Quote:
Originally Posted by serialk11r
Hmmm so you're saying the other parts of the intake system can contribute a lot of restriction as well...that's somewhat of a surprise to me, since I'd imagine sucking air through a porous filter would be much worse than say a narrow tube.
So seeing that variable valve lift technology is soon to arrive en masse, eliminating the need for the throttle body to do anything, how do you guys think this could affect intake modification?
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Air intake systems are designed to allow air to flow more smoothly. If you look in the tube of a stock air system they are usually rubber, maybe bumpy on the inside. While they may both be the same diameter the velocity of the air isn't the same as it travels.
So for example a smooth polished intake system is designed to allow air to flow at the right angles giving it the most velocity as it travels, with the least resistance from the interior walls and with fewer inefficient bends in the pipe.
As for the filter, you could figure it out mathematically.
If you have 4 inches of surface area using the diameter of the stock intake pipe, and your average filter restricts 30% of air per inch, and for example if you had 1 inch of paper filter then you have 0.3 inch of air flowing space. SO, to maintain that 4 inch space you'd want a filter 3.33 times as big. So you'd need 13.33 inches of filter surface to get 4 inches of air flow. Any bigger, and you're not getting anymore air because the tubing is only 4 wide.
This should already be taken into account with a decent intake system, and hence why they have folds and are cone shaped, because it allows them to provide more filtration surface.
I made up those numbers but they should be accurate.
As for the throttle body, air flows the same way regardless of if there is a throttle so it won't be affected. Plus I thought Toyota's with D4-S still use a throttle, and BMW was the one that got rid of it?