ND Miata Catch Can R&D, Part 1: Evaluation of PCV System
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If you've been keeping an eye on our blog or posts on the forums, you would notice some recent attention on ND Miata R&D. We have big goals to improve air inhalation for the 2.0L by way of a high-flow intake system, and we are knee deep in an awesome oil cooler setup, which will keep fluid temperatures in-check during track driving. Although this project might not be as neat in terms of testing data and added performance, it is equally important.
Why a Catch Can?
Catch cans and direct injection go together like Miatas and R-comps. You might not think you need it, but once installed, you won't want it removed. We've been designing direct-fit catch can systems for quite some time, for a variety of applications that greatly benefit from the addition. If you follow the progress of direct injection, you will see a variety of issues regarding valve carbon buildup. This can cause drivability issues, CELs, and require regular servicing for many engines. The primary reason behind this is the lack of port injection, which typically washes the valve with fuel, clearing it of most contaminants. Without this feature, we begin to see more rapid valve buildup, mostly brought on from PCV system blow-by reaching the intake manifold.
PCV setups are vital to modern combustion engines and function to improve pressures in the crankcase for optimal engine performance and longevity. The byproduct of oil/fuel passing through the valve is returned to the intake manifold and burned in the combustion process. This is an easy way to recycle the contaminants, but it is hardly optimal. Oil in the combustion chamber reduces the octane rating and degrades performance. More importantly, oil in the intake manifold accelerates valve contamination. If this is happening, you desperately need a Miata oil catch can solution.
Manifold & Valve Evaluation
To view the stock PCV assembly, we need to remove the intake manifold. This won't be required for installation of our kit but will allow us to better view what we're working with. In addition, we can peer inside the intake ports to see the condition of the valves.
The manifold comes off quickly. With that removed, we can see a ton of neat components, including the ports, the direct injection system, and the PCV assembly. Cool!
Check out a couple shots of the plastic manifold on our bench.
The ports seal to the cylinder head with the green rubber gaskets on each runner.
On the rear of the manifold, we find the MAP sensor and the port that connects to the PCV assembly. We will be tying into this with our Miata catch can lines.
Above, you can see the throttle body connection point.
In a perfect world, this manifold would be dry. Unfortunately, this was not the case with our 3,300 mile test vehicle. Check out a few shots of the manifold's interior, clearly showing some oil coating and collection.
This fluid could either be entering the manifold directly from the PCV system or making its way through the intake system, which has a valve-cover breather plumbed in. We checked the throttle body for traces of oil.
This component was clean. This tells us the oil in the intake manifold is likely coming from the PCV valve.
With the manifold removed, we decided to check the valves to see if any carbon buildup had started on this ND. Check out a couple shots below.
The general condition is average. There is some buildup on the first cylinder, with the valves getting cleaner as you move to the back of the engine. Keep in mind this vehicle has not seen a ton of mileage. Considering this, a catch can will definitely provide some peace of mind.
Development continues for our Miata catch can system!
PCV System Evaluation
The first image gave a quick look at the PCV assembly on the 2.0L. Here is a closer shot.
The strange shape encompasses internal baffling and reduces the chance of fluids entering the intake. We see how well that worked out.
The hose connection point is a standard barbed connection, unlike some other modern engines which use quick-disconnect fitting at these points. This makes things a bit easier for our team during ND Miata parts development.
With the assembly removed, we can see fluid within the chamber.
We can also see the various baffles in place.
Our last image shows the short hose that routes air from the PCV valve assembly to the manifold port we referenced earlier.
Summary of Evaluation
Now that we have an in-depth look at the components that play a role in the PCV system, we can draw conclusion regarding the role of a catch can. We won't produce a product that doesn't yield results. The oil buildup within the manifold and the buildup on the valves are enough evidence to support continuation of this Miata catch can project. Installing a catch can early in the lifespan of the vehicle is crucial. We will be working to put together an effective bolt-on solution as quickly as possible.
Our next post will highlight the catch can bracket creation process. We will be using interesting prototyping equipment to quickly put our ideas into motion. Check back soon for another look at Miata oil catch can development and be sure to check out our blog for other ND Miata parts development.
Thanks for reading!