And let's remember that an IC engine, in its best form is about 28-30% efficient. You can get a couple of points better but its costly.
The biggest loss of heat (power) is the exhaust. I remember my first data logger. I forget the brand but I had EGT's and all the rest. At that time...the sampling rate was 5 times a second!!! 5 times a second. At the time that was pretty good. A few short years later a sampling rate of 100 times a second was easy.
I mention this because it's relevant. This is because if you think about it, if you divide a second into five segments, and then understand that once you sample the data there is a huge gap in time until the next sample. Let me see if I can show this in text.
Let's make a dot the sample point and a dash the time in between the sample points. Sooooo...
.----.----.----.----.
That is five samples per second. What do you see??? Huge gaps between samples. That is all time the computer isn't getting information.
Now think about sampling 100 times a second and how much less time you have between samples. I'm looking at a data logger that can sample two hundred times a second.
My car at that time was a 9.80ish car. At 5 samples a second you only get 50 samples per run! That ain't much. If it was sampling 100 times per second, you'd get 1000 data points per run.
I said all that to say this:
The rate of change of almost any function you can measure happens so quick that transient response time is critical. IOW's things happen so fast that one system can't overcome another. As in, the rate of temperature change happens so quickly that even the head can't reject the heat fast enough to affect detonation resistance. I hope that makes sense.
Another thing I learned when I started data logging was even with relatively quick sampling rates, some other limits were expose. Such as transient response time of the EGT probes. Those damn things respond so slow it's almost useless to use them for anything other that cylinder to cylinder balance, and that can take you right down a rabbit hole all by itself. You make changes based on those slow buggers and you'll be sorry.
I also learned that when running alcohol (it happens on gasoline too but you have to be real rich to see it) if you get too far to the rich side the exhaust gas temp will go through the roof. I think the highest EGT's I'd seen on my junk was like 1660 or so. The headers should have melted off the car, the plug should have been missing it's ground wire and much more.
What happens when you get too rich the fuel doesn't get burned before the exhaust valve opens and that combustion continues into the exhaust pipe. It makes you think you are lean but you are pig rich and adding fuel makes it worse. That's just one more way a measuring tool can screw you if you aren't thinking about the entire process.
Slow ignition timing does the same thing.
Funny story. A customer had a friend who was running an ex Pro Stock Truck in Comp Eliminator. He called me from the pits and said my buddy has EGT's that are going through the roof and he's deathly afraid to lean it out as he can't afford to kill his engine.
I forget what engine it was but it was a Dodge. Anyway, I said what does he have for timing and jets? The timing was 24 degrees total and I forget the jets, but they were way too big. I said tell him to drop 4 jet sizes and put the total timing to 30 degrees. Make a pass and check the EGT's.
He was scared but he did it. Temps started dropping like a rock. He eventually got to 32 total and ended up dropping 8 jet sizes.
You can get real crossed up in a New York second of you ain't careful.
