The oil system
After I had the turbo mounted to the frame I decided to get the oil system running. To date this has proved the most complicated part of the engine to get working. I had previously seen on the web that people had successfully used an oil pump from a Ford Escort car engine. This pump is a good choice as it has the oil filter mounted on the pump body itself. The use of an oil filter is essential in any turbocharger based engine. The oil passages in the turbocharger are quite delicate and any contaminants in the oil could cause damage. The pump is also fairly common. I managed to find one at the local 'Pick-a-part' car yard. This is a scrap yard where you take your own tools and retrieve the parts yourself. I was very lucky in that I happened to find a Ford Escort engine just lying on the ground. All I had to do was turn it over and unbolt the pump! And the pump actually cost less than the new oil filter I had to buy for it.
Once I had the pump and filter I needed to make a plate to bolt it to. Normally the pump bolts directly to the engine block over two holes for the oil inlet and outlet and a third hole for the pump shaft. I made an adapter plate from a piece of brass a few mm thick. The plate has a hole in the middle to allow the pump shaft to poke through as well as two holes that line up with the inlet and outlet ports. I soldered on two curved copper tubes to serve as inlet/outlet pipes to attach oil hoses to. The pipes are curved to move them away from the shaft. This whole assembly was then bolted to a piece of aluminium plate to allow it to be mounted to the frame. I used normal automotive gasket material and glue between the pump and brass plate. Since the shaft of the pump normally goes inside the engine block there is no seal around the pump shaft. Any oil that leaks from there normally goes into the sump. Unfortunately this means that there is a very small amount of oil leakage around the shaft but the amount is negligible.
To drive the pump I decided to use a 12v battery drill. The drill can easily provide enough torque to turn the oil pump and since it uses a DC motor I was able to build an electronic PWM speed controller to allow me to vary the drill speed and therefore the oil pressure. The speed controller is a kitset from the local electronic hobby shop. The drill itself was used unmodified and it is mounted on a bracket make from Dexion and aluminium. It is mounted into the frame in a way that allows a small amount of adjustment so I could align the drill chuck and the oil pump shaft. I used a small piece of reinforced hose on the shaft of the pump with a round hex socket screw in the other end. The shaft and screw are held in place by hose clips around the hose. The threaded part of the hex screw is gripped by the drill chuck.
The turbo itself has two flanges for the oil inlet and outlet. I made two small plates out of 10mm thick aluminium that are bolted onto the flanges. The outlet plate has a hole tapped into it for a brass fitting. The inlet plate has a similar fitting with a copper tube soldered to it. The plates were attached with a gasket and gasket glue between them and the turbo flanges. I used a larger brass fitting on the outlet as it is important that the oil can drain from the turbo with as little restriction as possible. For an oil tank I am using a large coffee tin. Into the tin reach two brass tubes. The first reaches to the bottom of the tin and is used as the inlet pipe. The second reaches just past the top of the tin and is the outlet pipe. Oil flows from the inlet pipe to the pump and filter. Then from the pump to the turbo oil inlet. Then from the turbo outlet back into the tank. To make all the connections I used hose designed specifically for oil. No other type of hose (e.g. PVC, rubber, etc) should be used as the oil can cause other hoses to break down.
The final part of the oil system is an automotive gauge to read the oil pressure. The gauge was mounted on the instrument panel and, as it is a mechanical gauge, I used a T-piece between the pump and turbo inlet as the connection point for the sensing tube. I used Teflon tape on all the threaded connections as well as hose clips on all the hoses.
The drill and variable speed controller allow me to vary the oil pressure up to a maximum pressure of around 40PSI when the oil is cold. The pump can be turned on using a toggle switch on the control panel. A push button switch is also provided to momentarily run the pump if needed.
I am using Mobil 1 5W-50 fully synthetic oil.Back to page 3 contents
The ignition system
For ignition I am using a standard car spark plug and a standard ignition coil. The ignition coil is driven by a small switching circuit using a 555 timer chip and a switching transistor. The circuit is driven from a 12 volt supply and is controlled by a toggle switch on the control panel. I also provided a push button to spark the coil momentarily. The ignition only needs to be switched on during startup of the engine. Once the engine is running the ignition is switched off.Back to page 3 contents