h a l f b a k e r yIdea vs. Ego
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I've been looking into these electric superchargers on the market. They all seem to use a small fan to push about 700-800 cfm. How about using a much larger fan. An off-the-shelf 16" fan can move 1550cfm. Attach this to a funnel and the narrow end of the funnel to the intake. This should produce
alot more boost than the smaller fans. It will need a scoop or some other creative solution for the space requirement.
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Not certain a simple change in size makes the cut here as a new idea. Try again. And welcome to the .5bakery, BTW. |
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Definately an "X that does Y" idea. |
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There is a limit to the air pressure that will produce an increase in performance in engines. Pushing too much air will dilute the fuel mixture and produce less power. |
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That assumes a fuel injected system with oxygen-sensor limits to mixture compensation (most do have limits). Carbureted systems, though, can handle a very large increase in air volume while maintaining mixture. |
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But, hey, who uses carburetors anymore? |
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Most modern fuel injection engines run massively rich anyway for emissions reasons, you can get more power and economy from leaners mixtures, a low-power fan could help without messing up your engine. |
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A fan probably boosts power more by creating vortices in the airflow which results in better air-fuel mixing. There would be a small power gain from reduced pumping losses, which is really that the fan would be putting energy into the engine , you might as well hook up a electric motor to directly assist the motor. |
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Turbos spin in excess of 100k RPMs at top speeds. This setup would never be able to pressurize the air more than about 1 - 3 psi. Not to mention the power requirements for this type of fan, and a DC -> AC converter, considering this off the shelf fan will most likley be built for AC input. |
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The problem with electric superchargers is this: they can provide some usable boost, but what do you do with the supercharger when it's not needed? Belt driven superchargers spin continuously, as long as the motor runs, but electric superchargers are turned off until needed. This is an obstruction under normal driving conditions. You can't have an electric motor running continuously just to provide ordinary airflow. They will wear out. You need some type of gate that can switch from regular vacuum conditions to boost. |
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for example _____________________ indicates an
_____SUPERCHARGER___ inline supercharger, which boosts at times, but is an obstruction when boost isn't needed.
_____________________
_<__<___ \ __________
\ S \
\ C \ This represents the supercharger when needed, with a valve preventing boosted air from escaping back into the atmosphere, and the supercharger is out of the way under normal conditions, like this.... |
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____________________________________
<_<__<__<__<__<__<__Normal airflow____
\ S \
\ C \ |
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This shown, that a simple mechanical one-way gate would suffice to keep air from backing out into the atmosphere, a good strong leafblower would be capable of generating a few pounds of boost for a little while. I wouldn't run it continuously for too long, though. |
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Why would the electric motor wear out any sooner than the engine or other accessory? |
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Those things are just a bilge pump... what happens if the fan comes apart? Do it right and get a real supercharger. |
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How about you give a kid a cookie sheet and have him flap it at your car's intake. I am sure he could top 300cfm after a few weeks of practice. CFM means NOTHING without pressure and since they don't tell you what kind of pressure these things produce that should trigger your bullshit detector. |
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'what happens if the fan comes apart?' crunch, clank, crunch, BANG, rattle, rattle, sputter, cough, POP |
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you do need pressure - also, the more air pushed in, the
more fuel the car sprays. Air is measured on the way in
by a sensor, whether it be pressure or flow. There are
two companies claiming to have made an electric
supercharger and an electric supercharger-- eRAM and
ACTurbo. The only thing you have to modify when
installing a REAL turbo of supercharger are the fuel
injectors. They might not be large enough to suffice
when you get more than 5-6 psi or so. Also, make sure
your engine can handle the pressure :) |
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Looking at the Eram site and some quick and dirty calculations, it's within the envelope of possibility, but pushing it. Say 5-10 HP for like $300; reasonable. Compare to headers or fancy intake. 50 Amp current draw for a few seconds? Possible, barely. Generating 1 psi with enough cfm to feed a smallish engine from an axial fan from 600 watts? I'm a little out of my element, but it doesn't seem unreasonable. 5-10 hp from 1 psi? Well, that's 7% more air, so you could expect 7% more HP gross, minus whatever losses. Could the EFI handle 7% more air? Probably.
That looks like a powerful little fan they have there. It' s supposed to be from some sort of model airplane application, and I believe it; the video shows that the airflow is enough to actually lift the thing vertically up into the air. I looked up some bilge vent fans, and they don't come near this delivery. |
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Oh yeah, also; the magazines are all saying within a decade or so new car electrics will all be 42 volts, specifically so that the electric motors will be smaller and lighter for the same power, so they can start using them for power steering, AC, etc. That oughta make this electric supercharger idea much more feasible. |
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the E-Ram electric supercharger works. Just look at it this way, when you install an aftermarket air intake you are trying to reduce the restriction for your engine to suck air...so why wouldn't adding 750cfm of air @ 3psi NOT work? It is the same as putting in a ram scoop, but it kicks in at W.O.T to give you an HP boost when you are racing only. When you are stuck in traffic you don't want your engine boosting for no reason. So why is this thing so unreasonable? For $300, that a bargain for an instant 5-15HP boost at W.O.T. without going turbo or Spray...And if you already have an aftermarket filter and FIPK then it just adds even more to the total HP gain from the E-Ram. I give it 10 of 10 all the way around. Great idea. |
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I think the only desent way to do electric super charging would be to have a larger motor to power a roots type of charger. the motor would be actuated by a button and would be a short lived event say to race someone at a stop light.there would probably be an extra battery so the engine was not loaded during the time of the race to power the electric motor. |
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I own a business that specializes in aftermarket turbos, so I'll share a little of what I know. This might help you out a little. As others have stated, you can't just consider the CFM. That's simply how many cubic feet of air are moved. You have to consider the pressure of that air. A typical factory turbocharger might product between 5 and 10 PSI. Some more aggressive systems run up into the teens. If you look at the electric turbochargers on ebay and such, you will find that most of those are bilge fans for boats. They are incapable of producing any significant increase in pressure. They may flow high volume, but if you tried to get them to flow agains a 1 psi pressure differential, you would get virtually 0 volume. The E-ram seems legit. The motor is strong, and I can believe the 1 PSI claim. That's not nearly as much boost as a real turbo system would get you, but it's worth having. To evaluate their product I bought one. While the idea is good, the build quality is not. E-Ram superchargers are (in my humble opinion) very poorly built. The housing was made of cheap plastic that flexed so much that the fan blades kept hitting the housing. I ordered the one with the dual inline motors, and when it arrived, one of the motors was burnt out. However the motor that did work seemed up to the task of producing one pound of boost on a relatively small engine. |
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If someone wants to make a real, decent electric supercharger, I think there would be a good market for it, provided you made a decent product. But there is a catch. Contrary to what was said above, there's more to it than upgrading your injectors. If that were the case I'd have a turbo kit out for every car on the market. The powertrain control module of most cars is capable of measuring the air coming into the intake and adjusting the fuel delivery to acheive a proper air to fuel ratio - up to a point. First off, most of them can not sense pressure above atmospheric. That means that as soon as you develop boost, you are puting more air into the engine than it realizes. Second, they can only adjust the fuel curve up to a certain percent. So if you are blowing a whole lot of extra air in there it'll have trouble making it work. Third, the engine isn't that great at getting the air-fuel ratio correct once it's working very far out of the territory for which it was programmed. The best way to do it is to put the turbo on there, run it on a dyno with a wideband O2 sensor and then completely re-program the computer. That's the hard part. |
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The E-ram skirts around this by producing only one pound of boost. That's not enough to throw the computer way off, but just enough to make a measurable difference. If you could come out with something that produced a solid 3-5 psi then you might have a seriously marketable product with genuine performance potential. |
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My mother has been trying to get me to install this disgusting aged jet-tub she pulled out of somones yard for free. I keep coming up with ways around by I have recently discovered that the pump for it is shaped like half a turbo (intake or exaust but not both) mounted in a water proof way to a very large motor. This motor is supose to create several powerful jets in the tub (I beleive the number is 4) and as the motor is in no way relient on the water flowing through the pump and the fact that air is less dense and thus easier to move than water, this pump may provide the PSI boost you guys are looking for. Poviding your alternators and possibly power inverters can handle it (it looks pretty beefy) it may just be what the doctor ordered. |
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You're just trying to get out of installing the tub....you're mother will be unhappy if you give that motor away. |
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"The most efficient type of supercharger, flowing 265 cfm and developing a boost of 11.5 psi, takes 14.5kW to drive it. Figures aren't readily available for centrifugal blowers, but they'd be of a similar magnitude. So the best blower design (the same type that's used on the Mazda 800) takes about 14,500 watts to drive it on a modest-sized engine. This power is derived from the engine via a belt connecting the blower to the engine's crankshaft. |
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But let's say that instead of using a belt-drive from the engine, we power the supercharger by using a 12 volt electric motor powered from the car battery. For an electric motor power of 14,500 watts, we'd need a current flow of about 1000 amps (14,500 watts divided by 13.8 volts = 1050 amps). So, to supply the current to drive an electric supercharger having the same airflow output as the most energy-efficient type currently available, it would take 1000 amps. To generate this much electrical power would require at least 8 heavy-duty alternators bolted to the engine. "
-autospeed.com |
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the problem is you got an ancient 12volt battery. If it was say 100 volts, you'd only need about 125 amps. But then you need a 100volt motor to spin your compressor, and a 100volt alternator. It would probably better than a turbo in one respect, you wouldn't have exhaust gases heating up the housings creating your high inlet temps, wouldn't need to be water or oil cooled(big assumption) and you could have it always going (with a b.o.v) and just have it with water injection. |
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Following up on [Brad88], the supercharger requirements are very interesting, and not something I have noticed on the web before. In a 4 inch intake, it means the airflow is something like 240 feet per second. Whew! So far everyone has considered generation of the pressure when required, which requires electrical power rates that are high for a motor vehicle. But if air was compressed at partial engine loads, or especially during braking (no alternator or motor required, new meaning for compressed air brakes?) and stored in a air receiver, then it could be discharged when required. A 3ft cubed tank could hold enough air at 100psi to give boost for approx a minute, if the numbers quotes by [Brad88] are correct (and my mental arithmetic is OK). |
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Sorry [Ling], I think your calculations are off. A 3 ft^3 tank of air at 100 psig would hold about 17.25 ft^3 worth of air at 20 psia (5 psi boost). That would feed the engine for about 4 seconds. |
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The reason I think your calculations are off is due to the difference between gage pressure (measured as a difference between atmosheric and the tank) and absolute pressure (measured from a perfect vaccuum). At standard pressure (14.7 psi), the 100 psig tank contains about 115 psia. If we want to have 5 psi boost, that means we are going to need 20 psia. 115 psia/20psia = 5.75. Times the 3 ft^3, that gives us 17 ft^3 of air at 20 psia. |
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The reason I use psia is that the engine will have to run completely off this tank. If you try to use the tank to simply boost the pressure while the engine is still connected to the outside air, most of the pressure in this tank will simply run backwards out the intake. |
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[Genyus]: I hold up my hand for the mistake, you are right to account for gauge/absolute pressures, but please note that 3 ft cubed is not the same as 3 cubic feet. The former would be 3ft by 3ft by 3ft. This would store 9 times the amount that you state, so 4 seconds becomes 36 seconds (admittedly, my mental arithmetic was astray). Perhaps if we also account for the fact that when the tank empties, it will stop giving any boost when the pressure falls below approx atmospheric.....
I used 100psi because it is a common supply pressure, and many valves, pipes and fittings are designed for this pressure. Higher pressures could also be used. Air amplifiers could be used (they use the vortex phenomena, I believe).
Not a project for the family saloon, of course. |
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Since the turbo would only run for a short time the required current could also be stored in a series of capacitors (lighter than a high-psi air tank?) The air volume sensor problem could be resolved just by switching it out with a sensor from a turbo model vehicle... since we are changing out the fuel injectors for higher capacity ones anyway. I think a target of 5psi boost is realistic, I know the ECU (computer) on my Nissan craps out around there. |
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Such an electric system exists, and you can buy it for 2,000 - 3,000 $ depending on the size of the engine. Instead of a Turbocharger, an Eaton M90 or M62 Roots type Supercharger is used with three 12V electric motors.For more info look: www.boosthead.com |
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Think of it this way. Your car runs a certain mixture of air/fuel. If you use an instant on solution like eram, your gaining like 5hp to throw your fuel map out the window in on demand situations. Its like the scramble button on boost controller. Kinda cool, but for $300??? A better idea would be to buy a fuel computer and a chip to adjust the fuel map completely and draw the 5hp power of the motor itself. Your still capitalizing on the fact that factory fuel systems err to the conservative side. Chances are, you would also find more than 5hp (probably between 5-20hp depending on the motor). Also you wouldn't have any cheap moving parts that could end up somewhere in your motor. These too have their drawbacks, but on minor mods fuzzy logic can be a good thing. I know have a pressurized system seems cool, but with the risk you are taking using these cheaply made peices, you might as well run NOS. If you want real bang for the buck a smallest NOS system will give you 25hp on tap. I do not ever recommend NOS, but if cheap power is your choice, and you need to have street cred for having a suped up ride (and not just a computer/chip), then aim for NOS. Back to getting 1PSI for $300. a downpipe, exhaust, or even underdrive pully would give you the same power or more, and be much better for the car. For a while there I tried to squeeze every drop out of my system by adding products like eram, octane 104+, tornado charger, etc. Then I realized all of those combined didnt match what a good intake & exhaust will do for a car. A K&N alone will net you at least 5hp, and can be found new on ebay starting at $50. The FIPK is better and runs aroung $200. Take my advice as well as that of others. If you want a supercharger or turbo, either buy a car that has one, or get a good bolt on. If you want cheap power go with NOS, but be aware of what it does to the engine, seals, etc. And if you want good performance, but cannot afford the bolt ons, and dont want to punish the car with NOS, buy a good intake & exhaust and a computer, and save up for the bolt ons. Its your best bet! |
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Actually I thought about an electric supercharger too. Since there is no parasitic drag you can get more power out of your engine without overstressing it than with a mechanical supercharger or even a turbocharger. In addition you can generate a devil terrifying low end torque. I think this concept makes especially sense in a lightweight sportscar. Instead of batteries you could use capacitors, since they don't require that much weight. An electric supercharger basically allows you to lever the actual power of your electric motor. So if you use a 30 HP electric motor you might generate an extra 120HP on your combustion engine. Imagine the Toyota Prius would use its 70 HP electric motor to supercharge its own little gasoline engine (you'd end up with a real 'vette-cruncher!) |
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An electric supercharger is actually buyable: http://www.boosthead.com/home.php If you install a powerful alternator and feed your extra 'boost-batteries' or capacitors only when you hit the break you could actually claim to own a hybrid. Or if you stick a solar panel on your trunk to charge your batteries you could claim to own the first solar powered supercharger. Who could possibly beat this? |
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Following comment from Ling.
Compressed air direct to the intake made me think of powering a turbo from the compressed air. I am not an engineer nor posses excellent math skills but, If you have 100 psi and are trying to create 5 psi boost than would it be possible to create a small turbine (powered by 100psi) directly linked to a larger turbine creating (5 psi to the intake) using near a 1:20 relationship. Obviously there would be a power loss from turning these tubines and escaped (lost) air. But wouldn't this require near 1/20th the CFM of straight "injecting" compressed air? Am I way off? Or should I patent? lol |
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If you want to save yourself a lot of trouble, you can buy a supercharger from www.electricchargers.com and install it yourself. Only set you back 100 bucks. I can testify to the customer service this company provides. |
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well most moder fuel injections run rich due to emmisions before the electric turbo so that mite actually level out the mixture. |
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