Bad mpg?

[Antonm]

Error 5. You are taking a specific operating condition for a 6.2 and substituting it into a 5.3 and assuming the only variable that changes is manifold pressure. If/when throttle opens up a bit, so does engine speed. Edit: see engine dyno example below.

Negative there ghost rider, not true, not even a little.

Engine speed (RPM) is dependent on the ratio of power production to load.

If the engine is making more power than the load is holding back, engine speed is goes up. If the load being applied to the engine is greater than what the power the engine is producing, the engine speed goes down

We'll talk about this two ways/ give two examples of how you're wrong.

1.) First lets use your own engine dyno example (because you brought it up). An engine dyno places a load on the engine that can and is varied. Have you ever seen an engine being broken in on a dyno? The dyno operator will set the engine at some throttle position/ power level, then vary the engine speed up and down by raising and lowing the engine load. So the throttle position is not changing, yet as they lower the load engine speed goes up, and as the raise load engine speed goes down.

And the dyno operator can also park an engine at any speed (RPM) they want and just leave it there. This is sometimes done to heat soak the engine to simulate a towing condition.

Even during the dyno power pulls the resistive force/ load on the engine is varied to give a consistent rate of engien speed change, 300 RPM/ sec is kind industry standard. You can actually cheat a dyno by making the rate of change slower/the sweep time longer by reducing the rate of change to say 200 RPM/sec, because at the lower acceleration rate some of the power that was being used to accelerate the engines rotating mass can be absorbed by the dynos load cell, which makes it look like the engine made more power.

2.) Real world/easy to understand examples that don't require knowledge of dyno operation (which you obliviously don't have).
Have you ever driven a manual transmission vehicle and killed it with the clutch by letting the clutch out to fast? I have , a few times actually. Not terribly long ago I was teaching (well trying to teach anyway) my oldest son to drive a stick, he revved up the engine to about 1500 rpm , basically dumped the clutch, and the engine shut right off.

So while the engine had no load, it was running fine, he even opened the throttle some, but when he applied more load than the engine was making, engine speed went down (all the down in this case).

Here's another easy real world example that perfectly demonstrates that engine speed is determined by the ratio of engine power to load applied ,,,ever drive up a hill??
If you kept the same throttle position (and same gear selection) trying to climb a hill as you did driving on flat ground, the engine rpm would go down. Heck if its a steep hill, you might open up on the throttle and still have the engine speed slowing down.

And while this post is already getting to long, the whole discussion this was taken from was/ is abuot two engine of different displacements making the same part throttle power at the same RPM. And it even states that in your own damn equations that you don't apparently know how to read or understand. The "N" in the numerator of your power equation is engine speed.
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[Antonm]

Error 6. This example says the entire induction system upstream of the short block, is absolutely meaningless.

What the hell are you talking about this time? The last things you said were meaningless were two scientific laws (Boyels law and Charles law).
Not sure where you're pulling that the discuss about pressures at bottom dead cylinder were outside the short block, last time I check the cylinders where in the block, but I guess logic, reality, common sense and other such inconveniences hasn't stopped you from saying anything yet, so why should it now.
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[Antonm]

Error 7. The difference in performance between a 5.3 and 6.2 are only reflected at wot, and not at any other rpm range.

Not sure what your tryig to get across here.

Are you saying I only reflected performance differences at wide open throttle ,,,or are you saying that there are only difference at wide open throttle?

Because nether of those are true, but I'm not sure which one your trying to say is.
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[Antonm]

Put a 6.2 on an engine dyno.

See what power it makes at 14.7 afr at 1200 rpm. Record mass air flow and mass rate of fuel flow.

Put 5.3 on engine dyno. See what power it makes at 1200 rpm and 14.7 afr. Record the mass flow of air and fuel.

You will notice the 5.3 is making less power at same afr, same engine speed.

Power is Torque x rpm. Incorporate this into the power equation.

You do understand that you can make different powers at the same RPM , at the same AFR right?

SO far we've been talking about two engine making the same power, and power comes from fuel (seems like I'm having dejavu, its like I've said this before).

Lets show that you're wrong (again), it two separate ways (again). First lets use your own equations (because, I mean you brought them up, so you must think they're correct/ meaningful and wouldn't jump logic and flip flop like a politician to argue against them after being shown you wrong using), then we'll use a very simple to understand, real world, example that we've all experienced.

Equations first. You are overlooking the fuel terms (you have habit of doing that).

Look-a-there, a fuel rate term (see red boxes), that says if I raise or lower fuel rate, that this value will change. So even If were to leave B2 alone and just change fuel, torque would change,,,,,amazing. And even funnier, in plain English below that is says "Thing to Notice" (also red boxed, so maybe you'll notice this time),




So now lets talk about that easy to understand, real world example, of how you can make different power levels, in the same engine , at the same RPM and same AFR.

Lets say you're hauling ass down the road in an empty vehicle doing 80 mph at 2000 RPM, getting the best fuel milage you can at stochiometric ratio, on you way to the Home Depot (or Lowes, or whatever hardware store you like).
Now you load up the back with bags of quikrete from the store, like really load that sucker down, add like 25 bags or 2K lbs worth.

Now you're hauling ass back home, going down the same road, again at 80 pmh, again at 2000rpm, GM still wants to maintain catalytic converter life (because that has a government mandated warranty) so still runing at stochiometric ratio,,,,, but the vehicle has a higher mass now ,,,,so it takes more energy to move that vehicle now than it did before,,,,, what could possibly be going on ,,,,,,, oh yeah, you're injecting more fuel and making more power at the same engine RPM and same afr (just like your euation above said you could.

Another easy to comprehend rea world example. Lets say that someone wants to warm up their engine (or something), so they rev up the engine to 3000 rpm in park and hold it there with their foot n the gas. No load, making almost power. just revving the engine in park, heck their foot is barley even on the throttle because it takes very little throttle just to free rev it to 3000 rpm.

Now that same person puts the car in drive and take off down the road hauling ass at 100 mph with teh engine at 300 rpm again,,,,was that engine making the same power free revving in park as it is hauling ass down the road at 100pmh?? So something else beside B2 must be able to affect power output,,,what could that be,,, oh yeah buring more fuel.

So if one where to free rev the 6.2 in park to 1200 rpm (your example), then take a 5.3 and drive it around at 1200 RPM , the 5.3 will be actually making more power, at the same RPM, and same AFR. Of course if the rolls were reversed (which one just free revving and which one is driving), then the results would be reversed too.
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[Antonm]

Torque is proportional to SQUARE of bore size.

This is an insurmountable technical fact that can't be overcome by concocting a Boyle's law tautology.

The 5.3 is making less torque at a given rpm. This makes less power at same rpm. Same afr in both engines.

lesson concluded.

There is an "insurmountable technical fact" that you can't read and don't understand what your own equations are telling you.

Not only did you miss the fuel term, you even missed the big statement that says "Things to Notice". Like did you really think that when an engine is at given "X" speed that it will always be making a "Y" amount of power?

 

[Antonm]

The 5.3 is making less torque at a given rpm. This makes less power at same rpm. Same afr in both engines.

That is not always true. It is certainly true at wide open throttle, or anytime the capacity of the less powerful engine is reached. But it takes the same amount of energy to move the same mass at the same rate.

So when both engines are making low hp, just cursing hp, (which is what we've been talking about) both can draw in the same amount if air, burn the same amount of fuel and make the same power at the same afr and same engine speed. Your own equations have shown that, the smaller displacement engine just has to open its throttle body a little more to take in the same amount of air as the larger displacement engine.
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[Antonm]

lesson concluded.

Why conclude the lesson, you might actually be starting to learn something,,,, i mean yeah, probably not,,,, but you can certainly keep trying, maybe you'll get it eventually. Don't give up, maybe one day you'll grow out of your internet troll stage and actually become a useful member of society.
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[Antonm]

So a 6.2 isn't a 6.2 until WOT. Until that throttle position, it is the same as a 5.3.

Wow, you've said some really dumb things , but this is definitely top five material right here.

How does the concept of not needing to fill a space completely up allude you?

Here's a real basic analogy that should be easy enough to wrap your brain around ,,, get ready;

Lets say I like to drink 8oz of coffee every morning, that's how much coffee I've determined that I need to get going.

I could pour that coffee into a 12 oz mug ,,, but the mug would still only have 8oz of coffee in it, Likewise I could pour 8oz of coffee into a 20oz mug. Then I would have two mugs of different size, but both would only contain 8oz of coffee, which is less than the max capacity of either mug.

If I were to drink the coffee out of either of those mugs I would get the same amount of caffeine kick, even though one came from a 20oz mug and the other from a smaller 12 oz mug.

You know, this analogy could go work afr too....

Now lets say I've decided I like 0.5oz of cream in my 8oz of coffee (so my preferred coffee to cream ratio is 16:1).
I could pour that 8.5 oz solution of coffee and cream into either the 12 oz or the 20 oz mug, and if I were to drink either mug , they would taste exactly the same, and I'd get the exact same caffeine hit from them both, because both contain the exact same amount of all constituent components.

And similarly, you can also put the same amount of an air and fuel mixture into two different size engines, and because like the caffeine in coffee, the power comes from the fuel, so you'll get the same kick out of burning that fuel in both engines.

Now lets say I'm hung over, or had a late night, and I've decided I need twice my usual amount of coffee. Well can't fit 17oz of coffee/ cream mixture into the 12oz mug, so if i want anything over 12oz (or 1.411 times the amount of coffee I normally drink), I have to step up to the bigger mug. But anything up to 1.411 times the amount of coffee I normally drink , could still be handled by either mug. Just like anything up to 355hp can be handled by the 5.3.
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[Antonm]

I tell ya...what a rip off. To pay a premium for a 6.2 and it is the same as a 5.3 until at 90%+ throttle position.

And GM wasted a ton of money and effort designing the heads, intake, valve train, and throttle body when they could have just swapped over the 5.3 induction system.

If you never chose to exceed the power available form the less powerful engine , then it would a waste/ rip off.

Probably why way more 5.3 are sold than 6.2's, because people say/ think to themselves ,,,I don't need, or won't use that extra power , so why pay for it.

Personally I like the 6.2, makes driving, passing, merging just easier and more fun. Not that the 5.3 is a weak or anything (we test drove a few) and I'm sure we would've been happy with a 5.3 most of the time. But a 5.3 wasn't available in the models we were looking at (High County, Denial , and Escalade). I initially wanted the baby Duramax, but decided it was likely more trouble than it was worth, and went with the gasser option.

As far as the intakes go, they are pretty similar, yeah the 6.2 is bigger because it has to flow another 70-ish hp worth of air eventually, but they're not drastically different, especially at part throttle when neither intake is actually being taxed and can easy flow the air demanded (which again, part throttle operation with both engine making the same power has been the topic of the discussion argument thus far).
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