Had the z at Morgan Park sprints over the weekend and it all went very well until I found the oil catch can we plumbed to the four rocker cover breathers was being pumped full of oil. Didn't expect that and had not provided a drain back to the sump, only a breather so had oil p***ing out all over the place. I was hitting the rev limiter a fair bit early on whilst I got used to the new e-85 set up and the performance difference, but has anyone else had this issue? Is it just needed to be drained back or symbolic of another problem? On the plus side must applaud the Max Pro adjustable lower rear control arms, the car was so stable, noticeably different.
You mentioned 4 points from the rocker covers. I assume this means you've connected up to the PCV inlets. Did you use a valve? If you've just connected a hose to this point, every time you go around a corner oil will just exit the engine straight down this hose lol! Better to block these points off and just connect the catch can to the inlet covers at the front of the engine under the plenum / throttle bodies. If my assumption above isn't right, then you have serious engine issues. Get a compression and leak down test done. I suspect your rings are shot.
That sounds like a lot of oil (even for a race session) Did you overfill with oil to start with? No valve in plumbing?
Its somewhat arguable but ideally any oil/ vapours found in a catch can should be regarded as contaminated and ideally discarded, rather than returned to the sump. Hope you find what's wrong with the PCV plumbing
For motorsport use I would totally agree. You also get a lot of condensation in the catch can. For street use though I don't think this is legal? But is a catch can itself even legal? Probably not. Really you shouldn't be seeing any oil in the catch can, maybe a drop or two from vaporised oil but that's it. Any more than a few drops and you have engine problems (yes I know this doesn't apply exactly to all engines but does to the VG).
Catch cans are legal, breather cans are not. Crank case emissions was on of the very first emissions controls to become compulsory, even my '76 datsun has a PCV system venting into intake manifold.
the passenger side rear pcv breather is notorious for pumping out huge amounts of oil on a track as centrifugal force allows oil to collect in the passenger side exhaust rocker cover without a catch can this results in huge plumes of smoke after taking a long right hand sweeper at speed you only want to be using the two front breathers if youre tracking the car, or relocate the rear ones to the centre of the intake cam covers (not neccesary, i run 28 pounds of boost on a track car with only the front breathers in place, rest blocked off) link below is to my old setup http://www.aus300zx.com/forum/showthread.php?t=248418&highlight=pcv+relocation
Thanks for the input and link. I think we have blocked off the pcv's and have the two front breathers PLUS two from the rear of the engine, further back behind the pcv's and basically facing the firewall, going to the catch can. I am no mechanic (duh) but if I recall correctly the two rear breathers are both on the passenger side? This is a 1996 engine I had transplanted a few years ago (if that makes any difference)
Yep, so there's your problem. They'll be pouring oil into the catch can every time you go around a corner lol. They need to be blocked off. Only run the front breathers to the catch can.
Thanks Shane and Minivan. Was a bit concerned about just blocking them all off but not any more. Might be able to go racing again yet!!
yeah wizard had the same setup as minivans original setup but then later also blocked off all the pcv system from cam covers and plenum etc and only runs the front two to a catch can in his recent setup. also dont plumb it back using e85 it would be contaminated
My new setup only uses front two. That link was my old street setup. Race car uses two front ones only to catch can other two blocked off. After a few hours on dyno. Race wars, and a track day had less than 50ml mix that separated half-half oil / Ethanol
Really if your blocking off the back two and just running the front 2 you should double the diameter of the front to keep up with stock flow. Off memory the exhaust cam breathers are wider than the intake ones also. Not saying it doesnt work.
No need. The stock front ones actually have a restrictor in the line. Just running straight through hose of the required diameter to go over the fittings on the intake cam covers (14mm from memory) will be tonnes. A healthy engine should see diddly squat coming out these breathers. Two track days now and I've not seen a drop in my catch can. As per Z32TT just venting these to atmo. Not only is this illegal on the street, it's also illegal on the track. Scruts pick you up they'll send you home
Common misconception, Front ones are the only ones that do all of the hard work on a stock setup anyway. Rear ones close off under boost as these are the ones with PCV valves. Front ones vent to the inlet of turbos and handle all of the on boost blow by. Which is when you have the greatest amount of blow by anyway. Rears are purpley an emission control requirement and useless as they dump oil Into inlets under hard right cornering. And pcvs jam open leaking boost pressure into sump I had no issue on stock lines with restrictors (technically flame arresters not restrictors) at 24psi I'm running twin dash 8 hardline into a single dash 10 braid to vented catch can now Off front ports at 30psi
so when you ran the dash 8 hardline into single dash 10 braid to catch can did you take out the stock hose with the restrictors in them ? im currently doing this setup and i was going to install the stock hose with restrictors in them and then put a joiner and then new hoses going to the catch can ?
^incase anyone searches this in future, i just did as mentioned earlier and installed a 13mm hose i think it was straight to catch can from the front two points , no restrictors etc.
