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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 12-07-2007, 12:09 PM   #61
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Quote:
Originally Posted by Braineack View Post
PCV is connected between the crankcase and IM.

Breather goes straight to the intake.


The reason i put the catch can on the breather side, is because in boost, when blow-by is accelerated, you have a constant vacuum source (1-2~hg.) hook up to the intake. As pressures build up and some boost leaks through the PCV valve itself, it exits the breather line to be recirculated back into the IM.

Since the pcv is technically closed at idle and boost, I don't see that side being much of a deal, and any fumes/spray that gets past the baffle and the valve itself during cruise is easily mixed in the airflow and burns off without issue.

I still propose, since the pcv valve itself is for emissions, the best solution is this:

thanks scott, this makes sense, i think this is how im gonna do it
i think a friend of mine did this on his 240, i remember because he has a wire type cup holder in his engine comparment holding the can in place
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Old 12-07-2007, 03:38 PM   #62
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Wiggy. It leaves the suction thing alone, and is essentially just a breather/filter on both ports, but keeps oil from going everywhere? Certainly no PCV there, but whatever, I guess.
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Old 12-07-2007, 03:50 PM   #63
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yep, two large ports to the atmosphere should "breathe" better than one small one in the intake in boost.
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Old 12-07-2007, 03:59 PM   #64
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Quote:
Originally Posted by Braineack View Post
yep, two large ports to the atmosphere should "breathe" better than one small one in the intake in boost.
So instead of having the intake at vacuum remove crank case pressure you are just opening it completely to the atmosphere from both ends.
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Old 12-07-2007, 04:00 PM   #65
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that the ideaer.
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Old 12-08-2007, 04:54 PM   #66
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i have my exhaust side plumbed to a diy catch can- which has the output plumbed to my exhaust test pipe (moroso's crankcase evacuation tubes)

this works pretty well, if i pull the hose off the cam cover i can feel it pulling vacuum at idle.
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Old 12-08-2007, 05:02 PM   #67
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Moroso's crankcase what?

What's your exhaust set up like?
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Old 12-08-2007, 05:45 PM   #68
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moroso sells beveled 1'' cromo tubes that you weld into the exhaust.
the exhaust flows past and pulls a vacuum in the tube
they include a metal pvc valve that keeps you from pushing pressure into your crankcase (i can't think of a time that'd happen..but it can't hurt)
i ran heater hose from there to my catch can output, and vacuum line from the valve cover to the catch can input
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Old 12-08-2007, 05:50 PM   #69
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my exhaust is a stainless begi divorced wg 2.5'' pipe -down to a 2.5'' resonated test pipe (with the little pipe welded in) and then (for now) an enthuza racer (naturally aspirated).

hopefully after the holidays i'll have a little scratch lyin' around and will get an enthuza 3''
...
those wily honda guys thought of it first, but there is a long thread on it here:

http://www.honda-tech.com/zerothread?id=1199935
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Old 12-08-2007, 06:23 PM   #70
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yeah - we had one on a diesel project car I was working on, and it seemed to blow as much as it sucked, or sucked because it blew. :-) But it wasn't giving us a heck of a lot of suction. I've wanted to do it, it makes plenty of sense - it'll always have good flow since there's at least as much flow as there is in the intake. Maybe I'll thread a nipple or a EGT valve into my lower O2 bung on the DP.
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Old 12-08-2007, 08:08 PM   #71
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Quote:
Originally Posted by ___ View Post
i have my exhaust side plumbed to a diy catch can- which has the output plumbed to my exhaust test pipe (moroso's crankcase evacuation tubes)

this works pretty well, if i pull the hose off the cam cover i can feel it pulling vacuum at idle.
Seen afew drag racers do that before.

Supposed to work really well.
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Old 12-08-2007, 08:31 PM   #72
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a few caveats:
i don't run a cat, your flow may suffer with one-i don't know what blowby/oil vapor/etc would do to a cat.
if the output of your catchcan is clean...maybe it'd de-smog the blowby?

if carb or the smog ***** catch you with this thing on...i don't know you.
the georgia 'clean air force' guys never gave mine a second glance, but they were busy looking at the turbo hardware.
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Old 12-08-2007, 09:42 PM   #73
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The Moroso system is only going to work well at high rpm. Been there done that. An electric pump is a good idea. I used to run a Cobra Mustang electric emissions pump to evac the crankcase of my 5.0l engine. Whatever pump is used it has to have a motor strong enough to pull around 8-10" vacuum or it is useless. I think it's 8-10", been a while.
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Old 12-09-2007, 02:45 PM   #74
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I have yet to see one honda article that had a clear diagram like I drew. I always try to read an undersand wtf they are talking about and always fail.
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Old 12-09-2007, 03:52 PM   #75
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the catch can vent to atmosphere orifice is routed to a port in the exhaust-bernoulli's principle pulls a vacuum as the exhaust gasses flow by and give you a slightly lower pressure in your crankcase.
just like pcv to intake, but it'd work under boost and wouldn't coat your intercooler/ic piping/throttle body/intake mani/etc with oil
on a 'v' engine, this would help make horsepower as the pistons would move down against lower pressure. on a flat crank inline-4...probably not much help there.
i kept my pcv valve on the intake side of the cam cover, just in case there was positive pressure for some odd reason...it'd keep my dipstick from popping out.
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Old 12-09-2007, 04:07 PM   #76
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i undersatnd the concept completely, i was just commenting on honda people's inability to make things easy and staright forward. I urge someone to find my diagram difficult to follow...
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Old 12-09-2007, 07:24 PM   #77
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As a *challenge* it's hard to tell what you capped off.

But if someone can't follow that drawing, they are already pretty "challenged". Like my spelling.
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Old 12-10-2007, 07:55 PM   #78
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Just thought I'd add that aftering running with the valve cover line to the intake I'm pissed about how much oil built up in my comp housing, never again.
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Old 02-02-2008, 03:40 AM   #79
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Quote:
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i undersatnd the concept completely, i was just commenting on honda people's inability to make things easy and staright forward. I urge someone to find my diagram difficult to follow...

the diagram rocks, i'm gonna try this.
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Old 02-02-2008, 12:30 PM   #80
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I think there's two desirable functions in the vent setup- 1. release the crankcase pressure and 2. remove the vapors. What the stock system does extremely well under vacuum is remove water/oil/fuel combustion by-product vapor and that diagram doesn't do it nearly as well because the high vacuum is removed from the system. It relies on the crankcase pressure only. In a street environment, you'd ideally have the PCV valve hose as stock to the manifold but with another catch can inline. The vent hose would then vent to air with a catch can inline (or vent to the intake pipe pre-turbo). This way you'd get vapor removal more regularly since the street car most likely sees vacuum as much if not more than the boost.
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