How much is too much brushless motor timing?
I had not thought about max motor timing for brushless motors for quite a while; examining the way the 2 pole brushless motors are made and how the ESC interacts with producing the varying magnetic field at the correct time takes a while to digest.
For these DC 2 pole rotor, 3 stator phase brushless motors we use, the MAXIMUM safe, and useable timing is 60 degrees total, including the timing on the motor AND all the timing you set in the ESC (including Turbo and the other special additions to the timing total). This is based on the original design parameters when the change from bushed motors to brushless motors.
His recommendations (see complete article below) are on point, although our on track work for most motors break some of his suggestions for oval and off road racing. But for very low turn motors (less than 6.0) used in drag racing, timing is everything due to the large current being consumed and the work the ESC is trying to do.
Jim Campbell, the guy who runs Team Tekin, had the best article lately and I wish I had his input three years ago! His explanation is a great read.
"MAX TIMING: This is a little long but we get this question a lot and it is a bit to explain... but sooo important !
In general the max Static Timing set in the motor is 60deg. This is not because we suggest it, this is because that is the point where the motor wants to go backwards when starting. The motor commutates 6 times per revolution ( we change which ABC tab we are putting the power into). So every 60deg of shaft rotation we have to change what coils are being powered.
The actual usable max static timing is more like 50deg in some special light car classes with high turn Spec motors, with most finding the 35 to 45deg range to be the sweet spot in Spec motors. Mod motors should be 30deg and below.
Many have probably pushed past 50deg just see what really happens and the motors run poorly and get very hot quickly ! The effects are very exponential in that there is not much difference in rpm from 10deg to 20deg of timing, but there is a huge difference in rpm from 45deg to 55deg of timing. Every degree matters a lot above 40ish…. every degree above 50deg matters twice that much !
Low turn mod motors used in Drag Racing are completely different than high turn Spec motors and like a lot less timing. With low turn motors we like only 5 to 10deg of static timing in motor and add any more that is needed in the esc (Dynamic Timing) as the rpms are increasing. 30 or 40degs of total timing in a low turn motor is a lot !!!
Once the motor is spinning you can get away with more total timing than you can when starting a motor. With high turn Spec motors some are running timing over 60deg in special cases. The rotor coasts thru the backwards drive portion, which actually is applying brakes to the motor, then starts pushing the motor fwd again once it gets to the 60deg point. It should not work well even though some swear it does…. I am not convinced…
For those running silly things like 50deg of boost timing and another 30deg of turbo timing you are not getting what you think. We limit total timing in esc to about 58deg, again not because we want to but because that is the limit due to the 60deg commutations.
However we have no idea where the static timing is set in the motor. So someone with 40deg set in the motor and 30deg of boost timing, and 20deg of turbo timing really is running the motor at 90deg !! That means the motor is actually trying to go backwards for 30deg of rotation, and then go forward for 30deg of rotation. Again I am not convinced as an engineer that this is ever a good thing.
Anytime you mess with a lot of timing you have to adjust your gearing down significantly to compensate for the higher rpms and lack of torque. Perhaps one of the biggest mistakes we see people make in race track setups that does not let the motor spool up quickly and fully.
Always start low and work up instead of starting strapped and have to work back to a good consistent setup.... Heat is the summation of all things Evil !!!"