ST does not need a catch can. They already come with an internal catch can my FORD mechanic said.
If it's internal, how does it get emptied and where is it?
5,000 miles in my JLT catch can.
ST definitely needs one.
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OEM catch cans are a thing - sort of. So, to keep from adding another regular maintenance cycle (like changing oil, coolant flush, etc.) , IE emptying the can, OEMs typically use an air/oil separator that's integrated into the PCV system and drains back into the oil pan. WE've actually seen systems like this quite often, especially on Euro vehicles like VW/Audi. Ford's system for the EcoBoost's is pretty similar and it basically just looks like a big plastic box on the side of the block. Here's the PCV/AOS on the 2.3L Bronco:
On paper, it's a great concept, but in practice, there's more to be desired. These OEM AOS systems and catch cans operate using the same principle - It's a baffled chamber (some Ford parts include fluid traps too) that allows the blow-by to condense and collect before traveling to the intake system. From our experience, and especially with just about every iteration of the EcoBoost platform, this OEM AOS still needs some backup. Even with these installed on the vehicles, blow-by is still making its way through the system (see above). Since the OEM systems drain that milky mixture back into the oil pan, it can reduce your oil's lifespan since blow-by is typically a mixture of oil, fuel, and water condensation (depending on climate and the current temperature). Basically, it's better to collect blow-by elsewhere and just remove it from the system. This is a sample from a 3.5 EcoBoost, and I don't know about you, but I wouldn't want this in any part of my engine:
Basically, yes, these have a form of catch can from the factory, but OEMs, including Ford, for the most part still need to make compromises during design and production to reduce maintenance and costs for their vehicles.
The previous generation had what could be considered a "catch can" of some sort (at least for a few years of the model run), but I've seen nothing of the sort for the '20-up models. Since Ford removed the previous version somewhere around '17, I believe, it must not have been worth much. In any case, they are a good add-on for sure. Looking forward to this one showing up, but no word yet from Mishimoto on the shipping date.
Our kits are already on the way to our warehouses, and we'll begin shipping in a few weeks!
-Nick