New Boost Idea - Has this been done before?

[Schmieder]

So I was reading about runner length, plenum volume and the such.

I read the runner length determines when the high pressure pulse returns to the intake valve stuffing more air/fuel into the cylinder. And how it is generally tuned for a specific RPM range.

Well, if a higher pressure wave/pulse can make a noticeable difference, then my idea should work very well.

I post this in the boost forum area because it creates a positive pressure increase just as the intake valve opens.

So here is the idea,

Fasten a strong enough yet small enough subwoofer to the plenum and have the sound wave aim into the plenum volume. Just as an intake valve begins to open, have the subwoofer drive a pressure front sound wave so the sound wave reaches the intake valve just as it opens. The woofer would fire 6x's per engine revolution.

This would provide a positive pressure pulse to every intake valve at the right time through the entire RPM band since the device can be easily controlled/tuned.

The negative pressure wave caused by the woofer could be induced when the air charge begins to ram in the runner when the intake valve closes. Preventing the negative pressure wave to cancel the positive presure wave and aiding in the air ram effect in the runner.

Basically another method of creating a pressure wave to help cram more air/fuel into the cylinder just as the intake valve opens.

The system would probably work even better if each runner had it's own mini-subwoofer.

It wouldn't be as strong as a supercharger but it would enhance a n/a engine. Possibly even enhance a FI engine.


And it can't be too hard to construct. The hardest part would be customizing a lower intake manifold to house the subwoofer per runner. The woofer could be triggered to fire at the same moment the fuel injectors are triggered for the specific runner. Or, for greater tuning abilities, one could probably code megasquirt or another capable stand alone ECU to trigger the woofer at the perfect time.

It has to work! We all know the benefits of the positive pressure wave reaching the intake valve at just the right time. This system would provide such a pressure wave at extreme accuracy through the ENTIRE RPM band instead of just a small portion of the RPM band.


Has something like this ever been done before? If not, this may be a big idea.

The potential could be tremendous since the cost would be mild compared to the potential power increases across the entire rpm range.


Let me know what you guys think, please. I really want to begin building such a system. I have a spare 3100 small port LIM I can modify.

If anyone has any advice as far as timing the system, please chime in.

Thanks

PS - I'm fairly good with engines but if anyone here knows more about intake runner tuning and pressure fronts please educate me on any specifics I may need to know about before I start designing my prototype system.

[SappySE107]

Um, no.

[1988GTU]

Is this a long description for detonation?

[Schmieder]

Um, no.

Ok, any reason why not?

Do you understand the idea I presented? I'm sure you do.

Because there is a high pressure pulse that arrives at intake valve opening at a specific rpm range, correct? So all this would do is introduce the same concept but the pulse would be created elsewhere in the intake manifold under control.

Please be a little specific as to why it would not work. I try to learn as much as I can. I have a fascination with the internal combustion engine.

[robertisaar]

lets see... at 6000RPM, 6 cylinders on one speaker would be 2.16MHz....
one speaker per cylinder would be 360KHz...

good luck getting ANY speaker firing at those frequencies!

[Schmieder]

This is what I read about..

When the intake valve is open on the engine, air is being sucked into the engine, so the air in the intake runner is moving rapidly toward the cylinder. When the intake valve closes suddenly, this air slams to a stop and stacks up on itself, forming an area of high pressure. This high-pressure wave makes its way up the intake runner away from the cylinder. When it reaches the end of the intake runner, where the runner connects to the intake manifold, the pressure wave bounces back down the intake runner.

If the intake runner is just the right length, that pressure wave will arrive back at the intake valve just as it opens for the next cycle. This extra pressure helps cram more air-fuel mix into the cylinder -- effectively acting like a turbocharger.


All I'm considering is creating a pressure wave via a powered speaker like device to reach the intake valve at the right time and not letting the negative wave found behind all sound waves to occur until the valve closes, enhancing the stack up.

Honestly it really makes a whole lot of sense to me.

But don't take me as being a know-it-all. I could be wrong but damn, it feels so right to me.

[Schmieder]

lets see... at 6000RPM, 6 cylinders on one speaker would be 2.16MHz....
one speaker per cylinder would be 360KHz...

good luck getting ANY speaker firing at those frequencies!

I see.

My next idea was to have a variable volume just outside the intake valve that is controlled mechanically. Just like a mini piston, that would create pressure at the right time by reducing volume slightly as the intake valve opens and then create a reducing pressure by increasing volume slightly as the air stacks up when the intake valve is closed.

Operating in a mechanical method not using a speaker powered system.

Make any sense or am I confusing?

[robertisaar]

sounds like a pre-chamber, which i have heard of used successfully before, but not in that exact method.

[Schmieder]

hmmm, the mechanical version would be a mother f**ker to build. I believe tha kind of machining is beyond me.

Maybe a metal drum like wall that can contract and expand through electro-magnetic control.

I don't want to seem like I'm beating a dead horse here but this idea struck me hard and I can't give it up so early. I gotta try it somehow with out messing up the engine.

I do believe I could get a strong enough woofer that is small enough to pulse at speeds fast enough to reach 6k rpm. All it would need is a stronger current. And many people are already adding some really powerful subs for music. Can't miss it when they pull up next to you. If that sub woofing power could only be directed into the intake runner at the right time.

If we can feel the subs knocking on our chest as some punk drives by, it definately should have a positive effect on cramming air into a cylinder.

And it would really make the car sound so much more bad ass since each sub pulse would coincide with combustion.

[ForcedFirebird]

I picture a pulse jet.

If you use the returning wave from the back of one valve to feed another, you can achieve boost (ie over 100% efficiency).

Any idea on how you would approach testing this theory?

[robertisaar]

if you could get them to fire fast enough, then yes, it could have a benefit. but even at just 1000RPM, that's 60,000Hz. i don't even know of tweeters that reach that frequency. obviously, that number needs cut in half since we're dealing with a 4-cycle engine, but still, that's 30,000....

can you imagine the racket that would make? a high pitched whine that would make dogs go running for miles?

[IsaacHayes]

It's hard to comprehend how much air is being sucked into an engine. A sub woofer if you could get it to fire that fast (would have to move faster than tweeters) would not generate enough psi or volume to create any psi, let alone time it just right to get the pulse at the right time.


Much easier to just throw a real turbo on...

[Schmieder]

I picture a pulse jet.

If you use the returning wave from the back of one valve to feed another, you can achieve boost (ie over 100% efficiency).

Any idea on how you would approach testing this theory?

Pulse Jet, sort of but I don't want to add more air to the mix leanignt he system out.

It would have to be a closed system of pressure oscillation timed to enhance both the intake charge with high pressure and the air ramming effect when valve closes with negative pressure to pull that little bit more in.

Testing is easy. Dyno the car before the modified LIM is applied, then apply an identical LIM with the modification and Dyno the result.

On paper it makes complete sense.

[60dgrzbelow0]

Ok, any reason why not?

Do you understand the idea I presented? I'm sure you do.

Because there is a high pressure pulse that arrives at intake valve opening at a specific rpm range, correct? So all this would do is introduce the same concept but the pulse would be created elsewhere in the intake manifold under control.

Please be a little specific as to why it would not work. I try to learn as much as I can. I have a fascination with the internal combustion engine.

Listen... Friend... "All Solutions... Breed NEW Problems..." As clever as the thought might be...you are forgetting the problem of RESONANCE. While you are investigating Volumetrics... try and get your hands on some of the writings by Nikola Tesla... and yes...everything physical as well as electrical is subject to destruction through Harmonic Amplitude. The fundamental problem with your theory is that you are forgetting what will happen to the relationship between the Valve Stem and the Valve Guide when being bombarded with so much concentrated sound energy. At the levels of energy you are suggesting the sound pulses must be raised to be effective enough to work... those sounds waves will generate enough energy to turn into HEAT...and add yet another energy dimension into the air stream that is disruptive to its movement. The sound wave you suggest using in time with the 6X sensor will accumulate elsewhere in the block and in particular... be added to the longitudinal vibrational forces in the crankshaft. The Harmonic Balancers on our engines can only absorb so much vibration before things begin to fall apart. So take a moment and consider these other forces in your equations.... Sometimes...less engineering...is more...


Oh...and to ask Ben a question predicated with words ladled in sarcasm such as, "Do You Understand?... Of COURSE you do..." is to reveal completely your lack of understanding that while you are only ankle deep right now in the waters of this little problem that you posit... Ben's knowledge of mechanical things plunders many more fathoms deeper than you comprehend at the moment. So... try not to SOYD so soon since coming here...while you find yourself temporarily on this Fool's Errand... and make nice with your Betters while you have the chance...

[Schmieder]

It's hard to comprehend how much air is being sucked into an engine. A sub woofer if you could get it to fire that fast (would have to move faster than tweeters) would not generate enough psi or volume to create any psi, let alone time it just right to get the pulse at the right time.


Much easier to just throw a real turbo on...

I won't argue that. It is much easier and a proven method.

But if my theory works it would be a cost effective alternative to gain cheaper power increases and control the cramming effect across all rpm ranges instead of the range the runner length is tuned to.


I got to sleep on this idea and think some more on it.