Got 514 problems!

Back in Black · #1 (**permalink**) 07-03-2006, 10:22 PM

Bump!

Back in Black · #2 (**permalink**) 07-05-2006, 04:23 PM

Great news, we did a complete compression test and all cylinders are virtually identical, two pumps per cylinder made 150 PSI, more pumps much higher and still identical across the board, less than 2 PSI difference!

Plugs look a bit rich but not wet at all, no oil usage.. what I thought was slight oil smoke out the sidepipes was likely mostly slightly rich running, possibly due to the PCV valve being disconnected

Shop that was doing the work seems to be the problem.. no understanding of these large bore super stroker engines. Many people have told me these engines must have a PCV valve or they will have problems (which is why I installed it in the first place)

fordracer · #3 (**permalink**) 07-05-2006, 06:54 PM

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No offense here but I see a couple of things in this picture. The breathers on the valve covers suck. You need some open element type push in breathers.

Remember, an engine is an air pump. You have a large chamber above the piston correct? You also have a very large chamber under the piston. It's called the crankcase. A piston moving up and down is going to cause pressure in the oil pan. When you removed the PCV the pressure built to a point that it had to go somewhere. Lucky for you all it did was blow the breathers off. The PCV draws in fresh air through the breather.

Look at your everyday driver. There will always be a tube goint from one valve cover to the air inlet tube or air cleaner box. This allows the PCV to draw in as much filtered air as possible.

Back to your Cobra. If the breather is restricted the PCV will start sucking oil thus causing your slight oil burning.

Ask your mechanic friend, I am an ASE Master with an L1 Advanced

Back in Black · #4 (**permalink**) 07-05-2006, 09:22 PM

No offense taken, thanks for the advice..that's a very old picture of the original junk breathers that came on the original crate. 4 year old pics

I have billet aluminum breather/PCV valve with all an fittings/SS braided lines now.. got them from JEGs

I drove it home today across town, wonderful feeling. PCV is disconnected due to the way it was programmed (with PCV way too lean and saw white spark plugs, slightly rich with PCV but driveable) All readings look good and we changed the oil and filter just to be safe

It's going to a different shop for proper tuning before I drive it any more. I have a good lead for a fuel injection specific shop already

Back in Black · #5 (**permalink**) 07-05-2006, 09:34 PM

To clarify the PCV is run into the intake and has a high quality billet aluminum breather on the opposite valve cover to pull fresh air from

What I thought was oil smoke must have mostly been simply rich running. There's no sign of oil burning in that engine and it looks to be fine. Plugs look nice and dry

The person dynoing and programming my car was the problem.. although highly recommended by several people and seemingly a well set up shop he (The owner) apparently knew less about this specific issue than I do, which is to say not much. That's the optomistic view of his intents. I'm just going to move on and get someone to properly program my ECU so I can finally drive my machine

The shop also knocked my front bumper out of true (shoved in on one side) but that's another issue and no doubt easy to fix. I only noticed it after I got home tonight

ByronRACE · #6 (**permalink**) 07-06-2006, 04:59 PM

Sorry, but the pistons moving around in the crank case do not cause the crank case to "pump up" and build pressure. Sure, when a piston moves down the bore it displaces air...and if all 8 were moving down the bore at the same time, you'd create quite an air compressor. That would be a very stupid design, and amazingly enough...they figured this out way back in the beginning and designed around it ever since. As one piston moves down, another moves up, keeping the volume and pressure in the crank case constant. Yes, turbulent...but constant on average.

If this "pumping crankcase" theory was correct, every "sealed system" engine (just about every single engine built since 1980, probably even earlier) would blow the PCV out as well as the pan and intake gaskets, shoot oil out the front and rear seals, etc. This doesn't happen, right.

The truth of the matter is, if you're building crank case pressure, it's combustion pressure coming past the rings. Sounds scary, but every engine does this to some degree, and the larger the displacement and higher the compression, the more this will occur. Newer engines leak more as well. On a 514, a single factory style breather isn't sufficient at wide-open-throttle. One or two open element breathers (as suggested) should do the job. In addition, the more breathers you put on the crank case the better. Every time you double the area of the breather path to the crank case, you cut the velocity of the air flow out the breather in half. Air velocity is what carries the oil out of the breather.

I have a pair of -10 lines running from the valvecovers of my blown 435" bbf, and I have no crankcase pressure at WOT. It does vent some, and I do see some "fog" at fire up as well as some oil fog at WOT. The fog at fire up is steam/moisture/condensation that goes away when the engine warms. The fog at WOT is oil vapor, combustion gasses, etc..."blow-by". With just one -10 line venting the engine, I see about 1/4 psi (data logger) at wot. With two, it's zero. I keep my eye on it...it's an early warning system in the event I were to crack a ring or damage a piston.

fordracer · #7 (**permalink**) 07-11-2006, 04:46 PM

Quote:

Originally Posted by ByronRACE

Sorry, but the pistons moving around in the crank case do not cause the crank case to "pump up" and build pressure. Sure, when a piston moves down the bore it displaces air...and if all 8 were moving down the bore at the same time, you'd create quite an air compressor. That would be a very stupid design, and amazingly enough...they figured this out way back in the beginning and designed around it ever since. As one piston moves down, another moves up, keeping the volume and pressure in the crank case constant. Yes, turbulent...but constant on average.

If this "pumping crankcase" theory was correct, every "sealed system" engine (just about every single engine built since 1980, probably even earlier) would blow the PCV out as well as the pan and intake gaskets, shoot oil out the front and rear seals, etc. This doesn't happen, right.

The truth of the matter is, if you're building crank case pressure, it's combustion pressure coming past the rings. Sounds scary, but every engine does this to some degree, and the larger the displacement and higher the compression, the more this will occur. Newer engines leak more as well. On a 514, a single factory style breather isn't sufficient at wide-open-throttle. One or two open element breathers (as suggested) should do the job. In addition, the more breathers you put on the crank case the better. Every time you double the area of the breather path to the crank case, you cut the velocity of the air flow out the breather in half. Air velocity is what carries the oil out of the breather.

Then explain why when the PCV gets plugged up or totally removed oil will be blown up into the air filter?? In fact I am so positive about this I'll give you some homework.

Go out to your car and start it up. Plug the hole in the valve cover where the PCV goes. Plug the hole or holes where the breather element or tube is. Rev the car to 2500 rpm and see how long it takes to blow out every seal in the engine.