ScottFW

iTrader: (4)

Front wheel drivin' not rear wheel drivin' like they should. They're lucky those massive -10AN lines don't blow the welds on their catch cans.

Braineack

iTrader: (62)

just want to remind you what won the $2009 GRM challenge:



IIRc it was 2nd in autox and 3nd in 1/4


the best miata placed 4th. only .08sec slower in autox and 2 seconds slower in 1/4 mile. so HA 1.6L running a turbo with MS.

stranges12712

iTrader: (1)

I have the same problem as you levnubhin, i want to see how yours turns out and i will probably do the same. My catch can right now is hooked up to the right side of valve cover and the intake. Every time i hit full boost u dont want to be behind me lol. Heres a pic...

bbundy

Some pictures of 323 GTX 1.6l lower vents.

I believe these two ports that are capped off with a rubber cap are for a crank case vent and catch can return. In countries where to meet regulations a PCV system was required these were not used and were simply capped off.

I suspect the upper one would serve as a lower crank case pressure vent and the lower one which goes to the very bottom of the sump would function as a catch can return.

I have 3 GTX blocks right now and 2 of them have the upper vent nipple in the block and one does not. I also have had one 1.6l Miata block that had it and one that didn’t. None of the 1.8ls I have seen have had this vent in the block I suspect the whole thing was scrapped for the better emissions controls a PCV system has.

I think what happens if you only vent the valve cover and vent it well, as in better than what you can get from a PCV system, is the pressure and gas flow from the bottom end generated from blow by has to go back up to the top of the head through the oil drain back passages if it gets too much it will impede the oil trying to drain back from the head to the pan and basically cause much of your oil to get stuck in the top of the head where it can slosh up into the upper vents or even possibly cause an oil starvation issue. A PCV with the tiny vent isn’t vented that well so I think you end up with just higher pressure everywhere in the engine.

Bob

levnubhin

iTrader: (30)

So far so good. Nothing leaking in the engine compartment and no big puffs of black smoke when I went wot a few times this morning. Eventually I'll move the hose coming from the crank port to the big catch can that's mounted in the front.
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bbundy

Has me wondering about drilling and tapping a hole in the side of my 1.8 block to attach a lower vent to. I think putting a drain back in by taping into the pan well below the oil level would fix the spewing problem but it dosnt seem like it would function as a blowby vent that way.

Bob

JayL

iTrader: (12)

Anyone thought about running a pump?

Jeff_Ciesielski

iTrader: (10)

Like the air pump on a 'vette? I've considered it. Hooking up a catch can and then running the top tube to the inlet of the air pump. If you had it switch on in boost via a hobbs switch it could theoretically create negative pressure in the crank case which would create a better ring seal (assuming it drew enough air).

stranges12712

iTrader: (1)

Hmm thats a good idea...now i need to get 2 new catch cans...lol. So are you running a pcv or no? I cant tell in the pic

levnubhin

iTrader: (30)

No, the intake manifold port is capped off.
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m2cupcar

iTrader: (5)

I think the reason those hondas get away with giant ports/hoses with minimal cam cover shielding on the ports is because they have a good OE return for the vent system. I'm up to two 1/2" OE ports on the FE, chopped one my baffle covers in half and got mass quantities of oil in the can. When I replaced it with an full untouched OE baffle plate it dramatically reduced the oil in the can, but still prevented the leaking cam cover gasket. I think the PCV port is a good port to use for venting, since it's shielded well and big. I'm also using two right angles immediately off the cam cover which helps keep oil in the engine.

bbundy

Like I said I think what happens when you vent the valve cover real well is the blowby gases from the bottom of the motor shoot up the oil drain back holes between the head and the lower portion of the block so fast that it prevents the oil from draining back to the pan from the top of the head good enough. Too much oil collects in the top of the head and with some sloshing action it finds its way out the vents.

I think what we need is a good way for blowby gasses to get from the bottom of the motor to the top without having to fight its way up the oil drain back passages. The existing passages between the top of the valve cover and the lower pan area are not big enough to handle oil flowing in one direction and blowby combustion gases flowing opposite directions at the same time especially in a motor making over 3 times the hp id did in its stock configuration.

Another thing I have been thinking of doing is just connecting like a -10 line from above the oil level on pan to one of the vents on the valve cover and only venting one side of the valve cover to a catch can and atmosphere.

Bob

m2cupcar

iTrader: (5)

I'll buy that given the same pressure is blowing oil past the internal cam cover baffles and through the vent hoses to a catch can.

It would almost make more sense to run that line to the upper part (or isolated vent side) of the catch can, so there's no way oil will be forced down the tube/hose/line from the head. That keeps it open for vent directly from the crankcase while the can has a separate line for draining back the oil vented from the head.

bbundy

Problem is I tried that. The result was that during a hard braking and turning maneuver a slug of oil gets sloshed into the tube going to the pan and then it gets shot out like a spit ball with enough force it shoots through the breather filter and coats the engine compartment.

It's freaking hard to find a spot to vent where you just vent gas and not get oil with it. It is easier to do up top and even that is hard as evidenced by how important the labyrinth of baffles they put in from the factory valve cover.

Looking at the head It looks as though one of the passages between the top of the head and the bottom of the block is designed for gas flow as it is raised up off the floor to prevent oil from running down into it. Both the heads have one of these ports, in addition The 1.6l has 3 oil drain backs and the 1.8l has 4.

I also am thinking about running less oil in the pan but adding an accusump.

Bob

sicklyscott

iTrader: (1)

I'm having an issue with oil coming out the dipstick tube and I'm only at 7 psi on a 2554. It's possible I have bad rings but I'm trying everything I can before pulling the motor. Can anyone tell me what size the fitting is for the crank case vent? I'd like to route that into my catch can setup and see if it'll solve my problem.

JasonC SBB

Has anyone actually measured blowby flow and pressure? Examined the blowby routing in the cam cover baffles? I have.

With my old tired 2000 motor the pressure was too high - 20" water at mid RPMs.

I opened the valve cover's baffles and added plastic kitchen scrubbers. I discovered that all the blowby passed through a tiny hole (3/16" IIRC) connecting one chamber to another. I enlarged this hole to a pair of 1/4" holes. This mod reduced the crankcase pressure to about 10".

Before this mod I'd also discovered that the fittings and hoses to my home-made catch can was worth about 7" of pressure loss. Larger fittings helped a lot. The scrubbers reduced the rate at which my catch can filled up.

The problem I was trying to solve was turbo seals weeping when the car was driven hard. The above mods reduced it a lot.

Just for comparison, a stationary turbo diesel setup crankcase pressure spec is <5" water. IIRC aftermarket turbo manufacturers recommend <10".

On my new 2001 motor I measured blowby FLOW and it was a bit over half of what a healthy motor shows. However at redline and full power the crankcase pressure is around 10-15" water. This motor has a stock valve cover. So the pressure is marginally high despite the tight ring seal.

What this all tells me is that the tiny hole that separates 2 chambers in the baffling of the valve cover is too small for when you turbo the motor. Blowby is proportional to power production (and ring condition of course). If you double or triple the horsepower, it stands to reason the that said hole may need to be enlarged. If I now get weeping out of my turbo seals with my new motor at the track, I'm gonna do the same mod I did before.

The reason turbos may weep with high crankcase pressure, is that this same crankcase pressure can cause the oil drain line to back up. If anyone wonders why some turbos don't weep with high crankcase pressure, perhaps it's due to variance in how the drain is routed. In my car, the drain hose has a very slight uphill portion where it passes under the a/c compressor.

m2cupcar

iTrader: (5)

I know the MSM has addressed CC venting, but I'm not familiar with it. Anybody?

No, I didn't measure it with gauges, math and science. I did enlarge the stock breather port along with a second and got the desired results though. I would have never guessed just how small the passage was. That's it - the white circle. 1/2" gas pipe on the left.


A quick look at NA vs. Turbo versions of production cars using the same engine reveals that the added power is requires addressing the blow by (CC pressure). Somewhere in my catchcan thread is a pic of this.

levnubhin

iTrader: (30)

Update: It's been almost 2 weeks and everything is working perfectly. I think the biggest help is having that crank case vent.
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devin mac

iTrader: (2)

so, to summarize: you vented the blocked off port on the passenger rear of the block to a small'ish catch can, ported the two standard VC vents out to larger (-10AN equiv) openings, and ran both of those to a second, larger catch can. no internal mods (aside from porting out the vents) to the valve cover baffling or valve cover itself, correct?

I'm looking to get my car up and running again and i know i was struggling with some crankcase venting issues at 17psi when i put it away, so i want to get it right the first time, this time.

levnubhin

iTrader: (30)

Correct.
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