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The race to develop The World's First Tuned Air Intake

The evolution of the entire Injen intake line is paved with industry firsts and innovative designs. Cold air intake design prior to 1996 was a relatively straight forward process, but when OBD II became mandatory for all new vehicles, the game changed forever. Real time monitoring of the vehicle's engine forced aftermarket manufacturers to start engineering their products to perform in harmony with the vehicle's electronics. As the years passed, the OBD II processors became faster and faster, which allowed the ECM (engine control module) to become smarter and adapt to changes and/or modifications quicker.

In 2003, Injen Technology started designing two separate intake systems: one for the 2003 Mazda 6 and one for the 2002 Subaru WRX. It was business as usual inside Injen's R&D department, but this time, something had changed within ECM and how quickly it interpreted the information it received from various sensors. No matter what intake tube design the R&D department came up with, the ECM would adjust the air/fuel ratio from one hour to the next to compensate for the changes our intake provided. This might not sound like a big deal to most, but Injen Technology intakes rely on two key characteristics to produce power: improved airflow AND a tuned air/fuel ratio to extract every last ounce of safe power. If the ECU was now "tuning" around Injen air/fuel adjustments, this obviously posed a severe problem that required revolutionary solutions.

Many of the applications in which Injen designs its cold air intakes are for use on a Hot Wire style Mass Air Flow Sensor. Within this sensor there is a wire placed in the airflow path and a specific amount of current is required to maintain the elevated temperature of the "hot wire". As mass air flow increases, the wire is cooled. As the wire cools, the resistance within the wire decreases. A decrease in resistance allows additional current flow to maintain the wire's "hot" temperature. The current required to maintain that hot wire temperature is interpreted by the ECM as a specific mass airflow. The ECM will adjust fuel injection to match the available airflow in order to maintain proper air/fuel ratios.

The challenge of controlling the mass air flow sensor for our air/fuel ratio adjustments without the use of add-on electronics obligated our engineers to go back…way back! Those basics being the principles developed in the 18th century by Bernoulli. In its most basic form, Bernoulli's Principle reminded our engineers that in order to keep our mass flow consistent (or to increase mass flow), there are dynamic changes that must occur within an intake tube in order to guarantee that sufficient air is being supplied to the engine. These dynamic changes are governed by very specific laws of physics and we needed to harness those laws in order to extract every last bit of power safely and without activating check engine lights. For example, if you have a fluid flowing through a pipe of varying cross-sectional areas, the fluid will speed up in the constricted areas and the pressure the fluid exerts is least where the cross section is the smallest. This phenomenon is also called the Venturi Effect. Looking further into the works of this 18th century physicist reminded Injen's engineers of the importance of developing a streamlined air intake system that would provide the least amount of resistance within the intake.

Example: P=pressure and V=velocity
From this law, it follows that where there is a velocity increase in a fluid flow, there must be a corresponding pressure decrease. Swiss physicist and mathematician Daniel Bernoulli formulated this theorem in 1738. Bernoulli's Theorem

The illustration gives us a better understanding of how velocity and pressure work together: an increase of air velocity (B) decreases air pressure and a decrease in air velocity (A) and (C) increases air pressure. The same is true, all things being equal: the volume of air in chambers (A) would be equal to that in chamber (C) as air travels at a greater speed in the mid-section (B). 

The Bernoulli Theorem is applied to the intake sensor housing

After a few sleepless nights, Injen engineers started considering incorporating a venturi type tube along the path of an intake tract to control the flow rate to the mass air flow sensor. By learning how to control air speed and the resultant pressure, Injen engineers were able to maintain the desired temperature of the "hot wire" located inside the mass air flow sensor without the use of external electronics! In doing so, Injen now had the method to tune the air/fuel ratio for optimum power built directly into the Injen intake system.

Along with controlling the air/fuel ratio, Injen also needed a way to control short term and long term fuel trim levels.  Short term fuel trim levels refer to adjustments being made in response to temporary conditions.  Long Term fuel trim levels compensate for issues that arise over a longer time period.  Fuel trims are expressed in percentages and can be monitored by accessing the ECM through the OBD II data port.  A positive value indicates lean conditions (add fuel) and negative values indicate rich conditions (subtract fuel).  Evaluating this data during the R&D process allows our technicians to properly fit and tune Injen's Air Fusion device if needed.

With all of this research compiled by the end of 2004, Injen began an aggressive restructuring program that would involve a total overhaul of the R&D and production departments. The engineering department began redesigning air filters, couplers, step hoses, and incorporated larger bend tools and forming equipment that would allow us to build a "tuned" intake with the least amount of air resistance for maximum horsepower and torque gains.  Today, all Injen filters, molded couplers, and elbows are equipped with built-in velocity stacks. In addition, mandrel bent tubes are bent with larger radii for streamlined airflow and intakes are fitted with the correct tube size to minimize the amount of air restriction and maximize engine efficiency. 

Injen's MR Technology and Air Fusion working together

Air Horn - MR-Fusion

The cat was now out of the bag and every aftermarket enthusiast began experiencing the step-down tuning process known as MR Technology and referred to as "The World's First Tuned Air Intake System."   This process required no recalibration of the mass air flow sensor; no re-flashing of the ECU and certainly no electronic devices to trick the on-board computer.  The new "Method and Device" was in itself a calibration and tuning process for the intake to be used in conjunction with the stock mass air flow sensor, where all stock parameters remained untouched.

As the new line of SP intakes began to fill the streets, forums got slammed with questions as to how the step-down process actually worked and controlled air/ fuel ratios. As soon as Injen Technology learned that the competition was trying to mimic the method of tuning intakes, Injen immediately began to file for patents to try and stop the production of knock-offs.   


Exhibits of all tuning patents granted for Method and Device,               
see links to four US Patents:      Method used to determine the size of the sensor housing            Applying the device to the air intake    Applying the device to the wall of the sensor housing    Method used to determine the size of the AF tube

After the patents were initially filed, a few of Injen's competitors instantly started making claims that we had detuned our intakes by adding excessive restriction.  As we've outlined above, it's quite obvious that we've done the opposite and that there are laws of physics that cannot be broken and/or ignored.  Now, whoever said that Injen technology was detuning the air intake by restricting air flow obviously needs to go back to school or stop calling themselves engineers.   Ask yourself, would you trust a company trying to defame its competitors because they themselves can't comprehend the physics behind it?  The company in question should be selling air intakes based on its own merits and not defaming others.  We've laid out our design and engineering process in an easy to read format, provided links to our patents regarding the technology, and been as upfront as possible.  If you want to purchase products from a company that provides you with an air intake that will throw a check engine light or require you to purchase additional electronics to tune around their flawed design, then the choice is yours.  Before you make that decision though, ask yourself if you just want an average intake or if you want a proven air intake system that is engineered to perform. 

When considering the purchase of an air intake system, consider the following:


1. The length of time the intake manufacturer has been in business.
2. What new innovations do they have to bring to the air intake market?
3. A manufacturer with a patent is usually a positive sign that lengthy testing has been conducted prior to the release of any intake.
4. If a manufacturer openly offers to talk about Air/fuel ratios and Short term and long term fuel trim levels, that's  a pretty good sign that they have nothing to hide and they are applying their own technology
5. If a manufacturer has products that look similar to others, chances are they have no integrity or creative ideas of their own to distinquish themselves from any other air intake manufacturer.
6. Being first to market is not always a good reason to buy from a manufacturer. Problems may surface in the long run and then you're stuck with a lemon!
7. Injen Technology has been building intakes for 15 years and has always been on the cutting edge of technology.  Injen also has four US tuning patents to prove that we are always in the know, using our own technology to tune air intake systems.
8. If it looks like an Injen air intake system with a step-down process, you can bet that "Reverse Engineering" has been attempted and no amout of copying is going to come close to Injen's results.
9. Remember, Injen is the only intake manufacturer that holds 4 US tuning patents to tune an air intake system the right way!
10. Injen Technology, The World's First Tuned Air Intake System!




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