Outer Limits 4x4 Board

have others heard about these? what are they like and do they work. thinking of one of these on a sierra. this is a link to one on ebay for sale.

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 29849&rd=1

It won't even spin enough to give you 1psi of boost.

Waste of money.

Think about it, it's just an electric fan --> not even those psycho 240V AC fans can push enough air to overpower the engine's natural ability to suck air.

An electric blower can be made to generate useful boost for an internal combustion engine.

Last time I heard about them (a looooooooong time ago now) the largest problem was accelerating the motor fast enough to provide decent throttle response. With advances in materials and technology I expect that will change eventually.

I expect the one significant limitation will be the power required to accelerate the turbine in a short enough time. At 12V it will probably require more current than most batteries are capable of delivering, but I've also heard that automotive manufacturers are looking to up the battery voltage (to 42V?) to power all the accessories they're adding.

Hmmm. Power is proportional to the square of the voltage - 3.5 times the voltage is more than 10 times the power into the same resistance.

Cheers,

Scott

Let's assume that your motor is consuming 200cfm of air when you ron the throttle, and you want 5 PSI of boost.

an electric compressor (fan) powerful enough to produce 200cfm @ 5 psi will be very, very heavy and bulky, advanced materials or not. I recall seeing some info onthe amount of HP it takes to actually spin a supercharger and it was pretty amazing - I seem to recall for an average old school blower, up to 60hp was actually being absorbed by the supercharger in loss that it had to overcome before there was any net benefit.

A 60hp electric motor is quite large.

I've seen these advertised before and the numbers just don't add up - a motor just consumes more air than any form of bot on fan type compressor could deliver so you could never get +ve inlet pressure.

I don't believe they were very successful and the main marketer of them in AUS no longer sells them.

its cheap enough, if you do get one, make sure you post up the results and let us know how it goes

Hehehe I think it's funny. It looks like one of those traps for the fully sic cheap brigade. Like HiClones etc etc.
Like mentioned above, the numbers just don't add up. Maybe if you put it on a peewee 50 or a lawn mower?

All of the commercially available 'electric superchargers' are marketing wank with no actual benefit designed to take money off stupid people. I'm willing to organise a group buy for anyone who is interested in one of these.

As others have mentioned, they simply aren't capable of delivering the volume of air flow at any reasonable air pressure ratio, most of them resemble two computer-type cooling fans in a fancy housing. Free shipping to the first five idiots who put deposits on the group buy.

This ad has a picture of it at the bottom.

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 4539038059

I think some people are thinking too conventionally. You don't need a large heavy fan to generate useful boost for an engine - look at the size of your average turbocharger impeller. You need to turn it fast.

DC motors can be made to spin at these sorts of speeds - they just need bucketloads of current, which is today's biggest limitation.

There is also one potential benefit of an electric supercharger over a conventional engine driven/turbo charger, and that is the theoretical ability to deliver full boost at idle, or at max revs, or anywhere in between. It all comes down to control.

Also consider that the fans most people think of for this application are rated for continuous use - hours on end, day in/day out for years. Outside of racing applications, how often is a super/turbocharger required to deliver full boost for much more than a few minutes?

I won't write them off yet.

Scott

There is no such thing as a free lunch, it takes a given amount of energy to compress a gas a given amount. So you don't just need it to spin fast, you need it to spin fast and have a suitably high output. Powerful, high speed electric motors aren't cheap and you're just adding another step of inefficiency when compared to driving a supercharger directly. Eg;
Belt driven supercharger
1) crankshaft rotation
2) compressor rotation

exhaust gas driven turbine supercharger (turbo)
1) exhaust gas motion
2) compressor rotation

electric supercharger
1) crankshaft rotation
2) alternator converting to electric energy
3) electric motor convertying eletric energy back to motion
4) compressor rotation

IMHO the best chance of a practical electric supercharger would be to use a belt-driven centrifugal supercharger like a vortech or similar and then find a suitable electric motor to drive it.

the picture at the bottom looks to be different to the one in the car.

And for an extra $50 he will supply a K&N "style" filter???? Supercheap do a K&N style filter for $20 don't they?

hotgemini wrote:There is no such thing as a free lunch, it takes a given amount of energy to compress a gas a given amount.

<snip>

electric supercharger
1) crankshaft rotation
2) alternator converting to electric energy
3) electric motor convertying eletric energy back to motion
4) compressor rotation

No arguments with any of that. But you're still thinking about extended periods of continuous boost.

Where does it say that the turbine MUST spin up using alternator energy? With an engine driven supercharger you're drawing power from the engine as you want to add more. An electric driven supercharger potentially allows you to draw energy from a storage source, to provide boost for short duration (Traffic light Grand Prix, overtaking, accelerate up a hill, power through a soft patch) without drawing power from the engine at that time. Get the control side right, and you replace the energy used to spin up your impellor at a time when you're not using boost.

Theoretically, you could provide boost to your engine while it's off! (NFI why you'd want to...)

But I do agree, for extended periods of boost (racing, towing etc...) an electric system doesn't add up.

Think outside the square.

Scott

A few years ago there was a magazine report on a electric supercharger fitted to a Daihatsu Charade (1.3L?). This was a big mother of a device and drew around 100 amps current IIRC with massive electrical leads to suit routed to the battery. The net gain was only 7kW at the wheels......

This was not one of those cheap fans you see on Ebay and it only gained 7kW!! It was custom made for the purpose- not some recycled fan off something else.

was reading about these and everyone has some good points. I think it would only work on small engines. It would have to be set up so it only works when it is required say at full throtle by using a vac switch. at HWY speeds air would already be getting forced into the engine but at low speeds the fan would help draw air into the carby not force it in. I see this as quite usefull when crawling about in low 1st and ya floor it.

if everyone wants to send me a few dollars each then i will buy one and test it out.

Problem is, the electric supercharger would need to be spinning at like 120,000 rpm to do anything.

(That's what my old turbo's spun at to get 7psi)

They need to be oil/water cooled at this sorta speed, and none of them are: it's a pretty good indication that they are full of shit.

If you want a supercharger for you serria, go to a engine importer and get one off a 4agze. It will cost about $300.

Lets pretend that it can produce 5pounds of boost. Hell lets make it only 2psi. It wont work on a carby motor because you need vacuum for the carby to work. Unless you pressurise the float bowl, and the fuel pump. Block off the vac' lines to the dizzy and what ever else doesnt like pressure. Up grade the alt. More power more heat, so bigger Radiator.
Not as easy as they make out. You'll prob' end up spending as much money developing it than had you just fitted a bigger motor.
But hell, it might be fun to play with. Knock your self out, and post pictures.