juddz

I think that putting the device in the exhaust will create a slight restriction, and probably cost you a little bit of flow if anything. Remember that exhaust is a resonant device, much like a trumpet. Daimeter and length are important, as they can determine the resonant frequency at which pressure waves within the system will be amplified, and if you tune just right you can tailor your resonant frequency for a certain rpm range. Proper exhaust design WILL net you more torque and power as you hit that resonant frequency, and it pulls spent gases away from the exhaust valve. Folks who tune two strokes know full well the importance of this, as proper two stroke operation is all about scavenging. Get the length and daimeter wrong in a two stroke, and it won't run correctly. It's simple physics, folks. Bacon's Law if I recall. If you want to know more, I can dig out the formulas from my old college notes. But as far as sticking something inside of the exhaust, to create more hp? I am skeptical. But if anyone wants to prove me wrong, it's easy enough for you to test out and it would make for an interesting thread.

juddz

....BTW I noted two strokes because the effect of proper exhaust tuning is more pronounced in them than it is on four stroke engines. In a four stroke engine, like our Mazdas, resonant exhaust tuning is similarly advantageous if to a lesser extent...

Da P-Funk!

Rodimus-
Good theory - but as i picture it - the 'cyclone' created at each exhaust port on the head wouldn't create suction from the 'spin' from flow until after the valve had closed again. By the time the cyclone started suction it would be too late (inertia). I believe the suction would just pull the valve closed and not suck the exhaust out... The cyclone would have to occur where the 4 headers join so that the last pulse pulls the next one...

Lastly - you don't get something for nuthin' (law of conservation of energy) says i am pulling energy from the flow. Wouldn't the metal have to be a monocrystal or ceramic to be strong enough to last in the hot gas path but thin enough to be of value? I am thinking quite expensive...

You da' man - i trust your judgement on this...

Roddimus Prime

my "cyclone theory" was a short in the dark. It was the only way I could rationalize a power gain from this.

I'll pull out my old physics books and see if I can find anything that applies here.

Omron

I posted earlier with the fantasy idea of using the Tornado intake idea and apply it to an exhaust application.

I have a couple of jokers who think they can pull it off. with a Stock pipe. I have a somewhat fresh Stock exhaust pipe from a late 2002 protege ES. with low km.

So it looks pretty fresh. Does anyone wanna look over the design and ponder where to apply the facimilie tornado devices.

Do we have a science geek in the house?

The idea, to produce more power with a modified Stock pipe, and compare the hp difference over a unmodified stock pipe.

Another useless project for 2005 lol hahhaa but eh? why not

vielster

To build on Roddimus's cyclone idea and also address juddz's mention of harmonics, my spin (no pun intended) on this whole thing is that with a cyclone type device in the exhaust (essentially a turbine...sorry if this is not the totally correct way to refer to it), you would cause the system to no longer be pulsed. Since the exhaust in a car is pulsed, you get a scavenging effect based on length of the header pipes, diameter of the exhaust, etc. You create a system so that the pulses at certain frequencies (RPM's) give you optimal flow (thus power). So, now what if you take this system, and instead of having pulses, you have a constant average flow created by the turbine. Thus, there are no longer resonances, but a more constant scaveging effect across all RPM's.

Additionally, there would be added benefit in racing the vehicle because when you rev the engine before the race and drop the clutch, you're spinning up the turbine to a high speed, and then dropping the RPM's way down when you drop the clutch. So, you have a vacum created in the exhaust by the turbine since it will carry some momentum and thus aid in pulling the air from the exhaust, reducing resistance....the same will happen between shifts.

Just my thoughts....Constant avg. Flow vs. Pulsing exhaust

Roddimus Prime

hmm....i think in order for us to actually try any of these theories we'll have to use our own custom exhaust manfiold and piping. Trying to work around the horrible stock design is like shooting yourself in the foot before running a marathon.

Imagine an EL 4-1 header (this will line up all pulses at the collector at the same time. Each pulse gives the turbine another nudge (just like a turbo header) allowing it to spin faster and faster. This may not be TOO dificult but we'll need sit down and draw out a design for the impellor that can spin at high speed and withstand the heat of the gas whithout lubrication....then once that's done we need to work on fin design.

Tyrael6666

i agree with roddimus, if i were u i would work on getting two as near identical custom exhausts as possible and then go for it, doign it to the stock exhaust probably wont show much significance, think about how ridiculous our muffler is alone, it weighs like 30 pounds and does nothing for flow.

FlyinHawaiian071

I only came onto this thread recently and would like to give you all some additional food for thought. I am a licensed pilot and have spent a lot of time in gliders, which require you to know a lot about aerodynamics and the properties of airflow. When you fly on an airliner on a fairly windy day, you'll notice that as you climb, you'll go through periods of fairly rough turbulence and other portions of glassy-smooth flight. What you are experiencing are the transitions between air-layers that are moving at different speeds and directions. As these two layers come in contact with each other, part of one is speed up and the other slows down, and creates very disturbed, inefficient air. I think that in your theory, when the smooth flowing air meets the cycloned air, you're going to have a lot of disturbance that will slow the exhaust down and decrease its net result. In fact, all you will be creating is a smaller tube for the free-flowing exhaust to exit from, which will be constantly slowed down and, in-essence, you'll just be making a smaller pipe.

With the turbine idea, I’ll be the same as flying a jet without the engines on. You'll just be making a lot of drag. The reason why the turbo works is that it has a propulsion device to keep it turning, just like the jet engine does..

Only food for thought…

macdaddyslomo

think of it like this....those cheap little whistles with the little fan or whatever that raise in pitch the harder you blow in...sure the air coming out is moving pretty quick, but if you remove the little fan could you blow more air out ?? of course you can..same idea with exhaust...bad idea, waste of time ...have fun though

Da P-Funk!

and, i pictured a non-moving air 'director' to impart spin. As soon as you say 'spinning' i say - remember the gas path corrosion and environment. How long would this thing keep spinning (using low cost materials) before it siezed?

I vote let it die...

goldstar

macdaddyslomo is exactly right. Any "turbine"-like device anywhere in the exhaust system will only act as an impediment to exhaust gas flow.

Reference: The Scientific Design of Exhaust and Intake Systems, Third Edition, by Philip H Smith and John C Morrison

The design of an efficient exhaust system is extremely complicated as the material presented in the above book demonstrates but basically involves designing a header that eliminates interference among the gas pulses exiting the cylinders and creating a smooth-flowing system of the proper diameter and length that produces minimum back pressure. The resonant frequency of the sound waves generated in the exhaust system and their effect on flow must also be taken into account.

The only time a turbine-like device might help would be to utilize it as a vacuum pump in the exhaust system to create a pressure below atmospheric to literally suck the spent exhaust gases from the cylinders over and above what could be accomplished through normal scavenging. Such a turbo or supercharger in reverse would be highly impractical and much inferior to blowers placed on the induction side of the engine.

In the bad old days before the wide-spread adoption of SAE net HP ratings which, among other things, require the factory installed exhaust system to be in place during testing, many auto manufacturers would report inflated gross HP ratings as a marketing tool. As Smith and Morrison report, one technique utilized was to attach a vacuum pump to the exhaust system during testing to place the exhaust system at a sub-atmospheric pressure to help get those big advertised HP ratings.

Omron

Hey, whats wrong with Sub atmospheric Pressure lol doesnt everyone drive up that high lol