A new power plant for model helicopters is the 91-P5Hi (ignition) motor, which is designed to run on petrol instead of conventional model fuel. To ensure that the 91-P5Hi has adequate structural strength for petrol operation, we were obliged to revise the Webra 91-P5 methanol motor completely; the main change being a new steel connecting rod fitted with needle roller bearings for greater mechanical strength and lower friction losses.



For optimum heat dissipation the new motor's piston / cylinder set exploits the proven Webra AAR*) system. The Webra ULTRAMIX carburettor is responsible for throttling, in this case used in conjunction with an external pressure regulator. The fuel mix is ignited by the Webra "Spark II" thyristor ignition system and a sparkplug (M10 thread - Webra Order No. 4312). Energy is supplied to the ignition system from a 3.6 - 8 V battery, for which conventional LiPo cells or other battery types can be used. For this power plant we recommend a fuel consisting of 20 parts petrol to 1 part two-stroke oil.

This new engine provides a means for the cost-conscious pilot to reduce his operating costs considerably - by using petrol as fuel - without incurring a significant power loss. Since petrol produces more energy than methanol when burned, the fuel consumption of the spark-ignition engine is also lower - by up to 50% - which means that you can safely reduce the fueltank size by about one half.

A = 44,00 mm B = 25,00 mm C = 95,00 + 36,00 mm D = 52,00 mm E = 108,00 mm