Hypothetical System?

[Ryan]

So I thought of this, not sure when, but its been percolating...

The whole idea of Forced Induction is to cram more air into the cylinders than our natural 7 PSI atmosphere can push into the chamber in the time given. Superchargers and turbos do this by using power from the engine, may it be mechanically from a belt or using the exhaust... either way its directly related to engine speed... I'm just rambling, this isn't even part of my thought.

What if someone were to rig up a compressor into some cavity... which would pressurize a tank to something like 200 PSI, and were able to release it into the intake for a 'shot' of forced induction? not 200 PSI into the cyls, you would regulate it down to 3-40 PSI, whatever you can run... but kinda like Nitrous, but just air?

The problems I see:
-Your intake would need to be air tight (no problem, usually) and have a one way valve to stop your 'shot' from just firing backwards away from the engine back to the atmosphere.
-The ECU would have no idea how to handle a huge change like that in air. The MAF/VAF would max right out, and you would never get enough fuel... could this be corrected with Megasquirt?
-You would only want to do this a WOT, otherwise you might blow up your idle control...

The benefits:
-You could have a very small compressor that would fill the tank very slowly over time, may it be electric or belt driven, and when the tank is pressurized, you could have it on a shutoff. It wouldn't really sap power at all, never more than an AC or something.
-You could operate it only when you felt like it, like nitrous.
-No fuel to buy, aka NOS.
-Its unique
-You could probably rig up a pressure regulator in the cabin so you could choose your boost ammount.
-It could be any sized tank... you can cram a lot of air into small spaces.

Opinions? Ideas?

[Daninski]

Ryan what ever your smoking, I want some.
7 PSI? I thought it was 14.5 at sea level?

[RS_OBD'oh_2]

An air tank is very heavy and the motor tends to be loud.

For a good laugh... look up mustang + leafblower

[Savin]

This almost sounds like cold air injection, but not. (which already exisits) Even still, it wouldn't be too great of an idea, the benefits would be small from a small compressor. You'd need a high CFM compressor that would have a big opening. With whatever PSI you have coming out of the compressor, it likely won't be the same going into the engine. Going from small to big equals decrease in the once high pressure. (little to no benefit)

All in all, it is not practical with going with a compressor IMO.

[MCNano117]

Turbo/supercharging is basically the most efficient way of doing what you just said. You're going more along the lines of electric supercharging, and you can buy a kit for that on eBay for like $10 lol.

[fowljesse]

I brought this up, in almost exactly the same way, a while ago. My idea is to run a charger with a 2-stroke engine. You could vary the speed, to match the production of pressure with the need. I also thought about having a big pressurized tank, with a variable valve, that would give the right amount of pressure. Also, it would have a blowoff valve that would recirculate it back to the tank. I have a 6.5 HP engine that would fit where my battery used to be. I would love to play with this, with someone who knows about air charging!

[Ryan]

Ryan what ever your smoking, I want some.
7 PSI? I thought it was 14.5 at sea level?

More than one person has said this to me on here... am I really that odd? Do I sound high ALL the time?

This almost sounds like cold air injection, but not. (which already exisits) Even still, it wouldn't be too great of an idea, the benefits would be small from a small compressor. You'd need a high CFM compressor that would have a big opening. With whatever PSI you have coming out of the compressor, it likely won't be the same going into the engine. Going from small to big equals decrease in the once high pressure. (little to no benefit)

All in all, it is not practical with going with a compressor IMO.

I meant small compressor... okay, I don't really understand the things, but what I meant was filling the tank painfully slowly, but still to a higher PSI.... The rest of this quote I don't really understand, or maybe I'm overthinking it. They must have burst type valves, how else would a hammerdrill or a jackhammer work?

Turbo/supercharging is basically the most efficient way of doing what you just said. You're going more along the lines of electric supercharging, and you can buy a kit for that on eBay for like $10 lol.

Your missing the storage of the air part. That was the main point.

Thanks for your input so far, but I still don't feel I got the reply I was looking for.... or even that you understand me at all.. ahah...

[shameem]

Say you have an 1.8L engine (which holds about 1/2 gallon of air) - at WOT the flow would be somewhere close to 250 CFM - the "best" industrial compressor does about 20 CFM. Its not about just pressure - its also about the volume of airflow (P*V=R*T) - commercial air compressors jack up pressure by sacrificing volume. Whereas IC engines need volume.
The storage doesnt make sense because a 1.8L engine sucks slightly less than 1.8L (0.5 gallon) of air of air every 2-4 RPMs depending on load, throttle opening etc- Imagine the tank size you need to have to supply air for any meaningful duration....

Compressed air however is a good "conveyor" of energy like electricity - There is a bunch of guys who have come up with a compressed air engine for a car - you basically fill your tank with compressed air and a pneumatic engine converts the pressure to mechanical energy (like a reverse compressor). The engine has been fitted into lightweight cars and there are claims of 100+ MPG equivalence....

[Ryan]

Thats more like it

So unless you had a nutty compressor to do something like 4000 PSI and a tank to handle that... you'd never have enough air to run for 3 secconds at 5-7K RPM

Does my engine really use that much air? I guess so.... those pistons giv'er in there.

Thanks, shameem


Okay did some calculations... 4L at 4000psi translates to 30808 litres of air.... divided by 1.8, you have 17115 times the engine can suck in 1.8L, which according to shameem is every 2-4 revs, which leaves 8557-4279 revolutions.... which is a considerable ammount, I suppose.

Say doing 5K RPM, thats 83 revolutions per seccond, 103 - 51 secconds...
at 6K thats 85-42 secconds. considerable. Who wants to run boost for a minute?

but also, 4000 PSI is rediculous

Say, 200 PSI, that I can imagine...

[shameem]

4L at 4000psi translates to 30808 litres of air....

What? 4 litres of "gas" at any psi is 4 litres of gas (given the increase/decrease in temperature). If temperature is held constant somehow then the volume would actually decrease......
The gas law is - Pressure * Volume = R * Temperature
So if one wants to increase pressure and volume - the temperature would have to drop to ridiculous levels to obey the gas law....

Increasing pressure doesnt mean volume is increased - increasing pressure increases temperature and when that pressure is released (lowered) temperature drops along with it according to gas law. That's why compressed air nozzles and spray cans always feel cold when in use.

You can see this at the output of a turbo or supercharger - as the compression is increased - the temperature increases to the point where you would need an intercooler. The intercooler transfers the temperature to air thereby increasing density which decreases volume (v=mass/density) and maintains the gas law.

[Dragyn Vyrus]

go to your nearest paintball pro shop and pick up a Carbon Fiber air tank, your can get them in any size up to i think 68Cubic inch. It will be under 4500PSI too. the tank would therefore be called an 68/4500 most common is 45/4500

not sure if you would need some other ind of pressure regularor but after the regular on the tank the air is being released at a pressure of around 850psi, and with a full tank at that pressure it will last around 5 minutes or so of non-stop air being released. best thing about it is that if you need a re-fill, if you have a field near-by it will only cost you around 5 bucks to re-fill the entire tank! If you could get the pressure right so that it was strong and like a supercharger then it would probably be worth it the tanks themselves will run you $300 max, or you could get a used one for around $100. Their light, only a couple pounds at most, and about a foot long and 6 inches wide.

[se7en]

lol, first things first guys....

Nitrous is at 1900psi in the tank....and if it drops below about 1200psi I think, it can destroy your engine....

The reason I say this is, using a co2 bottle(way to small too BTW) would be calibrated for your engine, and you will be walking back.

Also, Both my turbo cars run at 7psi and 15 psi @over 300cfm. which is way more that you will get out of a bottle(exponentially higher)

if you spray compressed air out of an air line(1/2" line) at 50psi, and then spray 15psi out of 2.5" turbo line, you will see why it won't do squat.

Trust me guys, if any of these things worked, they would be marketed already.

Also, don't forget the extra fuel you will need......as increased air means increased fuel(by a lot too)

I say, spend 2000$, and turbo the thing like I did, and don't look back.

[MCNano117]

Word.

[EGR]

Actually I know the best way to get the most power out of your engine, I've been keeping it a secret for years but As I am feeling Generous I will let the mx-3 community know.

Turbos and superchargers are useless in this system, infact they are just a waste of money. All you need to do is get you an oxygen tank and have your exhaust rerouted back into your engines intake "intercooler would be helpful as my exhaust gas is very hot" (hell I've been doing this for years you guys just never pay attention to it). Now because your engine cant run without oxygen you add the o2 into the mixture. Just make sure you rig it to your gas pedal so the more fuel you give it the more o2 you get. The harder you press the gas pedal the more power you will get, the only down side is your going to have to figure a way to have a unlimited supply of oxygen, so you'll just have to get a machine to pull it out of the air for you

[MCNano117]

...get out.