1927 Ford Model T Double-Trouble - video

[nova_robotics]

Some guys who put blowers on hotrods don't even have the rotors in them. Some will use an old damaged blower housing with a pulley on it just for visual effect. They certainly do not need the extra horsepower, as there is no way to use it.

If you really wanted to make a QUICK and FAST hot rod, you would not put two engines in it. One of those engines, properly built, unsupercharged, in an identical hot rod, could blow the doors off of that two engine rod. As shown it is eye catching, clever, well built, I am taking nothing away from it.

There are many reasons hot rods are built, many are just a very cool form of visual art, expressing their makers imagination and fabrication skills, rather than a exercise of applying the laws of physics.

I wasn't taking away from the amazing build. I made that clear in my first comment. In the video it says the hot rod makes 1200 horsepower. Those blowers are functional. My comment was a footnote about about the physics of two compressors, not about the practicality of the build, which is awesome. Two intercooled compressors in series is far more efficient than a single compressor. It takes much less horsepower to drive two series compressors than a single (or two parallel which is the same as one large single) compressors. My intention was not to take anything away from the build, which again is awesome.

In regard to parallel vs series. There is a lot of physics involved in that. Compressors in series can create more pressure, up to the pressure limit of the last compressor. But, if the compressors are identical, the second compressor has to be driven at a higher speed in order to further compress the gas coming from the first.

*slower speed. But there's no good reason to use identical superchargers. There's a lot of really good reasons to not use identical superchargers. 600 HP out of a 4.6L modular is well within the realm of a single supercharger; there's no reason you'd need two for flow. Two stage air compressors do not use similar first and second stages for this reason.

As you know, each succeeding cylinder in a multi stage unit is smaller than the proceeding one. But the compressor can move no more air than passes through the first stage.

If one compressor can create the pressure you need, in order to make more volume, you connect them in parallel. I have used 3 compressors in parallel to generate enough volume for a sand blasting job. Connecting them in series, they would not be able to generate the volume needed at their maximum pressure. I admit it probably did use more power than having one compressor large enough to create the same volume.

In your example, connecting them in series, even driving the second one faster as required, would not generate as much volume at 30 PSI as driving them in parallel, each at 30 psi (2.68bar).

One large supercharger is certainly much cheaper than two tiny ones. If you have enough budget to purchase four identical superchargers for the aesthetics of an insane hot rod you're not going to buy parts that don't flow enough air.