rcguyfpr

iTrader: (52)

Bruce, I m using Reedy with 2.9 FDR. Still 120F after the race.

eR1c

iTrader: (2)

Interesting,
Now, have you tried both motors on the ground (not on an analyzer)? -do they confirm the test results. The reason I ask is that I've noticed that motors that had the highest RPM values on a motor analyzer were not necessarily the best performers when wheels hit the ground.

eR1c

iTrader: (2)

WHAT??? 2.9 FDR!! ...no wonder my car seems slow ...my last race I was at 3.95 ...I think the last heat I swapped pinions and got it down to 3.65 ..but w/ serious cogging issues.


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Lots of good stuff here to keep me busy w/ some tests on my motor. You all know what I'll be doing tomorrow! (I got the day off work). ...i'll post what I find out w/ my motor and getting my FDR to something more reasonable.

rcguyfpr

iTrader: (52)

what chassis?

belewis01

iTrader: (5)

I'm not surprised - I need a little extra punch for when I screw up in the in-field

rcguyfpr

iTrader: (52)

But still not fast enough to catch the 1st guy. Need to find more grip from my PF tires.

eR1c

iTrader: (2)

I am running a 2014 Hobao H4e,
https://www.tqrcracing.com/shop/prod...YaAnIWEALw_wcB

I did quite well w/ it in our TC 17.5 class. Its a solid car, just not supported and have no idea what happened to the co', ..but they never continued improving it, etc. ...I have replaced it w/ a Schumacher Mi6 evo

belewis01

iTrader: (5)

The Motiv is a different beast, I ran it one time in VTA and didn't get the timing / gearing figured out, so I put the Reedy back in since I knew that motor. Put the Motiv in my F1 and it hauls butt in the same configuration.

I think most 25.5 motors will work in VTA, but you need to find the timing / gearing sweet spot. I used to out run everyone on the straights, but got killed in the in-field, you have to find the best compromise.

eR1c

iTrader: (2)

From everyone's comments I think your statement sums it all up best. Its a new class for me, so I think I just need to figure it out a bit more. Thanks for all the help, there is still hope for my Tekin! I plan to go back and really get my gearing correct as it obviously isn't right now.

Bri

The Motiv looks to be the better motor. I would try it at 49 or 50 degrees timing but will most likely need different gearing than the Reedy since it's turning much more rpm. Get the gearing right on the Motiv and your car will be really fast.

Generally, what your looking for is when advancing the timing yields very small gains. When this happens, the motor is starting to lose it's efficiency and will start to run really hot. The Reedy data isn't as clear cut except the amp draw really jumps up with timing 50 and above. I would say 48 to 49 degrees timing is the sweet spot for the Reedy. Keep in mind that this is no load and will just get you in the ball park. I would use the data to find a good timing starting point and then go 1 degree each way and see what happens.

Best regards,
Brian

eR1c

iTrader: (2)

...It looks like there is a serious RPM gain from 49 to 50 timing w/ the Reedy, -why wouldn't you go w/ 50 timing (instead of 48-49)? ...or am I missing something/not looking at it correctly?

old_dude

iTrader: (1)

Amp draw.
What you don't know is what the torque and power curves look like for these motors. The big decision maker.

eR1c

iTrader: (2)

..ah, missed that the amp draw.

yes, .. the torque and power curve is important. ....I've seen motors that put out insane RPM's on the analyzer only to not perform as well as those w/ RPM's much less.

Kevin Marcy

One thing you didn't mention was how big your track is. Low 3's are usually good for large tracks, but if it's a small (carpet?) track 3.9 might be better. IF everything is working properly, a sensored system should not cog. Some things to check (if you haven't already):
1-Try a different sensor cable.
2-Make sure your ESC is in sensored mode (if it has a setting for that)
3-Have someone check it with a motor analyzer. The Sky RC/G-Force one will usually give an error (or maybe just get stuck in an infinite loop) if the sensors are bad or a phase is gone.
4-Have someone else try your motor to see if it's an ESC problem.

You didn't say which ESC you were using, but I had a similar problem with a Reedy motor and a Tekin ESC. Swapped the ESC and was back to full speed. It may have been a settings issue in the ESC, but I haven't tried it since the swap.

howardcano

iTrader: (37)

There is insufficient information to make that determination. Torque measurements are also required, just like Old Dude said.