I apologize if these have been covered before. I have searched and have not found answers... and I am spending way too much time searching this forum at work. :-)

1) It appears that the airbox's sole source of air is via the crossover duct to the intercooler, which serves to pull air through the intercooler for heat exchange, right? IF those observations are accurate, then I would think that open intakes and/or airbox mods would diminish or completely eliminate the airflow through the intercooler. If so, these mods must be quite detrimental to intercooler efficiency?

2) What is the hose that exits the side of the airbox that goes nowhere? If that hose is left open by design, then it is pulling unfiltered air into the airbox.
What am I missing?

 

Let me try to help.

The stock airbox and intercooler use the same duct for air flow. Mazda found that under hard acceleration and use that air would flow backwards, i.e., from the engine bay back through the intercooler causing a complete heat soak resulting in detonation and engine failure. This is why the stock setup can be detrimental to the intercoolers efficiency. This was corrected in later Japanese models but unfortunately it came to late for the US market issue cars. This is why separating the intake from the intercooler is one of the functions of most intake mods and after market air boxes (there are exceptions, i.e., PFS).

I believe that you are refering to he moo hose. Keep it, it does surve a purpose.

Sincerely,
Jason C. Williams

 

That hose muffles the exhaust from the airpump bypass (the other 1" hose mounted to the top of the air box) they are connected to a muffler chamber built into the top of the air cleaner box that is completly sealed from the interior of the air box. On some cars (most actually) removing that hose causes the bypass to produce a MOOING sound at certain rpm/load ranges.

 

Okay, I'm obviously very confused. Sorry. It appears to me that the airbox pulls all of its air through the crossover duct. The only other hole in that duct is to the front side of the intercooler. The shroud on the front side of the intercooler has no other significant openings, so we are effectively pulling all intake air across the intercooler, out of the engine compartment (?) If not, how is air moved across the intercooler with no fan or surface exposed to fresh air?

 

The air enters a duct in the nose of the car. This leads to the air box duct which is before the intercooler. Forced air enters that duct. The passage toward the battery side is moving cool air over the battery and ac component.

I plugged the duct toward the battery side. ( don't use AC other than to lubricate system now and again, have small battery with warranty) I also made foam gaskets for the removable duct which leads from the forced air intake to the air box. The original smaller diameter rubber gasket which connects to the air box has been rolled inward to enlarge the duct size.

intake mod picture

I'm not sure if my home made modification is as good as some aftermarket intakes, but it definitely does a better job of forcing air into the air box over just leaving things assembled as stock. It would seem the more forced nose air, the more it aids the turbos ability to pull air with less effort. The faster the car is moving the more air it will force air.

 

It works like a ram air system. While the vehical is moving air flows into the duct and through the intercooler.

 

When the car is in motion, air flows into the hole in the front of the car. Some goes into the intake, and some passes thru the intercooler. The only time that hot air would be pulled back thru the intercooler would be at a stop, or at high acceleration at very low speed. Here's a thread on a great modification to the stock airbox.

https://www.rx7club.com/forum/showth...hreadid=121491

Let me know if you are interested in the airbox mod.

Adam

 

my bad. In the less-than-perfect light of my garage I would have sworn that the shroud on the front side of
the intercooler was sealed (besides the square opening to the crossover duct). Hence the confusion. It certainly makes more sense that we are not (intentionally) drawing hot air through the intercooler as our intake air.