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During the development of our new intake system for the 1999-2005 BMW 3-series, we identified yet another component that would be a vital upgrade as the E46 chassis begins to age (gracefully though, right?). With a lack of support in offerings for a silicone E46 intake boot set, we decided to design a set that would replace the failure-prone stock rubber units. If you've ever owned a BMW (E30, E36, E46, etc.) that utilizes such rubber intake elbows and hoses, you may have experienced failure at some point. Typically the area of flex begins to develop cracks and tears over time. The unmonitored air entry results in a rough running straight-six " not exactly ideal. So let's get to the project!

Stock Intake Boots

First, check out the factory-equipped boots!

Stock BMW E46 intake boot assembly

Stock BMW E46 intake boot assembly

Stock BMW E46 intake boot assembly

The stock E46 intake boot uses a two-piece unit with three individual ports. The two-piece design allows for easier installation.

3D

Interested in picking up our E46 intake system? Check out our product page for more information!

Mishimoto BMW E46 Performance Air Intake

Final Intake Images

With successful testing data acquired from our first prototype, it was time to make a final prototype and perform our last test fit before producing a batch of final intake systems. Check out a shot of the shroud, intake hose, and filter!

Mishimoto E46 air intake shroud, intake hose, and air filter

The airbox is constructed of powder-coated steel, and we line the edges with weather stripping to prevent any vibrations or damage. The silicone coupler is a four-ply unit designed specifically for this kit.

The air filter shown above is the Mishimoto Oiled Air Filter. These filters are completely serviceable and can provide a lifetime of service if appropriately cleaned and maintained.

We also designed an internal CNC-machined connector that will allow the silicone intake hose to mate properly with our air filter. This setup can be seen

Interested in picking up this aluminum E36 expansion tank? Check out our product page linked below!

BMW E36 Aluminum Coolant Expansion Tank!

The time has come and the anticipation is over. Our final prototype unit has been constructed, and we are ready to check fitment! On to the pictures!

Final Expansion Tank Images

Mishimoto expansion tank prototype

Mishimoto expansion tank prototype

Mishimoto expansion tank prototype

Check out a closer look at the lower coolant hose fitting and our threaded fluid level sensor bung on the base of the tank.

Mishimoto expansion tank prototype fittings

We also stamped our Mishimoto "M" logo into the side of the tank. Although not super visible once installed, this is a nice subtle inclusion to identify this tank as another awesome Mishimoto component.

Mishimoto expansion tank logo

Now the cool part! Check out the fill neck and dipstick we have designed for this tank.

Mishimoto expansion tank top

This part of the tank deserves some extra conversation. The

Interested in picking up our E46 intake system? Check out our product page for more information!

Mishimoto BMW E46 Performance Air Intake

After completing our initial prototype it was time to strap this E46 to the dyno and make a few pulls. We would be evaluating power output, monitoring vital engine sensors such as AFR, and collecting sound clips for comparison against the stock intake system.

Dyno Testing

E46 on dyno for intake testing

E46 on dyno for intake testing

E46 on dyno for intake testing

Time to make some pulls! Check out the dyno video below.

Initial Impressions

The video shows the changes our setup made in  intake noise. This is likely a result of our open-element filter residing within the engine bay. Although closing the hood seals off the airbox portion of the intake, it is still more audible than the stock unit. The stock airbox is designed in a way to reduce noise and create a more drivable experience for non-enthusiasts. That said, this creates a numbness among car

Quick project update! As noted in our last post, we had finished collecting data points and dimensional information for the stock tank and were setting our sights on creating a tank of our own.

After pulling our engineers out from under shop vehicles, we set them behind the computer to get this project moving. Check out some of our initial 3D models!

Mishimoto expansion tank, 3D model

Mishimoto expansion tank, 3D model

Mishimoto expansion tank, 3D model

Mishimoto expansion tank, 3D model

Mishimoto expansion tank, 3D model

And here's a shot showing our fill-neck design and upper hose connection!

Mishimoto expansion tank, 3D model

Below is a shot showing the quick-connect fittings located on the base of the expansion tank. As noted in our first post, these attach to the plastic plate on the radiator fan shroud. One of the ports will be capped on manual models.

Mishimoto expansion tank, 3D model

Our tank is being designed to function with all stock connection points and will not require any

Interested in picking up this aluminum E36 expansion tank? Check out our product page linked below!

BMW E36 Aluminum Coolant Expansion Tank!

Time to break open the stock tank and see what lies within. If you follow some of our other development projects, you would know that we recently split an E46 3-series expansion tank and found quite a complex system including both internal and external features. Although this added some complexity and difficulty to the project, it seemed like our engineers enjoyed the challenge.

Stock Expansion Tank Internals

First, before we slice this guy in half, a look inside the tank from the cap.

Stock expansion tank, internal design

We can see from this shot that the tank does indeed feature a unique internal chamber. A tube appears to run the full length of the tank. Let's get to the band saw so we can split this component for evaluation.

Stock expansion tank, internal design

Stock expansion tank, internal design

Stock expansion tank, internal design

The internal

Interested in picking up our E36 fan shroud? Check out the full details on this kit on our product page!

Mishimoto BMW E36 Performance Fan Shroud Kit!

Our final prototype is complete and looks fantastic. The fan mount is constructed from 1/8" steel that has been cut to a specific shape allowing for additional airflow through the radiator core at speed. Additionally, the mount is powder coated black to provide a durable finish. As noted in our last post, we tested this unit extensively with our 16" fan to ensure that coolant temperatures were properly regulated during both idle and all driving conditions.

Check out a few shots of the mount!

Final prototype of fan mount

Final prototype of fan mount

This shroud has been designed to function with the stock expansion tank as well as the aluminum expansion tank we have been working to develop. Check out the mounting system our engineering team designed to secure the tank properly in the stock location.

Final prototype of expansion tank mount

Interested in purchasing our E46 aluminum radiator? Check out our product page linked below!

Mishimoto BMW E46 Non-M Performance Aluminum Radiator!

3D Modeling

After some serious 3D modeling work in Solidworks, our first prototype unit is complete. Let's check out a few of the renders!

Mishimoto E46 3-series aluminum radiator 3D model

Mishimoto E46 3-series aluminum radiator 3D model

As you can see, the rear of the radiator features a variety of complex pieces. The quick-disconnect fittings have been replicated and will be CNC-machined. All stock mounting points have been included in our design so that this radiator drops into place just like the stock unit.

Take a look at the front side of the radiator.

Mishimoto E46 3-series aluminum radiator 3D model, front view

Mishimoto E46 3-series aluminum radiator 3D model, front view

Mishimoto E46 3-series aluminum radiator 3D model, front view

Although you can't see much of the core in these shots, we did spend a great deal of time designing this

Enthusiast groups' feedback plays a massive role in our product development process. Not only is it a great way to bounce ideas off our potential customers, but it also allows us to see exactly what our customers want and need for their vehicles. This project is no different. Due to a substantial amount of demand via forums and social media, we decided it was time to get the ball rolling on this coolant expansion project.

Stock Expansion Tank

In typical BMW fashion, this tank was quite unique and featured some very interesting components, both internally and externally. First, a look at the exterior of the tank. Many of you are very familiar with this, based on the rate of failure reported for this plastic tank.

Stock E46 3-series coolant expansion tank

Stock E46 3-series coolant expansion tank

Stock E46 3-series coolant expansion tank

Stock E46 3-series coolant expansion tank

So, there are five - yes, five - unique fittings located on this tank, excluding the fill-neck connection. Check