1982 380sl leaded or unleaded

[greg_smith]

can some one tell me is it ok to use unleaded fuel in a 1981/2 380sl

[Dee8go]

Is leaded gas still available? I didn't know it was even an option anymore.

[TX76513]

Originally Posted by greg_smith

can some one tell me is it ok to use unleaded fuel in a 1981/2 380sl

Greg. If you are living in the US what else are you thinking about using?

[GermanMarque]

Originally Posted by greg_smith

can some one tell me is it ok to use unleaded fuel in a 1981/2 380sl

Here is a very interseting article, worth a read.
PUMA RACE ENGINES - UNLEADED FUEL - A TECHNICAL GUIDE
The introduction of unleaded fuel created a level of panic and misinformation rarely seen in the car world. Suddenly everyone needed to know whether their car would run on it without problems and firms offering miracle potions and other snake oil cures sprang gleefully out of the woodwork. Even now, 12 years after all new cars in the UK have had to be able to use unleaded from new, there is still a lot of confusion about the issue. Millions of pounds a year are wasted by people buying conversions they don't need and bolt on gadgets that don't work. They are preyed on by firms who rely on the subject being complicated and frightening enough that most potential customers don't really understand it and therefore waste their money for "peace of mind". To understand the topic fully you need to be an fairly well versed in physics, chemistry, metallurgy, engine design, combustion theory and Samurai sword making. Since that description only applies to about three people in the entire world, everyone else might as well carry on reading. Copyright David Baker and Puma Race Engines
The Early Petrol Engine
One of the first things that early engine designers noticed was that valves and valve seats wear out. Hardly earth shattering news because all highly loaded mechanisms wear out of course but exhaust valves and seats tended to do it rather fast. Early engines were made out of cast iron which is a pretty decent structural material but not ideally suited to the temperatures and loadings experienced inside a combustion chamber. Valves were, and still are, made from various grades of steel. Valve seats were machined directly into the cast iron parent material of the cylinder head. The problem that became apparent was that the material comprising the valve seat gradually wore away leading to the valve sinking deeper into the "throat" of the port. This reduced and eventually eliminated the necessary valve lash clearance in the valve opening mechanism leading eventually to the valve not closing at all and the seat then burning out very quickly indeed. Research into this wear, or "erosion" revealed what was actually happening.

See next post for the rest!

280SL

[GermanMarque]

The Mechanism Of Valve Seat Erosion
The rate of wear was far higher than pure frictional or mechanical considerations alone could account for. If one were to construct part of a dummy engine consisting of just a valve and a cast iron seat and cycle it open and shut millions of times on a test bench, very little wear would take place. What this fails to account for is the temperatures that are reached inside a running engine. Copyright David Baker and Puma Race Engines
Components inside the combustion chamber of a running engine are exposed almost continually to the heat of the burning air/fuel mixture. In the absence of any cooling this would be enough to melt the hardest steel. As it is, most of the heat is transferred away into the cooling system or flushed out as hot exhaust gas and the steady state temperatures of the various internal components obviously stay well under their melting points. The hottest component is the exhaust valve and its seat. All the heat picked up by the valve head has to be conducted away though the seat and to a lesser extent through the valve stem into the guide. The thinner the valve seat the less area there is for this heat to be conducted away - something many race engine builders ought to bear in mind. Temperatures in these critical seat areas can reach 800c which is enough to make steel glow red. This is still well below the melting temperature of steel (or iron) but enough to soften it somewhat and significantly reduce its strength. Part of the increased wear rate can be explained by this reduction in the material strength but it still only accounts for a fraction of the wear experienced. To understand the rest we need to make a quick trip to Japan.
In conventional welding it is necessary to melt both the parent material and the filler rod. A "weld puddle" is formed directly under the torch or arc in which the two materials melt, run together and then cool as one. There is another way of joining metals without melting them though. When a sword is made it is heated till it glows yellow and then hammered into shape. As the strip gets thinner and wider it is folded over onto itself and then heated and hammered again until the two layers join together and the process repeats until many layers have been rolled over and forged into one. The process is one of heat and pressure which together achieve a similar result to that of the higher temperatures of "melt welding".
Now back to valve seats. The temperatures over a seat won't be the same everywhere. High spots and minute flaws in the material can reach higher temperatures than their surroundings because they are less well cooled although they still won't be anywhere near melting. Under the pounding of the valve these imperfections form microscopic pressure welds between the valve and its seat just like the forging of a sword which then get burst apart next time the valve opens and a speck of material is lost. Each weld might be too small to see but over millions of cycles they combine to form erosion which wears away the seat and pits the valve. Copyright David Baker and Puma Race Engines
The higher the temperatures inside the combustion chamber the more these welds are created and the erosion speeds up. So a very important factor is how hard the engine is used. At low rpm and small throttle openings there might be very little wear even when the materials are not ideal because valve and seat temperatures stay low. Under more severe operating conditions the wear rates can increase exponentially. What might be deemed acceptable wear rates then depend very much on the expected life of the engine and its operating conditions. Inlet valves are not generally a problem in any case because they run at much lower temperatures than the exhaust ones.
Solving The Wear Problem
The first and most obvious thing to do is use tougher materials for the valve and seat to resist the wear. Exhaust valves already had to be made of a very tough steel just to withstand the operating temperatures and it was the cast iron seat in the head that was the primary concern. Machining a recess into the seat area and pressing in a tougher steel insert provided an easy solution to the problem but was expensive. So research took place into additives to the fuel to find out if anything would help resist the erosion process more cheaply without modifying the cast iron seats. This also came about as part of the research into raising the octane number of fuels to enable higher compression ratios to be used without detonation and hence increase power and improve fuel economy. A substance that stood out as being very effective in both raising the octane number of fuel and also preventing seat wear was tetraethyl lead (TEL). How exactly it reduces the erosion is not clear but it seems that a thin coating of this material on the seat prevents the microscopic welds from forming. TEL was added to petrol in amounts up to about 4 grams per gallon depending on the level of octane boost required. As concern about lead emissions grew, the amount of TEL per gallon dropped until finally unleaded fuel became mandatory.
Aluminium Cylinder Heads
Aluminium has gradually replaced cast iron as the material of choice for cylinder heads until nowadays almost all petrol engines have them. Aluminium is much lighter and easier to machine but is far too soft for a valve to run directly on it. So all aluminium heads have to have separate seat inserts by definition. How well such inserts resist erosion depends on what they are made of but as a general rule any modern aluminium head will have inserts that are tough enough to resist erosion many times better than plain cast iron. Copyright David Baker and Puma Race Engines
What Is Meant By "Suitable For Use With Unleaded Fuel"?
Here we start to get into one of the areas of confusion when people are trying to find out, perhaps from the OE manufacturer, if their engine is ok to run on unleaded fuel. Let's firstly be clear about one thing. There is no such thing as an engine where the valves and seats don't wear at all because these are after all heavily loaded components. What is really being asked here is "will the valve seats last an acceptable period of time on unleaded fuel?". The answer to that is really "acceptable to who?". It depends on the view about engine life that the OE manufacturer took in the first place. You might perhaps expect a Mercedes to be built from higher quality materials than a Ford and have a longer design life to start with. There are hundreds of different materials that can be used for valves and valve seat inserts and every car manufacturer will use different ones from different suppliers depending on cost and design constraints. Even when leaded fuel was the only choice there were engines that lasted a long time and engines that didn't. All we can really say therefore is that a car sold after 1989 in the UK will run on unleaded for as long as that manufacturer decided was a minimum design life for the engine. A car built before 1989 might run for a perfectly acceptable period of time on unleaded whether the manufacturer says it is ok to do so or not. And don't forget that there is very little incentive for an OE manufacturer to say that a particular pre 1989 engine type is perfectly ok for use with unleaded because if something wears out there might be a claim against them. The safe option is to say no. So there are plenty of vehicles that in my own opinion run fine on unleaded with very little wear despite the manufacturer saying otherwise.
When I'm cutting valve seats it's fairly easy to tell how hard the material is by how easily it cuts. There are certainly major differences in the types of insert material used by different car manufacturers or between different engine models from the same manufacturer.
The same question applies to someone taking their cylinder head to a machine shop for a "conversion to unleaded". What quality of materials is the machinist going to use? A higher quality insert might last longer than a cheaper one but in practice either of them is probably going to be fine for normal use.

[GermanMarque]

It's worth restating that all this hinges greatly on how hard the engine gets used. Even a plain cast iron valve seat might last perfectly well if you never use the car hard. A supposedly "unleaded suitable" insert might wear out very quickly in race use.
So in summary there is really no such thing as "suitable for unleaded". There are just a range of materials which will have longer or shorter service lifetimes. Only with plain cast iron can one really say that it is unsuitable for unleaded in anything other than very gentle usage. Copyright David Baker and Puma Race Engines
Can I Use Unleaded In My Engine?
All engines made after 1989 can run unleaded with no reduction in service life. For pre 1989 engines we can summarize all of the above into two rules - one for cast iron heads and one for aluminium.
Cast Iron - A cast iron head without exhaust inserts is not suitable for unleaded except for very gentle use.
Aluminium - Any modern aluminium head (let's say post 1975) will have inserts that are able to run on unleaded petrol, even when the OE manufacturer says it is unsuitable. What they mean by "unsuitable" is that they are unwilling to guarantee the same 200,000 mile or so service life that they would expect from a post 1989 engine. They do not mean that the engine will suddenly and immediately fail just because you run it on unleaded petrol. In practice it will have no impact on the average car owner at all given that very few people keep their cars that long. If you have an aluminium head from a major manufacturer (Ford, VW, Peugeot, Vauxhall, Fiat, BMW, Mercedes etc) then stop worrying and just run it on unleaded. The worst that can happen is that eventually, in 100,000 miles or so, the valve seats will have pitted enough to need recutting but by then the chances are that the rest of the engine will be worn out too. There is no way the inserts will just burn out though in the same way as can happen to plain cast iron.
Valves
All valves have to be made from very tough steels anyway just to resist the temperatures and stresses inside the engine. The same steels are used whether the engine is designed to run unleaded or leaded fuel so in effect it is not an issue. Nearly all modern petrol engines use the same types of steel for valves with small variations in the alloying mix. Inlet valves are generally made from a single forging of EN52B or similar. Exhaust valves have to cope with much higher temperatures on the valve head so they need a higher grade material there. Exhaust valves use EN52B for the stem part of the valve which is then friction welded to the much tougher 21/4N steel for the valve head. Why use two types of steel in one valve? Simply because 21/4N is more expensive and as it is only needed for the head of the exhaust valve there is a small cost saving in using EN52B for the stem. The saving in material cost outweighs the cost of the friction welding operation. It might be minor but when you are making millions of valves it all adds up. Copyright David Baker and Puma Race Engines
The simplest test the home mechanic can use to tell which type of steel a valve is made from is with a magnet. EN52B is magnetic and 21/4N is not. If you take a magnet and an exhaust valve it is quite easy to find where the friction welded join between the two types of steel lies as the magnet will grip the stem until the point at which the material changes to 21/4N. The only important issue for use with unleaded is that the head of the exhaust valve be non magnetic 21/4N and as it is certain to be that anyway on a modern engine you don't need to change the valves for use with unleaded. If in doubt just apply the magnet test. If the valve is all non magnetic then it is one piece 21/4N but that is of no extra benefit really in a road engine. The valve stem doesn't get hot enough for it to matter which of the two types of steel it is made from.
Valve Guides
Valve guide material is not an issue with regards to unleaded petrol. You do not need bronze guides with an unleaded conversion. In fact many post 1989 engines still use cast iron guides by choice.
What Do I need Then With An Unleaded Conversion?
With a cast iron head you just need steel seat inserts fitted on the exhaust valve side.
With an aluminium head you don't need an unleaded conversion in the first place. The chances are that even if you take an aluminium head for a "conversion", absolutely nothing will get done to it except maybe the seats will get recut. If the seats finally burned out several years and many thousands of miles later, do you really think you'd have any chance of proving that the inserts didn't get changed for better ones? To do that you'd have to have the inserts machined out again, sent to a lab for chemical analysis and compared with the same analysis for known OE inserts. You'd be way past any possible guarantee period even if you bothered doing all that. So hands up anyone who thinks they can now tell me just what the incentive is for those companies that advertise unleaded conversions on aluminium heads that never needed a conversion anyway to actually waste time and money doing anything constructive with your head when they can charge you the same for doing nothing. Copyright David Baker and Puma Race Engines
Ignition Timing
The first issue with unleaded is the one of physical wear of the valve and seat. The second one is whether the engine will detonate - otherwise referred to as "pinking", "pinging" or "knock" depending on where you come from. Unleaded fuel usually has a lower octane rating than leaded and also burns differently. It might be necessary to use a bit less ignition advance with it but on many cars the standard setting works fine. There's a simple rule - if the engine pinks, usually heard at low rpm and high throttle openings, then retard the ignition timing a couple of degrees. If not then leave it alone. Pinking sounds like a light metallic rattle, a bit like a nail being shaken about in a tin can. In small doses it does little harm but in severe cases it can damage pistons and cylinder heads.
Thats it. May be the end of discussion or a whole new discussion!

[t walgamuth]

the above posts are very interesting though i didnt read all of them.

the 81 82 380 was designed from the get go for unleaded gas so forget about worrying about running leaded.

it has the hard seats already. (valve seats)

tom w

[London380sl]

Also leaded gas will plug up the catalytic converter. That's why gas went unleaded in the first place.

[dkveuro]

Originally Posted by London380sl

Also leaded gas will plug up the catalytic converter. That's why gas went unleaded in the first place.

Sorry to disagree old boy......the ban of lead...or the reduction of same, was an enviromentle concideration.

The ability to incorperate a catalitic converter was a bonus. Gasoline is also one of the sources of pollutant gases. Even gasoline which does not contain lead or sulfur compounds produces carbon dioxide, nitrogen oxides, and carbon monoxide in the exhaust of the engine which is running on it. The final reason cat's are used today.

Addendum :http://en.wikipedia.org/wiki/Catalytic_converter




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[GermanMarque]

Sorry to disagree old boy......the ban of lead...or the reduction of same, was an enviromentle concideration. Here goes and I'm not tyring to start a flame war! But.....

THE BIG CON
Eventually the blankets of sulphur and nitrogen oxides, better known as smog, grew so thick and so unbearable that "public opinion" caused America's legislators to start looking for answers. Obviously the place to start was with the oil companies. The oil companies announced quite loudly, and mostly erroneously, that the problem was "so many cars". There were only two solutions, they said: either limit the number of cars, or put something into the cars to "change" and limit the emissions. Was such a thing possible, asked the legislators? Certainly, replied the oil companies. Let us tell you about "catalytic converters" which can be fitted to the exhaust system of every car. The legislators, although they toyed with the concept, were not about to try and seriously interfere with people's rights to drive motor cars. Such action was perceived as electoral suicide, especially when there was the alternative "magic bullet" solution of converters available. Neither were they about to listen to all the "extremists" who were trying to tell them that the problem was in the type of oil being refined in the first place, and the only long-term solution was to get the oil companies to clean up their act. Such people contribute very little to election campaigns; the petrol chemical giants contribute millions.
There was only one problem left for the oil companies. Unfortunately, while platinum doesn't react to any great degree with the products of burnt petrol, it reacts very readily with lead-so readily, in fact, that burning a single tankful of "leaded" petrol in a car with a catalytic converter will render the converter useless. (This is the reason it is illegal to put "leaded" petrol in the fuel tank of a car designed to run on the "unleaded" variety.)
Trouble was, the oil companies couldn't simply stop putting lead in petrol, because the original reason for its presence-to stop "pinging"-still existed. There were available alternative additives that could be used, but these all had the disadvantage that, untreated, they produced emissions far more deadly than even the lead. On the plus side, however, these emissions could be filtered out by catalytic converters. What was needed, then, was a campaign to convince people that "leaded" petrol was a grave danger to the environment, and that the only solution was to cease using it, replace it with the "unleaded" variety, and then run the emissions through a catalytic converter. Such a campaign would ensure that legislation was passed forcing the fitting of catalytic converters, which would overcome the original problem for the oil companies-the increased levels of sulphur and nitrates in their fuel. You see, the campaign never had anything to do with lead: it was simply a matter of convincing people to use a fuel that wouldn't wreck the converters, so that the petroleum companies didn't have to spend any more money refining the oil and could get away with selling a dirtier product, forcing the motorist to bear both the responsibility and the cost of trying to clean up the air.
Anybody who doubts it was the quality of the petrol rather than the number of cars which caused the massive increase in smog in the period in question, need only look to actual figures. While it is true that the number of cars in use was increasing, the rate of increase was fairly steady. At the height of the "smog wars", however, the levels of emissions were increasing at nearly four times the rate of growth of car ownership. On top of that, this was the period where petrol was starting to get more expensive, and "economical" engines were becoming the order of the day. That is, although both car ownership and petrol consumption were on the increase, rate of ownership far outstripped rate of increase of consumption. (Source: Peter Sawyer, Green Hoax Effect, Groupacumen Publishing, Wodonga, Victoria, Australia, 1990)

[dkveuro]

And your point would be, GermanMarque ?





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[dkveuro]

Au Contraire!

For your concideration....... *


"The UK got unleaded because Johnson Matthey make catalytic converters.

* And because Margaret Hilda Thatcher needed the Green vote to get her 2nd term in office.

* You cannot "mix" lean burn technology (in which the UK once led the world) with catalytic converters (which are an american invention/bandwaggon).

* You need unleaded petrol with a cat., because ANY lead will poison the catalyst. There is no need for unleaded apart from the introduction (mandatory) of Cats. - by the above mentioned witch.

* All cars with cats. run on the rich side of stoichimetric (sp?) 'cos a lean mix would damage the cat. Catalytic converted cars use more petrol than they would if they did not carry cats.

* The data on which lead in petrol was presumend to be a health risk is spurious. In particular, lead levels in children living near Spaghetti Junction have not fallen since lunleaded came in. there is no definite link between lead levels in the air and in the blood nor between lead and low IQs.

* Engines run on leaded petrol last up to 20% longer - even if "designed" for unleaded.

* Unleaded petrol is VERY toxic. It may not (dubious) make kids stupid, but it DOES increase everyone's risk of cancer. Benzene levels HAVE been linked to cancer rates. Benzene is far ligher than lead; far more active in the environment and lighter, so it spreads further.

* It is unlawful to sell certain foodstuffs in petrol stations in Germany, as the benzene from the petrol contaminates them (e.g.: sandwiches in clingfilm) to beyond the safe level.

* Since the mandate for unleade petrol in the UK, the highways people have used a LOT (ISTR half as much) less weedkiller on motorway verges etc. Unleaded even kills plants!

* The only "value" of unleaded petrol is that it lets you use a catalytic converter. But catalytic converts are not good things.

* Even in California, where the studies were done, Cats take about 10 minutes to reach operating temperature. Before this, even Johnson Matthey admit the catalytic car is releasing more pollution than a normal car. [A lean burn car would release less than either, but there are no lean burn cars, 'cos GM & JM squashed the technology].

* In the UK's climate, it probably takes about 15m for a Cat to begin to "work". BUT - the average journey length in the UK is shorter than in the USA - about 17minutes or so. So, for 90% or so of the time, the catalytic fitted car is spewing out more polution than it would if it didn't have a cat. AND much of that pollution is benzene or contains partially burnt benzene.

* It is illegal to operate a waste incinerator in the UK which releases the chemicals found in the exhaust of a car running (on choke) on unleaded petrol with a cat. Not at ANY measureable concentration - they are banned chemicals.

* Vehicles without catalytic converters [such as motorcycles!] can run a lot less rich, particularly on choke, than those with cats - as there's no risk of burning out the cat. Even so, running unleaded, they do spew out high levels of benzene - particularly until fully warm. The exhaust fumes would be illegal in any industrial environment - merely from the benzene content - ignoring the soot and other nasties. [Types the man who runs 'bikes in the shed with the doors shut - but at least I use leaded!]

* Johnson Matthey are venal and evil in the true sense of the words. They have no corporate conscience. Their plants (often in third world) to make / mine the heavy metals for the catalytic converters are the among the worst polluters (because 3rd world countries have laxer pollution laws). Mining/extracting palladium etc. is a VERY energy using and highly polluting business.

* JM have persuaded the Indian government to mandate catalysts on new cars. yet there is no readily available source of unleaded petrol in India. Remember - folks: even a small amount of leaded petrol (well under a gallon) run through a cat will poison it for EVER. The cat will not recover - it is scrap. It is WORSE than scrap: because the engine is set up to run with a cat and will run rich, even though the cat is just dead weight.

* India does NOT have the fuel delivery infrastructure to keep unleaded petrol free from lead contamination. They barely keep the petrol and diesel separate.

* All catalytic converters, and every gallon of unleaded petrol (or anything) comes to you, the consumer, with a "pollution debt." The equations are very difficult, so error is likely. however, it is estimated that only about 1/5th of catalytic converters in the UK do any good. That is - 80% of cats are "worse" than running a properly set up car of the same capacity, running "ordinary" leaded petrol [I think they mean modern low lead stuff - not the old heavy leaded mix].

* The best thing you can say for cats is that they may export some of the pollution to the country where the cat. was mined/made. But don't forget that, when the cat. is finished (about three years, when cars last for 10 to 15) it has to be disposed of or recycled - more pollution (the pollution that the cat should have stopped) and more energy usage.

* The situation is better in the USA - where most (over half) cats are beneficial. probably 'cos their cars were gas guzzlers before cats. came in.

* In India - etc. - cats are just a drain on the economy - and a source of income for the evil bastards at JM.

* Finally: Unleaded fuel is NOT VERY good. [Ask a racer]

* You will be aware of the ~5% loss in power that the 500GP bikes suffered when forced to switch to unleaded? And those boys have all the technology in te world at their disposal to make the best of a bad job.

* You may also be aware how the health & safety rules for the new unleaded racing fuel make the old stuff look like mother's milk. Unleaded fuel, if it tries to achieve a reasonable octane level, is very toxic indeed.

* Unleaded petrol as sold in the UK will cause a noticeable 'pinking" in even quite mildly tuned 'bikes. It will definitely run leaner/ hotter than the same 'bike run on leaded.

* Both my main 'bikes were tuned at Rhino Dyno [remember - a well tuned engine should be optimised and should be less polluting]. Nick Turner's main recommendation on both was to "Run it on leaded; not that unleaded **** and never on Shell or Jet".

* The downside is that leaded costs more, because govenment is either trying to hide these facts or is ignorant of them. "

..........So there !



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[GermanMarque]

[QUOTE=dkveuro]And your point would be, GermanMarque ?


Your post "that the removal of lead from petrol was an environmental issue". I read that to be a supporting comment for the lies and deceit that our Governments have perpetrated on us, as they strive to make us believe unleaded is better for us without the lead. I now realise we are are both on the same side! My apologies, breath deep and enjoy the fumes.

[dkveuro]

[QUOTE=GermanMarque]

Originally Posted by dkveuro

And your point would be, GermanMarque ?


Your post "that the removal of lead from petrol was an environmental issue". I read that to be a supporting comment for the lies and deceit that our Governments have perpetrated on us, as they strive to make us believe unleaded is better for us without the lead. I now realise we are are both on the same side! My apologies, breath deep and enjoy the fumes.

Glad to see, you can see MY point of view.



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[t walgamuth]

so you guys think the leaded is good for us?

tom w