Darren Mayer Just like the roots blower, the screw blower is made up of a case that houses the two rotors and other parts that force the air into the motor. The screw blower requires less energy to do the same amount of work compared to the roots blower. As you can see, the bigger the number, the longer the rotor, and the more power it will make.” From that day forward, a 15-inch rotor blower is called a 6-71, a 16-inch long rotor is called an 8-71, and a 19-inch long rotor is a 14-71 blower. “The numbers are derived from the original GM diesel trucks that had a roots blower on it called a 6-71,” Mayer explains. These are just random numbers assigned, yet they have a unique meaning. Roots blowers are often referred to based on a number like 8-71 or 14-71. Here are some examples of different roots blower case designs from DMPE. The case provides a sealing bore for the rotors to run in and a location for rotor centers to direct air in and out of the unit, along with a way to mount the supercharger to the motor.” The case is a billet or cast housing that houses the rotors. All modern performance rotors have sealing Teflon strips machined into them that are replaceable. The rotor has three male lobes and the area between them that accommodates the opposite rotor is called the root. “ The rotors inside the blower are a helical, three lobe design. He provides more background on what makes up the modern roots blower. As this is done, the rotors move more air than the motor can ingest, creating boost inside the manifold of the supercharger.ĭarren Mayer, owner of DMPE Inc, is an expert when it comes to supercharging and its parts. The air is held inside pockets that are around the lobes and is then moved from the intake to the discharge side of the lobe. Inside the blower, there are two rotors that typically have three lobes each, and they’re what move the air inside the case. The roots supercharger acts like a large positive displacement air pump on the top of a motor and is what the nitro-guzzling NHRA Top Fuel and Funny Cars use to make their power. The roots and screw blowers you see at the track may look like they bring air into the motor the same, but there are actually a few differences in how they function.īlowers have been a part of drag racing since its earliest days and old blowers can still be seen on nostalgia cars like these. The supercharger forces more oxygen into the motor, allowing more fuel to burn, and that in turn creates a higher power output. Today, we’re going to take a look at these superchargers to discuss their internal workings and how they’re so similar yet so very different.īecause an engine acts as a giant air pump, the best way to make more power is to increase the amount of air that flows through it. The two most common types of superchargers in drag racing are the roots and screw blowers that can be seen sticking out of the hoods of different racecars in venues around the world. The supercharger has been a staple in drag racing since the sport began, from the first hot rods on the salt flats to the beginnings of Top Fuel racing. A supercharger is one of the oldest methods of adding power to an engine, so it’s no surprise that racers around the world have always found ways to harness that power to make their cars faster.