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HOWTO: Build an Electric Supercharger
(Do Electric Superchargers Work?)

Written by Wild Weasel

Who Should Read This?

If you're considering building your own electric boost system or have seen one available for sale somewhere and are considering purchasing it, this page is for you.

A lot of forums link here as the first response to "Does this electric supercharger work?" when someone is asking about some crap they found on eBay or some other source. The short answer is probably "No. It's a scam." and if you keep reading you'll find all the reasons why.

Recently (May 2013) however, I had the opportunity to test out a new one for myself, and it actually works. If you're coming to this page from an old thread on some forum or other, I highly encourage you to post the link to the testing page (Wild Weasel Tests An Electric Supercharger) and let people know that there is some promise in this technology for the near future. Of course, the one you're looking at is probably still a scam. Read through this page to find out how to tell.

Right then... so on to the bulk of what you're looking for...

An electric supercharger is generally a waste of money and can potentially cause some very expensive problems if you try to use one. Take the time to read this whole page and I'm sure you'll learn quite a bit about why I'm saying this and how to avoid being scammed.

Click here to skip past the updates...

Update: May 9, 2013

Well... I've got good news and bad news. If you've been following my updates from the testing I mentinoed in the April 7th update, then you know that there is now a WORKING ELECTRIC SUPERCHARGER out there that makes very real gains and is a real riot to use. Go here for the details.

You can't actually buy it just yet, but it's coming soon and I'll post more info when it does.

The bad news is that I'm now going to have to revamp this page with a whole lot more detail about what to look for when someone is selling one of these things. So far as I'm aware, other than the one I tested, ALL of the rest of them are still scams, so don't waste your money! This page has been helping out people for years and years, and all of the info below still stands. Please read through it and save your money!!!

So bad news for me... but good news for the aftermarket auto enthusiast!


Update: April 7, 2013

There's some interesting developments going on in this space these days, and I'm giving everyone the heads-up that you may want to check back here soon.

Note that I've moved the test to it's own page. Click here for the story.


Update: November 11, 2011

I still haven't read any real definitive info on the BMW units, but from what I understand right now, they're working on a pretty clever idea. I believe the idea is to have a powerful motor in line with the impeller that will be used to help spool up the turbo to prevent lag. The turbo is then powered by the exhaust as normal. The electric motor could never keep up.

The really clever part though is that I've read they're going to do away with the wastegate and instead, use the motor as a generator to recover excess energy while keeping the turbo from over-boosting. The real engineering feat in all that, I'm sure, was to make all the bits withstand the heat involved.

Kudos to BMW for thinking outside the box. Not that we should be surprised. :)


Update: July 8, 2011

Before we continue, I just want to get this out of the way. Word has it that the new BMW M3 is going to have a tri-turbo engine and that one of those blowers is going to be electric.

I'm fairly certain that every scammer selling garbage boost systems on the Net is going to be pointing to that as obvious proof that their system works. Thanks a lot, BMW. :)

Please continue reading this article. There's mention below of another system that works as well. This isn't a revelation. Electric boost can work. It just doesn't work the way whoever is trying to sell you something says it can. While I have absolutely no details on this BMW unit, and look forward to reading about it, I guarantee you that it is not using a 12V motor to turn a fan in your intake. Again, I implore you to please read and understand this article before spending any of your hard earned money. If you don't fully understand, feel free to leave a message in the guestbook.


What's Boost?

First I'll explain the theory behind boosting an engine and the basis of this modification. This is an extremely simplified guide but we're not here to discuss the intimate details of boost. You'll get the idea and that's what's important.

An internal combustion engine makes power by burning a mixture of air and fuel.

For a street driven car, the fuel is usually gasoline and the air comes from the outside atmosphere.

When you have the right combination of air and fuel (called a stoich mixture) it will burn efficiently and produce a minimum of waste. This mixture will consume almost all of the fuel and oxygen in the mixture.

If you want to make more power, you have to efficiently burn more fuel and there's a few different ways to do this. The first and most obvious way is to simply use a bigger engine. If you've got 6 or 8 cylinders to work with, you can obviously burn more fuel than you can with a typical 4-cylinder engine.

Alternately, if you can cram more air into your engine, you can burn more fuel. The more air you get in there, the more fuel you'll need to maintain a stoich mixture and burn efficiently. The more fuel you burn efficiently, the more power you'll make. This is the basis for boosting an engine.

The term "boost" refers to forcing more air into the engine than it would otherwise pump in on its own and there are two main ways of doing this.



Types of Boost

The two main methods of boosting an engine involve using a turbo or a supercharger (also referred to as a blower).

A turbo is an air compressor that's driven by the exhaust gases. It is placed in the path of the exhaust, whose force is used to spin the compressor and force air into the intake.

Turbo

A supercharger is similar but is driven by the engines belts rather than by the exhaust gases. There are two main types of superchargers. The roots type and the centrifugal type. The roots type generally mounts right over (or replaces) an engine's intake manifold and works by forcing the air directly into it while the centrifugal type looks very much like a belt-driven turbo.

Roots Centrifugal

Both of these systems work by forcing more air into the engine which allows it to efficiently burn more fuel and make more power.



Electric Supercharger

So now we ultimately come to the discussion on the idea of an electric supercharger.

First I want to note that this article doesn't apply to the few electrically driven compressors that have been specifically engineered for the purpose of providing short-term boost over a quarter mile. The Thomas Knight products are an example. Those kits are similar to a turbo or centrifugal blower driven by a high-amperage electric motor and require heavy duty wiring and entire banks of batteries to drive them. They do not hook up to the stock 12v vehicle electrical system and are not meant for street-driven vehicles as they are only capable of producing boost for very short periods and require a long time to recharge. These kits cost thousands of dollars and if you're considering purchasing one, I'm going to assume that the scope of this article is elementary in comparison to the knowledge you must already have.

Update: June 6, 2013

I've had the above paragraph on this page for years, but it's worth noting that I've never actually heard of anyone HAVING the Thomas Knight kit of yore. I don't know whether that ever progressed beyond a concept or whether anyone actually bought and used one. That said though, there's now a new one in a similar vane but using modern technology, so it's not as expensive and the batteries aren't near as big or expensive. In fact, it uses a pair of standard 12V batteries connected in series and works quite well.

Because of these pages, they sent me one to test. Click here for the story.

So then, back to the topic of electrical superchargers. Understanding that forcing more air into the engine will make more power, it stands to reason that if we can place an electric fan in the intake path that will force air into it, we can make more power.

The problem with this idea is that most people who think of it really have no idea how much air gets pumped by the engine during its normal operation. The engine acts as a big air pump and is capable of moving huge volumes of air all on its own. With that in mind, any electric fan that you place in the path of the intake is only going to act as an obstacle to efficient airflow and not provide any level of boost whatsoever. In order to provide boost, the fan has to be able to force more air through the intake than is already being sucked and that's simply not going to happen with some off-the-shelf computer fan or bilge exhaust blower or whatever else you've found or had marketed to you.

Electric Supercharger

Now that you realize how futile the idea of an electric supercharger is, consider the dangers. If you place something in the intake path between your air filter and the engine and that thing isn't made to be there, you now run the risk of having it break and send unfiltered pieces into your engine, potentially causing catastrophic failure. I would hope this is more than enough to discourage experimentation in this area.

As a general rule, if something seems too good to be true it generally is. Modifying a car to add power isn't a cheap endeavour and most of these sorts of shortcuts will only end up burning you in the end.

Interestingly, the company from whom I got that image above even has a small disclaimer on their site with a list of cars that showed no gain from their units. The list included GM's 2.4L engine in both the Grand Am and Cavalier Z24. I suspect it likely includes all cars from ripped-off customers who bothered to get the system dyno tested.



Notes

I've had some questions posted about this that I'd like to address. First off, on the topic of whether one of these things will actually be a hindrance to the airflow, I did some calculations to determine the maximum airflow of a 2.4L engine. If you're interested in this, the thread can be found here. Please let me know if you find the link to be broken.

Secondly, someone just recently mentioned in my guestbook that these fans can be found rated to move upwards of 1000 cfm. I just wanted to note that those ratings are referring to the amount of air moved in an unrestricted environment, for which they've been designed. If you install one of those in your boat to bring outside air into the cabin, it may very well move 1000 cfm. If, however, you place it in a restricted path such as your engine intake where there simply isn't room to move that air without building up pressure, it will not build up that pressure that you want. While it may be capable of moving this much air past it, it is not capable of forcing that air to compress into the smaller space.

Tuesday, Apr. 8, 2008:

There's been some questions lately about a company called Thorton making wild claims about their electric blowers.

The Thorton site is http://www.electricsupercharger.net/

Looking at their site, there are all sorts of warning signs that should send you running away.

Firstly, you'll note that they get their power from the car's 12V battery. There's no way they're making the boost they say they are with the battery as its power source.

Secondly, they're offering an "EPROM Performance Chip" with it, which is a load of hogwash. That's an entirely different scam and I have a page here devoted to explaining it. That's the first big warning that they're pulling your leg.

Next, you'll notice that their "100% satisfaction guarantee" requires that you return everything to them within 2 weeks. If they were really standing behind it, they wouldn't need that quick a turnaround. This doesn't give enough time to even install it and book a dyno test.

Now take a look at their fabricated dyno sheet. If you know how to read a dyno sheet then it'll be good for a laugh. In case they change it on their site, here it is.

If you don't know how to read a dyno sheet, then take my word for it that this is not only BS, but actually a completely impossible to attain dyno graph for any car.

Finally, take a look at their forum and note all the BS talk on it. I tried to sign up to ask some questions and every single forum there requires administrative rights to post in it. It's a fake forum filled with fake entries.

The bottom line is that it appears to be just another electric fan in a metal casing and, especially after reading this, you'd be stupid to waste your money on it.

Note that the people at NE Performance Inc were the exact same scammers as the Thorton folks. As I type this, the two share the same hosting company and both list the exact same phone number (1-253-882-6900) as their contact number.

Note that I removed the link to NE Performance Inc as it appears they gave up on it and it is currently just a spam link site.


On Thursday, Feb. 24, 2006, a Mr. Ed. Walker left a note in the guestbook saying the following:

it is about the cfm, and not the psi. as long as your giving the vehicles motor more air than it can naturally draw in(cfm). read the definition of the supercharger in the dictionary. and our dyno results. www.streetfreakzperformance.com

I won't address all the spelling and grammatical errors. I'll leave that up to the reader to make their own conclusions about. As for looking up the Dictionary Definition of a Supercharger... Well the reader can do it themselves and find that my reference above is quite accurate and that nothing about an electric blower fits it. An electric blower doesn't force air and doesn't compress it.

Let's look at what he's saying though. Obviously Mr. Walker didn't read the whole page but I wouldn't expect that from someone trying to bilk people out of their hard-earned money. He suggests that CFM (Cubic Feet per Minute) is the key here, rather than PSI (Pounds per Square Inch). He's saying that flow is more important than pressure.

First of all, I stress again that the CFM rating of those electric blowers is completely irrelevant in this application and does not reflect how much air the fan will push into the engine. That number reflects the amount of air the fan can move through it in an unrestricted environment. An intake tube with an engine powerfully sucking air through it is hardly an unrestricted environment.

An industrial exhaust fan, 4 feet in diameter and turning at 100 rpm, may be capable of moving hundreds of thousands of CFM of air but if you were to stick it to your car and create a funnel leading into your intake, it wouldn't do you the least bit of good. The same goes for these little blower fans people are hawking as superchargers. As mentioned above, just because it is capable of moving 1000 (or more) CFM of air through it in an unrestricted environment does not mean that it is going to force that much air into the engine. With air already in front of it, the fan blades will just churn through the existing air causing a restriction in flow while the engine continues to suck just as much as it was before.

In a boost application, PSI is important. CFM is also important, but only in how it is applied in conjunction with the pressure. The CFM of the whole system, engine included, is key but adding an electric blower to the system does NOT increase that CFM by any significant amount no matter how high the CFM rating of that blower is.

People will tell you CFM is important, like Mr. Walker did, and here I will provide an example of how that is true with respect to the whole system.

If you take a stock engine and add forced induction via a roots style supercharger, you will increase your manifold PSI and the engine's CFM of air consumption. By forcing more air in, you obviously move more air through. Note here that electric blowers do not force more air in because they do not increase the manifold PSI. They are not a form of forced induction. Now that you've got your boost (PSI increase), let's say you go and replace your entire exhaust system with something much better flowing. The result here is that the air can pass more freely through the engine so the CFM can increase. This may bring with it a corresponding DECREASE in manifold pressure (PSI) while providing more power. Your boost gauge will read a lower amount but your engine will make more power. This is because the supercharger is still forcing in the same amount of air but the engine is consuming it faster and making more power. If you had used a turbo, the turbo would simply supply more air to keep the PSI at the level you'd set. To get your PSI back up with the supercharger, you'd need a smaller pulley.

Now an unscrupulous salesman might spin these numbers to note that with the higher CFM you're making more power even though you've got less manifold pressure (PSI). With that in mind, clearly having an electric blower with a huge CFM rating will help you.

Let's look at that scenario.

If you take that same engine stock, there will be no pressure (PSI) in the manifold. Air is simply flowing through as fast as the engine can suck it in and blow it out. With a good intake, this is fairly efficient. Now let's add our high flowing exhaust system. We still don't have any manifold pressure, but our CFM has increased. We're making more power because the engine is more efficiently consuming the air it's sucking through. Now you add an electric supercharger. They tell you that it's got some monster CFM rating but curiously, the CFM hasn't changed or, perhaps, has dropped a little. This is because the air can no longer smoothly flow through that section of your intake. They want you to believe that the fan is helping the air along, but the truth is that if the intake was free flowing beforehand then all you've done is put in a restriction. The fan can't compress the air in front of it so it can't move the CFM that it could with no restriction. In turn, the fan itself provides restriction to the overall system, bringing down the engine's CFM of air consumption.

For a little bit of amusement for all my fans here, this is taken directly from Mr. Walker's website.

The E-Turbo from Street Freakz Performance is designed for just that. At full throttle, your performance turns to 800 cubic feet per minute, equivalent of 185 miles per hour of wind being shoved down your throttle body. Or get a twin setup, which will be 370 miles per hour!

Now here's a picture of his ghetto hair-dryer looking contraption.

Anyone dumb enough to think that this thing is going to provide hurricane-force winds to their engine probably deserves to be suckered out of their money. That fact aside though, the speed that air flows through a fan is entirely dependant on the rpm of the fan and the amount of restriction to airflow that exists. If you put 20 fans in a row, the air flowing through them does not accelerate faster and faster through each fan. The fans later in the line will simply have less load on them as they won't have to work to move the air. It's already flowing as fast as they'd be trying to move it. Of course, if you put a powerful vacuum at the end of this chain, all those fans would just be providing more and more restriction to the flow.

UPDATE!!

June 9, 2006

These same clowns showed up on j-body.org and tried to defend their garbage so they could kick up some more sales to poor souls who don't know any better. Check out the discussion here and be sure to read all the way to the end: http://www.j-body.org/forums/read.php?f=40&i=113561&t=113561

As I did in that thread, I'll reproduce their "FAQ" here along with the truth to explain their lies and marketing spin. The questions and answers are taken directly from their site, without change. The title on the site is "Q & A with Street Freakz Performance.

Here you have the original questions, answers, and my addition of the truth.

Question: Why don't they work with my vehicle?

Answer: The computers map sensor will not adapt to the increased cfm flows that the E-turbo pushes out.

The Truth: Someone actually did tests on those cars and proved our product is garbage. When people test other cars, they too will be added to the list of cars not supported. MAP sensors read pressure, not CFM so our explanation doesn't actually make any sense.

Question: Why not call it the electric supercharger instead of the electric turbo?

Answer: The turbocharger is defined as a centrifugal blower, not the supercharger, and we use the centrifugal shape.

The Truth: The shape has nothing to do with the name. There are centrifugal superchargers, most famously from Vortech. The turbo is actually defined by the fact that the engine's exhaust gases provide the power to turn the compressor. A supercharger is traditionally belt-driven but other variants of compressors not driven by the exhaust are also referred to as superchargers. They're actually calling it a turbo because they think it sounds cooler and will scam more people into buying them.

Question: What is the difference between your electric turbo and the bildge pumps?

Answer: This is rather simple to answer, in order make a difference in the motors hp range, you must be able to give the motor a higher volume of air than it can normally take in (cfm), this is why a ram-air system will not function correctly unless your doing speeds of 155+ mph. the largest (bildge pump) or ventilation fan pushes 250 cfm, so after around 2500rpm's your now creating a (restriction) in your motors air flow. Our electric turbo pushes 803 cfm per unit, this lasts through the entire rpm range of your vehicle. Why? Because it pushes more cfm (volume of air) than the motor naturally draws in.(even at max rpm) but remember, even though it pushes more cfm than it takes in, a V8 will require 2 units to make a respectable difference.

The Truth: There is no difference. You can get bilge blowers that flow over 1000 CFM. CFM stands for "cubic feet per minute" and refers to the volume of air that the fan is capable of flowing through it in an unrestricted environment. This rating has absolutely no bearing whatsoever on the capabilities of the blower in a restricted environment such as an engine. In this situation, the blower has to be able to push the air such that pressure is build (PSI) and these fans are not capable of such. Don't let their marketing spin confuse you. When it comes to boosting an engine, it's PSI that is important. Increased CFM for the engine is a byproduct of having an unrestricted intake and exhaust. It is not something you're looking for in a boost solution.

Question: What makes your units defy the laws of physics, claimed by others?

Answer: They do not defy the laws of physics because if the theory doesn't match the facts then the theory must change, because the facts will always remain. Our facts are the dyno sheets.

The Truth: They don't know anything about physics or theory when it comes to engines. They forged up some dyno sheets though to make it look like their product works so you'll buy it. They don't know that it would take over 10 psi of boost pressure with associated fuel mods to accomodate it to give a 60% increase in power to the 1995 Cavalier they tested. They only know what they made the chart say it does. Suggesting that basic engine theory and perhaps physics itself should be changed to support their forged dyno sheets is just plain ludicrous!

Question: If the electric turbo is so great, then why arent the bigger companies either making or using them?

Answer: Well, you must understand, that the electric turbo was never intended on replacing the higher psi turbo's or superchargers. the electric turbo was intended on being an economy turbo, with the on demand setup. but it became much bigger than that. it started getting better results on many vehicles than the base 4psi supercharger or turbo setups, even the factory option units. for example; the factory option supercharger for the 95-99 cavalier recieved a 40hp gain and costed over $2,500. then you have our electric turbo that recieved a 53.8hp gain for the same vehicles but only costed $460 for the entire kit. this is why the bigger companies don't use these or care too, it's a direct threat.

The Truth: They don't work and everyone who knows anything about engines and boost knows that. If a company could produce a solution for even $1000 that did what a $3000 system could do they wouldn't see it as a threat. They'd see it as an opportunity to make massive profits. The simple fact is that these don't work.

Question: Explain how yours differs from those axial flow units?

Answer: Well, axial flows were supposed to be designed to act like a jet engine, but they forget to add the other 5 fans like a jet engine has. There are alot of faults with the axial flow designs, the biggest being that their all using toy airplane motors and a plastic 6 bladed fan. and not to mention that the motor is mounted directly in the center of the air flow path. what do you think will happen to your motor if that axial flow motor fails? And the restriction that it causes when it's not in use. our units on the other hand do not pose any of these problems our faults mentioned, and we have what nobody else does, overheating protection. Every motor that we manufacture has an internal thermo switch imbedded in the motor, so if anything happens, it will shut itself down.

The Truth: First of all, an axial flow one is absolutely nothing at all like a jet engine no matter how many fans you add to them. These people don't know how boost works and clearly don't know how jet propulsion works either. The clear answer here is that there is no difference. Their piece of garbage is also in the intake path and if things break on it, they're still going into your engine. They chose this design because the shape looks similar to a turbo and people think turbos are cool.

Question: Why are you using a mild steel fan instead of the plastic or aluminum like the other units out there?

Answer: Our units spin at 22,000 rpm's, we don't want the fans to implode.

The Truth: This is a good time to mention that turbos spin upwards of 150,000 rpm to produce around 10 psi and do so while actually compressing air. These guys are using metal fans instead of plastic simply because that's what sort of fan comes on the ghetto bilge blower they decided to use.

Question: Why do you need to reboot the vehicles computer when adding the electric turbo?

Answer: A lot of computers simply have to be tought that the added air flows are there. Even when dealerships add the optional superchargers to their vehicles, they have to reboot or reflash the computer system. we give the buyer the instructions on how to do this, it's very simple and takes about 10 minutes to do.

The Truth: Resetting the ECU and reflashing the ECU are 100% different things. They talk about them as though the terms are interchangable. Reflashing means you're actually reprogramming the computer to change the fuel tables and other parameters. Resetting simply involves cutting power to it for a certain amount of time so it loses it's saved parameters. To suggest they are the same just shows the level of misinformation being spread by these people.

Question: Do you have any type of warranties or guarantees?

Answer: Yes to both, We have a 30 day money back guarantee, if you don't like the product return it in the original packaging, undamaged for full refund. We also guarantee a minimum 10 horsepower gain over stock with a dyno test proving under a 10 Hp gain (what we need is a copy of the dyno tests within 90 days) and we even refund the dyno test itself. Now as for the warranty, the Electric Turbo includes a warranty card that must be returned, and you get a Limited Lifetime warranty on the casings. Motor,fan, and wiring harness Limited 1 Year warranty. And a 1 time replacement for 1 year on the brushes.

The Truth: Most people won't have the time to install and test this crap within 30 days so they've got nothing to worry about. If someone actually tests it, they'll just add the car they tested it on to the list of cars it doesn't work on. Good luck actually getting compensated for the dyno time.

Kevin




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