Below in the technical specs of your speedo and according to themthe lowest brushless motor wind you could use is a 12.5 and the maximum voltage input is 9.6v so it not possible to use a 3cell lipo as the voltage out put is 11.1v
Special A.I. Brushless Features Waterproof
Fail Safe
Forward/Brake/Reverse
Sensored Design
Multi-Protection-System
Plug in and Drive
Limited-Lifetime-Warranty
Motorlimit Brushless: Over 12.5 turns
Motorlimit Brushed: Over 10 turns
Voltage Input: 4.8 - 9.6V
Type:
hth Jono