I have a question for the guys who know.
 

Would a smaller motor pushing a lower gear with a higher kv be easier on the esc than a big motor pushing a taller gear. Example a castle 2650 compared to a castle 2200 on equal voltage geared differently for same speed. Reason I am asking is the 1.5 d motor I have is extremly torquey and I it was causing traction problems when I got on it for the speed runs. I was thinking a smaller less torque motor would be better and just spin it faster to make up for the gear drop. I am amazed how small some of the motors are in some of those 100mph + cars. Those guys couldnt believe how big my motor was in my truck. They said I was probably putting out 5 hp in that thing. To bad I couldnt use all the power.

I wouldn't think so. Higher RPM makes the controller work harder, outputting more pulses to the motor. The fact that to go a certain speed the vehicle requires a certain amount of power, coupled with the higher RPM would be a step in the wrong direction. You would also run a higher risk of burning the motor. Though if the vehicle were lighter because of it, you might see a few more MPH from that power. I'm not sure if it would help so much with the torque, either, because although the smaller motor has less it would just be multiplied by the lower gearing.

I thought excessive load make he controller work harder like when you jump on it fom a dead stop. Doesnt the excessive amp spike what burns esc's. Isnt that why they rate them on how many amps they can take. Seem like a smaller motor spinning higher with lower gears (Higher numerically) would require less amps.Then a bigger motor spinning slower with a taller gear IDK???. I dont think heat would be an issue because it not going to be a long drawn out race track. I am talking 15 second run at the most.

You can never get the same power with less current given a voltage source unless you sustantally increase the efficiency. Power is volts x amps x efficiency. So any motor regardless of size, kv or number of poles drawing less amps to make the same power is somewhat impossible when motors these days are almost 90% efficient and don't go much higher than that.

You can however, use a smaller motor to draw less current at the beginning and have it draw current afterward when power actually matters.

I can't say for your exact case, but I have 2 very close in speed setups that I use in my Rustler. The first one is the MM and the 7700 Kv motor geared 13.95:1 running 3S2P A123 it's geared for about 58 mph.

The other setup is using 4S4P A123 and a 3300Kv motor geared 8:1 which is about 57 mph.

The 3300 Kv motor is harder to keep the front end down when you first start taking off, but the 7700 seems to really come alive at about 3/4 throttle. If I had the chassis sorted a little better I think the 7700 would be a little easier to control. Its a bit of an extreme spread between the 3300 and the 7700 but both setups run the same speed and it gets real hard for me to control anyway.

Hope this helps.

Jeff

My issue is I am making so much power that when I am on it and the tires just spin causing me to loose control. What good is that? I think if I used a higher kv, smaller less torque motor with higher numerically gearing I would be faster because I can control the car better better. Even with 100 % punch control with my setup it still will wheely if I hit it at a roll. My question is will the esc be able to handle the smaller higher kv less torque higer rpm setup better and be less likely to burn the esc or would it be about the same with the bigger motor less kv more torque motor. What I am trying to get at is you can have all the power in the world but if you cant put it too the ground without spinning the tires and going straight down the track what good is it.

Seems to me
 

Seems to me that if you have less torque you would have less of a load, but would it have enough to[ end power to get you up to speed considering the short distance you are traveling on a drag strip? Plus your wheel spin seems more related to your weight being too lite. Thats why they use such extreme down force on drag strips to get the power to the ground with less wheel spin. You could also use wheel warmers, which will give you better traction from the starting line. Your lucky you got to see some of the reall speedsters out there, and hopefully you learned a few more ideas from their setups.

I use smaller higher kv motors for my speed cars. Lower kv and/or bigger motor is just way too much torque and no way able to control of the line. Sure you can gear it high enough to control the torque, but pay for it by adding more time in your E.T. I have spend a bunch of mula on different motors and different cars to come to that conclusion. I've blown up countless tires just at launch with the overdose of torque. Most blow tires during a run and not within the first few feet. You need to find the happy medium of power to weight ratio in your particular car. In my case it's around 200-300W per LBS.
You can use startup power, higher timing, current limiter to control torque, throttle curves, etc, but a smaller higher kv motor is a whole lot easier to deal with. Totally different setup compared to offroad racing.
As in if it's easier on an ESC, it can be up to a point.

I will lengthen my distance to get to the traps. Downforce only works if you can get to the speed to utilize it. I am not even getting to those speeds before I loose traction. I am sure if I had a stickier rubber tire that would not blow apart at speed it would be better. My truck weigh ~11 pounds and heavier then 90% of the other vehicles out there. But My motor is able to put out more torque and power than 90% of the other cars also. My bigger diameter tires should have alot more traction than a little > 3" tires the other cars are running also. Bigger = more contact on the ground.

As an example is a f1 car has very little torque lots of hp and still can go 240 mph if given enough room to get up to speed. Where a dragster can get past that speed in less than a 1/4 mile and has extreme torque but if it has no traction it isn't going anywhere. I am thinking for speed runs a smaller castle 1512 2650 motor would be better than a neu 1515 1.5 d 2700 kv motor. Especially in traction limited circumstances. What good is all that power if I have to let off because I am going through through the finish line sideways .

I know what you mean, about having too much power to use, up until recently I rarely made it through a battery pack without breaking something. It usually goes ok until I really start picking up speed then it wheelies and I would end up cartwheeling to a stop.

As far as running a phyisically smaller motor I don't know if that would work, or rather what the smallest size you can use without risking damage to the controller. I have been trying to find the info that said that the MMM wouldn't be warrantied if used with a motor smaller than 70mm in length on a 36mm motor. I think this would be due to saturating the motor at that point the windings would act as a short and damage the ESC. I asked about this but for the MMP but haven't gotten an answer yet. I know the 2200 and 2650are too big and the 4600-9000 are not sutiable for 6S.

Can you use a traction compound like Koford? It might suck up some power but since you are way overboard on power it shouldn't be a problem.

I know you said that you killed at least 2 (was it 3?) MMM's on your last runs. When did they let go at the line? I wasn't real clear on that.

Jeff

On the traction issue, wider tires would help alot (re: F1 cars for example), and I doubt they would hurt the aerodynamics too much either, all things concidered. Only problem with that is finding something the same diameter as you have now & then some foams wide enough. 'Tis a tricky game making stuff go faster than it was designed to & remain controllable/ reliable....

Tricky
 

Tricky game in deed. Its games like these that run the fine line between frustrating and exciting. On one hand it is exciting to try out different things that may possibly get you over the hump of your goal, and on the other hand it is hellishly frustrating when you burn up one after another components trying to reach that lofty goal. Still the experiences gained are positive and hopefully cherished memories that one can carry throughout his or her life.

Whats really cool is living these experiences through Beau's inter active hands on efforts, which save us all some money as we learn from his mistakes and misfortunes. Sorry River but its true. I to hope to get my project up and running at some point and I am learning heaps of info through your project, and all it has cost me is time reading your posts and sharing opinions with you from my perspective. How cool is that???

You can always try using a XL 2 pole motor if the 1512 size motor doesn't cut it. Use drag brakes and than brakes to come to a complete stop. Much easier on the ESC.

I burnt 1 esc up during or after a run not sure when it went. 1 didnt work right out of the box and the third burt up testing it for about 3 minute in the pits.I am not sure why they let go the high gearing or the hitting the breaks after the run. I had them set at 25% breaking. As far as running smaller motors with a mmm esc alot of guys were doing it. Nic Case put one in a sedan for testing and ran 129 mph on 3s one of the fastest mph of the meet. It was amazing he could run it that fast on 3s everybody was wondering wtf! I know for a fact his motors are way smaller in diameter than a 1515 size.

I knew I was going to burn up at least one esc trying to figure out what gearing I could run but hey I only paid like $75 dollars for it on the bay. The new one that never worked I paid full price for,that should get replaced for free. The other one I am not sure about. I think Joe Ford might take care of me since I broke the and hold the current record with their esc. Another thing I learned is suspension set up has alot to do with the way the car or truck runs down the track. I need to fine tune mine and it should help me get down the track in a straight line. I was discussing wider tires in the rear with another racer out there it could help that issue also. Now that myburnt esc's have made my whole truck smell like a ash tray. Is there a way to check the motor as far as resistance to make sure I didnt hurt it? It smells burnt but the whole truck smells that way also.

If it were me.
 

I would strip the entire truck down and clean it up before starting the next phase of your trial and error project. That would really give you teh feeling of starting fresh.

Yea, thats the plan I want to change the bearings in the diffs & lube the trans. Shim up the suspension and make sure nothing is binding. I am going to get rid of the monoblock maybe run 2 3s high c batts to remove some weight and try to get the truck under 10#'s again. As far as being trial and error in my eyes thats whole fun of it. Putting something together that has allready been thought out for you, what fun is that. Anyway there can't be to much error since 81.75mph has never been reach by any maxx truck ever. So I must be doing something right. We all know it can be faster with a little more tweaking.

I'm not into speed runs but I'll put my 2 cents in :mdr:

I would think higher kv motor will give less initial amp draw making it easier on the esc. Being a lighter motor with less amp draw you could use slightly lighter batteries as well. An example would be the novak hv set up, the motor is an amp hog but the esc is only good for 60A (half of the mmm).

The trade off would be less efficiency from the esc at speed due to the high switching rate but your not getting to those speeds much by the sounds of it.

1:1 speed run cars take as much time as they need to get to their terminal speed but with rc your limited buy the radio and or track so it's more of a drag race and any possible weight you can lose is going to help.

I was thinking the same thing. Not sure what my radios distance is capable of.But I could of went farther than I did.