leaded gasoline and octane
Geez, what's up with you guys? I loved leaded gasoline and I wish they still dispensed at the pump. My 327 has stock 11:1 compression and it loved 102 Sunoco when I could get it. Even 96 octane ethyl let me run 12 degrees initial advance. I can only run 4 degrees on the high octane unleaded crap they sell now; there's gotta be some difference somewhere.
Yeah, I know all about lead pollution from gasoline, but I never knew of anybody that died from it. We all used to wash parts it the stuff and we didn't even get sick from it. Lead will kill you alright, you've just got to take it in the right form, like lead acetate for instance. That stuff will go right through your skin and into your bloodstream in a hurry. But, they didn't put lead acetate in leaded gasoline, they used tetraethyl lead.
And there is the reason leaded gasoline worked so well to control combustion in high compression engines in the first place. Lead is simply the metal atom that the four ethyl functional groups are bonded to. Breaking the bonds from the lead to the four ethyl groups is what slows the combustion process. The metal molecule could have been antimony just as well as lead, possibly even cadmium or zinc. Lead was probably chosen because of economics alone.
If everybody is so concerned about air pollution, especially the self-righteous, federally funded EPA; then how come someone doesn't yell about all the jet airliners spewing hundreds (thousands?) of tons of hydrocarbons into the stratosphere every day? Would it be economic suicide to impose smog controls on the airlines? I bet it would, so they go unregulated by the EPA and you get smog controls on your lawnmower and cannot cook out on a bad air day. Hoo Boy! What a system we've got!
Anyway leaded gasoline is not the demon it's been made out to be, or I'd be dead instead of 50. High octane allows for high compression which allows for more horsepower period. If you think octane rating doesn't matter, fill your tank with hexane, it has an octane rating of about 0. Where do you get hexane? Coleman lantern fuel is mostly mixed hexanes, you can try that. I guarantee it won't even run good in a lawnmower, and it will absolutely destroy an automobile engine. Ever hear of anyone running on drip gasoline or casinghead. Same stuff more or less, just more impurities.
You can put 2,2,4 trimethyl pentane (isooctane) in a high compression engine like my Nova's and it will not ping or knock when you lug it in 4th! I know this from my own experience, I've burned a couple of gallons of the stuff contaminated with tetracholoroehthylene (TCE) from the EPA lab that I worked in for 14 years as a chemist. Isooctane has a octane rating of 100 and is the standard used in the motor octane rating of gasoline to this day. The 0 octane standard is n-heptane, but n-hexane could have been used just as well. What's the idea behind telling motorists that higher octane gas won't help your performance? I don't know, maybe they figure that the higher octane fuel by allowing greater initial advance, will cause more air pollution? That' my best guess because I really don't know for sure, even after 25 years of living with unleaded gasoline.
As to the original question of this thread, leaded gasoline will shorten your plug life to may 1/6 of what you'll get with unleaded. If you still have a catalytic converter(s), the lead will eventually and irreversibly poison the platinum/rhodium catalyst, and render it useless. Some types of converters (GM) will also stop up with extended lead use, although I don't think Ford converters are so affected. And leaded gasoline will generally dirty up your engine (internally) more than unleaded, specifically in the combustion chambers of the heads. I suppose it could leave deposits in your fuel injector nozzles as well, but maybe not. Anyway, these days, since leaded gasoline is history, I really can't see any advantage to using it in your engine, especially since so many years of engineering design has gone into making engines live on unleaded fuel. You would probably gain about as much benefit by dumping in a gallon of acetone into your gas tank as you would using the lead additive. I don't think I would do it myself.
Randy