911tt

Thanks. It does make sense that if breather air is being introduced back into the throttle body you would want it to be accounted for by the MAF, meaning the breather should draw from a position behind the MAF. It would also mean that if the breather does expel any oil, the oil won't be drawn across the MAF. I have a short bridge between my LS2 throttle body and the MAF at the back of the intake where I would need to run the breather line.

I'll probably do something similar to this guy's setup: http://www.toquez06.com/fast.html

But he made the mistake of putting the fitting in front of the MAF, which means that the air drawn into the valve cover by the breather isn't being measured by the MAF first.

RapidC84B

Yes... in the OEM application there is a hose barb on the TB for the fresh air line. If your car has a LS2/3 TB it won't have it. On track at full boogie both of those lines can push crank pressure and oil vapor.

AND0

Regarding your sway bar contacting the control arms, that is not uncommon. Some adjustable end links from your favorite parts supplier Strano or similar will fix that right up. My 01 C5Z is lowered the "correct" amount (~1" less than stock) and has a stock front bar and still it would contact the a arm before I installed the adjustable endlinks.

acroy

2 things:
1)Re: PCV system, i had my own adventure recently. some info, and user aaronc7 is a good resource, you might pm him for help...
https://www.corvetteforum.com/forums...ng-please.html

2) re: lifting the car.
don't think, order one of these immediately
https://www.costco.com/QuickJack-5%2...100460313.html
SO MUCH safer, faster, more convenient.... I held out for years, finally got one. No regrets.

have fun!

911tt

Thanks! I'll read through your thread, I'm finding the learning experience to be a lot of fun.

I'm contemplating a 4-post lift for the garage so until I make a decision on that I'll stick with jack stands. Do you still need to run the car up on ramps to get it to work? I'm thinking that with the jacking pucks in place I wouldn't have 3" of clearance between the puck and the ground at my current ride height.

acroy

My car is lowered and it needs no ramps. I store the jack underneath the car at all times, I just reach underneath the car and position it in place when I want to use it. Jacking pucks are not necessary With the quickjack. If my garage was big enough, I would have a two or four post lift, that would be preferred for sure!

NSFW

This is a good point, if the tune uses the MAF. Given that it has that valve cover filter, hopefully the previous owner had it tuned for speed-density rather than MAF, but I would rather be safe than sorry.

I'd still prefer the check valve approach to using two catch cans though. I'll be putting the check valve between the valve cover and a pre-throttle-body fitting.

aaronc7

You don't want a check valve between the valve cover and pre-TB fitting.... at least in these more or less stock setups.... it's designed to flow air in both direction under different conditions. At WOT it provides the primary means for positive crankcase pressure ventilation and under cruise/idle, fresh air is sucked in to displace the "dirty" air in the crankcase filled with blowby gasses etc.

The "downside" to the setup as the OP has it is that it is sucking in unmetered air (bypassing the MAF). At idle, the amount of unmetered air relatively to total air mass is significant and might drive up your fuel trims +10 or so. At cruise on the highway...a similar amount of unmetered air will be entering the engine, but relative to total engine airflow, it will be very small, even insignificant. You could probably "tune around" the idle fuel trim issues. At the end of the day... it's not ideal, but not really a huge deal either.

Definitely add a pcv / check valve somewhere on the valley cover / intake manifold side. The main purpose of the pcv valve is to restrict the flow/vacuum on the crankcase. On a turbo/SC application, the pcv valve will also prevent positive manifold pressure from pressurizing the crankcase in boost. With your crazy amount of vacuum on the crankcase, it's not surprising that it's literally sucking up oil and filling up the can quickly.

On most setups the factory passenger valve cover vent seems to work fine. If you look at the underside of the cover, it has some baffling in place and is close to the center and highest point etc...all things that help liquid oil from getting pushed out. So I don't think having a can here is critical...but as always, your mileage may vary.

Overall you seem to have a good handle on things and how it's supposed to work.... good luck!

911tt

Picked up some goodies this afternoon


Also stopped by the auto parts store and picked up some fuel line, clamps, and oil filter.

I was feeling motivated tonight so I got a few things done:

• Spent more time cleaning the underside / engine compartment
• Changed the oil - Amsoil 10w40
• Flushed/Bled the brake fluid - Motive Power Bleeder, Amsoil Dominator racing fluid

Took her for a test drive and everything seems good. I hadn't done any hard braking before, the brakes are pretty impressive stock. I checked when I got back and I can already see a couple new oily spots on the passenger side of the leaf spring. Now that things are fairly clean I hope I'll have an easier time figuring out where I'm leaking from and how bad it is.

Both of my PCV valves arrived today so tomorrow I'll measure the oil in the catch can, empty it, install the Elite Engineering valve, and check the can again before my track event on Wednesday to see if I'm catching less oil. I also ordered some fittings today so I can plumb my valve cover breather line to the bridge in front of my throttle body. I think I'll hold off on doing that until after the track event, I want to see if I burp any oil out of the breather on the track.

911tt

I just discovered Elite's clean-side oil separator, it seems like a good way to stop oil coming out of the valve cover without adding a second catch-can and all that entails. Use this to replace the oil cap, run a line just in front of the throttle body, cap the valve cover outlet, done. I could also just vent it to atmosphere as I am doing currently, it would provide protection against oil spewing out.

http://www.eliteengineeringusa.com/c...oil-separator/

911tt

Elite Engineering check valve is installed.



I measured what was in the catch can, right around 60 ml again.



Let's not tell my wife what I've been using her measuring cup for (I thoroughly clean it each time, I promise).

This represents 133 miles of driving, probably not quite as aggressive as the previous measurement. That's 35% less accumulation per mile just based on driving style and or other factors I'm not accounting for.

I'll measure again before and after my track excursion.

aaronc7

I'll throw in one more track specific tidbit on the pcv stuff. All things equal I like a "closed" system that routes hoses back to the intake etc, vs a simple breather venting to atmosphere. I had a can with a breather on top....can filled up on track, overflowed, and sprayed oil directly on the headers. Big smoke cloud, I limped it off track. I'm just lucky the car didn't catch fire. A closed system would have had similar issues burning a bunch of oil etc., but no concern over the car catching on fire.

NSFW

Changing the design is the whole point. The cruise/idle behavior wouldn't change, and at WOT I am assuming that the valley cover vent, by itself, is sufficient. The idea is to route the blow-by through the catch can before it goes to the intake tract. Partly to reduce the amount of oil going into the combustion chambers, and partly to give a better indication of how much oil is getting blown out. A second can would also meet both of those goals, but a check valve just seems to me like a more elegant way to do it.

911tt

From what I've read, the breather needs to be able to assist in venting crankcase pressure when the valley-manifold line isn't able to handle all of it. What are you basing your assumption on? I think the idea behind a catch-can on the breather is to allow the breather to breathe in both directions and catch the oil so it doesn't go into the intake, I didn't get the impression that measuring the oil output was a driver behind the design. You're free to try it obviously, but without a way to measure crankcase pressure or breather output before and after your change you won't have a way to validate your results.

911tt

That sounds pretty terrifying. I agree that a closed system, despite some drawbacks, makes a good deal of sense. I have to imagine it cuts down on the aroma factor as well. My car is pretty cool, but it stinks in a literal sense.

911tt

Sadly the smoking gun remains at large.

I took my wife out for breakfast this morning and put about fifty miles on the car. Romped on it pretty hard and had a great time. I went ahead and checked the catch can. This is with the Elite Engineering one-way check valve installed (valley->catch can -> valve -> intake manifold) and there is roughly an ounce of oil. So it doesn't look like the valve has made any difference. I will probably go ahead and try out the other cheapo plastic valve, which seems to have less maximum flow, but not until after the track event.

I also have the Elite Engineering clean-side oil separator oil cap replacement coming, hopefully that will guard against oil spewage at the track, especially if I route it back to the intake area, which is my current plan.

And finally, I'm noticing two distinct spots, one driver side, one passenger side, where oil drops are starting to collect on the leaf spring. At some point soon I'll jack up the front again to see if I can pinpoint it. I imagine that means I've either got two distinct leaks or it's a gasket leaking/seeping from multiple locations.

NSFW

Mostly I'm basing this on the fact that someone else here is already doing it and happy with it (I didn't come up with this idea myself). But FWIW, my Subaru uses only one hose to vent the crankcase at full throttle. Granted, it's got fewer cylinders, but it's also running over 20psi of boost, and it's putting down about the same power as my C5Z... more at the crankshaft, I'm sure. The Subaru scored 377whp, the C5Z 371whp, but on different dynos. But both numbers are about what you'd expect (from a Dynojet) given the mods they have.

And I'll be removing the C5's PCV valve, so the valley cover will be able to breathe more than stock.

You have a good point about measuring crankcase backpressure though, that would be interesting, and I think I can make it happen later this summer.

911tt

Did a little cosmetic project this morning. The previous owner gave me a set of badges (from a C6 I think) that he'd purchased but never got around to installing. Heat gun and dental floss did the trick to get the old emblems off. Fishing line would probably be better - I broke a lot of floss.





The old emblems were looking a little tired, plus the black look fits the wheels and trim. Not to mention with my mods I should be right around 505 hp at the crank

911tt

My first track outing is tomorrow!


I went ahead and routed my PCV breather line in between the MAF and the throttle body today. I took it for a spin and everything behaved normally. I would say that it idled better on a cold start but that could be all in my head. Hopefully this will guarantee no oily engine bay.

911tt

I emptied and measured the catch can - 50 ml in 89 miles, a little worse oil per mile than my last measurement, which confirms that the PCV check valve didn't do anything to reduce oil being caught in the can.

I also took the time for another quick semi-cosmetic fix - the key remote. The old one was badly beat up with holes and cracks in the case, the graphics were largely worn off so I was often confused about which button was the lock vs. the unlock, and it would only unlock the car 25% of the time. I saw the replacement case at the Autozone checkout and bought it on impulse. Turns out to be a totally simple swap and now it works as expected.