Valach Engines

VM 170 B2-4T

  • Completely encapsulated valve train
  • CNC milled crankcase
  • Sensational smooth running and high torque
  • Spontaneous throttle response and smooth midrange transition
  • Extremely low vibration throughout the RPM range because of the four stroke principle
  • Honda valves and valve seats
  • Walbro carburetor
  • Valach microprocessor controlled ignition with auto advance and retard
  • An ignition integrated voltage converter allows the use of two LiPo cells
  • VM-engines are now being produced with state of the art machines and methods
  • Rapid spares delivery and repair service from Germany by Toni Clark practical scale GmbH

The Valach engines VM 170B2-4T Mk.2 looks just like an original aero engine, only smaller, it runs smoothly like an original aero engine and above all it sounds like an original aero engine.

Due to being a four stroke, the low vibration is nothing but sensational, and torque is really high. The response to the throttle being opened is so smooth without the slightest attempt to surge, making the Valach VM 170B2-4T Mk.2 absolutely ideal for your big aerobatic model.

Being a four stroke with a large capacity produces a very realistic full-size aircraft sound. With a relatively small silencer the sound level is very low rather like a small saloon car. The Valach VM 170B2-4T Mk.2 is a four stroke OHV engine running on petrol/oil mixture.

Image: Like on the VM 120 B2-4T, the valve train of the new VM 170 B2-4T Mk.2 is fully encapsulated, improving rocker arm lubrication and the valve train runs quieter. The crankcase of the VM 170 B2-4T Mk.2 is manufactured from solid aluminum and guarantees highest strength with a low weight.

Valves and their seats are manufactured by Honda, ensuring a very high quality. The totally enclosed valve train reduces sound, as well as ensuring the rocker arms are well lubricated. Due to the steel cylinder liners this engine will have a long life.

The recommended static RPM range for the VM 170B2-4T Mk.2 on the ground is 4,500–5,000.

On the VM 170B2-4T installed in the Pitts Special S1-S, we use the Fiala 34×12″ prop as this has proven to be ideal. Immediately after landing, that means with a hot engine, 28.5 kp static thrust was measured. When winds are strong I change over to a 34×14″ Fiala. As would be expected the ground speed is increased, unfortunately the “Pitts sound” is partly lost thereby.

The Fiala propellers are very efficient, this being due to minimal blade thickness. They sound especially good on four stroke engines.

The processor controlled ignition allows easy starting and a exceptionally smooth running in all throttle settings.

We had tried many oils, but recommend Valvoline SynPower 2T oil. Our BEL-RAY H1R, although excellent for two strokes, is not ideal for four strokes, as it burns very well without deposit and not much gets past the piston, as is the case by the Valvoline SynPower 2T. We recommend Aral Ultimate 102, as the smell is not so penetrating and it can be stored without deteriorating. It does not contain ethanol.

The fuel consumption is approximately 50% compared to that of a two-stroke engine with the same displacement. A 750cc fuel tank lasts for about 15-20 minutes of flying time.

The legendary perfectionist Henry Royce of Rolls Royce always insisted that an engineering construction to be right must look right. I defy anyone to tell me the Valach Twin does not look right.



170 cc


ca. 13 hp


52 mm


40 mm


352 mm

Length from engine mount to prop hub

185 mm

Weight: complete with ignition, two exhaust stacks, prop washer and prop bolts

5545 g

Ignition voltage range

4.8 - 9 V

Idle RPM

900 rpm


6200 rpm

Fiala Prop 2-blade:


5050 rpm
5000 rpm
4700 rpm
4050 rpm

Fiala Prop 3-Blade:


4850 rpm



Fuel: Valvoline SynPower 2T / Aral Ultimate 102

VM 170 B2-4T

More Information

Ram Tube #7480: This aluminum intake ram tube is for the VM 170, VM 210 and VM R5-420. Length 60 mm, inner diameter 22 mm, weighs only 12 g.

This Y-fitting makes it easy to remove the unwanted oil from the pressure tube of the carburettor. Loop-in the two “branches” into the pressure tube and extend the “trunk” about 6-12 cm to lead it to the lower side of the cowling. Place the Y-fitting underneath the carburettor and the surplus oil will be gathered into the “drainage tube” and can be dumped from time to time, without removing the cowling.

Attention: do not forget to close the tube securely with a plug!

This noble and super light carbon intake ram tube is made by hand in our own workshop. The intake tube is fixed to the carburetor without a gasket with the delivered custom made screws. Length 60 mm, inner diameter 22 mm, weight 7g. Suitable for VM 170, VM 210 and VM R5-420.

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