After building my first jet engine which can be seen in "Older Projects" I decided to build a jet powered go-kart for a challenge. I started off by finding a turbocharger to use, as the size of this component would determine the size I would have to build the combustion chamber to and the maximum size and weight that the go-kart could be. I found a turbo in the USA for auction on E-bay, I eventually won the auction with the turbo being bought for $450 Aud and $250 Aud postage. When I received the turbo I weighed it and it was around 30KG.
I started designing the combustion chamber, this is a very important step as it must have enough capacity to contain the combustion process required to spool the turbo to life. I believe there is a basic program used by some jet engine builders to design the combustion chamber and the amount of holes required in the flame tube which is inside the combustion chamber. This may be still available online. Originally I used an old steel fire extinguisher as the flame tube, but later upgraded it to a stainless steel flame tube which was also made out of an old fire extinguisher. I can't remember exactly how many holes I had to drill but there was around 90. Some sections had holes of different sizes which would allow more air to be introduced into the combustion process. I added a spark plug, liquid fuel injection port and propane injection port to the top of the combustion chamber.
I started working on the go-kart frame which consisted of about $170 worth of steel. I ordered some steering arms from E-Bay which were designed for racing karts. The area behind the seat was designed to house the fuel, fuel pump, oil pump, oil cooler, oil filter and some sensors to monitor things such as oil pressure. I got the oil and fuel pumps off E-Bay which ran off 12 volts DC and were of rotary gear type. The Oil tank was made of steel plate and steel tubing. The oil system has a capacity of around 4 litres, I would double the that capacity if I were to build this again, as the oil would quickly heat up and if there was a oil system leak it would quickly pump the 4 litres out of the reservoir. Leaving to turbo without lubrication, which would quickly damage the internal bearings.
The control panel contains switches for controlling the ignition, oil pump etc. It also has gauges for oil pressure, system voltage, EGT (Exhaust Gas Temperature), turbo compressor pressure etc. I added two speed controls for the oil pump and fuel pump which would vary the oil flow to the turbo to assist on startup and compensate for the thinning of the oil during operation. The fuel pump speed control would allow me to speed up the fuel pump which in turn speed up the turbine in the turbo (For safety purposes I added a fuel shutoff tap to the side of where the driver sits if there were some sort of emergency situation or electrical malfunction.
The turbo is started by a high powered leaf blower and started on gas which enables the simple fuel vaporizer coil to reach a sufficient temperature to vaporize the diesel petrol mix, the vaporizer is some copper tubing rapped around the exhaust flange on the end of the combustion chamber. This turbo should have a max operating speed of 60,000- 65,0000 RPM over speeding could lead to a catastrophic failure of the turbo which could result in serious injuries to the operator or even death. The smaller the turbo the higher it's max RPM will be, for example the turbo on a standard car will have a max speed of around 120,000-170,000 RPM. This turbo however was originally off a large truck with a 12 litre engine capacity.
Once I had finally finished building the jet-kart I tried starting it a few times but ended up having to make adjustments to the flame tube holes for the correct ratio. Then I finally got it started and the sound was absolutely deafening. I'm still yet to get the correct ratio of holes in the flame tube to get it to full operating speed.
I have minimal photos of the project due to a hard drive failure which resulted in a loss of many of my project photos sadly.
Project 95% complete as of August 2011