I have noticed a odd part on my intake. It is located pasenger side of the intake. It appears to be a vacuum controlled intake controller.

It has a shaft connected to it and it goes inside the intake anyone know exactly what this? I assumed this opens under a certain amount of vacuum. Does everyone get a extra boost at about 4500 to 4800 rpm?

 

It's a variable intake. At lower rpm it uses the rear/longer runners on the intake for more torque, and then the valve opens and let's the air flow through shorter passages when the rpm climbs. All the new 2.0L's have it although the MP3 doesn't have the VTC (variable tumble control) that all the other 2.0L's have. It's a cold start thing and is noisy so be glad you don't have one on the MP3.

 

I bet this is the reason why the 2.0L's have a high pitched whine when operating at 4000k rpm +.

 

The system you are referring to is dubbed Variable Intake Control System (VICS) by Mazda.

Two intake runners are utilized per cylinder. One intake runner is long and thin, creating a siphon/jet effect (imagine putting your thumb over the opening of a running hose). This runner is used at low rpm's (3,500rpm and lower) while the engine struggles to suck in air. This help with the air intake increases low-end torque. The secondary runner is short and fat. This allows large volumes of air to pass through at higher rpm's (3,800rpm and higher) when the engine demands it. This helps high-end power and response.

Most engines use a single intake runner which is compromised between low-end and high-end power. In other words, at low rpm's, the engine struggles to suck in enough air because the runner is too fat and short. At high rpm's, the engine is choking because the runner is too thin and long. The variable intake runner design is outstanding for spreading power across the board.

The VICS system has been used by Mazda (and Ford) since 1990, though possessing several different names:

1990-Current Protege (1.8L & 2.0L)
1991-1996 Escort GT (1.8L)
1993-1997 MX-6/Probe (2.0L & 2.5L)
1992-1994 MX-3 (1.8L)
1993-Current 626 (2.0L & 2.5L)
1994-Current Miata (1.8L)
1995-Current Millenia (2.5L & 2.3L)

-Jerry

 

My MP3 has this setup! I always wondered what this was. It acts very similar to the RX7 5th and 6th ports.

 

I didn't realize I had to be so technical! LOL.

Both VRIS and VICS achieve better torque, power, and response by using variable intake tracts, whether those tracts are seperated by cylinder or in the main intake before split.

To get really accurate, Mazda has been using a variant of this system since the 13B was reintroduced in the 1984 RX-7 GSL-SE.

If you want to get really technical, we could go into how these systems reduce pumping loss and how it's research started with the rotary and saw it's ultimate application in the Miller-Cycle.

One thing I learned from Mazda Product Knowledge and Master Certification classes is to explain everything as simple as possible, which is exactly what I did. I think only a small percentage of us on these boards will understand the fully technical explanations of any automotive technology and using such won't help the majority of the members.

-Jerry