Oversquare ops

[avbug]

Blowby IS increased, anytime you put more pressure into a cylinder you will inevitably get more gases that pass by the cylinder rings (more blowby), they teach you that in basic auto shop!

Apparently they didn't teach you that in A&P school...not a mechanic are you? (I am). Why, because it's not true. Nice try though. You're operating your aircraft in a turbonormalized condition, operating them only to sea level pressure...you're not inceasing wear in anything. Not even remotely close.

Also the fact that you say the 402 is turbo normalized leads me to believe you don't know a dang thing about the 402. They are not turbo normalized, 30 inches is just the cruise setting that we use, you can use 32inches and 2300rpm and they go up to 34.5 inches and 2700rpm for max power in the B models and 39.5/ 2700 in the C, BUT the C DOES have a different engine, still a 520 but a different model, where as the B's use the same model 520.

You're operating it in a turbonormalized state, not exceeding sea level pressures; anything more that is within limits of the engine is irrelevant, because you're not opertating it under those conditions. THINK!

As youstated, diffrent engine models, and therefore your comparison is no good. Different baffles, different inductions, different aircraft...you simply can't turn an apple into an orange. Nice try, though.

The inlets are the same, the baffling is different and the outflow are different to allow MORE cooling on the 402, which should make the engine last longer.

That's a very simplistic, but uneducated and wrong way to look at it, but once more, nice try. Too much cooling is just as bad as too little, but both issues are irrelevant. How the engine is cooled, where, and when is much more important, just as is peak oil temperatures...your oil breaks down thermally long before it's affected by contaminants...which accounts partially for the color, along with contaminants picked up and in suspension. Simply because one has more cooling available doesn't mean it lasts longer or is in a better state. You need to do a little study before you pursue that one.

In any case, that doesn't address the operating parameters, nor the warm-up, cool down, or other facets of operation that most operators neglect. You are giving the turbo a five minute cool down after landing, right?

Also color of oil is not irrelevant, if your oil is dark you have more particulates in it, which will break the oil down chemically or cause it to form sludge blocking oil passages, again basic auto shop here, nothing earth shattering.

Aaah, again, wrong. You really should study a little on this, before you pursue it. Next you'll be telling us you can tell the condition of the oil by it's color, or that the color has any meaning at all (it does not). Not such a nice try. READ!

If blowby and oil color was meaningless and irrelevant then we wouldn't have systems to remove blowby or change our oil. Why do you think you can drive 100,000 miles on your transmission fluid (which is just oil) but only 3,000 on your engine oil? It's because blowby breaks the oil down, since there's no blowby gases in the transmission the oil doesn't break down.

Again, very wrong...more than apples to oranges there...no comparison between circulating an operating fluid through a non-combustion transmission, an entirely different chemical formulation from engine oil, and engine oil in an internal combustion engine. Why not compare toe nail polish to beer? To what systems are you referring to remove "blow by?" Are you talking about crank case breathers? You understand that there's a lot more going on in that crank than merely venting for "blow by," and that the breather is necessary even if there isn't any "blow by?" You do get that, right? You're aware that some companies had systems for many years which pumped raw fuel into the oil after shutdown and before start as part of the oil dilution system...intentionally putting combustion products into the fuel, right?

You also keep referring to the fact that when you cruise in the 402 at 30 inches it's the same as a N/A engine at sea level. This is true, but a N/A engine is only going to be at that pressure for a few seconds because even at full throttle the instant you break ground the pressure will drop.

Actually no. A properly designed induction in a normally aspirated engine will experience a ram air recovery and even ram air rise with the ram effect of the propeller and forward airspeed...getting thirty inches or more is not uncommon in normally aspirated airplanes close to sea level.

No N/A engines cruise anywhere near 30inches and in most cases you don't even get 30inces on takeoff since the air is restricted slightly through the induction system and filter. Also I still don't understand your rationalization that an engine not running on the ramp showing 30in is the same as a running engine at any MP, that just doesn't make any sense.

One surely can get full barometric pressure in a normally aspirated engine...especially at sea level. As for the explaination about an engine at rest at sea level...you assert that pressure damages engines, and the terrible, awe inspiring tubonormalized setting of 30 inches of manifold pressure is causing excess wear in your engine...no it's not, and that's no greater value than you'll see on the gauge when the airplane sits for extended periods doing absolutely nothing. The manifold pressure you're seeing on the gauge is irrelevant. You get that part, right?

Why because we're running higher pressure through them, which produces more power, which produces more heat, more blowby and just generally causes things to wear out alittle faster over the long term.

If the oil is changed regularly, then the issue of blow by is irrelevant. Again, irrelevant. Once more, sing it together, irrelevant. If you are seeing blow by to the degree that it's causing engine damage or wear, then you have some serious mainainenance faults and need to look at doing better inspections. Even if that's happening, it's not going to cause the engine to wear out faster. Not happening.

If the engine is operated within temperature limits, you're not wearing anything out any faster.

Your comments do indicate why the FAA mechanic certificate takes lot more doing, and is a lot more complicated and involved than any pilot certificate...and why you need one before you put your fingers in something you don't understand. Do a little research on your claims here, then get back to us with your new found knowledge. I'm sure it will be enlightening for us all.

 

[VNugget]

How many 310s cruise at sea level?

 

[avbug]

How many are prohibited or limited from doing so?

 

[pilotyip]

I spent a lot of time cruising at SL, most of the time with an engine shutdown.

 

[RedGuy]

AvBug participates in class, BUT does not pay ATTENTION!:smash:

Here's alittle article about Turbo-Normalization. http://www.nar-associates.com/technical-flying/turbo/turbo.pdf

Apparently they didn't teach you that in A&P school...not a mechanic are you? (I am). Why, because it's not true. Nice try though. You're operating your aircraft in a turbonormalized condition, operating them only to sea level pressure...you're not inceasing wear in anything. Not even remotely close.

Not a mechanic, but I have a pretty good understanding of mechanics since I have some engineering background. I am not operating in a turbo-normalized condition. Running 30 inches MP in cruise would be equivalent to running 100% power in cruise, which is not the case I'm running at 65% power. No piston A/C that I've seen yet has cruise settings listed in the POH for 100% cruise power. Also as stated before I do exceed sea level pressure in a 402 every time I take off and climb since I DO take off at full power, which is 34.5 inches MP and 2700 rpm in the B model, and climb at 33in MP and 2500rpm. I also can run if I choose at 32in MP and 2300rpm for cruise.

From the article listed above.

"First, what is turbo-normalization? Simply put, turbo-normalization uses an exhaust gas turbine to drive a compressor which increases the engine intake manifold pressure. A turbo-normalization system automatically limits manifold pressure to that at sea level at all altitudes up to the system critical altitude."​

Ok so we've established a 402 is NOT turbo-normalized, and the A/C IS operated out side of sea level pressures.

As youstated, diffrent engine models, and therefore your comparison is no good. Different baffles, different inductions, different aircraft...you simply can't turn an apple into an orange. Nice try, though.

"BUT the C DOES have a different engine, still a 520 but a different model, where as the B's use the same model 520."

Again not paying attention. I said the C model uses a different model, I'm comparing the B which DOES have the same model IO-520-M series.

That's a very simplistic, but uneducated and wrong way to look at it, but once more, nice try. Too much cooling is just as bad as too little, but both issues are irrelevant. How the engine is cooled, where, and when is much more important, just as is peak oil temperatures...your oil breaks down thermally long before it's affected by contaminants...which accounts partially for the color, along with contaminants picked up and in suspension. Simply because one has more cooling available doesn't mean it lasts longer or is in a better state. You need to do a little study before you pursue that one.

From the article above.
" you can consider an internal combustion engine as an `air burner'. If you increase the amount of air in the cylinders, then an increased amount of fuel can be burned. Because fuel burned is power available, the horsepower is increased. The price you pay is increased engine wear because of the higher operating pressures and increased heat output."

I studied and I'm right.

In any case, that doesn't address the operating parameters, nor the warm-up, cool down, or other facets of operation that most operators neglect. You are giving the turbo a five minute cool down after landing, right?

As stated before yes we allow for proper warm up and cool down, no we don't cool the turbo for 5 minutes, we cool it for 4 minutes at 1000rpm as per the POH.

Aaah, again, wrong. You really should study a little on this, before you pursue it. Next you'll be telling us you can tell the condition of the oil by it's color, or that the color has any meaning at all (it does not). Not such a nice try. READ!

http://www.nordicgroup.us/oil.htm#The Dark Oil Myth
"Dark oil does not indicate the need for an oil change. The way modern detergent motor oil works is that minute particles of soot are suspended in the oil. These minute particles pose no danger to your engine, but they cause the oil to darken. A non-detergent oil would stay clearer than a detergent oil because all the soot would be left on the internal engine parts and would create sludge. If you never changed your oil, eventually the oil would no longer be able to suspend any more particles in the oil and sludge would form. Fortunately, by following the manufacturer's recommended oil change interval, you are changing your oil long before the oil has become saturated. Remember, a good oil should get dirty as it does it's work cleaning out the engine. The dispersant should stop all the gunk from depositing in the oil pan."

I'll give you that one, but I still stand by that because the oil turns dark faster that there are more contaminates in it from blowby.

Again, very wrong...more than apples to oranges there...no comparison between circulating an operating fluid through a non-combustion transmission, an entirely different chemical formulation from engine oil, and engine oil in an internal combustion engine. Why not compare toe nail polish to beer? To what systems are you referring to remove "blow by?" Are you talking about crank case breathers? You understand that there's a lot more going on in that crank than merely venting for "blow by," and that the breather is necessary even if there isn't any "blow by?" You do get that, right? You're aware that some companies had systems for many years which pumped raw fuel into the oil after shutdown and before start as part of the oil dilution system...intentionally putting combustion products into the fuel, right?

Yes I understand that you need a crank case breather for more than just blowby gases. But their main purpose is to provide pressure equalization of the crankcase and remove blowby gases. Also you can not honestly tell me that if you increase the pressure in the cylinder that you won't increase the blow by gases. Piston rings are not a prefect seal, this is why we get oil consumption and blowby gases. So since it's an imperfect seal any increase or decrease in force exerted on it will increase ore decrease the amount of gases that pass by it. Also yes, transmission oil does have a slightly different formula, very slightly. But you even stated in your response why it last longer as I did originally, because it's not in a combustion engine. Why does that have anything to do with it? BLOWBY GASSES! An internal engine has it a transmission doesn't. PAY ATTENTION!

http://www.autoshop101.com/forms/h63.pdf
http://www.bobistheoilguy.com/blowby.html

"Blow-by occurs when the explosion that occurs in your engine's combustion chamber causes fuel, air and moisture to be forced past the rings into the crankcase."

[SIZE=-1]"Blow-by inhibits performance because it results in a loss of compression. When the expanding gases slip past the rings they cannot as effectively push the piston down and make the vehicle go. As a result the car will have less horsepower. This also results in a loss of fuel economy. [/SIZE]​

[SIZE=-1]When the fuel, air and moisture slip into the crankcase they contaminate and dilute the oil in the crankcase. [/SIZE][SIZE=-1]Among the many gasses in your compression chamber are unburned fuel, moisture, sulfur dioxide and soot. Once these gasses slip into your crankcase they can dilute into your engine causing great damage. "[/SIZE]​

Actually no. A properly designed induction in a normally aspirated engine will experience a ram air recovery and even ram air rise with the ram effect of the propeller and forward airspeed...getting thirty inches or more is not uncommon in normally aspirated airplanes close to sea level.

One surely can get full barometric pressure in a normally aspirated engine...especially at sea level. As for the explanation about an engine at rest at sea level...you assert that pressure damages engines, and the terrible, awe inspiring tubonormalized setting of 30 inches of manifold pressure is causing excess wear in your engine...no it's not, and that's no greater value than you'll see on the gauge when the airplane sits for extended periods doing absolutely nothing. The manifold pressure you're seeing on the gauge is irrelevant. You get that part, right?

Yes 30 inches are uncommon even at sea level in a N/A engine. Ram Rise is insignificant in a piston engine A/C. The MP indications are not insignificant since they indicate directly what the pressure is in the intake manifold, thus the power that will be produced. Sitting on the ramp is irrelevant since the engine isn't running it's not producing power or heat thus not incurring wear! A/C do not operate at sea level for more than a few seconds since the second you leave the ground your going above sea level and pressure drops. Also again no piston A/C has cruise setting for 100% power, most cruise between 75% and 55% power.

Last I NEVER said excess wear, I said INCREASED wear, which with the articles I've listed prove my point. By increasing your manifold pressure your increasing your power out put, increasing your heat output, increasing your wear, and decreasing engine life.

So before you go spouting off about how great you are and why pilots shouldn't doddle in mechanical affairs, take alook at your flawed idea's.

Now I've shown you proof and wasted far too much time on this thread, I'm done.

 

[VNugget]

How many are prohibited or limited from doing so?

Where did I imply any were?

 

[CA1900]

I spent a lot of time cruising at SL, most of the time with an engine shutdown.

Fishing with a beer in your hand doesn't count...

 

[DC8 Flyer]

Fishing with a beer in your hand doesn't count...

It doesn't?! Well crap, there's 8000 hours from the logbook......

 

[orcfi]

There are numerous factors that contribute to engine life. Cylinder pressures are one reason, the higher the pressure the hotter the cylinder walls get. If the cylinder walls get hot, valves cannot cool properly, since they distribute heat through the cylinder head. If you want to increase engine life (no matter what engine MP/RPM combo you use), you must lean properly. If you are above 85% on any piston engine, you must run a full rich mixture, period. Above 9000 in a normally aspirated engine, no matter where you lean it, you cannot hurt the engine because the engine isn't putting out enough power. In a turbo charged engine (or a normally aspirated one at high power settings), that would be 70-85% power, you must stay away from leaning for best power (40-100 degrees rich of peak). When you lean to these settings, you increase horsepower, but you also are in peak pressure range and your CHT's are the hottest. Exhaust valve temperatures are the hottest at 25 degrees rich of peak. So, opeating at high power settings requires leaning to 70-100 degrees lean of peak. Cessna teaches new owners to run their engines 50 degrees rich of peak. Look in aero trader or something like that and see how many T182's and T206's that have already had a jug or top end done before reaching 1000 hours. Look at a Columbia or a Cirrus, these guys preach lean of peak and they aren't having problems with this. A common LOP power setting on a TSIO550 is 31.5" and 2450 RPM with 17.5 GPH fuel flow. This settings is way over square, but you have cool CHT's (usually between 330 and 360), low cylinder pressures, and still have a pretty decent true airspeed. Running lean of peak with an engine like a TSIO550 multiply 13.7 times the fuel flow and that will give you the horsepower output at that setting (only works LOP). So, I kind of got off subject with this, to make a long story short, run lean of peak, and get a good engine monitor.