Best octane booster? (engine, Benz, gasoline, 1967)
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
You've got two concerns when you operate a car with a (relatively) high compression engine designed in the days of tetraethyl lead.
1) Lead resists valve seat recession. You're gonna want hardened valve seats at some point, I predict. Octane by itself won't help you with this problem; there may or may not be other types of additives that will help. I don't know much about the Firebird OHC, if it has an aluminum then the inserts will be hard enough, but cast iron will be prone to it.
2) Lead and high octane resist pre-ignition and detonation (the little-holes-in-the-tops-of-the-pistons problem). You need to tweak ignition timing and fuel octane (since you can't tweak lead content, it's got to be zero) to avoid detonation. The general rule back in the day was that very occasional light pinging under heavy load and high temp was judged acceptable, but no more than that. You may also be able to adjust your vacuum and centrifugal advances to reduce/eliminate pinging.
You’re fine running the high octane from Costco. I use it in my Panoz Roadster and my S4 Audi, the latter with an 11:1 CR. Most so called octane boosters have very little effect on octane rating. If you want to actually change the octane rating more than a few tenths, use a race fuel concentrate like Torco.
Both your Audi and your Panoz employ modern engine management systems and will adjust engine parameters should the fuel you're using induce knock or pinging. The OP's '67 Firebird has no such engine management system. As such, you can't conclude that because a certain fuel works fine in your modern car, it will also work fine in an older car with an equivalent CR and no engine management system.
Octane increases the compression ratio. The higher the compression ratio, the better the horsepower of the engine. .
The compression ratio is defined by static physical components (the piston head shape, combustion chamber volume, etc.) Octane booster can not increase the compression ratio, period. Higher octane fuel simply slows combustion, thereby reducing knock and ping.
Last edited by YourWakeUpCall; 11-23-2020 at 04:17 PM..
The compression ratio is defined by static physical components (the piston head shape, combustion chamber volume, etc.) Octane booster can not increase the compression ratio, period. Higher octane fuel simply slows combustion, thereby reducing knock and ping.
It is amazing how many urban legends surround octane. the gasoline companies have done such a great job marketing premium gas to make people think it will make a car run better, faster, cleaner, more powerful ect. People just will not let it go. Premium gas makes a high compression engine run properly. That is all. Nothing more. High compression does not necessarily mean more powerful anymore. By way of example, my 390 hp dodge pick up uses regular octane gas. It probably produces considerably more horsepower than that Firebird will on premium gas (I do not remember the year of the firebird, but if it is from the mid 1970s to early 1980s it is probably less than 190 HP on premium gas).
Location: By the sea, by the sea, by the beautiful sea
68,364 posts, read 54,583,164 times
Reputation: 40841
Quote:
Originally Posted by Pilot1
Guys that have old muscle cars that can run on leaded gasoline, come to my airport and buy 100LL aviation gasoline and mix it 8/1 with auto fuel. I don't know if that is the correct ratio, but that is what they tell me. I am paying $5/gallon right now. So if you have small airport near you, you can go there to buy it.
For older cars made for leaded gas the lead in Avgas may be just as important as the higher octane. Or maybe there are additives out there made to ease the life of valves and seats missing the effects of lead in their fuel?
Another problem for old muscle cars is that they have removed the zinc from engine oils, since it interferes with catalytic converters. The result is high camshaft wear in vehicles with flat tappet camshafts.
There are special purpose motor oils with added Zn content. This is important but not related directly to octane in fuel - but it's another thing you have to consider in running older vehicles.
I should also have pointed out that a lot of benefit can be derived from modifying the combined vacuum-centrifugal advance curves of the distributor to reduce/avoid pinging/detonation. In the pre computer days that was a basic feature of hot rodding standard distributors and one of the features of aftermarket distributors was the ease of modifying advance curves.
Octane increases the compression ratio. The higher the compression ratio, the better the horsepower of the engine. .
Well that is total nonsense. The compression ratio is determined by mechanical factors in the engine. Fuel will not change piston and combustion chamber design.
Higher octane will not make your car run better, cleaner, or faster. You only need high enough octane to prevent pre-ignition. Octane does not work that way. If your car is not pinging on acceleration, you are fine and anything else is a waste of your money. Cracks me up when people use 104+ and think it is improving performance, or power or making their engine cleaner. If you are not getting pre-ignition, more booster is like putting socks on a chicken.
Amen to that. In my modest experience racing motorcycles, a very few specially-built bikes at the "Clubman Level" needed the actual track gasoline with 100+ octane. Most tracks have a couple pumps with this. And we paid a pretty penny for it. My buddy's highly-built RZ350 two-stroke needed race gas (plus premix) so we'd pay our six bucks/gallon or whatever it was back then at the track. Not using it would have caused detonation and an expensive blown motor, two strokes can be delicate (or at least that one was). The gasoline was independent of "power," it just needed it, period end of story due to the high state of tune. And that RZ put down crazy power for a 350, as well, and was a real competitor in certain Open classes.
Factory and certain other built bikes needed same, with engines right on the scary edge of HP vs. reliability. More the former than latter!
Drag and others are another story entirely, of course. Alcohol, nitromethane, all sorts of exotic fuels.
Good point, anyway!
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
