DIY - Oil Catch Can (w/ M370 + Batt Reloc)

wstar

This DIY is only completely applicable for cars with the M370 Intake Manifold and a relocated battery. The Motordyne M370 tees our engine's two PCV lines into one hose run (making it simpler to use a single can), and a relocated battery leaves a nice empty heat-shielded area to mount a relatively large and well-built can. Being in the relatively-cool battery box area has a side benefit: the cooler you keep the catch can, the better it condenses the oil vapors.

The catch can I used is this one from Elite Engineering. It's made for a C6 vette, but that's really just about the the mounting bracket they ship. It's a very high quality can (to quote their site: "The 2.6 inch diameter by 6 inch long body is machined from billet 6061-T6 aluminum alloy, and then anodized"), and it has nice internal baffling to help condense the oil. It's a little bit large for fitting in the edges of our engine bay normally (esp given that you unscrew off the bottom 2/3 of the can to empty), but it fits just fine in an unused battery compartment.

All pics were taken after the install was mostly complete.

This is the spot where the M370's hoses tee our two PCV lines together in the front. The hose taking off to the right is the factory PCV line to the driver's side valve cover, and the lower left one is the PCV line to the passenger side valve cover. The upper left one goes around to the rear of the manifold in the default M370 setup. We'll basically be splicing into this upper left line to insert the can, from a hose-connection point of view (actually, you'll probably use the whole original hose to run to the can, and the new hose shipped with the can to run from the can to the rear of the manifold).



For mounting the can, you'll want to find the highest and rearmost flat spot on that wall (it has some curves) beneath the hard brakes lines. You want to drill your two holes 5/8" apart center to center. Use a hacksaw to cut off most of the original C6 mounting bracket, leaving behind just the little aluminum piece with the two small bolt holes, and bolt the can to the wall here using the supplied bolts. Before you do any cutting, make sure you've left barely enough room to remove the bottom of the can for dumping oil when installed.




Update: When I was re-doing the hoses for this (after swapping manifolds a few times for dyno comparison), I realized the hose routing would work much better if I swapped the two screw-in fittings on the can opposite from how they shipped them:





I also took a hacksaw to the edge plastic for the battery area to make a little opening to route the two hoses through (remove the rubber seal first, you'll want to lay that back over the hoses when you're done):



When you're done, you should be able to put the rubber hood seal and battery compartment cover back in place, looking about like this:

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Red__Zed

Have you noticed much buildup? Id be surprised if there was much on an NA car, but I am curious.

wstar

Well the can's only been on for about 20 miles so far, I'll have a better idea after a few thousand. I know on my previous car/engine (NA LS1), I was dumping about 6oz of oil from the same model of can at every oil change.

One of the things that prompted me to go ahead and put it on this car was that when I did my M370 manifold install, I could see that my PCV hoses had a slick coating of oil inside them that dripped a little when I removed them, the inside surface of the throttle bodies/plates had a semi-liquid black buildup that I presume is mostly from PCV oil, and the metal intake runners on the lower manifold also had a light coating of oil on their walls. It doesn't take much to coat things like that, so again no idea what the long term rate is yet. I'd just rather not have oil in my intake and combustion chambers in general though

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Red__Zed

Yeah, i feel you, I was just curious.

SPOHN

I'm about to do a catch can myself. I used to get a tablespoon every 500 miles on my 350. Actually got about the same when it was FI also. Great write up. I would of wanted to make it more within the engine bay to keep the hoses shorter, even though you had the spare room.

Could you of only used the hoses from the front of the plenum and then routed to the catch can. Never really seen one that uses the hoses from the rear of the plenum for that don't come from the crankcase. Could you explain that more?

Oh yea, repped.

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wstar

So, to backtrack a little bit for anyone else reading this, I'll start with what the PCV (Positive Crankcase Ventilation) system does and how and why. Note that I'm not an expert on this: this is just my understanding from reading up on it and seeing how it works on cars I've owned. Corrections from more technically knowledgeable types welcome.

General PCV stuff:

The idea is that all combustion engines have a certain inevitable amount of blow-by, which is where combustion gasses from the cylinders leak past the piston rings and into the crank case in general. This is mostly fuel vapor. If you didn't have any PCV-like system at all, this would tend to build positive pressure in the crank-case, and eventually that pressure would find its way out by leaking past oil seals (such as at the crankshaft seals, etc), which in turn can lead to failure of those seals and oil leaks.

In some simple / old-school / dragster type setups, all that's done to alleviate this is they add some breathers to the valve covers of the engine. I suppose ideally, you'd put one on each valve cover with opposing check valves: one that filters in fresh air on one side of the engine, and one that vents crankcase gasses on the other. In this way you keep the air in the crankcase "fresh", and the pressure normalized. While the actual blowby gasses you're trying to vent off are mostly fuel vapor, in practice you tend to get a fair amount of oil vapor mixed in as well (from all the oil slinging around in the crankcase in general).

In modern pollution-controlled vehicles like ours, the PCV system does this in a slightly more complicated way. It uses some tricky little mechanical pressure-regulating valves to regulate everything at the PCV connections. On our car specifically, we have a total of four PCV connections at the valve covers. Each side has its own PCV inlet and outlet. The inlets are connected to your air intake tubes, drawing from the same filtered air the engine breathes for combustion. The outlets are connected to intake manifold vacuum lines to draw out the nasty fuel/oil vapor buildup, and feeds it right back into your combustion system to try to burn it for emissions reasons, even though this ugly fuel/oil crankcase vapor mix really isn't an ideal fuel for your high performance engine.

From a performance perspective, these nasty PCV gasses are contributing to lowering the effective octane rating of your fuel:air mix in the cylinders, and gunking up your intake manifold and intake valves with stuff that leads to carbon/sludge buildup. The point of the oil catch can is to put something inline in those PCV crankcase->manifold lines that tries to condense out the oily vapor and retain it, keeping your intake system clean of this crap, while still correctly maintaining crankcase pressures.

Here's the exploded view of the stock 370Z intake manifold collector from the service manual. What you want to pay attention to is the PCV connections, and the vacuum connections to the manifold in general. Aside from the big holes for the throttle bodies, there are 6 vacuum inlets on the manifold: two tiny EVAP inlets right next to the throttle bodies, a single brake booster connection in the rear (B), the hole that the MAP sensor plugs into (item 19, back right), and the two PCV connections (V-shaped inlets in the front/center, connected to PCV hoses numbered 10 and 12).



If you wanted to add an oil catch system to our stock car, you could go one of two routes. One way would be to install dual catch cans, with one spliced into each of PCV hoses 10 and 12 in the diagram. A simpler way would be to use a T-adapter to connect hoses 10 and 12 to a new single hose, send that to the catch can, and then connect the other side of the can to one of the original inlets, and cap off the other inlet.

The M370's vacuum inlet configuration is different than our stock intake manifold collector to begin with. It still has the same two EVAP inlets next to the throttle bodies, but there's no hole for the MAP sensor, no front PCV inlets, and there's two rear inlets in the vicinity of the stock brake booster inlet. When you install the M370, you hook up the dual PCV hoses to a T-adapter to merge them, and run the new line around to the rear of the manifold. One of the rear connections goes straight to the brake booster as before, and the other one gets a second T-adapter, splitting it between the PCV line that came around from the front T-adapter, and a short hose that your MAP sensor is plugged into. It makes more sense looking at it visually (but note in this picture, they replaced the driver's side PCV hose (number 12 in the SM diagram) with one of their blue hoses):



In my DIY above, I've taken the long blue hose that's mostly hidden above, which wraps around on the left between the two T-connections in the front and the rear, and effectively spliced my can in the middle of that. So the can's inlet is connected (via a hose, a T-adapter, and then hoses 10 and 12 in the SM diagram) to the crankcase (twice, once at each valve cover), and the can's outlet goes to intake manifold vacuum.

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SPOHN

Very insightful.

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wstar

Just a couple of updates here. I took the M370 off for a dyno run and then put it back, and in the meantime figured out a few better ways to deal with the various hoses:

1) Swap the screw-in fittings they ship on the can, so that the straight one's on top and the angled one is on the side, facing up. Makes for much shorter and neater hoses:



2) (This is more M370-specific than catch-can specific): Use the lower rear vacuum port on the M370 for the PCV intake (directly), and tee-adapter the MAP sensor to the brake booster going into the upper rear vacuum port.

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SPOHN

That defiantly looks better. Also is there a kit you buy for relocating the battery?

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wstar

No, I did that myself using an Odyssey PC680 Battery, the standard aluminum hold down box that Odyssey makes for it, some 1/0 gauge cable and various bits of hardware/insulation from the hardware store. I added my DIY for it onto Travisjb's DIY thread a long time ago.

It could stand a couple of minor updates as I've improved the system over time. Since those pics were taken, I drilled another small grommeted hole near the battery and ran my trickle-charger connector through so that I can hook it up from the outside, and I also moved the LCB-200 breaker (discussed later in the thread) off the top of the battery box and down to the trunk floor. The reason is if I tossed anything heavy into the trunk (on the unsupported carpet + carboard stuff), the upper trunk floor would dip under the weight and push my breaker disconnect button

I've always meant to eventually do something custom for my trunk floor, but never got around to figuring out what. I'd like to leave out the stock false floor and just have some kind of minimal plastic cover for the battery/breaker/ground to keep things from knocking into the connectors or shorting them, and free up all that depth for storage.

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Pezlo

any updates on how much the can collected?

wstar

I haven't really tried to log or measure it. I generally dump it 2-3 times per oil change cycle (including the one at the end), and it's generally anywhere from 1/2" to 1" of fluid in the bottom of the can.

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Wonka2581

subd

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Thorazine_IM

ok guys i got a question here. so between the pcv inlet and the intake tube hose there is this little black container that seems to be filtering air or something. what do these things really do? i have aftermarket CAI and i want to just get rid of these little "filters" and tap a hose straight to the pcv inlet and the intake.

DEpointfive0

They're baffles for extra oil, you can run without them

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