Motor changes for running boost?
 

Searched and searched, hoping a few folks will chime in about the logic and thinking behind changes to a motor setup to run boost vs. blinky. I have only ever ran blinky. Recently built a SCT based dirt oval car. About 90oz final build weight. Initially put a 13.5 MC2 Motiv in, standard high rotor, paired up to a XR10 Pro 160a esc. Set the motor up to about 42 degrees on the can and its perfect. Rules changed or i misunderstood them and now i am going to run boost. How do you folks go about making changes and whats the logic to the can timing and rotor strength to make for a better boost motor? Track is not as high bite as carpet, but not as loose a dry powder clay either, id say somewhere in the middle, sometimes a little more on the hard/abrasive side. I have talked to a few folks whom i really respect their opinion on the matter and the general idea on esc settings was 10k/12k boost on and 20k/25k max boost for the points.

I was thinking about going down to a Mid Rotor and turning the can timing down a bit and setting it up to run 20 on the boost and see where that takes me. Maybe taking about 5 teeth off the pinion based upon where i felt we needed to be with blinky mode. Any suggestions or theories to share on the logic behind something different? I am a sponge right now and looking to just soak up as much as i can about why we do what when we go outside of blinky.

Thanks

I ran a boosted 17.5 SCT on an oval back before blinky was standard. Here's what I use to do:

For blinky, I have settled on 50 to 55 degrees on the can, but when boosting I only had 35-45 on the can. How much you drop depends on how linear you want the power to be. For a smoother feel, drop 10-15 on the can and add 20-30 in boost. If you want the most power, drop 15-25 degrees on the can and add 30-45 degrees of boost on top of it.

For the start/end rpm, I used 5k to 8k to start (but this was on a 17.5) and 15-30k on the end rpm. I would usually keep the start RPM the same no matter what, but if the traction dropped or I had too much power, rather than reducing the amount of boost I was adding (thus limiting top speed on the straight) I would bump the end rpm setting up 2 or 3 thousand to smooth out how rapidly the boost was added.

What gearing you go with depends more on your total amount of timing change (can plus boost) from your current blinky setup. If you remove 10 on the can and add 10 in boost for a net effect of 0, I wouldn't change gearing at all. However, you will notice the motor running cooler than before with more punch and the same top speed. If you end up with a net increase of 10 degrees, drop the pinion size by 5-10%. (eg, 30 tooth down to a 27 or 28). Net increase of 20 degrees should see a 10-15% decrease in pinion size. I ran a net increase of 35 degrees (reduce 15 on the can compared to blinky and 50 in boost) and my pinion went from a 28 down to a 21.

If you find your car is lacking acceleration, but the motor is cold, reduce the start and end rpm settings first. If that doesn't help, increase the motor can timing a bit or add more boost. If the motor is hot, reduce can timing first, then reduce gearing. The best part of using boost is the ability to get more power out of the motor while running cooler than before and a cool motor is an efficient and long lasting motor.

Hopefully some good info is in there. I just kept typing. :lol: