How to Convert a V8 Engine into an Air Compressor

What You'll Need
8 cylinder engine
Crescent wrench
Socket wrench
Customized crankshaft
Customized intake and exhaust manifolds
Tractor power take off
Check valves
Air hoses
Air tank
Spring-loaded relief valve
Oil-air separator

It is possible to build an air compressor from a V8 engine. In the 1940s and ‘50s this type of setup was often seen on job sites, but has faded from popularity as self-contained industrial air compressors became widespread. The basic design involves using four cylinders on one side of the engine for combustion and four cylinders on the other side of the engine for compression. This is commonly known as the monoblock design. Performing this conversion requires significant mechanical skills and poses a risk of engine damage or explosion if done incorrectly. There are many different ways to go about this conversion, depending on the type of engine you are working with. Choose the best method for your situation.

Step 1 – Obtain Conversion Kit and Instructions

Disabling one side of the V8 engine will basically make it into a 4 cylinder engine. You will need to obtain the proper camshafts and intake manifolds to convert that side of the engine block to the appropriate timing and firing order. Detailed illustrated instructions for the conversion process will also be immensely helpful.

Step 2 – Disable Fuel Intake on Compression Side

Shut off the carburetor to prevent fuel from flowing into one side of the engine block. Pumping compressed air containing fuel vapors could be dangerous. However, these cylinders still need to be able to suck in air. Place weak valve springs on this side’s pistons so that they act as reed valves.

Step 3 – Disable Exhaust Valves

Disable the exhaust valves on the compressor side of the engine block by removing the rocker arms and pushrods. During air compression, these valves need to remain closed at all times. However, if you have an engine with fuel injectors, you may need to block these and collect the intake air from the exhaust manifold instead.

Step 4 – Pull Spark Plugs

Remove the spark plugs from the compression side of the engine block and plumb the cylinders with air hoses. Add check valves after each cylinder so that air can only flow in one direction. The last cylinder will connect to the air tank.

Step 5 – Install Oil Separator and Safety Valve

The compressed air from the engine will be very hot and may contain engine oil. This can be troublesome for some applications such as sandblasting. Install an oil-air separator before the air tank. Also, the air tank needs a safety release valve to prevent excess air pressure from building up.

Step 6 – Install New Governor

Finally, install a device to convert the combustion side of the engine to four-cylinder operation. Some options include obtaining customized cams or using a farm tractor power take-off. You will also need a way of controlling the motor speed; consider using an air compressor solenoid switch.