4x4Wire's TrailTalk Forums: The 3.0 build-up thread.

Balance between flow and turbulance??? That doesn't even make any sence. That's like saying you want a balance between your foot on the accelorator and your foot on the brakes! Turbulance = restriction. They are one and the same. And I have no idea what this "shock of the air" you speak of it.

The fuel injectors are already atomizing the fuel....and doing a good job of it. They're also placed in the lower manifold, right above the valve. Nothing you do to the air above the injector is going to effect it's performance. It is pressure changes and temperature that will atomize the fuel better....air flow direction or turbulance won't do a thing.....now matter how much you shake that air and those fuel droplets up, you're still not going to change the size of the droplets unless you change the pressure or temperature. At best, all you can do is spread the tiny fuel doplets more evenly in the cylinder...which might actually help.

And, if you can figure out a way to predict how to do that....a way to mathmatically calculate the concentration of a vaporized liquid dispersed in a vessel...Copyright your theory and calculations....you'll make millions. There is an entire discipline of engineering devoted to doing just that and they're isn't any real theory to speak of. Just trial, error and experience.

I'm not so sure you'd really want to do that in a motor anyway. Remember throttle body injection? Ever wonder why that isn't all that popular any more....or why, on fuel injected motors, the injectors are actually placed right above the valve? Seems to me this horse has already been beaten...and the idea of "mixing" the fuel and air better is bunk.

If you want to better atomize the fuel, you have to change the pressure or temperature of the air mass containing the fuel.....which is in the cylinder, not the intake runner. And, If I'm wrong about the pressure thing, it would never rain....literally. It's atmospheric pressure changes that make clouds and make rain.

Like I said, turbulance = restriction. Hydrualic equations describing fluid flow, velocity, pressure and just about any other property all have a "roughness" factor (Manning's 'n', Chezy 'C'...) in them. They are used to describe the engergy losses due to surface roughness, bends/direction changes, obstruction and the combining or splitting of flow paths....And, all are more or less emperical factors based on test results. All the theory, math and tests says make it straight and smooth and it will flow better.....and you will get more power.

The plenum or chamber part of this is the most interesting, I think. Essentially, the thing is a reservoir that, just like you said "acts to absorb the pulse from......the piston sucking in the air". If you size the thing too small, you'll create tons of vacuum, increase your air veolicty and also get tons more turbulance which will (say it with me) reduce air flow. And, if you size the thing too big, you're motor won't have any vacuum in the upper manifold...or atleast in the plenum...and I'm not so sure that is important. I do calculations similar to this one at work all the time...although using liquids, not gasses...and if vacuum (or pressure) in the plenum isn't a concern (and I can't think of why it would be..assuming you can get the vacuum you need before or after the plenum/chamber) make the thing at least the same volume as however many cylinders can draw off it at any give time (I belive that is 2 for a 6 cylinder motor). Anything bigger and I doubt you'll see any benefits.......(I should be charging for this!)

I think it's just as important how the intake runners are attached to the chamber too. You want them all to draw the air in the same direction and have only slight direction changes need to dump into any given intake runner (like in those pic's you've attached...or on the 3.4L intake. Not shift it back and forth like the stock 3.0L intake.

If I was gonna fabricate one from scratch. I'd try and copy the one in your pic's. If I was gonna modify the stock intake, I'd make a bigger plenum/chamber and I'd definitely move the intake to the other side of the plenum.....or even onto the end of the chamber (like in those pics).

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'93 4Runner - 3.4L 5VZ-FE, 2" body lift, on-board-air system, custom gauge cluster, rear e-locker, electric fan, custom built front and rear bumpers, sliders, 4,88 gears...all on 33x12.5's.

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