Stupid hairbrain idea? Engine boost alternative

[Spittybug]

Turbos and superchargers take engine exhaust pressure or direct mechanical connection to add extra combustion air for the car, allowing more fuel to be burned thus giving more power. Right? What percentage of time is one actually "engaging" the boost if this just a casual car or even daily driver? Accelerate up to highway speeds, passing, showing off... It doesn't really come into play on trips to the supermarket, does it?

What if..... how about using an electrical storage setup (a few big capacitors or something similar) connected to a high volume, fast-to-start air blower like you see with bathroom hand dryers? These suckers move a couple of hundred cubic feet of air per minute and start up pretty quickly. They are only "on" for relatively short bursts yet the electrical system works all the time to keep it ready to go. They could even be made to be spinning slowly all the time to decrease the lag.

Looking for fatal flaws in the idea.

[DMCMW Dave]

I can't say I ever tried one but if you look on other performance-car forums you'll find that they are generally viewed as a snake-oil product. The energy involved (size of the blower and battery needed, and then energy needed to recharge the battery) make it impractical. Google "electric supercharger" and you'll find a few folks selling them and a lot of people debating the issues. An electric motor with enough power to build meaningful boost is quite large. Do the math on the horsepower required to build enough boost at high flow....

I was on a BMW forum a few years ago where the mere mention of "electric supercharger" would get you banned from the list.



Turbos and superchargers take engine exhaust pressure or direct mechanical connection to add extra combustion air for the car, allowing more fuel to be burned thus giving more power. Right? What percentage of time is one actually "engaging" the boost if this just a casual car or even daily driver? Accelerate up to highway speeds, passing, showing off... It doesn't really come into play on trips to the supermarket, does it?

What if..... how about using an electrical storage setup (a few big capacitors or something similar) connected to a high volume, fast-to-start air blower like you see with bathroom hand dryers? These suckers move a couple of hundred cubic feet of air per minute and start up pretty quickly. They are only "on" for relatively short bursts yet the electrical system works all the time to keep it ready to go. They could even be made to be spinning slowly all the time to decrease the lag.

Looking for fatal flaws in the idea.

[Bitsyncmaster]

I can't believe you just posted this because I was thinking of what could be done mounting a large electric fan in the passenger side pontoon. But like Dave S says, you need a lot of hp to get the volume of air at a few PSI.

[Michael]

These types of forced induction units need to do two things to be plausible. First, they need to over come atmospheric pressure before they build the first pound of boost. I remember seeing one of these fly by night outfits demonstrating their product by allowing it to levitate out of his hand...unless that thing weighs at least 16lbs, all its doing it interfering with the velocity of the incoming air which brings me to my second point, blocking the intake path. That thing needs to be constantly powered and spinning fast enough to overcome the air velocity its blocking just to keep from hurting your performance, let alone enhancing it.

Companies spend millions in R+D to get a whisper of an edge in performance and fuel economy. If it was as easy as mounting an electric fan in your in ypur intake path, or pouring some magic fluid in your tank, they would be doing it.

[Spittybug]

Ha ha...yes, I have seen the so called "hair dryer", Chinese made blowers. I don't wish to be associated with that idea in any way!

I used a quick online calculator; 4000 rpm, 2.89l displacement and 75% volumetric efficiency gave about 150 cfm air intake. The really powerful air blowers that you see in public restrooms (the new models), move close to 400 cfm I believe. Yes, that takes a quick jolt of juice to do, so this wouldn't be a painless idea.

The concept was one of having quick discharge but continuous charging of some big capacitors, like high end stereos use to hit base notes. I don't have the electrical knowledge to guesstimate the requirements to run such a blower for a few seconds at a time.

Doubling the volume of air would be 14.7 lbs of boost (since atmospheric is 14.7 at sea level, right? Assumes constant temp.). Since we wouldn't want more than say 7 pounds, off the cuff we would need only 75 more cubic feet of air. I know there are inefficiencies and the mass of the air is what is really important, not the volume, so when we are squeezing it in, the temp goes up, so the mass per volume drops, but it looks as if there is plenty of volume to spare from these big blowers. The problem certainly revolves around the electrical requirement.

The cheapo Chinese jobbies simply seem to match motor capacity with electrical availability on a 1:1 basis. Some specs I saw were 3A draw for 1-2 pounds of boost. My concept is to "burst" the electrical availability to more align the actual amount of time boost is wanted to the volume of air required.

For that matter it could be done with a small compressor that occasionally provided a quick volume of air............... I don't have a turbo or supercharger, so I honestly have no idea what % of time they are engaged. My feel is that it is relatively small and that the real kick in the pants is from a big acceleration that lasts a few seconds.

[Spittybug]

That thing needs to be constantly powered and spinning fast enough to overcome the air velocity its blocking just to keep from hurting your performance, let alone enhancing it.

Companies spend millions in R+D to get a whisper of an edge in performance and fuel economy. If it was as easy as mounting an electric fan in your in ypur intake path, or pouring some magic fluid in your tank, they would be doing it.


A "reverse" waste gate type setup could overcome the resistance arguement when it wasn't in use
Car companies must also look at cost and reliability. We own Deloreans! It's a given that they cost alot and require above average TLC to keep them maintained!

[Spittybug]

I can't believe you just posted this because I was thinking of what could be done mounting a large electric fan in the passenger side pontoon. But like Dave S says, you need a lot of hp to get the volume of air at a few PSI.

Psst Dave; YOU are the one that comes to mind in figuring out the electrical control!!! Fair warning.

[DMCMW Dave]

Here's an interesting bit of timing. My new Car&Driver mag showed up today and lo and behold - an article about major manufacturers considering Electric Superchargers in the future.

No real specifics, but mention in mainstream automotive media is certainly promising. They do mention this company in the UK:

http://www.cpowert.com/products/vtes.htm

Look at the DC currents involved!!!

[Bitsyncmaster]

Here's an interesting bit of timing. My new Car&Driver mag showed up today and lo and behold - an article about major manufacturers considering Electric Superchargers in the future.

No real specifics, but mention in mainstream automotive media is certainly promising. They do mention this company in the UK:

http://www.cpowert.com/products/vtes.htm

Look at the DC currents involved!!!

1.8 Kw. So about two HP needed. That works out to about 150 amps so not sure where they came up with 350 amps. I have a small RC airplane cobolt motor which I think puts out about 1 HP. That may be enought to give a little boost.

[Spittybug]

WOW, big current numbers. Success of something like this definitely depends on the percentage of time that it actually needs to engage versus how much time can be spent "charging up" for the event.

Bit; is it reasonable to be able to deliver a "few seconds" worth of such current from capacitors or other means? Or is this out of the realm of practicality?

[Bitsyncmaster]

WOW, big current numbers. Success of something like this definitely depends on the percentage of time that it actually needs to engage versus how much time can be spent "charging up" for the event.

Bit; is it reasonable to be able to deliver a "few seconds" worth of such current from capacitors or other means? Or is this out of the realm of practicality?

Can't store much power even in those super caps. What could be done is charge a battery pack. Maybe use a higher voltage electric motor to get more efficiency. They do that with electric cars (200 to 400 volt).

[LEVY]

.


As far as I know, capacitors charge/discharge in a split second, so capacitors should be left out of the equation, unless used just to give a bust to start the motor, then batteries would take over



WOW, big current numbers. Success of something like this definitely depends on the percentage of time that it actually needs to engage versus how much time can be spent "charging up" for the event.

Bit; is it reasonable to be able to deliver a "few seconds" worth of such current from capacitors or other means? Or is this out of the realm of practicality?


Can't store much power even in those super caps. What could be done is charge a battery pack. Maybe use a higher voltage electric motor to get more efficiency. They do that with electric cars (200 to 400 volt).

[propony]

Back in May, HotRod magazine did a story story using gas leaf blowers on a 1985 Corvette they are giving a slow death to, spent $413.93 on 2 Sears blowers 470cfm's each, for a total of 940 cfm's, gained about 50 hp. Then for comparison, they just sprayed nitrous across the top of the carb, not into the intake, and it had better results.
In the end the blowers did work, although not electrically powered, it would be a good read or check out U-Tube, that is where they got idea.
Curt

[DCUK Martin]

I used a quick online calculator; 4000 rpm, 2.89l displacement and 75% volumetric efficiency gave about 150 cfm air intake. The really powerful air blowers that you see in public restrooms (the new models), move close to 400 cfm I believe. Yes, that takes a quick jolt of juice to do, so this wouldn't be a painless idea.

Hand driers are all about shifting air, not pressurising it. Even the best hand drivers barely acheive a pressure differential in the kilopascals. You can do some relatively simple Gas Law calcs to work out the kind of power required to shift a lot of air and generate a meaningful pressure gain. It's astonishing to realise how much energy is transferred down a turbo's shaft.

[Bitsyncmaster]

Hand driers are all about shifting air, not pressurising it. Even the best hand drivers barely acheive a pressure differential in the kilopascals. You can do some relatively simple Gas Law calcs to work out the kind of power required to shift a lot of air and generate a meaningful pressure gain. It's astonishing to realise how much energy is transferred down a turbo's shaft.

Isn't that why we need to cool the air? All that energy making the pressure raises the temperature of the pressurized air.

[DCUK Martin]

Yes. Pv=RT

Pressure x Specific Volume = Gas Constant x Temperature (Absolute)