Simple comparison with 4 stroke

Obtain a single cylinder direct injection petrol engine

Modify the fuel injection timing to half the usual frequency i.e. fuel injection on alternate 4 stroke cycles and optimise the fuel delivery.

Run this engine at full throttle in BC mode with full alternate 'air only' inductions.

Repeat the above for various speeds, but always full throttle BC mode, and record the fuel consumption

Change this engine back to standard with fuel injection on every 4 stroke cycle

Compare the fuel consumption of the 4 stroke and the 'Blackburn Cycle' at identical loads and RPM

You will see that the 'Blackburn Cycle' is much more fuel efficient than 4 stroke.

The above set up will not give the full efficiency gain if you test lower loads below full throttle BC mode, because the throttle will be partly closed. This reduces the 'air only' intake and reduces all the advantages alternate 'air only' provides.

You can also use a 3 or 5 cylinder engine, but an odd number of cylinders is essential for smooth running.

The absolute fuel efficiency of a direct injection petrol engine is less than the alternate opening inlet valve version of the 'Blackburn Cycle' as basic cycle, where port injection can be used. This allows more time, turbulence and mixing for the fuel/air, making a more ideal explosive mixture, right down to idling speed.

When you see a large efficiency gain for yourselves this should encourage you to run larger scale tests using the variable speed version of the 'Blackburn Cycle' which will deliver a larger gain, rising to about 150% gain at idling speed.