How many C5's smoke like this on track?
07-30-2016, 05:36 PM
#21
Melting Slicks
Thread Starter
07-30-2016, 05:45 PM
#22
Pro
07-31-2016, 10:16 AM
#23
Melting Slicks
Its a stock C5 Z06. Schwanke race engines recommended these changes. They told me to weld a #10 into the rear of the drivers valve cover and run it to a vented catch can. I was also told by them to cap the passenger valve cover off.
Rear of the driver valve cover did slow the oil into the catch can down, these cars are bad about trapping oil in the passenger valve cover and then running forward under braking.
I tried the separator cans inline, this was a no go as the car smoked like a pulpwood truck, so I capped the intake and vented the cans to atmosphere.
Rear of the driver valve cover did slow the oil into the catch can down, these cars are bad about trapping oil in the passenger valve cover and then running forward under braking.
I tried the separator cans inline, this was a no go as the car smoked like a pulpwood truck, so I capped the intake and vented the cans to atmosphere.
07-31-2016, 01:27 PM
#24
Safety Car
We have an LS1 CMC guy whose car has done this for years and years. It builds up on decel and as soon as you crack the gas, it huffs out some smoke. Now I'm curious as to how much oil he's using in a weekend. Funny that my garage honed LT1 doesn't do this or use hardly any oil at all. About 12oz per race weekend.
07-31-2016, 01:29 PM
#25
Melting Slicks
Thread Starter
The catch cans have internal separators. Line from valve cover goes in top with sticks down into the can 2 inches and has to go through like scotchbrite. outlet going to the intake is on the side of the can.
07-31-2016, 02:43 PM
#26
Melting Slicks
Assuming everything is machined properly and I am guessing not the oil is not draining from the heads to the pan. The concept of external oil drains from head back to pan is not unusual though maybe for a LSX but not unusual in general. The whole oil catch can deal is a pretty odd way in my mind to fix a design problem that has to be very large. I see only 2 or 3 possible problems.
Oil drains from heads to pan are too small at some point in the path.
Way too much oil is pumped into heads though is needed to cool valve springs and get back to drains to get it is back to the pan.
There is too much crankcase pressure to allow the oil to drain. Generally caused by poor ring seal and there are many reasons for that or very poor crankcase ventilation with air in. As a side note well prepped race cars have a crankcase pressure sensor as part of the data stream.
As far as the puff on decell using the engine to slow down rather than brakes will generate very low pressures in the intake system that few valve seals or rings can deal with. Assuming the valve seals Teflon or similar with pressure against the valve stems that gets you to the usually the second ring in the ring pack not doing it's job or possibly the oil ring with small drain holes in the ring land to let the oil get back to the pan. The design of a racing engine is a complicated thing and oiling systems one of the most complicated that will make or break the design. A passenger car oiling system in a road race car is woefully inadequate or at least has been for the last 45 years I have been playing with them.
The following 2 users liked this post by ddahlgren:
c5golfguy (01-03-2017),
FASTFATBOY (07-31-2016)
07-31-2016, 03:03 PM
#27
Melting Slicks
Thread Starter
That device won't fix anything. The idea is to stop it at the engine and let the oil go back into the engine. Scotch bright is about the last thing that sounds useful.
Assuming everything is machined properly and I am guessing not the oil is not draining from the heads to the pan. The concept of external oil drains from head back to pan is not unusual though maybe for a LSX but not unusual in general. The whole oil catch can deal is a pretty odd way in my mind to fix a design problem that has to be very large. I see only 2 or 3 possible problems.
Oil drains from heads to pan are too small at some point in the path.
Way too much oil is pumped into heads though is needed to cool valve springs and get back to drains to get it is back to the pan.
There is too much crankcase pressure to allow the oil to drain. Generally caused by poor ring seal and there are many reasons for that or very poor crankcase ventilation with air in. As a side note well prepped race cars have a crankcase pressure sensor as part of the data stream.
As far as the puff on decell using the engine to slow down rather than brakes will generate very low pressures in the intake system that few valve seals or rings can deal with. Assuming the valve seals Teflon or similar with pressure against the valve stems that gets you to the usually the second ring in the ring pack not doing it's job or possibly the oil ring with small drain holes in the ring land to let the oil get back to the pan. The design of a racing engine is a complicated thing and oiling systems one of the most complicated that will make or break the design. A passenger car oiling system in a road race car is woefully inadequate or at least has been for the last 45 years I have been playing with them.
Assuming everything is machined properly and I am guessing not the oil is not draining from the heads to the pan. The concept of external oil drains from head back to pan is not unusual though maybe for a LSX but not unusual in general. The whole oil catch can deal is a pretty odd way in my mind to fix a design problem that has to be very large. I see only 2 or 3 possible problems.
Oil drains from heads to pan are too small at some point in the path.
Way too much oil is pumped into heads though is needed to cool valve springs and get back to drains to get it is back to the pan.
There is too much crankcase pressure to allow the oil to drain. Generally caused by poor ring seal and there are many reasons for that or very poor crankcase ventilation with air in. As a side note well prepped race cars have a crankcase pressure sensor as part of the data stream.
As far as the puff on decell using the engine to slow down rather than brakes will generate very low pressures in the intake system that few valve seals or rings can deal with. Assuming the valve seals Teflon or similar with pressure against the valve stems that gets you to the usually the second ring in the ring pack not doing it's job or possibly the oil ring with small drain holes in the ring land to let the oil get back to the pan. The design of a racing engine is a complicated thing and oiling systems one of the most complicated that will make or break the design. A passenger car oiling system in a road race car is woefully inadequate or at least has been for the last 45 years I have been playing with them.
The bottom red can in this pic is the can(s) I have.
This is what's inside the inlet.
Last edited by FASTFATBOY; 07-31-2016 at 03:07 PM.
07-31-2016, 07:11 PM
#28
Melting Slicks
I have no idea how those parts would actually fix anything other than catch what will not drain back to the pan. Think of this as a pressure differential problem. If the pressure in the crank case is greater than the pressure in the valve covers the heads won't drain. Think of it like a sink with a plugged drain the water will either not go down or if it does it is a glug glug sort of thing.
I know nothing about LSX oil drains and their size. I do know a drain system needs either large smooth radiused drains or a pressure differential to make what is on top want to go down. You might do a more serious crank case vent to at least get to atmospheric pressure or run a vacuum pump or better yet fix the blow by if it is real and not a draining problem. Ages ago on budget builds we used to vent the oil pan with a tall baffled riser and a filter on top. Not the greatest fix to be honest but helped some unless ring seal going away.
Is there any way physically or financially to at least to steal a used dry sump system off a car that is crashed with one? Dual purpose cars always have compromises. To me the catch can is just an alternate location for what would have gone out the tail pipe but actually does not address the problem at it's core. There are a lot of ways to measure blow-by and that would be my first adventure and measure it in both crank case and heads to get a feel for pressure differential. Answering why the need for the catch can is the solution to the problem rather than a better band aid because everyone else does it that way.
My thoughts free and do with them what you will.
I know nothing about LSX oil drains and their size. I do know a drain system needs either large smooth radiused drains or a pressure differential to make what is on top want to go down. You might do a more serious crank case vent to at least get to atmospheric pressure or run a vacuum pump or better yet fix the blow by if it is real and not a draining problem. Ages ago on budget builds we used to vent the oil pan with a tall baffled riser and a filter on top. Not the greatest fix to be honest but helped some unless ring seal going away.
Is there any way physically or financially to at least to steal a used dry sump system off a car that is crashed with one? Dual purpose cars always have compromises. To me the catch can is just an alternate location for what would have gone out the tail pipe but actually does not address the problem at it's core. There are a lot of ways to measure blow-by and that would be my first adventure and measure it in both crank case and heads to get a feel for pressure differential. Answering why the need for the catch can is the solution to the problem rather than a better band aid because everyone else does it that way.
My thoughts free and do with them what you will.
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FASTFATBOY (07-31-2016)
08-01-2016, 09:21 PM
#29
Pro
I have used the same catch can as the one mentioned above. I don't know the engineering, but I do know that at the end of each day the catch can was full of very nasty stuff that I wouldn't want to put back into my oil pan.
08-02-2016, 06:27 PM
#31
08-03-2016, 01:17 PM
#34
Le Mans Master
08-03-2016, 01:27 PM
#35
Melting Slicks
Thread Starter
08-03-2016, 04:17 PM
#36
Melting Slicks
08-04-2016, 06:06 PM
#38
Melting Slicks
Until you identify the real problem how do you devise the fix? Just blindly try things?
Measure the crank case pressure in the heads valley and pan. If all the same drains are too small or too much oil sent to heads.
I am wondering if anyone makes a belt drive 2 stage scavange pump. I know they make smaller ones for turbos mounted low compared to oil level though never bought one to be honest. That would fix the problem put not identify the problem. Once the problem identified no more catch can and no more smoke on decell.
Measure the crank case pressure in the heads valley and pan. If all the same drains are too small or too much oil sent to heads.
I am wondering if anyone makes a belt drive 2 stage scavange pump. I know they make smaller ones for turbos mounted low compared to oil level though never bought one to be honest. That would fix the problem put not identify the problem. Once the problem identified no more catch can and no more smoke on decell.
08-05-2016, 02:15 PM
#39
Melting Slicks
A company called Daily was recommended to me makes a bunch of scavange pumps as well as dry sump systems easy to mount not all that big seems like a simple solution to the VC filling.
08-06-2016, 05:37 AM
#40
Jeeze, my stock motor with a tic over 21k miles has an Elite Engineering catch can, and I scribed a line on the dip stick at exactly 1 Qt over. After the typical 2 day track event, with plenty of high RPMs, it's maybe down a couple of ounces (if at all), and the catch can has between 50-70Ml in it. That's with 5w30 Mobil 1, not very thick when hot. Wondering how to avoid the problem, but conspicuous in their absence here are engine builders who you would think by now have figured it out.