Saturday, February 28

Want a new hobby?

Last night I had the privilege of meeting ‘Johno’, a talented lad who is a good friend of Mrs G’s younger brother. Johno had built a jet turbine from a turbo and was hosting a test-firing.

A group of about 20 people had gathered inside the small rented shed in the southern industrial area of Adelaide. Inside the shed were other successful projects designed to satisfy the primal needs of the typical rev-head such as; the newly built go-kart with spotlights and a kill switch for roaming the streets at night and the converted BMX with a 2-stroke lawn trimmer engine mounted on the back wheel.

The ‘jet engine’ we’d come to see was placed on a small rubber mat pointing out the shed door. A 9kg LPG cylinder was connected to the primary inlet. Notably missing was any form of regulator, the only control being a ball valve at the cylinder end of the pipe. There were several gauges, an oil cooling system, an ignition system made from auto parts, a fuel pump and a second fuel line running from a 4 litre bottle of kero.

The starting procedure involved using a cut down blower-vac to accelerate the incoming air while LPG in the engine is injected and ignited. Soon enough the engine began to whine and whistle like a turbo. Next the kerosene was injected into the second stage to create an afterburner effect.

Instantly the whole place smelt like an airport. The engine roared and sounded like a Boeing 747 was winding up to takeoff. The metal outlet was glowing red and apparently the operating temperatures were reaching 900C, though when stabilised were relatively cooler at 300C.

After two five minute sessions, the LPG cylinder was icing up and two gallons of kero had been consumed. From my limited knowledge, that’s a lot of fuel. Maybe not as much as a commercial jetliner, but certainly evidence of a powerful piece of homemade kit.

This thing was truly awesome! At its peak, flame was about 5 inches wide and 2 feet long. The roar was deafening. I can’t remember for sure but I think Johno said the turbo was doing and estimated 80,000 RPM (maybe even 800,000?). Having done his apprenticeship working on industrial turbines, I’ll have to take his word for it.

On the way out, I was shown some more of Johno’s work. Inside his inconspicuous Japanese utility (and before you ask, there was no V8 engine or twin 2” exhausts), is a chain suspended from the ceiling that activates a genuine air horn – from a prime mover!

Loud enough to send unsuspecting pedestrians into cardiac arrest, the horn runs off a reserve of compressed air that doubles as a supply for plasma welding and power tools when he’s out on a job.

Not satisfied with conventional methods of compressing air, Johno modified a domestic air-compressor, attached an air-conditioner clutch and hooked it up to the engine. The compressor cuts in when needed and even compensates for engine speed.

I am truly jealous! I took some photos and will have them developed soon. Email me if you’d like to seem them.