a. It's the size of the block
b. It's the volume of air/fuel that is drawn in to the block for compression and combustion on every stroke.
a. is definitely correct; simplified, but correct.
b. is theoretically correct, but it is not correct in a practical context, as not all of that area equates to air/fuel volume in a practical application!. Dead space, pressure fluctuations, turbulence, imprecise metering, or metering tuned for a specific result, such as fuel economy, high torque at low rpm (such as needed by a truck towing a trailer, or a 4x4 climbing a hill), adequate heat dissipation at extremely high rpm (such as needed by a super speedway Nascar or Indy racing engine for sustained operation at or near its rpm limit)...these and other variables are what determine "the amount of air/fuel that's sucked into the engine". Some of these variables are controllable (yay), others are as yet not (ie: turbulence, boo).
Your explanation is as over-simplified as his. You do not attempt to account, or even acknowledge as existing, any of these factors. Regardless, it's rather a hollow argument, as, explained from your point of view, engine displacement figures merely represent the amount of volume that is
available.
Remember, 351 heads will bolt right up to a 302 block. In the old days of the 289, another long-discontinued engine from the same family (it's an old family), swapping 302 heads onto a 289 block was an extremely popular modification. Every third 289 Mustang in California was running 302 heads back in the mid-70's. Why? To achieve a higher compression ratio. You can change cam timing (with a hotter camshaft), install larger valves, modify air intakes, install a higher cfm carburetor (or, nowadays, higher rate injectors), like like a 650 cfm in place of the stock 450 cfm, to increase or decrease air/fuel volume in a cylinder. What is cfm?
CUBIC FEET OF AIR PER MINUTE. Ah...it's variable! You don't seem able or willing to acknowledge that.
If you decide to modify your 351, 351 CI is the gross volume you have to work with when you set out. If you go overboard with say, an 850 cfm Holly double pumper carburetor, you're going to have issues due to an overly rich a/f. In other words, you can fit more air/fuel into a cylinder than what was intended, but it isn't going to compress and detonate efficiently. Remember, air/fuel is compressible; it can be compressed via vacuum as well as by the piston on the compression stroke.
Anyway, on an engine that is running too fat (rich), soot and deposits from incompletely burned fuel will build up in the combustion chambers, which will cause all kinds of issues; increased valve clearances, fouled spark plugs, glowing deposits on combustion chamber surfaces and piston tops, which will eventually cause pitting and even possibly melt a hole in a piston. Also, glowing deposits can result in detonation; premature combustion of the air/fuel before the piston reaches tdc (top dead center) due to glowing deposits and excessive heat in a cylinder that is running too rich.
It's a common mistake I've seen a lot of rodders make on the assumption that 'bigger is better'. They throw on a hot cam, bolt on the largest cfm carb/intake setup they can find and then burn a piston or valve 5000 miles later. Aggressive mods like that are intended for overbored blocks and milled heads, but I've seen guys do it to the 3512v smogger engines in their mother's 77' Ford LTD in an afternoon, fire it up, and then ask "Why is all that black smoke coming out of the tailpipe?"
Or you can go the other way. Say you have a sticking or slow intake valve on cylinder #1. The timing on this valve is out of sync; it's slow and restricting flow to that cylinder. Now your problem is an overly lean (that's what it's called, but it equates to "not enough") condition. That will result in pre-ignition, detonation, and 'engine knock' due to that piston being weak on its downward stroke due to insufficient combustive force. It can't keep up with the other cylinders, which puts undue stress on rod bearings, rods, and crank bearings. If left untreated, bent rods and spun bearings could eventually result.
In the late 70's and early 80's, pre-ignition became a common issue on US-built engines as manufacturers were forced to start lowering compression ratios to meet federal emissions standards, and avoid 'gas guzzler' penalties. This is what accelerated development of fuel injection systems for gasoline engines. Closed, pressurized system allows for more precise metering and higher efficiency. Highly atomized fuel creates a more 'combustible' air/fuel mixture.
Wow. So now, go check your 'peer-reviewed' sources to see if I am correct. I could provide you links but hell with that...do your own research. Now, assuming I'm right, what have we learned?
Ah...the
available volume of a cylinder is not an accurate determinant of how much air/fuel it
uses. It is merely a gross rating of how much potential volume is available. Some of the variables, like turbulence, have yet to be completely eradicated through controls (due to their random chaotic nature, it seems). Other variables can be altered, for better or worse, via modification of intake, injection, and other components.
Hence, your argument is as over-simplified as the other guy's, as well as being founded upon an incorrect assumption. Maybe you didn't intend it that way, but that's the way you're coming across to me, and probably your friend as well.
FUCK!
Now, one of the reasons I am an exceptional teacher is because I understand the fallacy of branding people 'stupid'. I have worked with students who are exceptionally intelligent, students of average intelligence, and students on the low end. I will say this: intelligence and stupidity (unlike size and volume) are not synonyms. I have encountered exceptionally intelligent students who didn't give a shit ie: chose to remain ignorant. Fine, but not stupid. I have also encountered students who were somewhat slow on the uptake but overcame that deficiency through raw ambition and effort. Even better, but not stupid!
Patience and the ability to tailor teaching methods to individual student needs are essential to effective teaching. You obviously lack both of these, so shove your hastily-contrived judgment of me right back into whatever orifice you pulled it out of. I'd also recommend that in the future you avoid digging holes of technical ecstasy from which you cannot escape. It's entirely possible that your shine is somewhat less brilliant than you perceive it to be.
Again, credulous of me to judge, but at this point I must place both you and your friend in the 'intelligent, yet ignorant' category. Not an insult. You've earned it, but I still won't call either of you stupid.
You see, the very reason I decided to partake in this thread stems from the same instincts that make me an exceptional teacher. In this country's native language, 'stupid' is considered a very harsh, demeaning, insulting adjective to throw at someone. If you do so, you'd better be able to back it up with either your fists or extremely obvious evidence. You have not provided such evidence. All you've furnished thus far is an invitation to a condescension circle-jerk. If they're stupid, you're a genius, is that how it works?
Fuck that one-sided bullshit.
Have a nice day.
SU
I'll usually attempt to make the correction and explain myself once, twice if they're semi-important/respected, and then ignore and express disinterest in the subject if they keep windbagging.
