September 29, 2020, 10:09:02 AM

Author Topic: LS2 Oil Consumption -  (Read 825 times)

Online largeorangefont

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Re: LS2 Oil Consumption -
« Reply #15 on: September 12, 2020, 10:56:55 PM »
I have fittings in each valve cover with 1/2" line to a custom catch tank near the sway bar.
It has a filtered vent to atmosphere.
I also have my PCV system connected through a small catch tank.
This allows my PCV system to pull air into the valve covers through the filter and catch tank and out through the small tank to the manifold during normal driving.
Under full throttle the PCV system has no vacuum, and any blowby gases vent easily through the lower tank and out the filter.

Iím trying to understand this setup. Thatís not really a PCV system then..well not one the is pulling any vacuum or doing anything the moment you vent it, and if you have a line to the manifold the engine is pulling some amount of unmetered air.

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Re: LS2 Oil Consumption -
« Reply #16 on: September 12, 2020, 10:59:48 PM »
This was the best thing I ever did. -10 from each valve cover and a -6 from the valley cover all to an open catch can. Everything is much happier.


I'm going to try and see what will happen now that i already ordered this new can. Sounds like worst case, ill be able to at least run everything to the can and leave one of the two nipples vented.


I did notice this...



Its a sensor in the valley area that has a hard line (abs plastic or such) running from it to the just behind throttle body into intake with this open nipple. Is this a vaccum leak?

I also would like to add that the driver side valve cover was completely capped off




That is a vacuum leak. Cap it off.
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Online largeorangefont

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Re: LS2 Oil Consumption -
« Reply #17 on: September 12, 2020, 11:33:14 PM »
can you expand on this? I'm not sure I understand how/why volume of airflow is important for this particular system.

Hey just saw this, and sure.

The big problem with LS engines is based around oiling and losing oil at high RPM. Oil falls from the heads onto the spinning crank. You have air being displaced in the crankcase, and oil is falling into the crank creating a hot oil mist. Hot air rises, and that hot displaced air can only escape via the stock valley cover PCV port and/or the port in the valve covers. That is akin to you breathing through a straw. You can sit down and breathe through a straw. Go try running and breathing through a straw. So at high RPM, the crank case is basically out of breath pumping oil and mist out of the the 3/8 ports, trying to breath in air from the ďclean sideĒ. This oil and mist goes up into the intake manifold. The oil gets to the intake manifold cools and pools up, and/or gets sucked into the combustion chamber. That is why LS engines consume oil at high RPM.

So in order to keep the oil out of the intake manifold, you delete the PCV completely, and run lines from the valve covers to a vented catch can. I did -10 lines for this. It helped but I was still pushing oil into the catch can. I still did not have enough fresh air breathing ability to satisfy the crankcase demand. So I added a 3rd -6 line from the valley cover to the same vented catch can after talking with a few more folks. Like magic the oil getting pushed into the catch can dropped by 80%, and now the engine consumes almost no oil.

Yes you are not pulling vacuum on the crankcase anymore like you are with a modern PCV system, but I believe this is a far better trade off than constantly burning oil at high RPM. I used to go through almost a quart of oil every track day. Now it is like 4-6 oz.

Quote from: cool
Sell it to spacevomit.  He'll finish it.

Offline jwvand02

Re: LS2 Oil Consumption -
« Reply #18 on: September 13, 2020, 09:07:19 AM »
can you expand on this? I'm not sure I understand how/why volume of airflow is important for this particular system.

Hey just saw this, and sure.

The big problem with LS engines is based around oiling and losing oil at high RPM. Oil falls from the heads onto the spinning crank. You have air being displaced in the crankcase, and oil is falling into the crank creating a hot oil mist. Hot air rises, and that hot displaced air can only escape via the stock valley cover PCV port and/or the port in the valve covers. That is akin to you breathing through a straw. You can sit down and breathe through a straw. Go try running and breathing through a straw. So at high RPM, the crank case is basically out of breath pumping oil and mist out of the the 3/8 ports, trying to breath in air from the ďclean sideĒ. This oil and mist goes up into the intake manifold. The oil gets to the intake manifold cools and pools up, and/or gets sucked into the combustion chamber. That is why LS engines consume oil at high RPM.

So in order to keep the oil out of the intake manifold, you delete the PCV completely, and run lines from the valve covers to a vented catch can. I did -10 lines for this. It helped but I was still pushing oil into the catch can. I still did not have enough fresh air breathing ability to satisfy the crankcase demand. So I added a 3rd -6 line from the valley cover to the same vented catch can after talking with a few more folks. Like magic the oil getting pushed into the catch can dropped by 80%, and now the engine consumes almost no oil.

Yes you are not pulling vacuum on the crankcase anymore like you are with a modern PCV system, but I believe this is a far better trade off than constantly burning oil at high RPM. I used to go through almost a quart of oil every track day. Now it is like 4-6 oz.

So is the issue with the small catch can that the oil mist will never have time to cool and condense and it will essentially be a hose? Or is the airflow part secondary in the sense that the catch can will work but it will fill quickly because it doesn't address the underlying weakness?

Online largeorangefont

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Re: LS2 Oil Consumption -
« Reply #19 on: September 13, 2020, 10:56:25 AM »
can you expand on this? I'm not sure I understand how/why volume of airflow is important for this particular system.

Hey just saw this, and sure.

The big problem with LS engines is based around oiling and losing oil at high RPM. Oil falls from the heads onto the spinning crank. You have air being displaced in the crankcase, and oil is falling into the crank creating a hot oil mist. Hot air rises, and that hot displaced air can only escape via the stock valley cover PCV port and/or the port in the valve covers. That is akin to you breathing through a straw. You can sit down and breathe through a straw. Go try running and breathing through a straw. So at high RPM, the crank case is basically out of breath pumping oil and mist out of the the 3/8 ports, trying to breath in air from the ďclean sideĒ. This oil and mist goes up into the intake manifold. The oil gets to the intake manifold cools and pools up, and/or gets sucked into the combustion chamber. That is why LS engines consume oil at high RPM.

So in order to keep the oil out of the intake manifold, you delete the PCV completely, and run lines from the valve covers to a vented catch can. I did -10 lines for this. It helped but I was still pushing oil into the catch can. I still did not have enough fresh air breathing ability to satisfy the crankcase demand. So I added a 3rd -6 line from the valley cover to the same vented catch can after talking with a few more folks. Like magic the oil getting pushed into the catch can dropped by 80%, and now the engine consumes almost no oil.

Yes you are not pulling vacuum on the crankcase anymore like you are with a modern PCV system, but I believe this is a far better trade off than constantly burning oil at high RPM. I used to go through almost a quart of oil every track day. Now it is like 4-6 oz.

So is the issue with the small catch can that the oil mist will never have time to cool and condense and it will essentially be a hose? Or is the airflow part secondary in the sense that the catch can will work but it will fill quickly because it doesn't address the underlying weakness?

I did forget a part of the story. I ran my car originally with a large Saikou Michi dual catch can setup with a billet check valve. Each catch can is close to a 24 oz. in size. This kept the PCV system intact and gave a small volume of air to draw from. The dirty side catch can was always filling up and the car drank oil. The small 3/8 lines are simply not big enough at high RPM. Occasionally ripping the car, it may have worked ok. At a track day you are burning 8-10 oz of oil in 20-30 mins.

A vacuum pump is another option, but that is $800-$1000

With all that you start to see how people have oiling problems quickly if they donít pay attention. I believe the LS2 and 3 donít have PCV valves, they just have a small orifice. That isnít helping.


I run my car 1 quart over full with the Fbody pan, and have a improved trap door baffle. I run the LS6 valley cover, and am running the Melling High flow/High pressure pump the internet says never to use. I run the pump with the low pressure spring. I have an Accusump for insurance, itís never activated on track before.

« Last Edit: September 13, 2020, 11:02:00 AM by largeorangefont »
Quote from: cool
Sell it to spacevomit.  He'll finish it.

Offline Cobranut

Re: LS2 Oil Consumption -
« Reply #20 on: September 13, 2020, 03:47:11 PM »
I have fittings in each valve cover with 1/2" line to a custom catch tank near the sway bar.
It has a filtered vent to atmosphere.
I also have my PCV system connected through a small catch tank.
This allows my PCV system to pull air into the valve covers through the filter and catch tank and out through the small tank to the manifold during normal driving.
Under full throttle the PCV system has no vacuum, and any blowby gases vent easily through the lower tank and out the filter.

Iím trying to understand this setup. Thatís not really a PCV system then..well not one the is pulling any vacuum or doing anything the moment you vent it, and if you have a line to the manifold the engine is pulling some amount of unmetered air.

When I bought the car it only had the vented catch can with the large lines from the valve covers.
Worked OK, but I like a PCV system to help keep the oil cleaner.

I reconnected the loop from the valley cover, through a small inline catch can to the intake.

At full throttle the flow is the same as before, out the valve covers thru the large hoses to the vented can and outt to atmosphere.

Under idle and part throttle, the flow reverses, in through the filter, the large can, to the valve covers.
Out through the valley fitting, through the small can, to the intake to be burned off.

Under somewhat aggressive street driving I've never had more than a few drops of oil in either can, and oil consumption is negligible.

I haven't tracked it yet, but I expect the large can may collect a bit of oil in that case.
1995 FD, 7.0 Liter stroked LS3, T56, 8.8, Samberg kit.

Offline driftnfb

Re: LS2 Oil Consumption -
« Reply #21 on: September 13, 2020, 10:25:22 PM »
Thereís some really good info on here. Iím running test right now on a few variables. MP and I have been PMing and he suggested a oil fill tube breather. He had it spill onto the valve covers after aggressive driving so I took it a bit further and hooked it up to a catch can and am currently monitoring that.

Right now Iím waiting on the second sealed catch can for the dirty side of the PCV system and am goin to hook it up. So far I feel the crankcase pressure is lower and Iím not consuming much with just the breather mod alone, I noticed less oil smell during cruising today.

As soon as I ordered a case of valvoline European 5w40, I read what has already been mentioned above by ďlargeĒ that these oils love to evaporate or ďmistĒ and thereís actually an oil called LS30 specifically made for LS engines and oil consumption. The season is slowly coming to an end so I donít think Iíll be able to try that oil till next year


Alex
1994 Mazda RX-7
LS2, T56, JTR Headers, Turbo II 3.73 Gears, A/C and P/S

Online largeorangefont

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Re: LS2 Oil Consumption -
« Reply #22 on: September 13, 2020, 10:34:11 PM »
FWIW I run Castrol GTX 20w50 in mine. I change it at about 10 hours of track use.
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Offline MPbdy

Re: LS2 Oil Consumption -
« Reply #23 on: September 13, 2020, 11:01:12 PM »
Huh Iím on Euro Mobil 1 right now. First time trying it. It was a small change but I like the oil pressure a little better than the 10w30 Mobil I always ran.