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CAI and A/F ratio


JaSSon
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I've been reading on stangnet.com that adding a CAI with a 90* bend in it can cause a rich condition. Well, it just so happens that my CAI has that bend. Is this true, can it cause a rich condition, or is it just a bunch of hippity hooplah?
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Im not an expert so please don't take what I say to heart. Hopefully someone will chim in and correct anything and everything I say ;) .

 

Question first: They cause a rich condition in some or all? I know when I first installed my intake I didnt reset the ECU causing the car to run a bit rich. ie: take the positive end off the battery let is sit for about 30 minutes while hitting the brakes a few times, letting ALL the power out of the ECU. (you know what im talking about). I dont know how a 90 degree bend would cause a car to run rich though :confused: . IMO you wouldnt want that sharp of an angle in your intake anyway.

 

Hope that helps at all :( .

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Jason,

 

What you are hearing about is when the MAF is rotated 90 degrees (I believe clockwise.) It is rumored that some have done this mod and it has improved their performance. To do that, the car would actually have to lean out a bit...if it ran richer, it would also feel lame. Technically it shouldn't make any difference, but some feel that the MAF reads differently once rotated. I think it is a myth.

 

my $.02.

 

Mike

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Is your MAF positioned directly after the 90 degree bend? If it is close to it, then it is very possible that rotating it would make a difference.

 

There is some fairly complicated fluid mechanics behind it, but basically, when you have non-turbulent air flowing through a straight round pipe, there is kind of a dome shaped velocity profile. Basically the center has the highest velocity, and thus the greatest mass flow rate, while the portions touching the wall are barely moving at all.

 

When you have a bend, the highest velocity is no longer at the very center of the pipe radius, it will bias off towards the outside radius of the bend.

 

Do you have a hot wire MAF, or vortex type? A hot wire will most likely have it's greatest sensitivity right at the center of the pipe, but with some blind spots along the sides, which are basically 180 degree opposite from each other. A vortex stle typically has the intake port off center to one side, with it's greatest accuracy for flow aimed at the intake port.

 

So basically, what I am getting at with all this babble, is that how the MAF is oriented, can cause more of less of the air to "slip by" without being read by the MAF, since it does not have the same sensitivity across the whole 360 degree spectrum. smile.gif

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He has the same type as I do, with a large round MAF and a smaller sample tube. Yes, it can read off if there is a bend before the sensor. It could be rich or lean or work very well. Both the stockers and the C&L will do this, the ProM with the 360* sampling will read okay with a bend in the tube. Put the MAF farther back, or the bend farther in front if you think its causing a problem. If not, don't worry about it.
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