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Discussion Starter #1
After experiencing the benefits of Snow Performance’s Boost Cooler kits on our direct-injected BMW engines, my brother and I decided to install a Boost Cooler kit on our brothers 2018 Mazda 6 … Ho, Ho, Ho! And, after seeing the intake valves at 2,700 miles, I’m glad we did. Mazda’s decision to go with a directed injected engine without additional port fuel injection (think Ford) to clean the intake valves (and the addition of exhaust gasses into the intake air stream), will cause the intake valves to build up deposits quickly.

Here’s a close up of the #2 cylinder intake valves (2,700 miles); the other cylinders looked the same.

Here’s a shot of what my BMW 335i’s intake valves looked like after walnut blasting. This is what I expected the Mazda’s valves to look like.

After receiving the Boost Cooler kit from Snow Performance, we picked up some odds and ends (grommet assortment from Harbor Freight, four 90 degree push-on fuel line connections from a hose shop, and some electrical quick disconnects from Home Depot) and got to work. One of us worked on the electrical side, and the other worked on the finding a place and installing the injector nozzle. For this application, Snow Performance recommends a #3 nozzle.

The engine compartment:
Step one was to remove the intake manifold so we could install the nozzle. You’ll need to move (not disconnect) the coolant recovery tank, intake hose from the output of the intercooler to the throttle body, throttle body (8mm socket), and EGR cooler (8 & 10mm sockets). The only coolant hose we disconnected was one leading to the EGR cooler; this allowed us to move the cooler out of the way so we could remove the intake manifold.

You’ll need a 21/64” drill and a 1/8-27 NPT tap to drill and tap the intake manifold for the injector. Snow includes E6000 sealant; use that on the injector threads when you install it, and don’t install it backward!

Now you can put the intake manifold (and all the other bits) back together.

Next, you’ll need to remove the battery, battery tray, and charge pipe between the compressor discharge and the intercooler. This is so you can drill and tap a second hole for the boost pressure switch sensing line fitting. Make sure you tap the charge pipe and not the compressor air-inlet pipe. The charge pipe is below the air inlet pipe.

We zip tied the boost pressure switch to the wiring harness that connects to the temperature sensor on the upper air filter housing.

The battery tray is an excellent place to mount the water/methanol fuel shut-off valve (SOV). Snow recommends this SOV for all trunk mounted tank systems.

For our installation, we decided to run the electrical wiring inside the car under the trim panels; the low-level LED and the injector ON indicator LEDs were mounted on top of the plastic trim that covers the steering wheel. We ran the methanol line from the tank at the left side of the trunk down and through an existing grommet below the left trunk storage bin.

The boost pressure switch is adjustable. Snow says it comes from the factory set between 9 & 11 PSI; our switch was set at 10 PSI, which is good for this installation, and we experienced no quench with the #3 nozzle.

The trunk:
The left side storage bin is a good place to mount the pump and the tank. We used some 1/8” thick plastic and a small piece of 1 X 2 to create a platform for the pump. We also put electrical quick disconnects on the pump and low-level sensor wiring to support future repairs if required.

The finished installation of the pump mount looked like this: Holes were drilled through the plastic for the fuel line and electrical wiring. We drilled additional holes in the bottom of the storage bin to feed the fuel line and wiring up to the pump. The electrical quick disconnect is right below the pump.

Here’s a close up of the mounting screw and finished fuel lines:

There is a screw just in front (and one behind the pump) that holds the plastic plate to the wood wedge that is underneath. We installed thread inserts on the underside of the wood wedge and installed screws from under the storage bin to hold the wedge to the bin. Again, this was done so we would have a flat floor to mount the pump to.

The final product looks like this:

There are multiple holes in the supplied methanol tank, and we had to modify the mounting brackets with a Dremel tool to make it fit.

We also used some leftover plastic to provide some rigidity to the left fender trim panel

With the injector, electrical relay, boost pressure switch, LEDs, solenoid valve, pump, and tank installed, the last installation step was to remove the under body panels and run the methanol line to the engine compartment and connect the line to the injector. We zip tied the methanol line to the existing fuel lines that run from the gas tank to the engine compartment.

With the water/methanol line disconnected from the injector and using a small container, we used a Mityvac hand pump (ignion on) to apply 10 PSI to the boost pressure switch. This energized the pump relay and activated the pump. With the pump bled, we connected the methanol line to the injector.

On the road, we monitored inlet air temperature with the installed Scan Gague II. Outside air temp was 65 degrees and indicated inlet air temp was 82 degrees. Under full throttle acceleration, we noticed a 17 degree drop in inlet air temperature.

The real benefit of this system comes from keeping those intake valves clean, and if we get some extra performance we can always tell the police officer … Sir, I was just cleaning my intake valves.


5 Posts
Discussion Starter #3
Well, the good part about taking a new car apart is that everything comes apart very easily ... no corrosion, seized fasteners, stuck on hoses etc., and the plastic trim pieces are still flexible so the don't snap or crumble when you take them apart. I'm just glad we got the kit installed before there was a lot of build up on the valves.

If you go back to my original post, you'll see a picture of my BMW's (also direct injected) intake valves after walnut blasting. Here's a shot of what they looked like before cleaning. The 6 was well on its way to looking just like that.

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