MAPerformance Civic SI 1.5T PCV System & Catch Can Testing/Observations

Great research, but i still have doubts about the actual efficiency, my catch can is still gathering "something" just like the picture in the below thread:

https://www.civicx.com/threads/more-mishimoto-catch-can-issues.31623/#post-530470

Could it be enough to require an extra maintenance along the road? (like walnut blasting, etc?)


Can an oil catch can throw a "check oil level" warning light on the car? If so, why? The can was empty when it happened and oil level was perfect.

The Ozzie Low Down on catch cans :-\



Love this guy -- says it as it is, no punches pulled , and all his video's are both entertaining and Informative.
(Stormy Daniels --- ROFL !!)


But even after watching this, I just went out and bought one. !!

Can't do any harm (or can it -- I guess it can if not fitted correctly).
Time will tell, when I see how much it :Catches over the next 1000 miles.

OK, I must admit -- what sold it for me were the cool BLUE hoses !!!
(I know !!! no need to say it ! )


https://www.amazon.com/gp/product/B01GRZX4KO

I think a lot of people conclude that if their catch can is collecting residue, then that means that the catch can was doing it's job. The problem with that assumption is that a catch can is going to catch something... there is crankcase pressure in any engine, and that pressure does contain oil that has been turned into vapor that is essentially being pushed around by that pressure.

When the vapor comes into contact with something significantly cooler, the vapor will begin to collect/accumulate and the evidence that there is oil/water/filth collecting presents, often times leading customers to the conclusion that the catch can was a mandatory upgrade, when in fact, the catch can almost always certainly will catch something. In my mind, the real question that one should be asking would be: "is there a functional benefit to alleviating that crankcase pressure by way of adding a catch can...and if yes, does that benefit outweigh any other characteristic engine behavior that was built into the engine from the factory that had a benefit?" That answer will vary from vehicle to vehicle.

For the purposes of this article, it is important to note that an assumption is being made...the assumption being that crankcase pressure rises at a rate that the factory designed alleviation tactics are not capable of supporting once the vehicle is modded. This is true of certain applications. For example, similar testing demonstrates that the EVO X 4b11t engine, when modded, will begin to produce surplus blow by that the factor pressure alleviation strategies cannot overcome. This inability to compensate will actually hurt performance and potentially risk damaging components... in fact, there were numerous theories, when the engine was relatively new, that the excessive blow by caused pressure to rise in the compression zone to the extent that spark plugs were being damaged and breaking. While that is more supposition and less definitive, the reality is that particular engine, when modded, needs a better crankcase ventilation method.

The 1.5t Honda is so simple... it manages to evacuate pressure as fast as it can build it... actually, fully overcoming the pressure in certain ranges of operation. It would be hard for me to say that this car NEEDS an oil catch can. It would be equally difficult for me to say that use of a catch can will hurt the engine, but I don't see a clear benefit. In fact, when I (earlier) suggested that there might be a benefit to the factory system, our testing demonstrated that the factory system worked so well, it evacuated pressure faster than the crankcase could generate it. It COULD be theorized that there would be a benefit at extremely high HP in that circumstance. When you switch to a catch can, the engine simply pushed out pressure as fast as it is made... but no more.

Soulnchain said:

Great research, but i still have doubts about the actual efficiency, my catch can is still gathering "something" just like the picture in the below thread:

https://www.civicx.com/threads/more-mishimoto-catch-can-issues.31623/#post-530470

Could it be enough to require an extra maintenance along the road? (like walnut blasting, etc?)


Can an oil catch can throw a "check oil level" warning light on the car? If so, why? The can was empty when it happened and oil level was perfect.

Click to expand...

MAPerformance said:

I think a lot of people conclude that if their catch can is collecting residue, then that means that the catch can was doing it's job. The problem with that assumption is that a catch can is going to catch something... there is crankcase pressure in any engine, and that pressure does contain oil that has been turned into vapor that is essentially being pushed around by that pressure... when the vapor comes into contact with something significantly cooler, the vapor will begin to collect/accumulate. So essentially, the evidence that there is oil/water/filth collecting is basically a given under any circumstances...the real question that one should be asking is, is there a functional benefit to alleviating that...and if yes, does that benefit outweigh any other characteristic engine behavior? That answer will vary from vehicle to vehicle.

For the purposes of this article, it is important to note that an assumption is being made...the assumption being that crankcase pressure rises at a rate that the factory designed alleviation tactics are not capable of supporting once the vehicle is modded. This is true of certain applications. For example, similar testing demonstrates that the EVO X 4b11t engine, when modded, will begin to produce surplus blow by that the naturally pressure alleviation strategies cannot overcome. This will actually hurt performance and potentially risk damaging components... in fact, there were numerous theories, when the engine was relatively new, that the excessive blow by caused pressure to rise in the compression zone to the extent that spark plugs were being damaged and breaking. While that is more supposition and less definitive, the reality is that particular engine, when modded, needs a better ventilation method.

The 1.5t Honda is so simple... it manages to evacuate pressure as fast as it can build it... actually, fully overcoming the pressure in certain ranges. It would be hard for me to say that this car NEEDS an oil catch can. It would be equally difficult for me to say that use of a catch can will hurt the engine, but I don't see a clear benefit.

Click to expand...

Clear concise and informative. Thanks for the info guys

Always happy to help!

Ok, so maperformance sold something to me for a good bit of money I might add, that your now saying I don't need and COULD POSSIBLY hurt my car or its performance.

I do believe it would be incorrect to suggest that it would hurt your performance at normal power levels... the delta of crank case evacuation counter force against the pressure that is building does not cross until you start to approach 400hp... beyond that, I have not seen any evidence to suggest that the car would be hurt or damaged, but the purpose of this post is to explain that we investigated the need for the component on this platform and found that the vehicle didn't need one... at LEAST at the power levels we have pushed the platform to, this far.

Found this...what do you guys think?

ElpacoSV said:

Found this...what do you guys think?

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Oil catch cans DO work, there's no doubt about that. But not all engines are the same. As the MAP guys have shown, the L15B7 was engineered to separate the blow by oil from the air with the buffeting in the valve cover, and it does this very well.

My question:

If the manifold has it's own baffled system, where does the blowby go? Rather, wouldn't there be build up in the manifold itself or is it "self cleaning"?

Syntek said:

My question:

If the manifold has it's own baffled system, where does the blowby go? Rather, wouldn't there be build up in the manifold itself or is it "self cleaning"?

Click to expand...

Basically the entire valve cover is one big "catch can". It has baffles that separate the oil out of the crankcase vapor as it's drawn through.

Just another example of Honda's engineering.

Ninja edit:

They also programmed the cam phasing at light duty/ cruise to induce intake reversion. Which helps clean the intake valves by allowing fuel cleaners etc to reach the backside of the valves during very low pumping losses.

PowerPerLiter said:

Basically the entire valve cover is one big "catch can". It has baffles that separate the oil out of the crankcase vapor as it's drawn through.

Just another example of Honda's engineering.

Click to expand...

Right but, I'd imagine it stays in the manifold, in which, I feel like that would be a bigger pain in the ass to clean vs having a catch can in place instead

Syntek said:

Right but, I'd imagine it stays in the manifold, in which, I feel like that would be a bigger pain in the ass to clean vs having a catch can in place instead

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Your confusing two separate parts. The valve cover is not the intake manifold.

The factory pcv system operates within the valve cover, only with supplied vacuum from the intake manifold.

PowerPerLiter said:

Your confusing two separate parts. The valve cover is not the intake manifold.

The factory pcv system operates within the valve cover, only with supplied vacuum from the intake manifold.

Click to expand...

You're right. huge brain fart I had

Syntek said:

You're right. huge brain fart I had

Click to expand...

happens to all of us lol