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devices on air intake tube.

20 years ago

On my truck and other trucks I've seen little tubes and plastic chambers on the air intake. On my mazda truck there's a 8x2 inch tube jutting off the big hose. I see no apparent purpose for it. The only explaination I was ever given was that it makes turbulence, and stirs up the air before going into the engine. It from the factory so it must have some reason right? Can I buy just a straight tube for it?

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Comments (5)

john_g
20 years ago
That plastic resonator on the air intake is there to smooth out the pulses of air that enter the engine on medium to hard acceleration. It actually helps performance while lowering noise. Why would you want to eliminate it?
timbulb
Original Author
20 years ago
Why would the air be pulsing? Seems strange.
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Could this be Google Nests going wonky? I've heard they can do weird things. It's almost like the air is reversed? Hi Davis, It would have to be investigated in person, to see what is happening as Honeywell zoning products aren't that great in my opinion. I ripped out a honeywell zone system with two nests a few months ago. Left the nests because the customer was adamant about keeping them. The honeywell zone system was the problem on that one. Typically the Nest can be the problem eventually as when the Nest ages the battery inside it doesn't retain the charge and it continually steals power from the HVAC system. That can cause erratic behavior when power availability drops, because the nest likes to hog it. A side note I recently replaced a Nest for a customer of mine without a zone system because I was there doing a service call and the discussion of potential other issues came up. They said the nest would shut off the system and restart it a few minutes later which on it's own is not that big of a deal in mild weather -- triple digit heat? Not a good thing. Other oddities, they would try to set a set point and the nest would occasionally say some weird response like that it's not possible right now. I don't know if Google and the power companies might be working together here in Texas as Ercot here has been telling people not to blast AC's / turn them up to 78F to conserve energy. That would be considered a conspiracy theory. So who knows? I've replaced nests over the years for other odd equipment problems. If you like paying me (or others) for service visits then the nest is the hands down winner. I only like them for that reason, they put money in my pocket. I service the Katy, Texas area.
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jemdandy
20 years ago
Why wouldn't the air be pulsing? Why not. A 4 cycle cylinder draws air only on one of its four strokes. The rest of the time, the intake valve is closed. In a 4 cylinder, 4 stroke, in-line engine, there are 2 intake, equally spaced, gulps per crank rotation. This creates pulsing for sure and the total air flow changes with engine speed.

Air flow is a little smoother for a 60 deg, V6. This is basically two, 3 cylinder engines on a common crank. There are 3 intake gulps, equally spaced in time, per 2 engine revolutions per cylinder bank.

Enough already! Don't get me started on why an 8 cylinder, 90 deg V8 needs cross-over passages (in the intake) to even out the air flow among the cylinders, or in some cases, equalizing holes between the two halves of the intake (ala 260 cu in, V8, 1964 Dodge Dart).
john_g
20 years ago
Engines seem so simple to so many people with half of an understanding, and they think that they can do dime store changes and make their cars and trucks run better. The facts are, some major changes can result in little changes in performance but it's rarely worth it in the long run. Simply getting a little more air into the engine for each cylinder can be very difficult over what the factory is already doing. That's why we have dual plane intake manifolds, with computer controlled intake manifold runer valves. I use my ocilliscope to monitor MAF sensor outputs, and with a hard throttle snap as the engine accelerates, you can see each intake pulse by using the trigger/save function. MAF sensors are so fast I can even see evidence of mechanical faults when I do this because affected cylinders will distort the pattern.

Some of the other details timbulb has to realize is not only does the air pulse as it enters the engine, each piston does not move at a steady speed. The pistons move faster center stroke, than they do at the top and bottom of each stroke as the crankshaft turns. Having an intake tuned to match this pulse of air can actually have the air pressurizing itself just as the next intake valve opens. That's how the system smoothes out the pulses.
timbulb
Original Author
20 years ago
Now those are finally some decent explanations. Thanks.

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