ew928

Looked up axial fan on the internetz.




Shrink that and bury a MAF wire setup in the middle.

LightStriker

I'm really sceptical on those thing.

Most seller will keep saying it's all about the CFM or the RPM. WRONG!
It's all about the pressure.

A common gaz engine will suck a lot of air. So a supercharger must supply more air, then the engine can suck alone, in other word, must supply more air pressure then the engine suck.

Most of those electric supercharger can't keep up with the pressure of the engine alone. So, they are basicly obstruction in the air intake. And those plastic one? I've seen people putting them after the air filter... Well, some people lost their engine to broken part going in!

If you actually get any HP from those, it's because your engine doesn't pull anything to begin with. (1.4l civic?)

You can find video of people crushing a soda can with one of those charger. Well, sorry, but if I was to put a soda can in my intake, it would crushed and shreded to peices.

Someone made some calculation on this forum, saying you would need like 100 amps of electric power for every psi supplied by an electric motor. Quite a lot! Most car alternator doesn't generate that.

mark kibort

We have always said, its about pressure and having that pressure at the the CFM (air flow required by the engine). crushing cans, static pressure are only indiations of potential pressure at high rpms. Power input is a great indication because it takes power to flow and produce pressure at the levels required by a gas engine. Now, the estimations of near 100amps are not too far off for 1psi. The 5th generation eRAM is about 60-70amps (800+watts). The current comes from the battery and has NOTHING to do with the alternator.The alternator responds to voltage drop ONLY, and it will replace what is taken over time. thats the beauty of the system. Ive raced with the eRAM for years, on the 928 with NO issues with battery power, and I used a little 14amp-hour Oddessy battery!

when we were at SEMA, the eRAM won best of show awards. Also, we tested it on a power-flow flow bench. it produces 900+cfm. Now, thats at no pressure. at 500cfm, it is approaching .5psi and higher at 250cfm, the air flow of a 2.5 liter engine at redline WOT.

yes, there is a lot of crazy, stupid , lame offerings on ebay. these are industrical centrifugal blowers that are used for cooling electric equip or ventilation of boat engine bays. First clue is 250cfm and only 2amps! if you see this 24watt device, you can bet that the only thing it is good for is venting your bathroom!

You gain HP because the axial flow supercharger produces some net change in pressure in the intake. Its that simple. Thats what the eRAM does. BUT, it does have a limitation of near 240rwhp before it doesnt provide much worthwhile gains. We have hundreds of dynos to prove this!

mk

mark kibort

we have found that the maf wire has to be at least a foot from the hot wire or you risk the chance of some air metering issues.

usually, on the otherside of the MAF works well.

LightStriker

What's taken over time? Are you saying that charger doesn't work all the time?
You know, if you take electricity from the battery, or the alternator, it doesn't matter where it come from. If you take 60 amps off the battery, well the alternator will have to supply that 60 amps to the battery, otherwise it will run out of juice.

The latest 928 had a 130 amps alternator. Which when hot will generate around 100-110 amps. So if you take off 60-80 amps from it, you will have 40-60 amps remaining for everything else. Might actually work for young 928... But older one won't have the juice for it. Mine has a 90 amps alternator, which means roughly 70-75 amps when hot. You see that for mine, I wouldn't have the juice for a eRam. It would dry out my battery in no time.

Amps doesn't come magicly from the battery.

So, 80 amps for the eRam? So let's say 1psi... How much PSI a stock 928 engine produce? You know you can calculate the pressure differential from a running engine. Like I said, a supercharger must produce more air pressure then the stock engine. (Charge pressure - stock pressure = pressure gained)

mark kibort

You are completely missing the point and understanding of how the charging system works as well as how the eRAM uses the electrical capacity available.

you ask, "what is take over time". the answer is current is replaced over time based on voltage drop of the battery. amps dont magically come from the battery, it COMES from the battery. the alternator replaces those electrons over time. make sense? the alternator doesnt have to replace the electrons (current) at the same rate, it just has to replace them over time. since the eRAM is ONLY used in WOT applications, it uses electrical current and then requires none. more often, it requires none and thats how the battery is recharged and never "runs out of juice".

Your starter takes near 300amps, but where does that come from? the battery!
depending on how long you use it, the voltage drop on the battery will signal the alternator to replace the charge. It can only operate at its max capacity, which might be 75 amps or 130amps. If you use your starter at 400amps, and you use it for 15min, (100amp-hours used) the battery might need near 100amp charge for over 1hour to replace the electrons. see how that works. The eRAM used for 5-7 seconds at a time, can actually run on the alternator, because most car functions are only 10amps to keep things running. But, the battery supplies the current and the alternator replaces the currrent based on voltage drop. the greater the votage drop, the greater the alternator draw. a battery in good shape resists voltage drop and might get charged at only 25amps even though it has a 65amp draw on the battery for a few seconds. this would then happen for 3x the time that the draw was used. see how that works?

you are very unclear below with regards to pressure and requirements for a 928 engine, so let me try and clear things up for you . when a 928 is at full throtttle, the CFM draw willl be a function of rpm and displacement. even with a closed throttle. However, the density of that CFM is what changed based on pressure drops and atmospheric conditions. Say , your engine was 100% volumetric efficient. that means the eRAM needs to make the 500cfm that the engine is using at 6000rpm WOT, PLUS be able to produce that air flow, at a higher pressure, and thats what it does. because the eRAM can produce air flow of 900cfm the difference of what it can make and what the engine requires , is pressure. not a lot, but enough to make a 3-5% HP gain in most cars.

does that make it more clear?

danglerb

Not talking about the tiny pressure, I am talking about 1000 watt air over cooling fan motors.

mark kibort

Also, negligible. think about 500cfm of air blowing over a a little 1.65" diameter motor. no measurable heating of the air. especailly if you are talking lower density. again, pv nrt for that as well. not even a rounding error.

Bottomline, it doesn matter, because we are seeing the gains for the pressure we are altering in the intake.

http://www.electricsupercharger.com/...no-article.pdf

mk

danglerb

Size of the motor means nothing, its the power (which almost all goes to heat).

Basic equation for duct heating is; Kw= (cfm*Td)/3000, which works out to 6 degrees F for a 1000 watts and 500 cfm.

Do these intake heaters run all the time?

mark kibort

It does matter, when it comes to short term cooling and heating of the surface.

Anyway, not to diverge, the motor is 800watts and 50% efficient at full power, so 400watts go up in heat, BUT, not all at once. It can be stone cold for 5 seconds and then the heat migrates to the surface. It is then cooled via any air flow going to the engine on the off or part throttle condition. If you are using in a racing situation, that heat might be about 3 degrees. again, less than a rounding error on air density and HP loss, if that is what you are getting at.

so, again, the motors do NOT run all the time. they only run under WOT conditions, which is not very often. a hot lap at laguna is less than 50% throttle. (i.e. on for 7 seconds off for 7 seconds on average for 30min)

mk

LightStriker

Ah! The part I miss was that it works only for really short time. (Like a starter)
Somehow, I had the idea it was working like the other electrical supercharger, all the time.

mark kibort

Thats the beauty and part of the patent. binary control due to the axial flow design. It doesnt have to work all the time. If GM or a big aerospace company designed it, this could be a revolutionary bolt on device. In theory, you could run substantial boost when you need it, but when it was not needed the car could run a smaller engine more efficiently for better economy.
To make this thing for 3-4psi, it would be a pretty expensive piece of hardware.


mk

RicerSchnitzzle

It's my duty as the rice on this board's schnitzzle to try the new erams out. I'll post up results and dyno when I finally get my hands on a pair. Of course if the suck, I'll stick to my rice and claim a 75hp gain from my fans and fart cans.