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The BRZ/FR-S is one of the hottest cars to hit the track in the past few years, and the Mishimoto engineers decided to do what they do best: cool it down. Naturally, we would be developing a performance aluminum radiator and silicone hose kit. Additionally we ended up with a killer direct-fit oil cooler kit, some very slick oil caps, and a low-temperature thermostat. As you may have seen in our other build-log, we are also developing a performance cold air intake, which we estimate will provide a nice increase in power and really bring out some of the engine tones being baffled by the factory system. This article is not about the full intake system we have planned. It’s about the silicone induction hose we developed in the mix with all the products listed above.
Somehow, this very unique and valuable product got lost in the mix of our other projects and we never really properly portrayed what this hose can do for your BRZ. The amount of product testing and development put into this project was quite extensive, and we have a ton of really neat information that the average consumer may want to know. If you are not interested in data, we also have plenty of neat behind-the-scenes images that should keep you entertained!
So, why would we want to develop a product like this? The answer is simple. Inlet, induction, and throttle body hoses are an easy upgrade in both durability and performance. Hoses from the factory are normally made from a rubber material. This rubber is exposed to oil and heat that begin to degrade the hose over time. We see a lot of rubber hoses with cracks or splits that can cause the check-engine light to appear. This is a result of unmetered air entering the engine, which will affect how the vehicle runs. So our first reason for upgrading will be general reliability, longevity, and durability. The factory hoses normally have some form of restriction, whether it be in the inner diameter of the tube or unnecessary bends. By eliminating restrictions, we should be able to provide some performance benefit. So, our secondary reason for upgrading will be to attempt to provide an increase in either airflow or power. In the process of creating this new hose, we determined it would be wise to perform extensive testing on numerous varying combinations of intake setups to see what worked best and provided the most power output.
Additionally we saw a ton of complaints on the forums and from enthusiasts regarding the use of a noise generator. Most see this unit as a foolish component that is completely unnecessary, and I would have to agree. To the true enthusiast, a noise generator is a gimmick. So the third reason for developing this component was to provide a clean solution for removing the noise generator. That being said, we would need to provide data to prove that removing this component would not negatively affect performance. Testing would be required to confirm this, and that’s the fun part.
Check out our initial goals for this project below.
- Silicone material should be used for increased durability.
- Potentially include ports for resonator and/or sound generator.
- Test the effects of the sound generator and stock intake resonator.
- Hose should install like the factory unit.
- Offer in a variety of colors.
These goals seem rather simple, bet let’s break them down a bit.
We use silicone for several of our product lines, from heater hoses to vacuum lines to intercooler couplers. You may be wondering why. The first and main reason is durability. Silicone has been proven to outlast rubber counterparts significantly. Oil, fuel, coolant, and varying temperatures all play a role in the degradation of rubber engine hoses. Our silicone hoses are embedded with layers of heat-resistant fibers, and they are thicker than factory rubber hoses. These features provide significantly improved resistance to expansion or damage. Mishimoto silicone hoses also have greater heat and pressure tolerances than EPDM rubber. This allows for years of service and repeated temperature cycling. We consider this upgrade as a nice safeguard against the dangers of a blown hose. In the event that this hose is carrying coolant, this could easily ruin a day at the track or add an expensive tow bill to your monthly expenses. Furthermore, an overheated engine can result in blown gaskets, warped heads, and ruined cylinder walls. Avoiding this is one of our main reasons we are attracted to silicone products. In this instance, the inlet hose is simply supplying a volume of airflow to the engine. Although this hose will not see extreme temperatures, it will certainly see its fair share of contaminants such as oil particles. These particles will expedite the breakdown process of rubber and lead to its eventual failure. The factory rubber hose also has an accordion portion that is meant to flex; however, it does create a restriction. So, the simple answer is that we are interested in replacing rubber components with silicone products to increase durability, reliability, and in this case performance.
Let’s talk more about this accordion bend. This normally helps to aid in providing a flex point so the rubber hose does not tear when the engine is twisting during acceleration. Although this is a great feature, it does promote a restriction for airflow. By smoothing out the interior of this hose, we can theoretically provide improved flow and maybe some extra power! We will have to let our testing prove this point!
Resonator and Noise Generator
These two intake components are finding their way onto numerous factory intake setups from several manufacturers. The topic has become a bit of a debate and it seems that most enthusiasts prefer to not have a noise generator unit. The resonator is a key component however, and our team will be testing to see what value keeping this resonator will have on overall performance. We surveyed several forum members and found that as a group, the noise generator is removed by most. We will be taking this into consideration with our design.
The resonator provides a pocket for a volume of air and its function is not so easily explained, but I will try. Intake air moves past the filter, through piping, into the manifold, and eventually past a valve into the combustion chamber. This air brings with it a pressure wave. Unfortunately not all the air/pressure actually makes it into the combustion chamber, which results in the pressure bouncing backwards and reversing direction through the intake manifold and piping. This pulse of air can result in a high-pressure area where the pressure coming in and pressure going out are fighting for space. So why is this a bad thing? This can result in limited airflow, not what you want with your performance engine. By including a resonator assembly, this pressure wave moving backwards now has a cavity for expelling its energy, therefore reducing its effect on the air moving towards the engine. So in short, the resonator is actually beneficial when it comes to airflow and performance.
We have quite a bit of data collection up our sleeves so we can fully test our product as well as the factory components. Our facility now features a Dynojet dynamometer, so we are able to capture power data for each of the intake combinations we would like to test. Our plan is to capture three runs with each combination in order to obtain a comparable average. More on this later on!
Our goal here is to provide a quick-installing product that requires little modification to the vehicle. If we choose to eliminate either the noise generator or the resonator, we will need to include hardware/plugs to do so. Access to the induction hose is rather simple, so installation should take a matter of minutes.
Everyone has differing opinions and tastes regarding engine bay accents. Although our primary goal for this project will be performance related, we are also anticipating this product as an upgrade in engine bay style. Normally we offer our silicone products in black, blue and red. At times we have recommendations for additional colors, so feel free to voice your opinion if you would prefer orange, purple, white, or any other color!
Now that we have our goals set it was time to remove the factory induction hose and inspect it for improvements and development ideas. Luckily we have several contacts in the BRZ/FR-S world and had several vehicles to work with on this project. Take a look at the factory hose.
Once removed, it was easy to see the general features of this hose. The factory hose utilizes three ports: one for the PCV system, one for the noise generator, and one below intended for the resonator. Otherwise this hose follows a simple shape and would be a simple task for our engineering team to develop. First, we worked up a hose with all factory ports. This prototype featured five-layer silicone as well as internal metal support rings to prevent collapse. Compared to the factory hose, our unit features a huge improvement in airflow thanks to a smooth interior surface.
Above is an example of the internal metal support rings we use on our silicone induction hoses, specifically in our WRX/STI induction hose. These rings are necessary to avoid any chance of the hose collapsing under pressure.
Check back with our next installment of this build-thread, where we conduct extensive testing on the factory induction hose as well as our prototype unit!