Official Turbo LSJ thread!!!
08-08-2013 | 03:33 PM
#6360
08-09-2013 | 06:34 AM
#6365
incorrect
not on the lsj
lol
An internal combustion engine is built around a series of hollow cylinders, in each of which is a moveable piston designed to glide up and down inside it. A mixture of air and gasoline is pumped through a system of tubes called the intake manifold through each cylinder's intake valve (or valves), where a spark from a spark plug causes the mixture to explode in the open space at the top of the cylinder called the combustion chamber. The pressure from this explosion drives the piston in the cylinder downward, where it causes the crankshaft to rotate. The rotation of the crankshaft not only pushes the piston back up into the cylinder so it can do all this again, but it also turns the gears within the car's transmission that eventually make the car move. Meanwhile, the rising piston pushes the air and gas left over from the explosion back out of the cylinder through an exhaust valve.
However -- and this is where crankcase ventilation comes in -- a certain amount of that mixture of air and gasoline is pulled down by the piston and slips through the piston rings into the crankcase, which is the protective cover that insulates the crankshaft. This escaping gas is called blow-by and it's unavoidable. It's also undesirable because the unburned gasoline in it can gunk up the system and produce problems in the crankcase. Until the early 1960s, these blow-by gases were removed simply by letting air circulate freely through the crankcase, wafting away the gases and venting them as emissions. Then, in the early 1960s, positive crankshaft ventilation (PCV) was invented. This is now considered the beginning of automobile emission control.
Positive crankcase ventilation involves recycling these gases through a valve (called, appropriately, the PCV valve) to the intake manifold, where they're pumped back into the cylinders for another shot at combustion. It isn't always desirable to have these gases in the cylinders because they tend to be mostly air and can make the gas-air mixture in the cylinders a little too lean -- that is, too low on gasoline -- for effective combustion. So the blow-by gases should only be recycled when the car is traveling at slow speeds or idling. Fortunately, when the engine is idling the air pressure in the intake manifold is lower than the air pressure in the crankcase, and it's this lower pressure (which sometimes approaches pure vacuum) that sucks the blow-by gases through the PCV valve and back into the intake. When the engine speeds up, the air pressure in the intake manifold increases and the suction slows down, reducing the amount of blow-by gas recycled to the cylinders. This is good, because the blow-by gases aren't needed when the engine speeds up. In fact, when the car is up to speed, the pressure in the intake manifold can actually become higher than the pressure in the crankcase, potentially forcing the blow-by gases back into the crankcase. Since the whole point of positive crankcase ventilation is to keep these gases out of the crankcase, the PCV valve is designed to close off when this happens and block the backflow of gases.
That entire text you copied from howstuffworks was for a CLOSED SYSTEM. Which is NOT what an lsj has. So sorry, you're incorrect.
You should have gone a couple links lower on google and you would have found this, which is how ours works:
The PCV valve is only one part of the PCV system, which is essentially a variable and calibrated air leak, whereby the engine returns its crankcase combustion gases to the air intake. Instead of the gases being vented to the atmosphere, gases are fed back into the intake manifold, to re-enter the combustion chamber as part of a fresh charge of air and fuel. The PCV system is not a classical "vacuum leak". All the air collected by the air cleaner (and metered by the mass flow sensor, on a fuel injected engine) goes through the intake manifold. The PCV system just diverts a small percentage of this air via the breather to the crankcase before allowing it to be drawn back into the intake tract again. It is an "open system" in that fresh exterior air is continuously used to flush contaminants from the crankcase and into the combustion chamber.
The system relies on the fact that, while the engine is running under light load and moderate throttle opening, the intake manifold's air pressure is always less than crankcase air pressure (see manifold vacuum). The lower pressure of the intake manifold draws air towards it, pulling air from the breather through the crankcase (where it dilutes and mixes with combustion gases), through the PCV valve, and into the intake manifold.
The PCV system usually consists of the 'breather tube' and the 'PCV valve'. The breather tube connects the crankcase to a clean source of fresh air—the air cleaner body. Usually, clean air from the air filter flows into this tube and into the engine after passing through a screen, baffle, or other simple system to arrest a flame front, to prevent a potentially explosive atmosphere within the engine crank case from being ignited from a back-fire into the intake manifold. The baffle, filter, or screen also traps oil mist, and keeps it inside the engine.
Once inside the engine, the air circulates around the interior of the engine, picking up and clearing away combustion byproduct gases, including a large amount of water vapor which includes dissolved chemical combustion byproducts, then exits through another simple baffle, screen, or mesh to trap oil droplets before being drawn out through the PCV valve, and into the intake manifold. On some PCV systems, this oil baffling takes place in a discrete replaceable part called the 'oil separator'.
Last edited by armcclure; 08-09-2013 at 06:40 AM.
08-09-2013 | 07:38 AM
#6366
Completely different from a supercharged LE5 where he has a second vac source (intake tube) that is metered air.
08-09-2013 | 07:45 AM
#6367
At idle, the check valve will be open. Pulling air from vc port, thru the check valve, into the intake manifold. It's unmetered because I have a blow thru setup. I will be switching to a breather setup soon.
Completely different from a supercharged LE5 where he has a second vac source (intake tube) that is metered air.
08-09-2013 | 08:18 AM
#6368
New Member
Joined: 07-22-12
Posts: 109
Likes: 0
From: Bardstown, KY
Is it damaging to the LSJ to swap a bnr turbo on it? I was planning on a K04 swap but it looks like everyone who has tried that eventually burned out their piston rings. Trying to run 320-350whp on my turbo setup. I have a LNF turbo manifold already.
08-09-2013 | 09:24 AM
#6371
New Member
Joined: 07-22-12
Posts: 109
Likes: 0
From: Bardstown, KY
I have pretty much everything I need but a turbo and MAF relocation kit, I have hot and cold charge pipes, BOV, cai, saab intake manifold already ported for lsj throttle body, an intercooler. LNF thermostat housing. LNF catless Downpipe. O2 housing.
08-09-2013 | 10:06 AM
#6374
^^for an ko4 swap ive heard yes you do..
Rockford, most turbo lsj's on here are making 400whp+ with no piston rings issues that ive heard of. 320-350whp is nothing for an lsj on stock internals
Rockford, most turbo lsj's on here are making 400whp+ with no piston rings issues that ive heard of. 320-350whp is nothing for an lsj on stock internals