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OSM18750OS Engines MAX 105HZ-R-Mad 4 Heli

OSM18750OS Engines MAX 105HZ-R

$734.99 AUD 
SKU: OSM18750
Nitro Helicopter Engine, 1.05 Size w/o Silencer

Product Information

The biggest, pure helicopter engine that OS have ever made delivers the levels of torque and power demanded by top fliers for both '3D' and sports applications.

The 15% increase in capacity offers a big increase over the .91 class engines yet still fits in mounts designed for that class. Modification to the cooling shroud is also unlikely. 

The distinctive 'blue anodised' cylinder head distinguishes the 105HZ engines from the 91HZ series yet retains the HZ series styling overall. 

General internal design is very similar to the 91HZ series and draws on OS's deep experience in creating the best helicopter engines for all classes.

Like the 91HZ-R 3D, the new 105HZ-R utilises the OS 'DRS' fuel delivery system to cope with the extreme manoeuvres of modern 3D flight.

Advantages over 120 size heli engines of other makes:

  • Uses same main gear ratio as .91 class engines
  • Vibration levels the same as the 91HZ so does not tend to break heli parts.
  • Easy carburettor adjustment that stays in tune.
  • Crankcase is noticeably cooler
  • More torque in the mid range for 3D
  • Velocity stack on carburettor sucks cool, undisturbed air from the fan flow.
  • Longer run time per tank
  • 105HZ with 15% nitro is similar power to a 91HZ with 30% nitro.


608.4g (21.46oz)
17.17cc (
29.0mm (1.142")
26.0mm (1.024")
Power Output
3.7PS @ 15,000rpm
Practical RPM
2,000 - 16,500rpm