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This is my 30" Bourke-Cycle Prototype engine. It was fabricated
around the parameters of the original prints. Video is posted on
bourkeengine.net click the picture
![](./mediac/400_0/media/gen~set-4.jpg)
I was surprised the first time it ran, after warm-up, in full diesel,
ignition switched off, with no power loss. The "exhaust note" is
unique. Combustion chamber pulses are supersonic with flame
speeds in excess of 5,000 ft./sec. The secret is in his "combustion
event management". Faster burns allow more time for expansion
and cooling in the cylinder.
Homebuilt Bourke 30 C.I.D. engine.
![](./mediac/400_0/media/proto~30.3.assm.jpg)
Initial modeling of the Proto 30" homebuilt engine. Count on
knowing a good tig welder. Bourke's cylinders and cases were
cast one piece. Proto cylinders are built-up from
base turning, weld on intake, transfer, and water jackets.
![](./mediac/400_0/media/proto~30.4.assm.jpg)
Line drawing cross section. This is a precision assembly. All
parts must be square and true. Parts require no more
precision than current conventionals. Proper heat treatment
and finish grinding go without saying.
![](./mediac/400_0/media/cylinder.jpg)
Basic cylinder turning. Gasflow is probably less than optimal
in this type of cylinder, although it satisfied the design intent
of the project. Proto II wil be flow tested.
![](./mediac/400_0/media/croshead-assm-30.jpg)
30" crosshead assembly with one piston blanked for clarity.
The geometry generated by this SCOTTISH YOKE is the
foundation of the design. Not only does it generate high
compression, but a LONGER DURATION of the compression
event. What does the formula say about FIXED VOLUME?
![](./mediac/400_0/media/rod-yoke-assm-30-exp.jpg)
Blow-up of the 30" rod yoke assembly. This represents one mass-
the "bullet"- that is thrown between two alternating
explosions (detonations). 100% dynamic balance is produced
by "exchange of momentum" rather than by counterweights.
The faster it revs, the smoother it gets.
![](./mediac/400_0/media/roller-cam-assm.jpg)
Roller cam is counterweighted and spins as smoothly as a
flywheel. Strobe balanced to 10k plus.
![](./mediac/400_0/media/piston~bench.jpg)
My Bourke workbench.
![](./mediac/400_0/media/piston-lathe.jpg)
My proto 30" model was made on simple machine tools.
Piston blanks are cast aluminum. With die-casting, cost
per piece can be comparable with conventionals.
![](./mediac/400_0/media/piston~on~mill.jpg)
Setting-up to bore pin holes and cut transfer slot.
![](./mediac/400_0/media/piston~grind.jpg)
I used my surface grinder with vertical rotary table to grind
cam relief for piston clearance. Cobbled, but it works.
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