Restorations 2

Renault 4P03 A

Brett James of James Aeronautics is restoring this engine to running condition.


Benz Bz IVu of 1918 Vintage

This engine is from the Brussels Air Museum, which has an extensive collection of engines dating from the early days of flight (pre-1914 ) up to the present day. These images appear through the generosity of Mike Lewis. They may not be reproduced in any form without the express written consent of Mr. Lewis.

The Benz Bz IVu engine powered both the LVG CVI and the Halberstadt CV two seater artillery spotting aircraft. Both aircraft were constructed in 1918 and it is probable that the LVG never saw action. The Halberstadt is unique in that it is the only surviving example in the world.

Engine Specifications

6 cylinder in-line  
Piston displacement 18,800 cm3 or 18.8 litres
Bore 145 mm
Stroke 190 mm
Aluminium pistons  
Engine mass 370 kgs
Inlet valve trave 11.8 mm
Exhaust valve travel 11.25 mm
Magnetos are set to 30° advance and geared to turn at 2/3 engine speed.


Engine Performance

All engines were tested before removal to the aircraft companies that used them and the power output (which varied slightly) was stamped on the maker’s plaque which in the case of the LVG is regrettably missing.
Nominal power: 200 hp increasing to a maximum 230 hp at sea level
Nominal RPM: 1,400
Oil consumption: 10 grams / hr


General view of Bz IVu engine showing carbs and inlet manifolds. As the engine was partially exposed in operation the manifolds were lagged to reduce icing. Note also the absence of a magneto, there should be one on each side of the engine but after nearly 90 years they are inevitably missing. The magnetos are of the Bosch ZH6 type.
The exhaust side of the engine (with exhaust stack removed). Notice the large air scoop which protruded from the right hand side of the fuselage, the air warmed as it passed through cut-outs in the crankcase to the other side of the engine and the carburettors. Again the right hand side magneto and a generator (used principally to heat the pilot and observers suits and provide power for the elementary radio equipment) are missing. Oil pump and filter can be seen at the bottom of the sump.
Very long push rods and valve gear evident as well as painted engine (military designation) serial number.
Rear view of engine showing water pump assembly and drive mechanism for the generator. To the left hand side of the engine can be seen the “all-in-one” fuel pump/mg interrupter drive/tacho drive mechanism.
Front engine view with prominent oil-filler tube. The red paint on the cylinders denotes that this is a high compression “uberkomprimiert” version of a Bz IV engine, hence the designation BzIVu.
This is the general state of the engine after an attempted restoration in the early 1990’s (essentially a cosmetic job with very little actual restoration). At this stage the engine could not be turned over.
Exhaust ports and valve-gear. Note the only original remaining spark plug.
Overhead view of engine. The valve gear was completely exposed to the elements in flight and the lack of a rocker-box cover must have covered the pilot in oil.
The prop was completely ungeared taking its drive directly from the crank shaft. It turned in an anti-clockwise direction as seen from the photo.
Each cylinder was equipped with two inlet and two exhaust valves which were pushrod operated. Note also the tappets which are in fact small circular bearings.
Restoration begins with an attempt to “free” the engine. After constant applications of large amounts of WD-40 over a period of 6months, squirted directly into the plug holes, the engine could be turned over 85 years later! This will now facilitate removal of the cylinders and all the valve gear.
The spark plugs are not the originals but are used simply to prevent any further moisture from entering the bores.
The spark plugs are not the originals but are used simply to prevent any further moisture from entering the bores.
In the previous restoration “attempt” the valve gear was painted black. In service this would have been bare untreated metal
Oil Pump


More information on this restoration at 1914-1918 Connections