How are the Rx8 & T8's holding up?

[TekinTeamMgr]

I'm trying to get a feel of how the car is setup along with how you drive. I'm not saying that a 5s/1700 setup doesn't work by any means.

If however your turning down the power that much I'd suggest other changes or a different motor.

For example since your PC is down to 60% I'd say that you need to gear up a tooth and try reducing power differently. Try turning down your epa's a bit, say 90% to start out. If your car is only 1mph that a nitro car that also leads me to believe you're undergeared which can cause excessive revs and motor heat. This is not good at all and will hurt efficiency.

We're going to be faster than a nitro car. It's "how much" that is key. These motor creat so much torque that if you rev them out they waste energy and get hot.

I agree that a bit heavier than a nitro is ok. It does give me an idea of what we're working with though, and no there is no "weight limit."

The more questions I ask the better advice and guidance I provide you.

I want you to have the best experienec possible.

Please explain what you mean 210 Amps per phase?

Phase are 3, right?

then means: 210 x 3 = 630 Amp?

are also 210Amp continuous or peak?

[TekinTeamMgr]

Worst Case would be a "non warranty" replacement. Those are quite fair priced. We will need to see it to determine the amount of repair.

[Marvin]

Originally Posted by TekinTeamMgr

I'm trying to get a feel of how the car is setup along with how you drive. I'm not saying that a 5s/1700 setup doesn't work by any means.

If however your turning down the power that much I'd suggest other changes or a different motor.

For example since your PC is down to 60% I'd say that you need to gear up a tooth and try reducing power differently. Try turning down your epa's a bit, say 90% to start out. If your car is only 1mph that a nitro car that also leads me to believe you're undergeared which can cause excessive revs and motor heat. This is not good at all and will hurt efficiency.

We're going to be faster than a nitro car. It's "how much" that is key. These motor creat so much torque that if you rev them out they waste energy and get hot.

I agree that a bit heavier than a nitro is ok. It does give me an idea of what we're working with though, and no there is no "weight limit."

The more questions I ask the better advice and guidance I provide you.

I want you to have the best experienec possible.

Would you suggest gearing up to a 16T instead? Only the very fastest nitro cars were quicker than mine, and only by the very end of the main straight. When I said that it was slower top end I meant that at absolute top speed it's slower. Having said that, you seem to suggest that even at WOT it should be faster?

I turned my PC down that far to help efficiency, not because it was uncontrollable (though it has also helped my driving). If you reckon a 1400kV buggy motor would be better, then so be it. I haven't got enough cash at the moment to afford a new motor as well as a slipperential.

Thanks for the quick turn around of the new rotor though! Top service. Just hope they last a little longer this time...

Thanks for the advice so far, I will take heed.

[brushlessboy16]

Alright maybe its just me. but Gearing up and down DOES NOT change motor rpm. I dont get why people keep trying to say that A different pinion will "slow down" your motor. Rpm is based on 2 factors. KV and the ability of your battery to hold voltage under load. Pinions have nothing to do with it- if your packs are not up to par however, a gearing change will equal a slightly lower rpm but moving up a tooth or two will not magically make your motor slow down..


Can any one tell me what rpm range in which the t8 motors are most efficient. I have heard around 28k rpm... can anyone confirm or deny this?

[Marvin]

I don't think anyone was saying that, but if you are geared higher, higher gearing = higher top speed and slower acceleration. I think TekinTeamMgr was suggesting using a larger pinion to help tame the low end a bit, as the acceleration would be reduced.

[SpEEdyBL]

Originally Posted by brushlessboy16

Alright maybe its just me. but Gearing up and down DOES NOT change motor rpm. I dont get why people keep trying to say that A different pinion will "slow down" your motor. Rpm is based on 2 factors. KV and the ability of your battery to hold voltage under load. Pinions have nothing to do with it- if your packs are not up to par however, a gearing change will equal a slightly lower rpm but moving up a tooth or two will not magically make your motor slow down..


Can any one tell me what rpm range in which the t8 motors are most efficient. I have heard around 28k rpm... can anyone confirm or deny this?

Just an FYI, here is how you find loss in rpm. Take voltage/resistance to get your absolute max theoretical current. Then take the no load rpm (kv x voltage) and divide that by abs. max theoretical current and you get rpm loss per amp. (You subtract this from the total no load rpm, not the kv) You will draw more amps when geared higher, therefore you will lose some rpm. You are right that is usually small, but not always. I've tried a 20 tooth with my 1900 and it did not seem nearly as fast as the calculated 49 mph and took forever to get up to speed. At the end of the run, pack was only 110F and motor 140F. 6s with a 14 tooth was just in comparison in terms of speed and power. Although motor temps are usually between 145 and 155 with this setup, its not like its less efficienct. It is making WAY more power with only a small increase in temps. So I would say efficiency is better described on a basis of how your geared and where you are running rather than what the rpm of the motor is. If I tried to go around the track with my 6s and use low throttle, im sure that would heat up more than if ran 4s with higher gearing.

[TekinTeamMgr]

Ok, I'm not gearing for "most efficiency" or a certain rpm range. I gear for laptimes, period.

If you find yourself turning down your system in some fashion you might be better off using the power you have in a different rev range on the chassis. This would be accomplished by a gear change. If the bottom end is to abrupt, gear it up. Electric cars should be faster ALL over the track , not just the bottom end. I've seen more people UNDERGEAR their cars rather than overgear. These motors make an incredible amount of torque and NOT taking advantage of it often shows up in motor heat, and too much current draw.

So grab a few pinions. Make a few laps, make a change. I reccomend doing this BEFORE adjusting punch control. Start with your timing advance at 10, it's a great starting point for nearly EVERY setup.

Gear for laptimes and "driveability" which is how comfortable you are with the car. If you're a smooth driver and require a smoother powerband gear accordingly. If you like your car to have snap all the time you fill find yourself geared lower than most.

[Marvin]

The main thing is that I need to get 20 minutes on the track, for finals. That's why I haven't geared that high, have reduced timing and punch control. I have all the power I need, temps are low, and I can get 20 minutes in a final. I'm not sure how gearing up one tooth will affect that run time, but I'd certainly like to keep it.

[RC-Monster Mike]

If you have good batteries, gearing up will make the power seemingly more abrupt and aggressive - brushless isn't like brushed - brushless torque is only limited by the battery's ability to provide current, so gearing up with powerful batteries will yield stronger acceleration. If it doesn't, your batteries can't keep up. Simple as that. If you want smoother power delivery, then a throttle curve and/or punch control is the answer. I prefer throttle curves, as I find punch control to give my trigger a muddy feeling in the mid range. The better radios have an adjustment called Exponential, which works in a imilar fashion.
The physical construction, quality of materials, etc. will all determine motor efficiency - some do much better than others at partial load(such as the T8 motors, making them ideal for our use). Partial throttle is less efficient than full throttle, but this doesn't make for fast laps usually(unless perhaps you have a large oval). If you are smooth on the throttle, you will see much lower temps(minimizes short amp spikes which are not efficient). If you drove nitro for 10 years and have a habit of pulsing the throttle, practice until you can control yourself - you will see faster lap times and lower temps.
If you are experiencing high temps, it could be one or a few of several factors. Errratic throttle input will increase heat(mentioned above). Lower quality batteries will increase heat(to make the power being asked, the amp draw must increase when the voltage drops, bringing resistance more into play). You could also be over geared or under geared. Over gearing is a more common problem and more likely to cause excessive heat. Poor tire selection can increase heat(similar to under gearing). Poor soldering will cause heat. Low wire quality or too small wire size will cause heat. Poor connectors can cause heat. Heat is indicitive of inefficiency. Cooler is better. If you have excess heat, check the above things and eliminate them one by one until you have ahappy system. :)

[TekinTeamMgr]

Yes try gearing it up! If you find that you aren't on full throttle and or you find you're "not into it" as often you will consume less battery and decrease motor temps! My ENTIRE point! LOL

Try it, let us know.

[Marvin]

Will do. Have ordered a slipperential too. Hopefully all will be here for next meeting, where I can give everything a try.

After reading your post Mike, I've done everything listed, but will try playing with gearing.

My temps are already low all round, which suggests efficiency, though it can't hurt to try.

I actually prefer punch control to throttle curves. I have a DX3R and when I first tried 1/8 BL, I tried using throttle curves (both ways) and just didn't like the feel of it. I don't have a problem with a 'muddy' feeling, I drove nitro!

Originally Posted by galaxy76

Please explain what you mean 210 Amps per phase?

Phase are 3, right?

then means: 210 x 3 = 630 Amp?

are also 210Amp continuous or peak?

Moreover, the BEC is of the type switching?

UPP!!!!

[brushlessboy16]

Originally Posted by TekinTeamMgr

Yes try gearing it up! If you find that you aren't on full throttle and or you find you're "not into it" as often you will consume less battery and decrease motor temps! My ENTIRE point! LOL

Try it, let us know.

Sorry to bring in another MFG but these principals apply to all.


I have an rx8 driving a sensorless castle 2200 (see we can all get along)
Motor temps were in the 170 range after 5 minutes of racing, geared 14/48

esc was at 3leds and batteries were at 120.

Would gearing UP bring motor temperatures down.

Its so hard to troubleshoot. Im just afraid of gearing the car up and unknowingly over heating my motor..

[SpEEdyBL]

14/46 is what I used to run with my castle 2650 in my 8ight, even with 5s and there is no to little increase intemps over an 11 or 12 tooth. With the 2200 which has more torque due to the longer can, you should at least be using a 16 or 17 tooth pinion gear, and you will see why castle motors are generally reputed way too fast for the track.

Once again my tekin 1900 only runs 10 degrees warmer geared 20/46 than geared 14/46 or 16/46.