What is tapping an oil pan?
A tap is a tool used to create female threads in a punched hole. “Tapping a pan” means to punch a small hole in the side of the oil pan above the oil line in a specific predetermined location. Then use a tap to create threads to secure the hose barb fitting. The oil drain line is then attached to the fitting.
Tapping vs. Self-Contained
The average engine contains 4-6 quarts of oil. This large quantity of oil is constantly filtered and cleaned before it makes its next pass through the engine and charger. An oil fed supercharger uses this oil to lubricate and cool the engine and the supercharger. Naturally, a larger quantity of oil is better suited to lubricate the charger and help dissipate heat. The average self-contained supercharger only uses 4-6 ounces of non-filtered oil and must rely on only that amount to lubricate and cool the charger. A small quantity of oil is more prone to breaking down (no longer acting as a lubricant).
The reason any supercharger needs oil is because aside from boost and horsepower, it creates heat and friction. Simple physics states that expansion is a byproduct of heat. An oil fed supercharger can pass the heat and expansion down the drain line into the pan where there is a substantially larger area to deal with this kind of pressure, thus eliminating the chance for expansion failures.
The biggest single objection to a self-contained supercharger is the frequent amount of maintenance. The oil in a self-contained supercharger has a useful life and must be replaced before it breaks down and causes the supercharger to fail. Changing the self-contained oil is something you must remember to do separate from changing the engine oil. On the other hand, an oil fed supercharger is relatively maintenance free. Every time you change the engine oil, you are automatically changing the supercharger oil.
The biggest single objection to an oil fed charger is the fact that you actually have to tap the pan. As we’ve shown, this is intimidating and a bit time consuming, but not difficult. If there is an engine or supercharger failure then there is a chance of passing particles between the two components potentially resulting in an additional failure. However, failures of these natures are extremely rare regardless of the type of charger and, if any, are found typically in extreme racing conditions. This fate is even more rare among street/strip cars.
Let’s Get Technical About Tapping This Turkey!
The supplied instruction manual describes and shows the exact location to tap your oil pan.
Do not drain your oil pan at this time! You will be working in the area above the oil line. Use the provided measurements to mark your target hole. Then punch your hole with the specified center punch. Simply “tap” the tapered center punch into the hole with a hammer. The deeper the punch goes into the pan the larger the hole becomes. Keep going until the hole is the required size.
Then use a tap to create threads to seat the hose barb. The tap has four channels called flutes and four threaded sections. Pack the flutes of the tap with multi-purpose grease. This will catch any particles before they can enter the pan. You must punch and tap, but not drill. Punching the steel pan causes the material to bend and flower inwards. This provides a tapered, tight and leak-free fitting for the hose barb to be threaded into. (Because the material is bending, not being drilled, the chance of flaking into the oil pan is greatly reduced). The next step is to drain the oil. The reason to change the oil after tapping the pan is to flush out any particles that might have slipped by, and act as a safety check for your tapping ability. Then connect the supercharger oil drain hose to the oil pan fitting and refill the oil to the manufacturer’s recommended level. An oil fed supercharger does not require any additional oil.
The High’s and Low’s of Oil Pressure and Its Path
Tapping the block is not necessary to get a fresh supply of pressurized oil. All engines have an external oil pressure sender on the outside of the block. The computer monitors this sensor to make sure the engine always has sufficient oil pressure. Simply remove the threaded sensor and install the supplied “T” fitting. Then reinsert the sender. There is now an available port on the “T” to get pressurized oil. The oil feed hose hooks up to the available port to transfer oil to the supercharger. The other end of the oil feed hose then hooks up to the oil feed nozzle on the supercharger. The pressurized oil is forced through a small filtered orifice to spray a constant oil mist on the gears. This lubricates and cools the gears. The oil then collects in the bottom of the supercharger and drains back into the oil pan. The supercharger and the oil drain are not pressurized.
The return process depends on the constant forces of gravity to return the oil down the drain hose and dump it into the oil pan. This is the reason the pan fitting must be tapped above the oil line so the oil can drain freely. Once
the system is installed the first time, virtually no further maintenance is required.
What if I Want to Remove the Supercharger?
If you decide to sell, or lease-return your vehicle, you can take your supercharger with you…even if you tapped the pan. After you unbolt your supercharger, and return the accessory drive to its original state, you have two options when dealing with the oil pan fitting. Either put a rubber cap over the end of the fitting, or remove the fitting entirely and insert a freeze plug in its place. Both options will allow the vehicle to operate normally and will prevent the oil pan from leaking.
Conclusion
An oil fed supercharger requires a slight bit more work during install but will require less oil changing maintenance while you own it. The oil fed chargers do not require any additional costs or labor time, but do require more work and install time initially. Oil fed superchargers are not to everyone’s liking, but if you do have an interest in this style of centrifugal supercharger, our hope is that this article has outlined the benefits, and demystified the art, of tapping an oil pan.