there: http://www.dimensionengineering.com/VHVBEC.htm and http://www.western-robotics.com/herculesHV.html. They also seem a bit smaller than the Koolflight unit.

Yeah, I could do that, but then the packs would be out of balance. If I was going to a higher voltage, I'd just use a linear regulator to bring the V from whatever to ~38v, and then let the UBEC take care of the rest. Or, just use an Rx pack.

And, I'm going to most likely use a single pack, so I'd have to use the balancer taps to get half the pack voltage since there won't be a series connection. Of course, a 9s pack will be a specialty item, but 8s should be good enough.

Even better! I'll keep those in mind if I decide to go higher V. And I don't mind the Koolflight's size really. I have TONS of room on this thing!