There are numerous different types and makes of electric superchargers available on the Internet. Some do what they claim to do while others are nothing short of useless. There are a few however that could be considered positively fraudulent. For example we’ve seen a couple of computer power supply fans mounted in a plastic housing masquerading as a supercharger. These fans couldn’t pressurise a matchbox let alone an engine yet the seller was asking $US300 per unit. The Internet is awash with legitimate traders and rouges all rubbing shoulders and all very difficult to tell apart. While we do not intend commenting on any of them directly there are ways to tell the good from the bad.

Most electric supercharger vendors will publicise various figures and statistics relating to their products performance. These are of course difficult to verify and may or may not accurately reflect the superchargers worth. An approximation of an individual electric superchargers real performance can be obtained from details of their current and voltage requirements. A supercharger is essentially a pump and has to do work to pressurise an induction manifold. They have to be a powerful pump as a huge volume of air needs to be pressurised to keep up with an engines demand. Even the most efficient electric supercharger designs need a substantial electric motor to drive them and such a motor requires an equally substantial amount of electricity to power it. Simply multiplying voltage (Volts) and current (Amps) together will tell you how much electric power (Watts) the supercharger uses. Our experiences showed that it is difficult to achieve worthwhile results with anything less than about 560W but gains down to 480W are at least conceivable. It is worth remembering that even a minimalist 480W uses 40 Amps of current at 12 Volts which is considerable. Many electric superchargers would need hundreds of Amps of current to achieve their stated power outputs. To put this into perspective typical starter current draw is between 100 and 250 Amps on most petrol engines. Batteries and charging systems have to keep up with this massive requirement which they won’t do for long and the resulting system voltage drop can become an insurmountable problem. Our electric supercharger has its operating voltage boosted from the host vehicles 12 Volt system to 24 or 36 Volts (depending on which version is used). This configuration yields power ratings of up to 720W at 24 Volts (30 Amps) and 1800W at 36 Volts (50 Amps).
  
Many Electric Superchargers advertised on the internet are in fact marine bilge fans or similar blowers that do much the same job. These are designed to ventilate confined spaces which they do well though unfortunately they do not make good automotive superchargers. Bilge blowers and their like mostly lack any form of diffuser (not required by and slightly detrimental to their intended function) which means they do not generate pressure efficiently (if at all). A diffuser is a static set of vanes arranged closely around the rotating compression wheel that allows a pressure wave to build up on their leading edges. Pressure can only be developed when there is a resistance to air flow and a diffuser provides that resistance without being too much of an impediment. You can think of it as a sort of one way valve that allows air pressure to build up in a moving column of air. Without an increase in pressure a supercharger is likely to be next to useless and shouldn't be called a supercharger at all. Another reason that bilge blowers do not make good superchargers is they simply are not powerful enough. Most are rated between 50W and 200W which is far below the minimum power that our testing indicates. Other similar advertised electric superchargers employ ducted fans as used in model aircraft. Technically these are axial impellors and would require a set of stator vanes to fill the same function as a diffuser in radial compressors if they are intended to produce an increase in air pressure. Ducted fans are usually designed to produce a high velocity air stream, eg to create thrust in a model aircraft. An increase in pressure requires a reduction of velocity in a moving column of air (pressure and velocity are inversely proportional) so these types of fans do not have a stator and are not designed to produce pressure. The very best of these bilge blower and fan type 'superchargers' may be of some benefit but the majority are a waste of time and money.

Whilst electric superchargers are a very cost effective and efficient performance enhancement they do have limitations. It is unreasonable to expect that a low cost electric supercharger will produce the same performance gains as a hugely expensive conventional supercharger. If they could match conventional chargers yet still only cost a tiny fraction of the price then electric superchargers would put conventional chargers out of business. Vendors who claim performance parity at vastly reduced cost are probably being less than truthful. There is one supercharger being widely advertised that claims to give 8psi boost from just 36W of electrical power. The laws of gas dynamics clearly state that this cannot be done as most electric superchargers would require at least 5000W (and this is highly optimistic) to achieve 8psi in a medium sized car engine manifold.

An individual superchargers ability to generate boost reduces as engine size increases. It has to do more work just to keep up with a large engines inherent capacity to displace air. Furthermore a larger cubic volume requires more energy to pressurise hence a correspondingly larger supercharger is needed just to maintain the same mean gas pressure. Electric superchargers generally have a lower volumetric efficiency than conventional chargers and are more sensitive to engine capacity. An electric supercharger that can blow the socks off a 900cc minnow may barely be able to tickle a 5000cc beast (depending on its total volumetric efficiency). This is an important aspect to keep in mind when evaluating published performance figures and it is worth querying the test conditions and engine used.

Unfortunately gas flow figures (CFM or L/m) are often misleading. Here is an excerpt from our performance page that details our thoughts on this -

Gas flow is probably the most misunderstood and abused measurement of all. Describing gas flow would take another web page just to skim the subjects’ surface. The problem being that superchargers operate in a dynamic environment where by it is extremely difficult to separate flow rate attributed to the engine from that provided by the supercharger.  Even simply quantifying the flow rate difference between a supercharged and naturally aspirated engine does not give an accurate picture as the mathematical relationship between the two is not linear.  Measurements taken when the supercharger vents into an open space are meaningless, a large fan would outperform a supercharger in this test yet fans are for the most part unable to generate significant pressure.  All in all we think it is best to leave these figures out completely rather than step into a quagmire of potential controversy for the sake of very little in the way of meaningful information. Boost pressures along with power and torque gains are the benchmarks that best describe a superchargers performance.

Some supercharger vendors will claim dramatic improvements in fuel consumption while simultaneously achieving large increases in engine power output. This is almost a contradiction of terms when large gains are said to be realised as a massive advance in engine technology would need to occur to make this possible. We contacted one vendor who claimed that a static piece of metal resembling a wind chime could instantly yield an extra 35 Hp and at the same time improve fuel consumption by 20 mpg. The seller was asked why none of the major manufacturers used this device to which they answered “the manufacturers don’t know about it yet”. A further question of ‘how is it that we know about the device but they don’t ?’ was never answered. We for our part find claims like this difficult to believe and would doubt the veracity of anything said by the claimant.

A good way to gain an insight into a merchants honesty is to simply ask them a question. An evasive answer or worse still no answer at all would lead to doubts about the products or merchants integrity. Answers to questions that read like an advert for the product are also likely to raise suspicions. Please feel free to ask us any questions about our electric supercharger by sending an email to support@gaprojects.com and we will answer within 24 hours.  We are very reluctant however to comment on specific electric superchargers (other than our own) as we assume no right to the position of adjudicator in these matters.

Hopefully this page will help individuals recognise the various supercharger scams that are out there. If you have any information or tips you think should be added to this page then please contact us at scaminfo@gaprojects.com

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