Autox engine leaked oil after extended high rpms
10-19-2018, 04:54 PM
#21
Oil Cooler - not necessary for autocross, 100% needed to road race. 280+ oil temps will kill your engine, period. Added benefit of putting another .75-1qt of oil in your total oil capacity, which further lowers thermal load.
Link-bar lifters - wise investment if the motor is apart. ditch the trays, allows oil to drainback faster out of the topend and back into the pan
Link-bar lifters - wise investment if the motor is apart. ditch the trays, allows oil to drainback faster out of the topend and back into the pan
Good oil will save you from high temps, but only for so long I'm sure and not for real racing, I just do hpde. I've been running about 300 on track using redline 5w-30 but I got a cooler as soon as I could and so far it's topped out at 240 and I'm much happier.
10-21-2018, 12:43 PM
#22
I've heard of the drilling lifter trays but not skipping them altogether, is that on all LS engines?
Good oil will save you from high temps, but only for so long I'm sure and not for real racing, I just do hpde. I've been running about 300 on track using redline 5w-30 but I got a cooler as soon as I could and so far it's topped out at 240 and I'm much happier.
Good oil will save you from high temps, but only for so long I'm sure and not for real racing, I just do hpde. I've been running about 300 on track using redline 5w-30 but I got a cooler as soon as I could and so far it's topped out at 240 and I'm much happier.
10-23-2018, 11:34 AM
#23
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Didn't think I'd get it out again this year, but my LS6 valley cover showed up and there was one more autox, so I got it out there. I was unsure if the valve covers were baffled, so I just plugged them and ran the valley cover straight to the intake so it should have had some vacuum. It was wet and I'm on slicks, so there was very little rpms or lateral g's, but after the morning session I pulled the hood off and there was oil again around the valley cover.
A friend of mine is loaning me a leakdown tester so I can rule out major engine trouble, then I guess I'll continue on with the list. I've got a good sealed catch can with oil separator on order, so I can install that. Next stop seems like it should be the restrictor pushrods.
Very frustrating as the car really seems to be working well but we couldn't run the dry afternoon session because of the leak.
A friend of mine is loaning me a leakdown tester so I can rule out major engine trouble, then I guess I'll continue on with the list. I've got a good sealed catch can with oil separator on order, so I can install that. Next stop seems like it should be the restrictor pushrods.
Very frustrating as the car really seems to be working well but we couldn't run the dry afternoon session because of the leak.
10-23-2018, 06:43 PM
#24
I think DietCoke is onto something here:
I had been trying to find a "good" solution to using a catch can, learned a bunch about crankcase airflow. It might be really helpful if you posted some photos of your engine. Would be good to see the hose setup, any catch can, PCV lines etc. Give us a few different angles, and maybe a diagram of hoses if it's hard to tell what's what. If you are full throttle for a few seconds then go off throttle instantly you're probably building up a load of crankcase pressure, and maybe that's blowing out somewhere (multiple places?).
All that aside, puking oil out the top is 100% a windage issue related to an inadequate pressure vent because a stock style pcv can't handle sustained high rpm (especially high rpm decel in gear), and has 0 to do with accusump anything.
10-23-2018, 06:51 PM
#25
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I had been trying to find a "good" solution to using a catch can, learned a bunch about crankcase airflow. It might be really helpful if you posted some photos of your engine. Would be good to see the hose setup, any catch can, PCV lines etc. Give us a few different angles, and maybe a diagram of hoses if it's hard to tell what's what. If you are full throttle for a few seconds then go off throttle instantly you're probably building up a load of crankcase pressure, and maybe that's blowing out somewhere (multiple places?).
Not much to see right now, it's got the valve covers plugged and a 3/8" hose from valley cover to the carby intake manifold. That's it. My catch can is on the way, so I didn't get to install it before the autox and so nothing else to show.
10-25-2018, 07:14 AM
#26
^^^with that setup you are not venting the crankcase, I would get the hoses back on the valve covers right away. Even a suboptimal pcv system is better than a no functioning one. The trick is to get the right flow. A member on frrax ran -10 lines from air intake tube to custom fittings on valve covers, then ls6 valley cover to catch can, then to intake. It's all about keeping the airflow but controlling the velocity. He went thru a lot of trial and error but that worked for him.
10-25-2018, 06:25 PM
#27
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OK, got my catch can. Not sure that I'm all that impressed. It's pretty simple, one inlet one outlet, 3/8 NPT with a little dipstick on top.
If I use this, the idea would be to T the lines together and then into the inlet and then outlet to the intake manifold.
Any thoughts?
If I use this, the idea would be to T the lines together and then into the inlet and then outlet to the intake manifold.
Any thoughts?
10-26-2018, 11:37 PM
#32
http://www.hawksmotorsports.com/lsx-...10-an-fitting/
Easiest method. Or drill a hole, add a baffle, and weld in a bung. Most aftermarket valve covers can also be got with a -10 or -12 already welded in
I use one of these, AND have the 3/8 factory vent in place from valley to intake for some extra vacuum evac assist on decel. You can see it in the photo I posted last week.
Easiest method. Or drill a hole, add a baffle, and weld in a bung. Most aftermarket valve covers can also be got with a -10 or -12 already welded in
I use one of these, AND have the 3/8 factory vent in place from valley to intake for some extra vacuum evac assist on decel. You can see it in the photo I posted last week.
Last edited by DietCoke; 10-26-2018 at 11:42 PM.
10-27-2018, 03:26 PM
#33
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Pretty happy about a good leakdown test result. So now I just need to decide on a system for getting suck to the crankcase.
I would prefer to either have a system that is sealed and goes back to the intake, or open and doesn't. If it's open and goes to the intake, you're introducing a vacuum leak.
Thinking about a vacuum pump. Can't do the old school exhaust scavengers, my headers go merge collector directly into muffler, so no room for the tube to be welded in.
I would prefer to either have a system that is sealed and goes back to the intake, or open and doesn't. If it's open and goes to the intake, you're introducing a vacuum leak.
Thinking about a vacuum pump. Can't do the old school exhaust scavengers, my headers go merge collector directly into muffler, so no room for the tube to be welded in.
10-30-2018, 11:26 AM
#35
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A vacuum pump is an option, but you may have problems with oil control because of the g-forces that you have going every which way in your application. We've had good luck with drift cars and some road racers, but sometimes, depending on the build, there is too much oil up top to keep it all away from the suction port. https://www.gzmotorsports.com/SVPK-L...-pump-kit.html
10-31-2018, 12:51 AM
#38
I have .040 on my pushrods. Regular ones are usually .1 or .120
Last edited by DietCoke; 10-31-2018 at 12:56 AM.
11-02-2018, 09:07 AM
#39
Even with a carb it isnt a vacuum leak to have an open mani to valley and open valve cover, because physics says so. The engine is the high pressure environment - the scenario of air coming IN a valve cover, and going OUT the valley into the intake causing a vacuum leak simply doesn't happen for this reason - the engine is the higher pressure area, air will not transit that space, because science. The valley to intake and valve cover to environment are two seperate ports and aren't otherwise connected.
I have .040 on my pushrods. Regular ones are usually .1 or .120
I have .040 on my pushrods. Regular ones are usually .1 or .120
Maybe we are talking about different things and I'm definitely not trying to get in a pissing contest, just that the pcv system is often misunderstood.
11-05-2018, 02:56 AM
#40
The air being pulled from the valley cover is the same air that went I to the valve cover. If it is being pulled from open air to valve covers, then thru valley cover I to the intake after the carb in this case, the carb must be tuned accordingly then no problem. But you take a tune carb and then introduce new air after the carb in the intake port, it is unmetered air. That's why on fuel injection the pcv takes metered air from throttle body into valve cover, thru valley cover to intake. That makes a closed loop that keeps the computer and mixture happy.
Maybe we are talking about different things and I'm definitely not trying to get in a pissing contest, just that the pcv system is often misunderstood.
Maybe we are talking about different things and I'm definitely not trying to get in a pissing contest, just that the pcv system is often misunderstood.