Going for the Land Speed Record in my TC4!

[nitrochubb]

I've Installed a Hv Novak system with 14 cells in the tc4 and have gotten 61mph out of it already at the bp. (Big parking lot!) I'm going to need a different set-up though cause there are about five guys all gunning for the record, three nitro and one brushed motor guy, and the Novak Hv just can't go any faster. The brushed motor guy is promising 70mph this weekend and i can't let that stand. I want to switch to 14.8 lipo's and a 6-turn but i don't have any experince with any other motors/esc's except Novak 5800 and HV. I want 100,000 plus rpm! Umm... Any ideas guys?

[TimisTim]

Alrighty then...get a hacker c40 6S some good bearings from Boca Bearings (I dont know if there are any rated for 100,000rpm's) and a controller that can handle a six cell lipo pack or some other way of getting a little over 20 volts. That is darn close to 100,000rpm's and I would imagine very easily near 100mph.

Now lets talk about how you would drive this :p

Theres alot more to it than just power. Like aerodynamics for one, and lets hope your not trying to use rubber tires with the above setup. Go foams.

[nitrochubb]

How am i go to drive it... Straight hopefully! Using Medial Pro rubber right now in 45 shore. They've held up good to 61 mph so far. I like them cause they don't balloon or wear out much. Do you think 100mph plus (Hopefully) will rip them off? Is that why you suggest foams? What esc should i use?

[nitrochubb]

Can't find c40 6s at hacker web site. I only see c40 6t and no specs on performance. Will the motor handle 20v? What's the kv?

[90MPHTC4]

Well I have the same goal. I have gotten to 61mph using a 10 turn modified motor on 13 cells 5.95:1 final drive on venom tires and wheels and novak super rooster speed control. I had asked the same question about hitting 90 in a tc4. look up my question theres some good info there. Also I did it using no body. Also here is some info I found on the Hacker Motors. http://www.aircraft-world.com/prod_datasheets/hm-C40.htm

[danjoy25]

C40 6turn is 6942RPM/volt and saw somewhere that can handle upto 70,000 RPMS as bearings might fail.

I run a 6turn with a Uforce with 10 cells recently on a drag meet and was very happy. Got beaten on the semis as I forgot that my throttle endpoint was only set to 60 percent.

[nitrochubb]

90mph... How fast have you gotten it up to so far?

[danjoy25]

Not close, can't say but the drag strip was only 40 metres. I guess would be close to 60-70. I read some where the same setup with 11 cells on any Xray TC did around 80+ MPH

[bomb-proof]

you dont need or want 100,000 RPM. You can get to 100mph with 30,000RPm. Go with higher winds, not lower.

[nitrochubb]

30,000 rpm and 100 mph? Please explain how...

[TimisTim]

Well...the higher winds will put out more power to push the car faster and be able to handle the longer gear ratios. Bomb is right, the way to go is lower kv and higher voltage. Look for a hacker 12S (probably 2000rpm/v)and run alot of volts through it. Then gear it to the moon. I think a hacker would handle the rpm's better because the armatures are smaller and have less weight so they might not break a magnet or bearing as easily. Jamie at www.starluckrc.com can order most any motor for you.

I know OptimaMan has an on-road car that he runs 14 volts on carpet with. Has problems with diffs it has so much power. Im sure if he had the room he could hit 70+.

[nitrochubb]

Ya, I burnt up the diffs already too... Speed Kills!

[90MPHTC4]

Right now top speed is right at 75MPH using a brushed motor And 14 3000 Cells. I have looked at running the hacker setup with a uForce seems to be the best way to go. I will be getting some li-po's soon just for the weight advantage. I will probally run somewhere around 20-30 volts. Maybe 3 11.1Volt 20C packs And the Hacker 10T or 12T.maybe even a Nemesis still have not decided. Right now I just want to see how much abuse I can put a brushed setup through before it explodes....lol However I have not destroyed my diffs yet. But rear arms and shock towers are another story. Likes to get airborne around 65-70 MPH.

[bomb-proof]

33v+ on a 9t or a 10t is going to destroy parts, not make power. You will need around a 20 turn motor for something like that.

If I can hit mid 50s with a 15lb monster truck in 1st gear, and still be able to run it all day with no issues....all with a 1900kv motor, looks like you guys are barking up the wrong tree.

You will be heading down a very expensive, very aggrivating road with the set up you are describing. High kv motors draw alot of amps. The more amps, the more the cells cave and lose voltage. So 20 cells will drop to 16 when you start accellerating, but with 20 cell weight. The same set up with a lower kv motor would drop less, allowing you to actually use those cells and make up for the lower RPM with gearing that it will easily pull.

example #1
this is my e-maxx (15lbs) running 26,000RPM and will run all day long at that pace with no heat issues.

E-maxx speed run (http://bomb-proofproducts.com/Mvc-846w.mpg)

[sugs]

90MPHTC4 - The uForce is only rated for 12 cells, and I think some people have tried 14 cells on it max. You'll need to find a different controller.

[kufman]

Bomb is right, the high rpm/v motors are not the way to go. The rotors are only rated up to 60,000 rpm and after that, who knows. Almost all insane speed run cars use between 1500 and 1700 rpm/v motors on like 20 to 24 cells. You have to use the torque. The u-force really isn't a good controller for this. 75 A isn't very high and 12 cells isn't either. You need to look at higher voltage controllers with a current rating around 100A cont. The u-force is good for sedan and 1/10th racing.

[60mphtc4]

i have a tc4 and rigged up a emaxx speed control to have one motor and two packs and its pretty fast

[TheSteve]

Do not exceed 20 volts into the U-Force, you will cook it - maybe not on the first run but it will happen, the power capacitors are only rated 25 volts and you need some safety margin to handle back EMF from the motor.

[krisI.925]

if you just want pure speed then dont pay attention to RPM ratings and what not. you should just be focusing on the wattage mostly, thats what going to give you high speeds not RPM. And of course the more cells the better. But I would suggest not going with anything for brushless in the RC car market as they are very limited in what they can handle. I would look into the Heli-market for stuff. Compared to the power that Helis run on this car stuff is nothing. Logo's usually run on 24+ cells. Iv seen them go up to 36 cell 3300 packs. Couple that with an AXI outrunner motor and what ever ESC. That will get it moving. I think anything above 1700 watts could probably get 10lb a car up to 100mph.

Also for RPM ratings in motors its not the bearings that fail, its the motors. The magnets in them usually break from the armature under the centripital force. The bearings can usually handle that RMP just fine. So looking at 100,000 RPMs is going to be pretty hard to do. I would just get something that runs at an efficiant 20-40k range and hope for the best.

[poconoblmaxx]

"But I would suggest not going with anything for brushless in the RC car market as they are very limited in what they can handle."

lol... :rolleyes:

[chilledoutuk]

steve is that the only thing holding the uforce-75 back then in terms of voltage?

would it not be possible to replace these caps with higher voltage ones with the same capacity?

[bomb-proof]

no, you are opening a can of very expensive worms.

[chilledoutuk]

Calm down mate im sure there are other components in the controller that may not like running higher voltages.

I was just really wondering as to what else may be limiting the voltage you could use on this controller as if it was just the caps then they could have used higher voltage ones and then people could use it for higher voltages.

I personally dont see the need myself to go over 4s lipo for myself.

[90MPHTC4]

The reason i have been looking at the hacker motors is because i talked to one of the tech guys there and told him what i was going to do. He said that he does not recommend that much power but did say they have run under 20 volts to them and where at rpm limit. Also the article in rc touring they used a Xray with 11 Fusion cells and hit 88 MPH wiht a Haker 10t and master series controller on foam tires. However when i talked with the guy from hacker he did say that the don't recommend using more than 12 cells. So there goes my warranty.....lol. I was also looking at the shultz 32 series controller for true speed runs because of the cell cap.

[90MPHTC4]

Also Here is a qoute from Optiman from my post about hitting 90.

Okay, here it is: Use the Kokam 3200 mah 20C discharge cells. Use a Schulze 32.80 and higher controller. Use a UBEC. Now, with the TC4, packaging the cells is the issue - but if you use say 6s lipos stacked on the battery side, you'll have about 20 ounces of batteries (a little off on balance - but not too much). A 6s 3200 Kokam will give out about 2000 watts peak for a brief moment of time. You'll be running 22.2 volts so approx 20 volts and a motor that will hit redline at that speed. If you run a Hacker C40 series, something around 4000 rpm/volt and if you go to the larger motors, you can only go 3000 rpm/volt. With the smaller motors, gear it at around 28/72 and you should be around 90 mph mark.

YOU NEED A GOOD BODY WITH GOOD DOWNFORCE. Otherwise, the car will float and flip like a piece of paper. Good luck!

BTW, I have a TC4, lipos, and have done plenty of speed runs.

[TheSteve]

steve is that the only thing holding the uforce-75 back then in terms of voltage?

would it not be possible to replace these caps with higher voltage ones with the same capacity?

I have never opened a U-Force up to check out the Fets but I would guess they are only rated to 30 volts. Thats pretty much the standard in a ESC that can handle 12 cells. Any increase in voltage is really asking for problems - kinda scary given the cost of the controller.

[OptimaMan]

Okay, here I go again...First of all, with sedan tires, if you want to go 100 mph (not including ballooning), and gearing it to the moon (like 68 spur and 35 pinion) you still need to pull over 62,000 rpm from the motor under load to go 90 mph!!! So, you CAN'T get too slow a motor unless you can truly get massive amounts of voltage into the small space... So, assuming about 25% voltage drop under extreme gearing, wind resistance, etc. we need to target about 80,000 rpm under no load. So, with 22 volts, we need almost 4000 KV. With 14 volts, we need quite a bit of RPM...

So, going back to what I said in my earlier post, it seems to me most logical to stick with a simple 6s pack utilizing Kokam 3200's 20C pack (at the minimum). From what I know, they give the most POWER (watts) per ounce... except for the new 26C from TP that I haven't tried yet. The 6s 3200 pack will fit neatly and balance well. You just need a 3500-4200 kv motor. The U Force can't handle 22.2 volts (actually, a 6s pack peaks around 25.2 volts).

Now, usually for racing, I recommend the smaller rotor motors, but since we're talking max power for brief amount of time, we're going to have to stick to larger motors. I'd take a Basic XL here or a B50 L series or Feigao L, or C50 L series. I like the Basic XL cuz it's the largest motor (rotor and magnet) for the smallest space - there's no dead air or excess aluminum in that motor - but you gotta make sure the mounting screws are nice and short... A Basic XL 4200, XL3600 would fit the bill here. The XL4200 will be beyond redline and could blow up on you rather easily. The XL3600 will also be beyond max, but the voltage drop could keep it just shy of the 65,000 rpm limit. These limitations aren't exactly the "rule". They're guidlines etc. I've had "50,000" motor go beyond 75,000 rpm. I've had 100,000 rpm motors go beyond 120,000 rpm... they just get HOT real fast. Also, some rotors (magnets) are inherently better balanced than others. Some of my brushless motors just don't vibrate or wobble as much as some of my other brushless motors.

Also, foam tires don't really work on streets that have a slight layer of dust on them. At least for me... I stick to rubber tires. Oddly enough, the stock TC4 tires are even better than the nice sticky touring rubber slicks. Perhaps a slight amount of tread pattern actually helps.

6s is my opinion really the MINIMUM for a true speed run on a touring car. If I were gonna join your drag race, I'd show up with 9s or 10s pack and a Basic XL 2000. Gear it 5:1 and I should be in the neighborhood of 90-100 mph... and I could run that over and over again for a good 10 minutes!!!!

My biggest challenge would be where to put 30 ounces of lipos. I can easily stack 6s in the battery tray, but the other 3s would have to sit right about the driveshaft so I would probably fabricate some kind of battery tray to hold all 9 cells in place - 6 cells and 3 cells off set. The would be stuck on to a plate of aluminum that would be bolted in place. Then I would get the UBEC. You probably don't need a super high amp controller - as long as it could handle 100 amp spikes so even a "measly" 32.80 should work just fine. Now, at this speed, you gotta keep the car on the ground.

BODY and WING. Stiff body with bracing if you're creative enough, a nice wing. Good ground effects, maybe not even cut out the wheel wells and cut out the back section to create suction as you drive forward. At 100 mph, it will have quite a big effect. also, keep the body as SHORT as possible - aerodynamic drag is velocity squared times the cross sectional area times coeffeicient of drag. So, have the body actually sitting on the shock towers.

Maybe I'll actually try to go beyond 70... 4s and 4200 takes me faster than I can deal with... but that damn VW beetle body is REALLY slowing me down and making it hard to handle. It's kinda funny when the little kids in the neighborhood think it some cheesy bug and zoom - it screams away pulling a nice dust cloud behind it.

Sorry for the long post.

[nitrochubb]

Some great info guys keep it coming. For the next coupe of weeks i'm going to try to squeeze out a few more mph out of the Novak Hv. I've got a few issues to work out with the car before i bump it up to the LSR (Land Speed Record) setup anyways. If you get a chance to try those 26c from TP OptimaMan and prefer them over the Kokam 3200 20c let me know. I prolly buy which ever ones you've tested to be better :)

[OptimaMan]

Just gear taller. It'll take a big fat emaxx to over 40 mph so taking a TC to "only" 61 doesn't seem right. I believe the motor has plenty of reserve torque so you can gear it like 36/68 and you should be beyond 70 mph.

[nitrochubb]

How can i figure out how much rpm the Novak Hv was pulling to get my car to 61mph?
The FDR is 6.00 and tires are stock...

[OptimaMan]

You gotta do the math...But it's about 47,000 rpm in case you're wondering.

[nitrochubb]

How can i figure out how much rpm the Novak Hv was pulling to get my car to 61mph?
The FDR is 6.00 and tires are stock size...

[tcolesen]

I got ~48,000RPM.