The Secret is in the Slant!
Tetraethyl lead was an effective and cheap octane booster, but it was not the only one, and the initial lack of a high-octane unleaded fuel in the '72-'79 timeframe was mostly a result of oil company marketing decisions based purely on sales volume and profit margin -- which I say not to slam the oil companies, just as a statement of fact; they devoted their limited pump space to the products that would sell in the greatest volume. Amoco sold a high-octane unleaded gasoline as a specialty product in some Eastern states as far back as the late 1950s; there was no lack of knowledge of how to make it, there just wasn't demand at the pump for awhile.
More generally, remember there were a bunch of things going on all at the same time in the first half of the 1970s. It wasn't
just the lead coming out of gasoline, it was also the new and rapidly tightening exhaust emission regulations, it was also the change from SAE Gross to SAE Net horsepower which made any given engine produce a lower number, it was also the change from gasoline pump octane labelling stating the RON to stating the AKI, which gives a number substantially below RON for fuel of any given knock resistance.
The difference is not small, it's large. For years, starting in the mid-late '50s, the standard octane rating of regular gas at sea level was 90 to 91. A 91-RON fuel will usually have an AKI of 87. Look around you…what's the octane of regular unleaded? It's 87! Likewise, the 91-93 octane premium unleaded is equivalent to about 97-99 RON. So the numbers really have not changed much at all. As for the "Super 100++" types of claims made back in the '50s, keep in mind octane regulations were a great deal looser as were truth-in-advertising laws at that time. But even if some of those fuels were in fact of 100+ actual RON, you can still get that kind of fuel today. It's not at every gas station, but a lot of Sunoco stations and some others have an extra-high-octane super premium (94 AKI, about 101-103 RON), and unleaded racing fuel is also available.
Gas mileage and performance was the pits for awhile there in the '70s to early '80s as automakers worked on figuring out how to clean up the exhaust effectively
and with minimal detriment to fuel economy or performance
and cheaply, all at the same time. They eventually figured it out; witness the cars we have today with 10:1 or higher compression, zero ping on common pump gasoline, perfect driveability, and clean exhaust. But for the first decade or so of serious emission control, they were playing catch-up bigtime, prevented by antitrust-paranoid legislators from forming an industry consortium to figure it out together. Read "Iaccoca"; each company had to do its own R&D independently of any other company (AMC got a special exemption to buy emission control technology from other automakers). So it took longer and cost more than it otherwise would have.
And yes, it really did need to happen. The air first in major cities and then in minor ones really was filthy -- dangerously so -- in the '60s. Now, fifty-one years after the very first emission control device (PCV valve) first hit the roads in California, we have a whole lot more people driving a whole lot more cars a whole lot more miles…but the air is a whole hell of a lot cleaner. That would be a freakin' miracle except it's not. It's the result of a whole lot of very smart, talented men and women putting their brains to work on the problem.
The catalytic converter, often blamed for killing car performance in '75, in fact did the opposite. The '74s were detuned with retarded timing and lean jetting and high-dose EGR on the jagged edge of where the engine would even run (poorly, and with lousy driveability, performance, and economy) just to squeak past the 1974 Federal emissions type approval tests so they could be offered for sale. And "squeak" is exactly what they did; there would not have been any way of meeting the '75 standards without an effective catalytic converter. Once that was developed (just in time; read
this interesting article), it gave back a lot of room to jet the carburetor and calibrate the spark timing for driveability, economy and performance again and let the catalyst clean up the resultant dirtier exhaust. Sure, there were some dumb early catalytic converter designs (GM's restrictive pellet-type units, Ford's half-system, etc.) but that all got figured out pretty fast, too.
How is it better? Does something in it build a cushion on the valve seats like leaded fuel did
No. That need has been obsolete for decades. Virtually everything on the road has hard valves and seats, and those few left that don't, will get them at next rebuild.
will I have to take my 1964 slant six head and have hardened seats installed
No, they'll last quite awhile on unleaded fuel in anything like stock-type service. If the exhaust valve seats go away sometime in the future, you have hard seats put in as part of the rebuild. It's routine and inexpensive; any machine shop competent and equipped to do a head rebuild at all would have to be competent and equipped to put in hard seats. Total non-issue. Obviously if you're running the motor harder than normal driving, that day will come sooner.
Is it better, in that I can actually run 15 pounds of boost in my turbocharged slant six without fear of detonation, as I could have with the earlier fuel?
Tell me more about the (street) fuel you were burning, and when, in your turbocharged 15-pounds-of-boost slant-6 without detonation. It's not that I don't believe you, it's that I would like more details, please.
I don't see any kind of a significant improvement in currently available gasoline, compared with the gas I could buy when I was a youngster.
I don't remember which well-respected engineer (maybe from Ford?) said it, but it was something like "From today's perspective, we designed and configured engines back then almost to run
in spite of the lead in the gas!". Obviously that's not quite true (he said "almost") because there was the exhaust valve/seat issue, but the hard-seat cure was well known back then, hard seats being used routinely in engines running on propane, natural gas, etc. Lead was a cheap and effective octane booster, but it substantially worsened the fuel in other real ways.
There's a lot I don't see because I don't know what to look at/for, so I wouldn't recognize it on sight, y'dig? I am not an
expert in motor fuels and emissions and such, but I do know a fair good bit about the subject -- enough to read and understand studies and news and technical documents on the subject. And one of the things I understand from having read and understood a lot of that kind of material on this subject is that while it was a rough ride in the beginning, in retrospect moving to unleaded has done only good things for the health and lifespan of vehicle engines. Leaded fuel craps up the combustion chambers and ports, because the scavengers don't burn cleanly, and without the scavengers the lead itself would accumulate in there and really ruin things. Spark plug life tripled with unleaded instead of leaded gasoline. Oil contamination likewise is much slower and less severe when the engine's running on unleaded instead of leaded. Also, exhaust system lifespan is much greater with unleaded than with leaded.
Has anybody reading this ever heard of a person or persons dying (or, even getting sick) from automobile exhaust fumes containing lead?
Actually...yes! There's been an enormous amount of brainpower and careful observation and study applied to that question, all over the world, for quite a lot of years now. The exhaust from vehicles burning leaded fuel is really and extremely destructive to the health of actual, real people in three main ways:
1. Because leaded fuel means no catalytic converter, the exhaust contains much higher concentrations of unburned hydrocarbons, carbon monoxide, and nitrogen oxides, all three of which are well known and shown, in concentrations well below those that existed in major American cities when all cars burned leaded fuel, to make healthy people sick and sick people sicker and sicker people dead sooner.
2. The lead itself accumulates progressively in humans. It is a neurotoxin and it causes and worsens a long and ugly list of very real diseases and other bad physical and mental health conditions. Many of these conditions used to be considered normal parts of life and advancing age, but then they took lead out of gasoline and the rates started going down and the age of onset started getting older.
3. The lead is toxic to the brain development of children, before and after they are born. Specifically, it degrades their ability to learn and it greatly increases their tendency towards violence and crime. The effect is not small, and once scientists caught a hint of what might be going on and took a long look, the data produced a graph of the decreasing crime-and-violence rate of particular age groups, which tracks damn near exactly with the graph of decreasing ambient lead levels, which tracks damn near exactly with the graph of the phaseout of lead from gasoline.
The data's published and easily available. It looks to me like very well done science, done without bias, and with conclusions repeatedly confirmed over the years and around the world. We owners and drivers of obsolete cars have to adapt to a world that caters for recent-model vehicles. Generally the adaptations are small and easy, and it is a small price to pay because absolutely everybody benefits enormously in length and quality of life from unleaded rather than leaded gasoline. It really, really is better this way than the way we used to do it.
