Air Induction Systems, Voodoo, and simple test

[DCColegrove]

Over the past decade or so I have seen about a gazillion articles, threads and ads for and about performance enhancing CAI systems. There has arisen this whole culture of Voodoo Science around it.

Most of this is focused on addressing air charge temperature and restrictions in the flow through the air filter to the AFM or AMM. For this there is a very simple test…

Install a temperature gauge and vacuum gauge in the center of volume of the filter or housing it’s self and compare the readings between systems… The lower (closer to zero) the numbers the better. This is a good test but ultimately it means very little.

On the other end of the Voodoo Science spectrum some have come up with ingenious ways to introduce turbulence into the induction system there by to mix up the air /fuel charge for better combustion.

Neither of these bolt on, shove in or what have you “upgrades” produce much of anything (though there is this turbine thing available on eBay that makes this spectacular noise)…

There are some slight modifications that can be made in the stock air box that will improve overall flow at the expense of slight noise resonance… But over all the stock E30 / M20 air cleaner with a clean panel filter element can efficiently flow nearly twice what a stock M20 can use.

Here in lies the rub:



In this area indicated the air flow tumbles and actually reverses its course. And the fix is beyond simple...

I am considering producing an induction system for these old machines…

But alas because it will not look or sound as mean as the current backyard technology I think it may be a waste of effort


.

[e30frosh]

Function will always overpower form. I'd buy a piece that works better than asthetic pleasure any day.

[Farbin Kaiber]

In other words, a smooth silicone intake tube?

[DCColegrove]

In other words, a smooth silicone intake tube?

No...that makes it worse.

[PhillyG]

So then what is the fix? :o

[z31maniac]

Build it, test it, and show its better than the stock setup or any homemade concoctions and people will buy it.

Period.

Be sure to set it up for the M30 AFM though. ;)

[DCColegrove]

So then what is the fix? :o

Well you either straighten the run or force the air flow to uniformly make the turn.

[DCColegrove]

Build it, test it, and show its better than the stock setup or any homemade concoctions and people will buy it.

Period.

Be sure to set it up for the M30 AFM though. ;)

I'm already running it on my M20 powered car and have had a whole different system for the M42 for several years.

The M30 AFM will only give you headaches the only step up is an AMM and that's not much of a step on a stock M20.

[xLibelle]

The M30 AFM will only give you headaches the only step up is an AMM and that's not much of a step on a stock M20.

this doesnt make sense

[DCColegrove]

this doesnt make sense

Why not?

The additional volume of the larger AFM is negligible in it's performance increase because it only serves to slow down the velocity through the entire system...

An AMM is more accurate and has no limit on what It can sense flow and density wise but in actuality it will only increase the throttle response unless the flow through the whole shooting match is increased to take advantage of the AMMs capability.

[blunttech]

i hate to point out the obvious but you fuckers are driving 20 year old single cam 6's. change your stock air filter once a year and call it a fucking day.

[delatlanta1281]

Wait, so if you add an afm with a larger door that runs the same as the original m20 afm, it DECREASES the amount of air going into the intake maniforld? I would think the amount of air going in would be the same, if not more. I roll an m30 afm and haven't noticed a hinderence at all.
edit. i agree with blunt as well, the head is a huge problem.

[DCColegrove]

i hate to point out the obvious but you fuckers are driving 20 year old single cam 6's. change your stock air filter once a year and call it a fucking day.

True...

But that's not very fun...

Some of us have this thing for pushing the envelope...

There is a certain elegance to the nasty old M20s that is hard to recapture in the more modern power-plants.

[DCColegrove]

Wait, so if you add an afm with a larger door that runs the same as the original m20 afm, it DECREASES the amount of air going into the intake maniforld? I would think the amount of air going in would be the same, if not more. I roll an m30 afm and haven't noticed a hinderence at all.

In a word... Yes.

(on a "stock" m20 configuration)

[der affe]

so are you talking about running a smooth 3" tube with a bend and a silicone or rubber boots at each end to allow for flex that may be needed in the intake boot. there by straightening out the air path, but still keeping it flexible without disturbing the air path.