'99 LS1 with 76K miles, and 4 years of mostly track duty, running 15w50 M1. I know these types of threads are all over, but most of them point to the normal LS venting issues and recommend a catch can, etc.. I'm way beyond that, been running catch cans for a couple years, I now have valve covers and valley pan routed to a VENTED catch can, intake manifold and throttle body ports blocked off. I cleaned the intake manifold from the oil that was there from the old vent routing. Good news - no more smoke after high RPM deceleration (win). Bad news, it hasn't cured the 5K+ RPM smoke. Doesn't need to be WOT in gear, I can hold revs at a standstill at 4K, no smoke, then 5K, starts blowing smoke, 6K, blows worse.

I've done compression tests - all 175-180psi. I've done a leakdown test, 5-10% loss per cylinder. I replaced the valve seals least year, and I get no smoke on cold start. Looking for other ways to figure out where the oil is coming from. Just installed new plugs and I'll check those after some rips this weekend to see which have oil residue, and perhaps try the seafoam trick to loosen any oil rings that may be bound up. Also thinking about installing an oil pan crank scraper if the problem is too much splash up into the cylinder walls, but that's a bigger job, and next track event is in 10 days and I already get too much grief for all the time I'm spending under the car. Any advice is appreciated.

 

Based on everything you've said, I'm going with rings. Despite good compression and leak down numbers, you can still have a ring issue.

 

Welcome! Some tracks I mark my car with an X and ask the club not to black flag me for smoking. I can put out a smoke screen at high rpm part throttle... WOT is clean and maybe some puffs on decel and initial throttle. I’ve concluded this is ring issue, maybe the ring flutter (pressure diff not seating oil ring under certain conditions) mentioned by GM in the past.

2001 LS1 with 120k miles runs strong... been doing this for 60+ track days. Can add 2-3qtrs of oil during a track day. I don’t worry about it anymore.

I would suggest freeing up the CC vents, I’d rather have more smoke and a CC well vented for engine longevity. I have 2 WOT vents routed to the intake and stock 04 valley pan to manifold vent.

 

Well that's a lot easier than waiting until they come to me, which inevitably happens. I'm going to try flooding the cylinders that show residue on the plugs with seafoam and see if that helps. Otherwise I may just have to live with it for now. Even short-shifting I'm faster than most of the cars out there.

 

An update - After a couple generous Seafoam treatments, and the subsequent smokey burn-off of that (thought the fire department might show up), things did improve at high RPMs. Still there's one predictable smoke event - hard braking while loaded on the drivers side. Because of this I smoke more on a clockwise track. Happened this weekend on a rt turn coming onto the straight. The smoke cleared half way down the straight, so it's not a high rpm condition any more but still I'm getting oil in the cylinders somehow. Both the VCs and the CC are vented to atmosphere, so oil's not coming from there. Maybe I have a bad valve seal, and oil sloshing up on the passenger bank is getting in? Thought I'd see evidence of that in the leakdown test... Well, I'll be pulling the plugs for inspection this week to see if I can find any more clues.

 

I'm in the same boat as you and I have to agree that it is the rings. Im no expert by any means.

 

Smoking under WOT is a little worrisome. I can smoke screen the hwy, part throttle >5,000rpms, but no smoke under WOT. Also smoke decel and corner exit. Here's a vid with my smoking, black vette... little woopsy with the porsche at the end.
https://www.youtube.com/watch?v=yrYg...BzXxEiYJyzDj1o

 

Most likely ring flutter. A lot of low tension ring engines experience this. Have you thought about adding a crankcase vacuum pump to your engine? That may help. Let me know what you think.

If you vent everything to atmosphere, you would have to change a lot of stuff to utilize crankcase vacuum to its advantage.

Bill

 

Hmm, I wonder why it would be any different at partial or WOT. What you show is pretty close to what I have - smoke after a hard corner, that clears after a few seconds. I always thought it was just oil in the intake because of the increased vacuum when closing the throttle at high RPMs. I battled it with catch cans and eventually direct venting, but apparently I was getting oil in the cylinders from the top and from the bottom.

 

I'm definitely aware of the issues when running without crankcase vacuum, and on decel I can see how increased top-end vacuum can suck in oil when the rings are not in great shape. I'd consider a vacuum pump, I'd also consider installing a crank scraper if it would help avoid oil splash onto the walls, especially when the accusump kicks in and injects another few quarts. If she didn't run so well otherwise I would just bite the bullet and ship it off for rebuild, but I have no complaints about power or reliability so it's tough to make that jump.

 

I've never seen it myself, but I've been told at the track that I puff a bit of smoke during high RPM revmatch downshifts. Made peace with it, since I just think it's somewhat worn oil control rings. My car doesn't significantly burn oil between oil changes anyway, so I'm not too concerned.

PS: I have the Mighty Mouse "Mild" catch can setup already, vented to atmosphere and not recircled to intake.

 

15w50 u say wow that’s some heavy stuff more like a gear oil smell burning ? Thicker whitish blue smoke ? U should try out some 0w20 full synthetic see if it still smokes give the intake manifold a very good wiping out with some towels and spray cleaner ...replace valve cover and Intake seals and maybe u have cured your issue. Inspect all your vent lines fog the valve covers for clogged .
Oil /carbon build up in your heads smokes when it’s hot depending on how old your parts are ......again clean replace anything needed ..


Smoke out the tail pipe usually indicates your burning oil which is piston related of the top end refresh did not cure the symptoms...

 

Thanks for all the replies - it's put away for the season and I'll be driving/instructing with the 1LE from here. I feel like I'm just delaying the inevitable, although even after the rebuild I may want to still invest in the vacuum pump to a vented can (any thoughts on electric vs driven?), as I like the idea of keeping oil out of the intake altogether.