Tetraethyl lead was primarily used as an antiknock property, if I can believe anything I've ever read or been taught about it. For example, this patent from 1939 specifically says that tetraethyl lead is an anti-knock additive, and this biography references plenty of sources from the 10's and 20's, and claims tetraethyl lead was the result of years of research into anti-knock additives. It also claims that Ethyl was the name for a small amount of tetraethyl lead that was sold to consumers, so they could add it by hand, as well as the name of the company that marketed and sold leaded gasoline.
Tetraethyl lead was primarily used as an antiknock property, if I can believe anything I've ever read or been taught about it. For example, this patent from 1939 specifically says that tetraethyl lead is an anti-knock additive, and this biography references plenty of sources from the 10's and 20's, and claims tetraethyl lead was the result of years of research into anti-knock additives. It also claims that Ethyl was the name for a small amount of tetraethyl lead that was sold to consumers, so they could add it by hand, as well as the name of the company that marketed and sold leaded gasoline.
Schneibster
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It has antiknock properties, but the cylinder heads on an engine designed to burn leaded gas must be refitted with valve guides that are self-lubricating and hardened steel seats or you will burn the heads if you burn unleaded in it. I did not know that the design of engines was not the driving consideration (heh); thank you for the information.
joesixpack
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Octane is not a measure of efficiency. It is a measure of resistance to detonation or pre-ignition.
ponderingturtle
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I will note that after reading my manual, it seems that regular will not hurt my engion, I just will not get optimal performance out of it in terms of efficency or power.
So it I load it up, I will think much more about putting in the 91 or higher that it reccomends.
So it I load it up, I will think much more about putting in the 91 or higher that it reccomends.
Just thinking
Philosopher
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Is this because the anti-knock sensors will compensate by retarding the ignition? If this is so, it will be better for you to run the higher octane -- high enough to prevent the car from retarding the ignition. This is a safety feature put there in the event you either get bad gas or only have lower octane fuel available to you (in a pinch). It's really not good to keep letting the engine run in this condition. Although fuel burns very quickly in a cylinder, it is still a controlled burn, and as such, your engine was designed and engineered around that burn duration for optimum performance and fuel efficiency. Yes, with newer engine technology we can eliminate the harm done by using the wrong fuel -- but at a cost. It can include loss of power as well as incomplete combustion -- which wastes fuel. Using the proper grade fuel is your best bet for all around performance, longevity and efficiency.
joesixpack
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I think your fuel efficiancy drops when the anti-knock sensor retards your timing. I have an old Toyota Previa. It has a four cylinder engine but it's supercharged, and the owners manual recomends mid grade (89 octane) or higher. Well, I didn't read the manual and I was putting 87 in there. Once I actually started using the higher octane fuel, my mileage went up by about 20%.
ponderingturtle
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Hmm, and that would be enough to counteract the price difference.
Track your mileage for a while using the lower octane, then track it for a while using the recommended octane.
I find I get 10% better mileage using the proper octane. Lower octane gas only costs a few cents less than the higher octane (at least here in Germany,) so I come out ahead financially. Since I'm burning less fuel, it's also better for the environment.
Price comparison. Super runs to just a couple of cents more than normal - that's less than 2% higher cost for 10% more driving distance.
Track your mileage. See what kind of improvement (if any) you get. Decide for yourself which way is cheaper - cheaper fuel or better mileage.
trvlr2
Muse
Indeed, Tetraethyl lead was both an anti knock AND valve lubricating additive. Not necessarily in the valve guide department, tho. It seemed to make a coating on the hi-temp valve and seat area, helping to transfer heat away from the valve edges,to the cylinder head.
When tetraethyl was removed from the fuels, the valve seats(which were ground into the cylinder head-no such thing as valve seat inserts for production engines), and valves would burn up, erode?-losing their seal. Manufacturers responded with the hardened seat inserts, to be installed into the burned area, and ungrindable valves replaced.
*snip* originally posted by Schneibster:
No. In older engine designs, the valve guides in the cylinder heads required lubrication. Tetraethyl lead was added to the gasoline to provide this lubrication. Originally, there was a separate, more expensive grade of gas, known colloquially as "ethyl," that people would run a tank of every eight or ten tanks to provide this lubrication; then they eliminated this, putting it in all grades, in lesser amounts, because people would forget and damage their cylinder heads. But lead is known to be a poison, and also interferes with the action of the catalyst beads in a catalytic converter, so they had to make cars that could burn unleaded gasoline; to do this, they used bronze valve guides, because bronze is self-lubricating on steel valve stems. Today, you can't get heads that don't have bronze valve guides and require leaded gas; most even of the cars that originally required leaded gasoline have had their heads replaced with ones that can burn unleaded.
end of quote. underline mine.
Mixed information, some not even wrong.
Updating a former leaded engine consists of cutting the valve insert pockets into the cylinder head, installing seat inserts, reground or new valves. Valve guides probably would be changed, if worn, or knurled, and reamed to fit. Certainly the valve stem seals would be replaced. (these are the little seals which control the lubricating oil quantities on the stems and guides.) Yes Virginia, it's true- OIL lubricates the guides and stems!) (Where lubrication is used. See below.)
As far as the wonder qualities of bronze guides-some engines today have them. Some do NOT, using cast iron guides .Irregardless, both seem to work equally well.
Some engines have alloy(aluminum based) cylinder heads, some are cast iron. Same concerning engine blocks.
Trick with alloy heads & blocks, is the coefficient of expansion: it is greater than the steel , iron, bronze ,parts, and if parts are not fitted correctly-the parts loosen , with disastrous results. Also the reason today's alloy engines are so susceptible to cylinder head leaks from overheat operating condition.
Engineers work this out in advance-hopefully!Well, maybe not.
Consider this- about 1950, your run-of-the-mill Chevy 6 OHV engine had NO valve train lubrication(it was an option), nor did it come with an oil filter(option). Those omniscient GM engineers just tapped a gallery, strapped the oil line to the valve cover, with penetrations as req'd, to oil the valve operating mechanism. The filter was strapped to the side of the engine with a stamped steel bracket, tapped off a gallery, and drained to the crankcase.(by-pass, not full flow)Oh yeah-you fished the element out of the canister. Some elements had little wire bails by which to grab them .(messy)
Cool, huh? Autos which made 100K miles were rare!
I still remember my dad telling me "What's good for GM, is good for America!"
trvlr2
Muse
Mortfurd-You are right on! Keeping a book on your usage of gasoline ,oil, and your maintenance is the best way to optimize your auto experience. Properly used(ya gotta figure mileage,actually look at the record now and then) it can tell you when you may be having problems which have not drastically manifested, yet.
joesixpack
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Only if you have a car that has a higher compression ratio. A regular economy car (one that is neither turbo- or supercharged, i.e.) won't get any benifit.
Check the owners manual.
ponderingturtle
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I have a turbo charged forrester, so it is not a regular economy car. And it recomended 91 octain for the turbo model. But if it is just power and effeciency or does it effect engion wear or have detrimental effects like that is the issue.
joesixpack
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It probably won't hurt your engine because of the anti-knock sensors, but it will probably cost you power and mileage (at least, for my mini-van, I got better mileage, I can't tell any change in power).
ETA: I am not a mechanic or automotive technician, nor do I play one on TV. I hope that, if I'm wrong here a smarter person will chime in and correct me.
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ponderingturtle
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Well I could ask my grandfather, as he has written books on auto mechanics and taught it for many years. But he retired about 20 years ago, and so I am not sure if his advice is as valid with more modern engions, as he got out when all the sensors and computers where getting in.
casebro
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Not quite. Everything had valve train lubrication. The system you speak of was usually to add an oil filter, which was optional into the mid fiftys.
However, some engines did have troubles getting oil to the valve train. Ford 292's and 312's, frintace. Seems the oil came up through the block, and needed to pass through a hole in the head gasket. There was only one hole in an otherwise reversible gasket. If you had a valve job, and the mechanic put the gasket on backwards, no oil got up. So, rather than do all the labor to replace the gaskets, the mechanic would add outside plumbing to the block. They would plumb the oil line in to one of the rocker cover studs, since the studs also held the rocker arm shaft.
Otherwise, I agree with Trvlr2.
LTC8K6
Penultimate Amazing
Light knocking under heavy loads or hard acceleration is normal, btw.
If you have to make an effort to hear the knocking or pinging, it's fine.
It's the heavy continuous knocking that you must avoid. The kind you can hear clearly without turning the radio down. That will do damage.
Occasional light pinging is fine.
If you have to make an effort to hear the knocking or pinging, it's fine.
It's the heavy continuous knocking that you must avoid. The kind you can hear clearly without turning the radio down. That will do damage.
Occasional light pinging is fine.
Just thinking
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As I mentioned earlier it's really not a good idea to keep using your anti-knock sensors to prevent problems while running on too low an octane fuel -- you're in all likelihood not realizing any gain (lower mileage along with lower fuel cost = no net gain). And any car that is in need of using the electronics to offset using too low an octane will improve in power when the proper octane is used -- you might not realize it due to personal driving habits; but your mileage will almost certainly improve, and that you can easily measure. (Oh wait -- you did!! See.)
So what it boils down to is ... use the proper fuel.
Just thinking
Philosopher
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Years ago the above was very true indeed -- it meant you were right at the proper advance in your ignition timing for overall optimum performance. But with knock-sensors and variable ignition timing most cars will not knock -- instead they will compensate with less MPG and power.
LTC8K6
Penultimate Amazing
http://www.subaru.com/shop/specifications.jsp?model=FORESTER&trim=SPORTS_25_XT&command=features
If it would harm anything, it would be clearly noted, I'd think.
Now, if you have reduced power, you probably do need a little more throttle to do the same work. A few more revs to maintain the same speed, etc.
So it seems reasonble to me to believe you will get less mileage with the lower octane fuel if the engine was designed for higher octane fuel.
You are wasting your money if your engine was designed for 87 octane, unless you are knocking heavily and the higher octane cures that.
If it would harm anything, it would be clearly noted, I'd think.
Now, if you have reduced power, you probably do need a little more throttle to do the same work. A few more revs to maintain the same speed, etc.
So it seems reasonble to me to believe you will get less mileage with the lower octane fuel if the engine was designed for higher octane fuel.
You are wasting your money if your engine was designed for 87 octane, unless you are knocking heavily and the higher octane cures that.