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Blow-By Verified – Oil Catch Can R&D, Part 1: That’s…A Lot of Oil

What do carbon-deposit caked valves, decreased fuel economy, oily intake tracts and inefficient combustion all have in common? The resulting effects of engine oil blow-by. During combustion, the top side of the piston forces combusted gasses, with remnants of fuel and oil past the piston rings, and into the crankcase. This would force the crankcase to become pressurized without some sort of relief, so the content of what enters the crankcase exits the system through a positive crankcase ventilation (PCV) system and gets recycled through the engine via the intake tract.

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Our shop Ram getting ready to go under the knife

You may have heard of a device called an air oil separator or AOS. These devices tap into your PCV routing system and are intended to separate the oil vapor from the incoming air. Well-constructed AOS systems can be of some use, but there is one crucial issue here. The separated content is usually routed right back into the engine, in many ways severely reducing the usefulness of the device. The reason they are designed like this is to limit the amount of maintenance the driver needs to do on the car. Many manufacturers have an AOS system built-in with their engines from the factory, but the reality of the situation is that preventing blow-by can be done with much more effectiveness.

Enter Mishimoto’s 2-Port Baffled Catch Can
Enter Mishimoto’s 2-Port Baffled Catch Can

The way to restrict the blow-by is by containing it. This is done with the use of a catch can. Catch cans tap into the PCV system, just like AOS kits, but instead of anything being recycled, the collected content stays inside of the can. How well these catch can kits perform their duties varies, depending on the design. Luckily, we have, what many consider to be a top-notch design.

Check out the internals of our catch can
Check out the internals of our catch can

Our can uses a baffle which does two things: 1) prevents anything caught from spillling back into the ports and 2) helps to condense oil and fuel vapors. Every can we make also has internal air diverters to help increases air turbulence the air, driving a more effective air-oil separation process. Another feature for this can includes a 50-micron bronze filter that helps clean the air going back into your system. The only drawback to this type of design is you’d need to empty the can to drain the contents. It’s another step regarding maintenance, but it’s worth it in the name of engine protection.

If you are an owner of a 2009+ Dodge Ram with a 5.7L Hemi, you have probably heard of blow-by issues. A clear indicator of blow-by wreaking its havoc on your engine is finding oil coating the inside of your intake tube or intake manifold. It’s not all bad though. We’re here to help.

Now that you have a clear idea of how we tackle the blow-by issue, we want to apply our design to the Dodge Ram. We explored the usefulness of our catch can on this truck. After locating the PCV system and a secure mounting point for the can, we applied a prototype kit.

Routing for our catch can experiment
Routing for our catch can experiment
Mounting location sits right on the fan shroud
Mounting location sits right on the fan shroud

The driver had planned some long-distance highway driving for the weekend, so it would be the perfect distance for our experiment. When the truck returned to our garage the following Monday, our engineer cracked open the can to see what was caught, and it delivered.

Collected catch can content.
Collected catch can content.

Is the above image a little tough to see? Let me clear that up for you.

That’s over 40ml of blow-by!
That’s not an espresso. That’s over 40ml of blow-by!

The near full beaker is the content we collected from our shop 2009 Dodge Ram 5.7L Hemi. In just under 1500 miles of driving, our can nearly hit its 2oz capacity with blow-by content going over the 40ml mark. We’ve never seen a can fill up so fast in such a short amount of time. It was startling to say the least. And this wasn’t a freak occurrence. We’ve had this can mounted on the truck for the past couple of months, and it consistently catches well over 30ml of blow-by when the mileage hits over 1000 miles.

We know this setup works, we now must make it completely functional. The bracket and lines are both still in the prototyping stage, in the next update, we’ll finalize our design and reveal what the final kit will look like. Thanks for reading!

-Diamaan

2 thoughts on “Blow-By Verified – Oil Catch Can R&D, Part 1: That’s…A Lot of Oil”

  1. This is great guys! I own a 2016 ram rebel with the hemi and I am FCA technician so I see this problem every day. Ive been looking at getting a catch can for the truck but a fully engineered kit for the truck would be awesome instead of using a universal one. Hope you have the kit out soon!!

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