We effectively have a 3 speed tranny. Instead of changing the gearing we are changing the rpms of the motor. As we add timing to increase rpms we loose torque. So we use lower timing during the launch where we need torque and add more timing as we accelerate and shift to second gear, and even more timing at top speed where the toque load is low and we want the extra rpms. If you add too much timing too soon it is like shifting half way up the tach in a real car only instead of bogging we just pull the power to get it done and make a lot of heat due to the inefficiency.
The heat effects are exponential as you pass the sweet spot. A few degrees of timing or turbo kicking in barely too soon can cause temps to increase significantly, but go fast for the first few minutes.
Motor Timing: Launch
Motor timing is an absolute. It’s effective throughout the entire range of the cars speed. This is the adjustment that should be made for the first few feet of car travel. It should not be forgotten in the “overall” timing calculation. Less motor timing gives you more torque and less rpm, more motor timing gives less torque and more rpm. With the additional advantages of mechanical gearing we can get a little of both worlds The additional timing we add above the motor timing as the motor spools up allows us to get the rpms for top speed without losing the extra torque at low speeds.
Timing Boost: Acceleration
Timing boost occurs after the car has travelled a short distance and has met a certain rpm. This setting should be adjusted for use in the infield sections and the majority of the track. This is along with motor timing is your midrange setting. This is a very critical setup as it can determine how much speed is carried onto the straight away, how much punch you have in the infield sections, etc.
Overall Timing Calculation: Motor Timing + Timing Boost = Overall timing
For the majority of spec motor racing you don’t want to exceed 30 degrees of overall timing. Spinning the motor to the highest limits is not the best answer for lap times. Remember that we race r/c cars, not dynos! Set your cars up to get the best lap times!
Timing boost is the acceleration
Turbo Timing: Top speed
Turbo timing is timing on top of Motor Timing and Turbo Timing. This is effectively used on longer straight away sections where lower gearing and timing settings that give you the edge for the infield sections isn’t the ideal setting for the straight away. This gives you the best of both worlds. You have a fast car/setup for the infield sections but will not give up the top speed on the longer sections. The optimal time for the turbo timing to come on is the apex or 10-20 feet past the apex leading onto the straight away.
Ideally you want your car to begin spooling out a bit, but not flattening out the acceleration curve. Imagine a real car; you’d want turbo to come on right where you’d be shifting into 2nd gear. If this comes on too soon, motor damage can be the result it just creates a lot of heat. This will show up initially as motor heat, cogging (should never cog in any condition, slow or hot maybe but never actually run rough. Then again if timing is advanced to the point of actually being in the next phase and we are not rotating fast enough to coast thru it we could be rough. I still hate to even say that term), etc.
There isn’t a “magic” setup for any motor or wind. Each track, each driver and each setup will differ slightly. I recommend setting up your cars Motor and Timing Boost along with gearing for the infield sections initially. Then once you’ve gotten that setup correctly and lap times in those sections are on then you move forward with Turbo Timing. Delay is critical. Too soon will get you excessive motor heat, too late and the car will stop accelerating efficiently.
Randy Tekin Team Manager
Tekin Setup Page: http://www.teamtekin.com/hotwire/ESCsetups/