I understand exactly how you're thinking Judge. And to make it clear as well, I'm not gonna say you're wrong in any way. Just my knowledge of engines in general point to a totally different conclusion.
My biggest problem with that guys post was the fact that he generically pointed out that the manufacturers just make it easy on the user. I don't believe this in any way, personally. If you think about it, an engine running at WOT will produce maximum heat, yeah, but also any engine that is ran at WOT is causing itself the highest amount of stress that it can go through.
(Just incase it isn't known by everyone, WOT = Wide Open Throttle)
My biggest problem with this is the wear principles. Almost everything you can get that has moving parts needs a period of breaking in. Where all the small flaws are worked out and the parts fit perfectly. This is especially true for ringed piston engines, as the rings will not seat properly until everything is just right. This is where two stroke motors really change against four strokes.
Basing the idea off of compression, the ABC non-ring motor is the same way, without the problem of rings being in the way. HOWEVER, rings bring longer engine life, and higher compression results during the lifespan. Almost anyone knows that running a ringed motor at WOT is bad in the first hour of the motors life, because rings seat on the cylinder walls constantly. Friction being the evil side here, all said and done, the wear-in period will cause the rings to seat in a perfect fashion and vwala, higher compression = more power.
ABC non-rings are different in every aspect, but very similar indeed. This "pinch" spot has many similarities, however it is very different. Being a cone shaped cylinder, the piston requires oil/fuel to cause compression to be at max. The oil/fuel here actually act as the rings, and cause a seal when the piston is near the pinch. BUT, without rings to support the piston in a certain place, the piston has every chance of tapping the cylinder wall. This is especially true during break-in periods where the pinch is low, and the tolerances are TIGHT. Heat does cause the cylinder to expand and create sloppier tolerances, however this doesn't always hold true as it is still possible to have the piston touching the cylinder wall.
Consider the lean vs rich idea. Richer just adds more fuel to the mix, causing this sealing effect to be higher, where it doesn't really ADD to the compression, but helps keep the piston off the walls even more. Running extremely lean, reduces the effect, causes more friction, higher temperatures are a direct result. This is why the motor will actually lose lifespan during lean settings. Less friction = longer life, but with less power. The engine can actually struggle to keep ignition and this is due to the ignition cycle. However, that's not important for this discussion, so I'll end this part here.
Now, back to the topic, thinking of break-in periods. Wide open throttle doesn't necessarily induce higher amounts of fuel into the engine. It does however induce higher amounts during acceleration. This is the "blip" effect that so many people use for break in. Running at constant throttle just keeps the engine moving. One of the biggest reasons engines fail, whether it be ABC or Ring style, is constant wide open running. Where the engine doesn't have enough load to need more fuel. This is called high RPM, low usage. Picture a car, street automobile running at 100mph. The engine won't run any faster, but isn't pulling the car any faster. It's not requiring more power to pull the cars weight, and the other variables don't add up to being enough to drag the car down to this point. That's causing major heat, as the engine is running high rpms, however not working to potential. This is causing major heat and friction, and can cause failure rate to increase ten-fold.
I understand the idea with the propeller, as the engine would have the stress it would need for running at high RPM. ABC's work the same way as a ringed engine in this aspect. Thirsting for fuel, an engine that is undergoing pressure, from the propeller in this example, is going to be dragging more fuel through the fuel system to try to push the propeller to higher speeds. This power input, is actually good for the engine in respect. That's why the Aircraft engines last under pressure.
HOWEVER, there is a difference with a truck/car engine. Running at full throttle where the engine just can't achieve more RPM and the vehicle is going as fast as the motor can pull it; there just isn't enough stress on the engine. The engine will actually be lax, compared to with say, the propeller. This will reduce the engines need for fuel, and actually cause it to run leaner than it would with the propeller.
Engines work on two principles, Air and Fuel. When the engine is "lugging", or accelerating, it will drag as much fuel/air as it can through the fuel system as it can. (Fuel injection changes this aspect, but doesn't need to be discussed).
Now, during a breakin period, the motor will already be going through high amounts of stress, as the parts will be tight in the first place. I don't see how running at WOT would be of any assistance in this particular time. Idling can be damaging to an engine as well, however, it is easy to do and requires little work. This is true, but the engine doesn't go through much major stress, and idling in a specific spot decreases much of the engines cooling effects. So, the heating aspect is also there as well. If you think about it, an idling engine can actually run hotter then one running at WOT down the drag strip. The idling engine is getting no cooling, but the WOT engine is getting cooling from it's own movement. This mostly points to ambient temperature, however I'm not going into that.
Either way, I'm sticking with my idea, as it works well for me. Just remember, break-in is an important time of your motors life, and no matter how you do it, make sure you do it right. 🙂 I must now leave for work, as it's a little after 5AM.
By the way Judge, good post. Makes for a nice debate either way. 🙂
