crank case pressure - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 12-17-2007, 02:33 PM   #21
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that would be cool, as i dont need my front o2 sensor....
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Old 12-17-2007, 03:51 PM   #22
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I think the exhaust scavenging would be perfect for a track (road course) car where the run through the gears is perpetual. Ideally you'd want a combination of all these "passive" systems to optimize evacuation/release of the pressure/vapor. IMO - First step in the stock system would be to enlarge hoses/passes and remove restrictions (improve flow) like mod the baffles in the vent chambers.
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Old 12-18-2007, 03:29 PM   #23
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Might be worth a try, not too expensive either
http://store.summitracing.com/egnsea...115+4294851516

hrk
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Old 12-26-2007, 07:39 AM   #24
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http://i50.photobucket.com/albums/f3...4/21344ev2.jpg

just an idea for a breather box location. i dont like their plumbing... but the location is nice enough.

vacuum is definitely a good thing for at least two reasons.

fred.
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Old 12-30-2007, 06:00 AM   #25
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Honda guys apparently love them some crankcase ventilation...


Check out this thread for more inspiration, the photo above has -12AN lines.
http://www.honda-tech.com/zerothread?id=1970101&page=19
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Old 12-30-2007, 12:05 PM   #26
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I plan to use the OE vent on the back and then create another behind the intake cam since there's an OE flange cast in the cam cover to shield the new vent hole from oil. I believe it's more critical for the FE to have vents on both sides since the "valley" is closed off from the cam cover (the B engines are open). And the only side to side connection is at the front.
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Old 12-30-2007, 01:27 PM   #27
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Crank vacuum pumps:

http://www.gzmotorsports.com/vacuum-pumps.html


Their **** pics:

http://www.gzmotorsports.com/sample-installations.html


Nothing plug and play for Miatas, but probably their kit for EVOs is the closest in the engine size components choice:

http://www.gzmotorsports.com/4G63T-kit.html


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Old 02-05-2008, 09:44 PM   #28
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Default Time for an update

Decided to tackle the cam cover since the rain put a stop to the boost control testing. The modded factory venting (pic below) worked reasonable for 10psi, but just a few runs near 17psi and I had some cam cover gasket leaks. With the new setup the pcv will return to the stock location and two vents at the rear will go to the can.

I managed to get two 3/8" NPT ports on each cam bank of the cam cover. I was amazed to see just how small the existing vent port at the back of the exhaust side was - about half the size of the actually opening - maybe 3/16". Pics show the difference - white circle highlights the actually interior passage. I used the step drill bits (if you don't have a set they're worth buying) to overbore the existing vent and to enlarge the pilot hole on the intake side. These should provide the venting I'm looking for (like the honda photo) - now on to the catch can. (Go kia power )





current modded: OE ports swapped, better flowing pcv port goes to the can
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Old 02-06-2008, 05:29 AM   #29
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Wow rob, nice!

Yeah, those are small, i pulled one out of mine years ago, but I'd forgotten completely about that! if you aren't going to and don't mind I'd like to hijack these pics and add them to that thread on mx6.com.

Thats going to work MILES better for sure :-)

Well done.

Fred.
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Old 02-06-2008, 05:32 AM   #30
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Also, good to see those leads being used :-) they even look good with the red.
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Old 02-06-2008, 10:33 AM   #31
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yes, use at will, and it'll save me from having to cross post.

You think those leads will look good with a silver kia cam cover? :gay:
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Old 02-06-2008, 11:33 PM   #32
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Exhaust side vent chamber plate is now modded and installed. Dramatically shortened, it still uses one cast fin from the cam cover and an opposing tack welded plate fin, plus the added fin/bend at the end of the plate.



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Old 02-07-2008, 05:37 AM   #33
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well, you weren't shy with the tin snips were you! i had imagined you mean the opposite bend on the end, and much much longer overall. interesting.
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Old 02-07-2008, 09:55 AM   #34
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Just trying to keep the oil out while maintaining a similar volume for pressure passage. It was less about length and more about getting two of those "fins" in for oil trapping. I think bending down would probably encourage the trapping of oil w/o any benefit of pressure relief. Tin snips did a good job for providing three drain back avenues for oil.
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Old 02-08-2008, 06:31 PM   #35
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in boost is keeping the crankcase in vacuum beneficial?
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Old 02-08-2008, 06:48 PM   #36
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Under boost there is no vacuum. But when you let off the throttle that vacuum is what pulls all the vapor from the crankcase. So boost blows it out via the vent(s) and the vacuum sucks it out via the pcv. Both are beneficial.
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Old 02-08-2008, 07:41 PM   #37
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Quote:
Originally Posted by gazurtoid View Post
in boost is keeping the crankcase in vacuum beneficial?
Yes if you have a suitable pump to try to keep up with the volume of flow, but it's not going to be easy :-)
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Old 02-09-2008, 12:24 AM   #38
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look at the pumps linked above.
at the corvette forums some people use such pumps. if i remember correct BigGulp was/is using something like that too

Quote:
Originally Posted by m2cupcar View Post
Under boost there is no vacuum. But when you let off the throttle that vacuum is what pulls all the vapor from the crankcase. So boost blows it out via the vent(s) and the vacuum sucks it out via the pcv. Both are beneficial.

Last edited by gazurtoid; 02-09-2008 at 04:57 AM.
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Old 02-09-2008, 10:54 AM   #39
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I don't think a vacuum pump is necessary. The problem is managing the cc pressure occurring from boost blow-by. The oe vent system was not designed with that intent (obvious since it has a ~3/16" vent passage). So the addition of the two larger ports should manage the "new" pressure fine. This is essentially the same thing done to the honda engine pictured and what comes OE from nissan on the their turbo engines pictured above. I'm only using two 3/8" npt ports because my engine has a valley, separating the intake and exhaust sides. This way pressure from one side doesn't have "travel" to opposite side. In this case, I don't think there's such thing as too big or too much.
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Old 02-09-2008, 11:37 AM   #40
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Rob, if you have a spare head, take a closer look at the middle and two ends, there is plenty of open area between the two that connect them. there can not be a pressure differential there really. i'm not sure how the rb one is laid out inside, but ours has good sized 1.5" x 1.5" channels in three places already. (not sure what i was thinking when i agreed with you about that on the last page, seemed like it was correct anyway :-) )

The other part of the vacuum pump is that it actually increases ring seal in the first place and reduces the blowby from the start. thats why its good. the increased seal A keeps things cleaner, B makes more power. its not necessary. but generally, its a very very good thing if you can afford/fit it.

i still havent got to writing what i think of your tin snipping in detail :-) i will though, i promise :-)

fred.
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