First road trip with aftermarket PCV oil separator

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Just finished a 560 mile run east on I-10 in the 2012 SRT today, and it turned in its best ever fuel economy- 26.2 mpg. That's a full 1 mpg better than the best prior, and conditions were pretty much the same as usual for this trip- speed limits mostly either 70 or 75, with a few stretches of 60. Temps in the high 80s. No wind for the first 3 hours, then a pretty stiff crosswind that did drag the economy down a few tenths for most of the day. Then sheltered from the wind by pines the last 2 hours of the run.

The only significant changes I can think of are that the car's another few thousand miles broken in than the last trip (20,900 mils at the end of the day), AND I installed a PCV oil separator a few months back. I installed it to keep the intake clean, but I know that oil mist causes detonation and that in turn causes the computer to retard timing (that's actually how the catch-can makers market them- "lose less timing and get more power." Maybe cruising in O/D without the separator caused a little more timing to get pulled than I had been assuming?

Anyway, I won't be convinced until I repeat it... but its not like I had a 20-mph tailwind or anything else obvious. In fact, I've made the trip WITH a slight tailwind once before and not done this well.
 
I'm glad you saw good results. Even if somehow your better mpg was a flukey thing, which I'm not at all saying it is, having a catch can is a good idea anyway. I had one on my SRT4, and I was amazed at how much oil it caught in such a short period of time. That's oil that would've been burned off and/or coated your intake manifold.
 
I agree that pics are needed
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. A catch can is the next thing I want to install on the Flex in my signature. I have read enough about DI engines that I believe it would truly be beneficial.
 
Originally Posted By: 440Magnum
I know that oil mist causes detonation and that in turn causes the computer to retard timing (that's actually how the catch-can makers market them- "lose less timing and get more power." Maybe cruising in O/D without the separator caused a little more timing to get pulled than I had been assuming?


The only way to know for sure would be to monitor it with Torque or a similar app.

I never believed that premium fuel made any difference in our Honda, but after using both types and monitoring timing via Torque, the computer DOES indeed increase timing when running premium fuel (even though the manual recommends regular). It's as much as 5-7 degrees, so it's significant. It makes a small difference in power and economy, but not much...not enough to justify the cost of the fuel.

But anyway...yeah, monitor your timing with Torque, and you'll know for sure.
 
All those driving conditions you have described could have easily attributed to the increased MPG. That oil catch can most likely didn't contribute at all.

Catch cans were first marketed towards Turbo cars, now they are being marketed for fuel economy. Next thing you know they'll be marketed for weight reduction... who knows.
 
Its a standard Arrington separator (their basic one, not the one with a post-trap filter). I'll snap a picture of my actual installation later, but here's the basic unit:

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I've only had it on there about 300 miles before this trip, and in that time it caught about a half teaspoon of oil. It should easily go a full OCI and only be maybe a third full. The Hemi has a factory separator before the PCV valve, so it already returns a portion of the mist to the crankcase.
 
Yes, the 6.4 is a 5.7 based engine so it has a nifty little factory baffled separator already in it.

EXCELLENT mileage btw. My car has returned around 26 if I can remember to baby it. But that rarely happens.

Nice to know you are not pumping a ton of oil out as blowby...
 
Made the return trip yesterday, and as always was about 1 mpg lower coming back. But still about 1 mpg higher than the return leg of the previous 2 trips over the past year. Certainly NOT enough data to say "its the separator" but its a data point. I'm honestly not curious enough about it to bypass the separator on my next trip, either. Sorry, science loses to laziness this time.
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Here's the actual installation on my car, they go on very cleanly on the 5.7/6.4 engines. The box shaped area on the back passenger's side of the intake is the factory separator. The "cap" on it is the PCV valve itself:

 
Putting a catch can on my Corolla was one of the best mods I've ever done because the baffling under the valve cover does nothing to prevent oil mist from getting sucked through the PCV valve. I'm convinced that's where the high oil consumption comes from in the AFE Toyota engines. Mine is the husky water separator type and it's full after about 1,000 miles.


It absolutely makes the engine run better and it eliminates ping in the summer. I think it also is why the car gets much better than rated fuel mileage.

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Perhaps I need to look into getting one of these. Is there a manufacturer who does one for the GM 2.4L Ecotec engine?
 
Originally Posted By: Benzadmiral
Perhaps I need to look into getting one of these. Is there a manufacturer who does one for the GM 2.4L Ecotec engine?

I'm not sure how you could make it work.

The ecotec has a passage in the intake manifold, and it lines up with a hole in the cylinder head.

You would have to redesign the whole intake manifold to create a catch can system.
 
Same on the 5.3L GM engine. The baffling they put in these really doesn't do much for airborne mist oil making it into the PCV line. I put one on my 2013 at 1190 miles. At 12,400 miles, it had cumulatively captured almost 16 oz of oil and junk. almost filled a 16 oz drinking water bottle. I wanted to see how long it would take to fill it.

I have been using the Conceptual Polymer high efficiency catch can.
 
I'm not at all surprized at how much mist gets by most factory systems- the baffling under the PCV air pickup point on many engines is very minimal.

However, the post-2011 (Eagle and Apache) Chrysler Hemi's have a mist separator built into the PCV flow path... and mist STILL gets into the line! Its not nearly as much as some other engines, but here's what came out of my catch-can over the trip that started this thread plus about another 700 miles. Its about a teaspoon and a half, and by the color it is pretty obviously mist, not a condensate. I'd love to know what percentage my API catch-can is letting past- obviously a reduction compared to factory, but I'm sure you could put a whole string of separators in series and still get a trace of oil in the 2nd or 3rd one. Probably not worth the effort, but interesting. Arrington's more expensive separator has a small "K&N-style" (cloth-appearing) filter that follows the gravity separator, and is there to catch even finer mist. I opted not to buy that version because its an extra restriction and eventual maintenance item, but I do see the value if you're really trying to scrub the PCV flow before it hits the intake manifold.

Side-view in a glass measuring cup:
17587CA6-3853-47D8-AF06-A212EFD21760_zpss9afkhm3.jpg


Looking down through the sample (the "grit" is actually on the bottom of the glass cup):
85E26179-55CF-4489-926A-58E4DFBC7A5A_zpsfjtyl7bb.jpg
 
I typically get just oil mist in mine when it's above 40 - 50 degrees outside. Below 40 degrees, I start to have to empty the can more often as it gets far more condensation in it, and in the dead of winter, it's usually almost all water with just a little oil in there.
 
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