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  • NA KA24DE Oil Consumption...

    Hey all, there's an oil consumption issue going on with my bone stock NA KA24DE. This is an endurance racing car so we're on full boil for 7+ hours in each stint. After each day of racing at my last race (7 hours Saturday, 7.5 hours on Sunday) I went through 2 qts of oil. Power felt great the whole weekend, oil temps were 220 *F (ambient temps were 40-50*F max) and pressure was 60-90psi all weekend, even at the end of each day. Don't datalog so I don't know if pressure dropped in high g turns or not. I run Redline 50WT race oil.

    Engine is from a 95 S14 and supposedly had ~70k miles on it. Valve seals were done last May (after false alarm leakdown test), never touched the bottom end. Engine always felt strong and still feels strong. In total there's 60+ hours of racing on this engine.

    There are no apparent signs of burning oil coming from the exhaust or soot deposits/blackness on the spark plugs. I have all emission systems deleted, with the exception of the PCV baffle box and valve off of the timing cover.

    Being an optimist, I'm hoping the fix is as easy as deleting the PCV baffle box/valve, plugging the timing cover hole, and just throwing an old school little filter vent on the valve cover. Has anyone had experience with the PCV system being the culprit of phantom oil consumption?

    Otherwise, it's either valve seals or piston oil rings, I'd assume. I still need to do a leakdown test as well. Just wanted thoughts from people who race a stock NA KA24DE and experienced oil consumption at this rate.
    Core4 Motorsports
    CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
    S14 VQ AER Endurance Racing Team

  • #2
    My '96 engine has a shload of miles and doesn't burn near that much oil. When I had the stock PCV/breather system in place, it would smokescreen on hard left hand turns until it got down about 1/2 quart. so after a few events, I just left the car a little low on oil and drove anyway.

    Eventually, I removed the valve cover breather and routed it to a catch can. that catch can would get a cup or so of oil in it after every session. I also noticed that the thing would be under slight pressure at WOT (because stock PCV and blow-by???), but pull a vacuum when I let off the gas.. Soooo, I just ran the hose in the breather tank to the bottom of the tank. now when I let off the gas, it sucks the oil back into the sump. voila. no more oil burn, no more smokescreen.
    Originally posted by SoSideways
    I don't care what color they are as long as they are LONG AND HARD.
    '04 G35 Sedan 6MT- The DD
    '96 240SX- The Track Toy

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    • #3
      Originally posted by Matt93SE View Post
      My '96 engine has a shload of miles and doesn't burn near that much oil. When I had the stock PCV/breather system in place, it would smokescreen on hard left hand turns until it got down about 1/2 quart. so after a few events, I just left the car a little low on oil and drove anyway.

      Eventually, I removed the valve cover breather and routed it to a catch can. that catch can would get a cup or so of oil in it after every session. I also noticed that the thing would be under slight pressure at WOT (because stock PCV and blow-by???), but pull a vacuum when I let off the gas.. Soooo, I just ran the hose in the breather tank to the bottom of the tank. now when I let off the gas, it sucks the oil back into the sump. voila. no more oil burn, no more smokescreen.
      So how much oil did your KA consume in an event before and after your PCV fix? Sprint racing, right?

      Sorry, can you elaborate a little more on what you did. Not sure I understand what you're describing.
      Core4 Motorsports
      CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
      S14 VQ AER Endurance Racing Team

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      • #4
        I did this mod about 7-8 years ago while doing DEs, so I can't tell you the difference in oil consumption.

        I mostly do sprint races, but I rarely have to add oil at all-- every 3-4 race weekends (so roughly 8hrs of track time), I'll have to add some. I think most of that is/was due to old engine leaks- valve cover, oil pan seal, front main, etc. (the bottom of the engine gets pretty crusty, but never leaves drips anywhere.)

        I also ran a 2hr WRL race a while back with a 1hr practice the day before, and I had no noticeable oil consumption per the dipstick.

        Castrol GTX 5w30, btw...
        Originally posted by SoSideways
        I don't care what color they are as long as they are LONG AND HARD.
        '04 G35 Sedan 6MT- The DD
        '96 240SX- The Track Toy

        Comment


        • #5
          Originally posted by Matt93SE View Post
          My '96 engine has a shload of miles and doesn't burn near that much oil. When I had the stock PCV/breather system in place, it would smokescreen on hard left hand turns until it got down about 1/2 quart. so after a few events, I just left the car a little low on oil and drove anyway.

          Eventually, I removed the valve cover breather and routed it to a catch can. that catch can would get a cup or so of oil in it after every session. I also noticed that the thing would be under slight pressure at WOT (because stock PCV and blow-by???), but pull a vacuum when I let off the gas.. Soooo, I just ran the hose in the breather tank to the bottom of the tank. now when I let off the gas, it sucks the oil back into the sump. voila. no more oil burn, no more smokescreen.

          So it's set up like the surge tank on my S2k's radiator. The relief hose from the radiator is connected to the cap, but the cap has a draw tube that reaches the bottom of the surge tank.
          Don Johnson (really!)
          Just so you know.

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          • #6
            yeah, just like a surge tank.
            I did a quick MS paint drawing earlier, but forgot to upload it.
            Attached Files
            Originally posted by SoSideways
            I don't care what color they are as long as they are LONG AND HARD.
            '04 G35 Sedan 6MT- The DD
            '96 240SX- The Track Toy

            Comment


            • #7
              Originally posted by gills View Post

              Being an optimist, I'm hoping the fix is as easy as deleting the PCV baffle box/valve, plugging the timing cover hole, and just throwing an old school little filter vent on the valve cover. Has anyone had experience with the PCV system being the culprit of phantom oil consumption?
              Definitely crankcase pressure pushing it out your valvecover. I'd plug the valve cover and run the largest line you can from your timing cover to a catch can with a filter.

              What oil BTW? My oil consumption went down massively when I switched to Redline.

              Originally posted by Matt93SE View Post

              Castrol GTX 5w30, btw...
              BUT WHY?! The car will literally make more power with better oil in it. I don't get people that have race cars and use conventional oil.
              Support innovation, buy from companies that design their own parts!

              Friends don't let friends buy knock-offs.

              Suspension before power.

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              • #8
                Ain't broke, don't fixit.

                Show me proof that spending 3x as much for oil will net me the same reliability and protection but still gain power.
                Originally posted by SoSideways
                I don't care what color they are as long as they are LONG AND HARD.
                '04 G35 Sedan 6MT- The DD
                '96 240SX- The Track Toy

                Comment


                • #9
                  Originally posted by PoorMans180SX View Post
                  Definitely crankcase pressure pushing it out your valvecover. I'd plug the valve cover and run the largest line you can from your timing cover to a catch can with a filter.

                  What oil BTW? My oil consumption went down massively when I switched to Redline.



                  BUT WHY?! The car will literally make more power with better oil in it. I don't get people that have race cars and use conventional oil.
                  I've only run Redline High Performance 20W-50 and Redline 50WT race oil. I plan to start oil analysis with the oil I have from after the previous race. Just keep forgetting to do it. It's more to see how long I can actually keep running the same batch of oil. Right now I change it after every race, but as Matt said, at 3x the cost of conventional this adds up. But, if the motor is consuming almost 2 qts of oil after each day of racing for me, there's constantly fresh oil in there!

                  So have you done this on your own car? Why from the timing cover and not the valve cover? I've seen most people recommend plugging the timing cover hole and keep the valve cover vent and catch can that port.

                  Matt, you're diagram is with or without the stock PCV valve and plumbing to IM in place?
                  Core4 Motorsports
                  CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
                  S14 VQ AER Endurance Racing Team

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                  • #10
                    I haven't touched the stock PCV system at all. just pulled that one large tube between the valve cover and intake tube, plugged the intake, then plumbed from valve cover to the bottom of the breather can.

                    Regarding the oil, the pumping losses from that thicker oil eat more horsepower than the expensive synthetics will gain you. If you can get away with a thinner oil, you'll gain more power.

                    A couple years ago, I thought I had an oil pressure issue from my tired old engine, so I went from 5w30 to 10w30 to 30 to 20w50.. The car kept getting slower and slower, and I was several seconds off my prior pace. I was changing oil after every race looking for sings the engine was sick. one day I had an epiphany and wondered if the oil pressure gauge was wonky, so I swapped it out. increase in 30psi on the new gauge. sheeit. went back to 5w30 oil and dropped 3 seconds a lap and gained several MPH on every straight.

                    that was about 4-5 years and 200hrs ago on the engine. it's still running strong. 175-180psi on all 4 cylinders when I checked compression a couple months ago.
                    Last edited by Matt93SE; 11-05-2015, 11:27 AM.
                    Originally posted by SoSideways
                    I don't care what color they are as long as they are LONG AND HARD.
                    '04 G35 Sedan 6MT- The DD
                    '96 240SX- The Track Toy

                    Comment


                    • #11
                      Plugging breathers up seems like a healthy step in the wrong direction - pressure in the crankcase (and valve cover - they're connected) is bad on all fronts - longevity, power, oil consumption....

                      On a fi motor, the problem is exacerbated but can still happen on a na motor. Typically you want to add breathers, not eliminate them.

                      On thing to keep in mind with a catch can vented to atmosphere and a pcv system hooked up, you have an air leak anytime there is vacuum. On a race car which is typically full throttle (zero or minimal vacuum na, none with fi) or fully closed under braking, it is likely a moot issue.

                      It is how I run my track car with much luck but would not run a street car this way.

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                      • #12
                        Originally posted by Matt93SE View Post
                        I haven't touched the stock PCV system at all. just pulled that one large tube between the valve cover and intake tube, plugged the intake, then plumbed from valve cover to the bottom of the breather can.

                        Regarding the oil, the pumping losses from that thicker oil eat more horsepower than the expensive synthetics will gain you. If you can get away with a thinner oil, you'll gain more power.

                        A couple years ago, I thought I had an oil pressure issue from my tired old engine, so I went from 5w30 to 10w30 to 30 to 20w50.. The car kept getting slower and slower, and I was several seconds off my prior pace. I was changing oil after every race looking for sings the engine was sick. one day I had an epiphany and wondered if the oil pressure gauge was wonky, so I swapped it out. increase in 30psi on the new gauge. sheeit. went back to 5w30 oil and dropped 3 seconds a lap and gained several MPH on every straight.

                        that was about 4-5 years and 200hrs ago on the engine. it's still running strong. 175-180psi on all 4 cylinders when I checked compression a couple months ago.
                        Well, in the end I just want oil that's reliable and can handle many hours at a time of racing abuse without breaking down with no oil cooler and low KA oil capacity. Admittedly, the 50WT is too thick for the race in New Hampshire a couple weeks ago where ambient temps were 40-50F and low 30's over night. Oil temps didn't budge over 215-220F all weekend. I suppose it helps that we don't rev the engine passed 6200-6400 since it's like trying to get more acceleration by whipping a dying donkey passed that.

                        And 3 seconds per lap?! c'mon! I have a hard time believing that you didn't adjust the nut behind the wheel a bit between those sessions also.

                        With the stock PCV valve in place, I guess it makes sense that you saw some pressure in the catch can under WOT and vacuum under closed throttle. Doesn't that suggest the PCV valve is faulty though?? More on this down below...

                        Originally posted by jfryjfry
                        Plugging breathers up seems like a healthy step in the wrong direction - pressure in the crankcase (and valve cover - they're connected) is bad on all fronts - longevity, power, oil consumption....

                        On a fi motor, the problem is exacerbated but can still happen on a na motor. Typically you want to add breathers, not eliminate them.

                        On thing to keep in mind with a catch can vented to atmosphere and a pcv system hooked up, you have an air leak anytime there is vacuum. On a race car which is typically full throttle (zero or minimal vacuum na, none with fi) or fully closed under braking, it is likely a moot issue.

                        It is how I run my track car with much luck but would not run a street car this way.
                        So let's think about this; isn't the valve cover port allowing fresh air into (in theory) the engine when the car is under low vacuum, high load (WOT) since that is when the PCV valve port is supposed to flow the most crank-case gases to be recirculated into the IM? And then the PCV is closed under high vacuum/closed throttle? Otherwise, we'd see oil residue/filming/puddling in the intake tube and throttle body.

                        If you close off the timing cover port where the stock PCV baffle box/valve are (and plug the IM) and just the route the valve cover port to a vented catch-can, crankcase pressure will just release through there since they're connected, as you mentioned.

                        Matt isn't the first guy I've talked to that mentioned oil plumes from hard left hand turns. Probably from oil going through the PCV valve port on the timing cover since that is nice and low.


                        Core4 Motorsports
                        CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
                        S14 VQ AER Endurance Racing Team

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                        • #13
                          My smoking was coming from the valve cover breather tube. The image above shows air flowing into the valve cover there, but under WOT and whatnot, it pushes oily air out. considering the whipping of the oil on a 6000rpm engine, it spits out a mist of oily air. If the engine is too full, the oil spray on the valve train also runs out of that fitting into the hose.

                          That muck gets sucked into the engine through the breather hose since it's always under vacuum (it's connected to the intake tube between the air filter and throttle body, so there's always a low pressure area there due to the air filter restriction and Bernoulli.)

                          Sooooo, when that hose is connected to your intake tube, the engine sucks that oily **** into the intake and thus into the engine. When I was having issues fogging for mosquitos, I could pull the intake tube off the car and see an oily stream from that tube down the intake and into the throttle body. As soon as I installed the breather/catch can, my fogging issues completely stopped.
                          Originally posted by SoSideways
                          I don't care what color they are as long as they are LONG AND HARD.
                          '04 G35 Sedan 6MT- The DD
                          '96 240SX- The Track Toy

                          Comment


                          • #14
                            If you follow any oil analysis, Castrol GTX does really well in Nissan engines. I switched to Castrol Edge when Mobile one broke down on me and caused a low pressure situation at a track day.
                            Chicago Region SCCA SM # 688 http://www.scca-chicago.com
                            TSSCC SM # 688 http://www.tsscc.org

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                            • #15
                              Originally posted by Matt93SE View Post
                              My smoking was coming from the valve cover breather tube. The image above shows air flowing into the valve cover there, but under WOT and whatnot, it pushes oily air out. considering the whipping of the oil on a 6000rpm engine, it spits out a mist of oily air. If the engine is too full, the oil spray on the valve train also runs out of that fitting into the hose.

                              That muck gets sucked into the engine through the breather hose since it's always under vacuum (it's connected to the intake tube between the air filter and throttle body, so there's always a low pressure area there due to the air filter restriction and Bernoulli.)

                              Sooooo, when that hose is connected to your intake tube, the engine sucks that oily **** into the intake and thus into the engine. When I was having issues fogging for mosquitos, I could pull the intake tube off the car and see an oily stream from that tube down the intake and into the throttle body. As soon as I installed the breather/catch can, my fogging issues completely stopped.
                              Thanks, Matt. "Fogging for mosquitos"....effing hysterical. This is all interesting because another endurance racing guy said his plumes were coming from the timing cover stock pcv setup port, yours the valve cover. He plugged the timing cover port and vented the valve cover port to a catch can and said it never happened again because of plugging the timing cover port. He might've been mistaken then.

                              So I went to check my car quickly and pulled off the valve cover hose on the intake tube side. Lo and behold there was a little pooling of oil at the end and oil residue/film inside it. Didn't get a chance to pull off the intake tube to inspect the throttle body, etc.

                              I also fired her up to test and there is a slight vacuum in that valve cover hose with the throttle plate closed like you said. When I opened the throttle it went away. You said you had about a cup of oil (1/4 qt) in the catch can after a sprint race or DE? If I'm burning ~2qts in 7 hours that's a little more than a 1/4qt/hour. Promising fix now that I found some traces of oil in there.

                              I suppose if you completely remove the stock pcv setup using your solution, there would be no vacuum in that hose and no drawing back of oil.
                              Core4 Motorsports
                              CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
                              S14 VQ AER Endurance Racing Team

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