Calling all Engineers and Motorheads...Where do de oil go?

Discussion in 'SRT Hellcat General Discussions' started by Hayabusa, Sep 5, 2015.

  1. Hayabusa

    Hayabusa Gold Member

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    Need help understanding...my professional world is human behavior, not deep understanding of mechanics. My frame of reference working on cars is late 60's American (gapping plugs, setting timing, adjusting Holley's, etc).

    Question 1: I am struggling to figure out where does the oil go in this design (see pics and quote below)? This Dodge engineered "solution" baffles me. Empty a catch can...I get it. This?...where's the oil after "air and oil go their separate ways"?

    Questions 2 & 3: I intend to add a catch can once I decide which mounting position and can design works best. I think the catch can draws oil before the Dodge oil separator intervention, therefore:
    • Is that why there is so much oil being captured in the cans and...
    • Does the engineering in the Dodge separator use or need that captured oil for something (hence why it isn't emptied like a catch can)?

    "The shape of the Hellcat's Hemi Orange valve cover has an unusual appearance due to an ingenious air/oil separator. The raised slab section of the valve cover is home to a labyrinth that draws crankcase pressure through it. Oil mist and air go in, but air and oil go out their separate ways."

    Read more: We Take A Hard Look At Dodge's Paradigm-Shifting 707hp Hellcat Hemi
    Follow us: @HotRodMagazine on Twitter | HotRodMag on Facebook

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    Thank you MVT for posting the link to this article back in February!!! It was a great read, very educational and informative. Really adds to my appreciation of my Hellcat :cool:!!!
     
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  2. SRT_HC_707

    SRT_HC_707 SRT_HC_707 Staff Member

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    I'm no authority by any means but based on how much oil I have found already in my JLT catch can I'd say the OE design is sub-standard at best. I'm glad I did the catch can and hope they make one for the left side. I can't believe how much oil is getting pass into the intercooler. Doesn't seem like a good thing long term
     
  3. Hayabusa

    Hayabusa Gold Member

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    I'm with you on that, SRT_HC_707, and will follow your lead on installing a can after I work through the following...

    Single point solutions run the risk of fixing one thing but screwing up something in the total system. It's the ole "unintended consequences" thing. I'm applying that logic to ensure I don't mess up something downstream.

    I'm assuming highly educated Dodge engineers mapped out details before the marketing team touts a working oil separator on this engine.

    That got me to the question...Dodge engineers designed their system to work a certain way, does removing the oil prior to that system negatively impact anything?

    This quote appears later in the article: "...the lube system has been given a very ingenious oil/air separator...actually a maze of passages designed to separate the air oil droplets from the crankcase ventilation flow prior to being recirculated." The underlined words caught my attention. Oil recirculated? Where and why?
     
  4. fnkychkn

    fnkychkn swollen member Gold Supporting Member

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    the PCV system draws fumes from the crankcase to be introduced to the combustion chambers. the unfortunate byproduct of this system is that oil vapour in the fumes will condense as it is cooled in the intake tract. the built-in oil/air separators are designed to minimize the amount of oil that will escape the crankcase by providing lots of cooler surface area for the oil to condense on (catch cans work on the same principle). the condensed oil droplets are then returned to the crankcase (oil/air separators, not catch can). any oil vapour that makes it past the oil/air separators will then become part of the combustion process. IMO, this is not harmful to the engine in any way.
    engines have been burning this oil for as long as PCV has been around. catch cans have been used on race and boosted applications because they, unlike the hellcat engine, do not have air/oil separators specifically designed for boosted engines.
    if you want to keep as much oil out of the intake tract as possible (you'll never keep it all out), then a catch can is the way to go.
     
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  5. fastguy

    fastguy BANNED

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    Like always the resident FCA technical expert has the answers we need, way to go bro
     
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  6. Hayabusa

    Hayabusa Gold Member

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    Yo, fnkychkn...love you man (bro hug). Appreciate the explanation!!!
     
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  7. SRT_HC_707

    SRT_HC_707 SRT_HC_707 Staff Member

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    I wonder how much oil the catch cans would be separating if the Hellcat didn't have the built in separator. I'm really quite suprised by how much oil mine collects in a short period of time (miles). I just changed my oil and I'm going to keep close eye on how much oil gets collected during this change interval out of curiosity.
     
  8. fnkychkn

    fnkychkn swollen member Gold Supporting Member

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    you probably won't have this issue but here in the great white north, moisture also condenses in the catch can. this is nothing to worry about until the temperature drops well below freezing. the catch can never gets hot enough to melt the ice inside it and evaporate the water, so it can block the flow through the catch can. therefore, when it gets really cold, i empty mine at least once a week.
     
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  9. Hayabusa

    Hayabusa Gold Member

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    Oh mighty Funky...you are not just Da Man...you are an Emperor!

    Had not thought of that but, damn, makes so much sense and makes ya feel a bit dense when ya say, "why didn't I think of that?"
     
  10. Catless

    Catless Silver Member

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    Even when it is zero here after the 15 mile drive home from work the catch can is too hot to hold on to. Just the underhood temperature is apparently plenty to keep it warm. May not get hot enough to evaporate the water but I have never found anything in our 2 catch cans but oil - smelly oil.
     
  11. Hemibuck

    Hemibuck Gold Member

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    So fnkychkn do you think we really need a catch can?
     
  12. fnkychkn

    fnkychkn swollen member Gold Supporting Member

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    my commute is barely 9 miles and at -5*F>, mine stays frozen.
     
  13. fnkychkn

    fnkychkn swollen member Gold Supporting Member

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    need is a pretty strong word to describe it. it does keep some oil out of the intake tract and looks really cool.
    i have one for my 3.5L because oil tends to coke on the SRV (short runner valve) and MTV (manifold tuning valve) and makes them stick inside the plastic plenum. the catch can helps prevent that. not sure how much benefit there would be for a hellcat engine but, if properly installed and regularly serviced, it can't hurt.
     
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  14. 2510

    2510 BANNED

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    IMHO I think the only issue is if you get too much build up on the throttle body. I never installed a can on my '08 SRT8 200k miles - I would just clean the throttle body and mass sensor with appropriate CRC product every other oil change. My throttle body looked like new on its last day.
     
  15. TallCool1

    TallCool1 Gold Member Hellcat Car Club Gold Supporting Member Nat'l Hellcat Tech Advisor HCC Charter Member

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    I dont like the idea of coking or gumming up the sc cooler fins. Cans will further assist to slow that and better combustion effeciency. Doesn't make them necessary, although the separators are there for a reason. Forced induction produces more blowby. Truly needed if so they'd be installed already but the oe setup isn't 100% effecient either.
     
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