Another intake tube and air filter thread

stevo1111 said:
Okay,

, a short run of 4 inch tube could be in order:
Click to expand...

that would be the best bet...

You dont want a sharp bend, OR the filter attached directly to the MAF.

You DO want a laminar airflow over the MAF sensor, and bends before the maf distrupt the laminar airflow over the maf.

A open element filter will draw air in from the "Sides" which in itself is just like having a "bend" just before the maf.

If it were me, I'd put 4 inches MINIMUM of pipe on the front of the maf, then connect the filter to that.

ALSO.. keeping in mind, that ANYTIME you make changes to the air tract, you are "changing the MAF transfer function".. which will require DYNOTUNING to get the MAF transfer function correct....

There is very little bang if ANY bang from a open air filter, and many MANY headaches associated with changing things in regards to MAF transfer function.
 
Of course someone is going to say "there isn't 4 inches of room"..but that is irrelevant... you dont want the filter closer than 4 inches from the maf sensor.

You could relocate the maf further up the air tube, not an easy solution..but none the less it IS the correct way to do it.

Just because it's not "home depot" easy, or not possible doenst mean it's not the correct way to do it.
 
Ut oh... laminar flow... transfer functions...

You mean like... Mx'' + cx' +kx = 0? (engineering anyone?)

But yes, I am well aware of this. Changing flow characteristics will change the MAF function. I'm not sure what mach numbers are flowing through the control volume, but it seems as if you're suggesting it will take the air 4 inches to overcome entrance length effects and transition to mostly turbulent flow.

The bend would result in a head loss, but I cannot see it triggering turbulent flow in relatively low mach numbers if the interior is smooth. It may cause a mixing effect, which would likely skew the MAFs.

Going into heat transfer... and assuming the element of the MAFs is a cylinder, you may use some correlation to determine which way it will skew the readings- cylinder in cross flow convection. This being, if the MAFs transfers x power in a laminar regime, how much more or less will be transfered in a turbulent regime.

Correct me if I'm wrong, but with a home depot set up, the MAF will read lower air velocities?

This being said, I am after the sound, no power gain. I still don't want to lose power though, that is why I am going to try and do it right

Unless you drastically alter the flow, your power loss or gain will be minimal. I would imagine that any home depot set up will result in 1-10% less power generated then the air box.

Just rambling now... cut myself off. ;)

Steve
 
Well... maybe i'll just keep the stock air box and get a drop in filter... There's no use in screwing with anything thats not to be improved upon.
 
stevo1111 said:
Ut oh... laminar flow... transfer functions...

You mean like... Mx'' + cx' +kx = 0? (engineering anyone?)

But yes, I am well aware of this. Changing flow characteristics will change the MAF function. I'm not sure what mach numbers are flowing through the control volume, but it seems as if you're suggesting it will take the air 4 inches to overcome entrance length effects and transition to mostly turbulent flow.

The bend would result in a head loss, but I cannot see it triggering turbulent flow in relatively low mach numbers if the interior is smooth. It may cause a mixing effect, which would likely skew the MAFs.

Going into heat transfer... and assuming the element of the MAFs is a cylinder, you may use some correlation to determine which way it will skew the readings- cylinder in cross flow convection. This being, if the MAFs transfers x power in a laminar regime, how much more or less will be transfered in a turbulent regime.

Correct me if I'm wrong, but with a home depot set up, the MAF will read lower air velocities?

This being said, I am after the sound, no power gain. I still don't want to lose power though, that is why I am going to try and do it right

Unless you drastically alter the flow, your power loss or gain will be minimal. I would imagine that any home depot set up will result in 1-10% less power generated then the air box.

Just rambling now... cut myself off. ;)

Steve
Click to expand...


Scary that I understood every word and comtemplated busting out a Calc.
 
not even concering a power gain or a power loss.

when you fubar the maf transfer function you LOSE the PCM's ability to control the Air Fuel Ratio..

the commanded AF/lamba numbers are no longer what is being delivered.

it's not always about "more or less power", sometimes it's about "melting stuff" too.
 
stevo1111 said:
Unless you drastically alter the flow, your power loss or gain will be minimal. I would imagine that any home depot set up will result in 1-10% less power generated then the air box.
Steve
Click to expand...

If you merely "rotate/clock" the maf housing differently it has an affect on the transfer function... and that isn't even CLOSE to a drastic change such as most of these cold air kits are.
 
EE guy can talk better with this one. AF/Lambda all comes down to power transfer from our friend the resistor in the MAFs. Yes, it will change with the MAF rotated because the flow characteristics are different at the top vs the side or bottom of the tube (as the location of the resistor is not at the center). You will have very small changes in velocity, flow type and air density from the top to the bottom of the tube.

Yes, you could lean the engine out considerably if the MAF reads low and melt many things.

I would never suggest a home depot job to be perfectly safe, but I have seen so many of them run without problems that I just not convinced that the full scale of the MAF is as... ehhh.. "narrow" as suggested.


Our intake systems should be left alone completely?
 
stevo1111 said:
I just not convinced that the full scale of the MAF is as... ehhh.. "narrow" as suggested.
Click to expand...

while there is alot of room for "leaning out" the stock PCM because it commands a 10/1 AF at wot at 5500.. the problem is.. the "unknown" amount of leaning out.

without a proper transfer function the car will not run at it's best.
 
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