What gasoline to use...

[RobbartK]

Fellow Lotus Fans, I am getting old. I remember a time when gasoline (petrol) had lead in it for lubrication. Another sign of my age is that I can admit I don't know everything to my wife. She knows everything (almost) but can't answer my question. I hope that you can. Woodstock, my 1970 Lotus Europa S2 is nearing the point that I can fill the gas tank and start the engine break in process. I have googled a fair amount but need a definitive answer on leaded vs unleaded and what octane gas to put in the tank. I admit I'm a little embarrassed to ask. I know you all will have the answer for me. Thanks. Woodstock and Robbart

[Kendo]

I'm sure the experts will chime in. But in the mean time, I think lead was needed back in the 1950's or so, for heads that didn't have hardened valve seats. You shouldn't have any trouble with unleaded gas as such. The real problem is having ethanol in the gas. It tends to do bad things to the rubber in the systems in contact with gas. Finally, get as high an octane as you can. Sometimes the higher octane gasolines are the ones without ethanol. Some have even gone to small airports and gotten avgas, which I think is not allowed to have ethanol.

I'll go put on my Nomex suit now

[Clifton]

Lead was use to reduce detonation (knock, instantaneous combustion of the flame front as opposed to slow) not for lubrication. It was originally called Ethyl then latter just lead. Piston planes are for some reason still using it. If you don't knock on 87, run it. Higher octane is wasted money if it's not knocking at WOT on the lower octane. Octane is the fuels ability to reduce/resist knock. Nothing else. I've only used 91 on turbo cars. Even newer n/a cars that say premium only will run on 87 just fine.

[Pfreen]

Tetra ethyl lead was used to raise the octane knock level of the fuel and to lubricate the valve seats.  It as outlawed because tetra ethyl lead is toxic and it poisons exhaust catalysts.
I do not know the Renault valve seat material.  On the Lotus twin cam seats, they were originally cast iron and were subject to wear with unleaded fuel.  So, hardened seats are always recommended for modern, no-lead fuel.
Ethanol causes problems with seals, aluminum corrosion, and water retention.  Alcohol absorbs water and can turn to gel over time.
So, If possible, I would change to hardened valve seats at the next head rebuild.  Running unleaded fuel will speed up the need for a valve job with soft seats.

[jbcollier]

Renault valve seats do just fine with unleaded fuels.

Ethanol has been used to in fuels for a very long time.  Some famous 60s high octane fuels had high levels of ethanol.  It is a good octane booster without the mind boggling health effects of lead.  Engines run cooler with high ethanol content.  And it is rich in oxygen so combustion is more complete.

Are there downsides?  Yes, especially if you live in a humid climate.  Dry climate?  Not so much.  Water causes the ethanol to “phase-shift” and separate out to a useless gluck. Ethanol also attacks certain rubbers and will, very slowly, oxidize some metals.  Only use ethanol proof fuel line.  Always run carbs dry before storage.  Short term storage, such as a single winter, top your tanks full (to reduce exposed surface area) and add a fuel stabilizer.  Long term storage should be with a dry tanks and a completely empty fuel system.

Modern fuels, regardless of ethanol content, have higher levels of volatile elements.  When these flash off, the fuel does not burn as well giving poor starting and drivability.  What can we do?  Can be difficult at times.  Using the vehicle is the best solution.  When this is not possible, filling to the very top and using a fuel preservative helps as it reduces/protects the exposed area.  Long term storage is, again, best with dry tanks and system.  Short term, say three months, full tanks, dry carbs and then drain half the tanks and top up with fresh fuel.  Burn that off and add the reserved half and do it again.  Or add the reserved half to your other vehicle — moderns have fewer issues with modern fuel.

[Bryan Boyle]

***DELETIA***
 Piston planes are for some reason still using it.
***DELETIA***

We're using it (here in the US) because of the FAA aircraft certification standards (which haven't been updated in decades for large swaths of the fleet) for the airframe/engine combinations.  It's not as simple as saying "you can use unleaded fuel"; it has implications for the airframe manufacturer as well as the engine manufacturer to get their agreement or reengineereing investment to ensure their liability concerns are addressed.

Unleaded fuels (premium mogas or 'motor gas') are available for use under what's called a "Supplemental Type Certificate", but, as JB points out, the volatiles and other additives are unstable over long-term storage periods, which, obviously can be detrimental to safety of flight.  There is a project underway for replacing the 100 octane low lead formulations with a lead-free additive, but since the embedded interests: DoD (which still consumes a measurable amount of the production), refiners, distribution chains, marketing...with us consumers at the bottom of the barrel...and the need to prove that the unleaded replacement meets the ANSI and Mil-Standards for aviation gasoline, it's a complex and time-consuming (it's been going on for a decade) task.  Just a taste: https://www.avweb.com/?s=unleaded+fuel

Second is that avgas is stable and has zero ethanol.  Aircraft fuel tanks, piping, fittings, valves, are Aluminum.  Ethanol loves to react with Aluminum.  Not good for aircraft, not to mention the approved flexible seals and gaskets in the fuel delivery chain are not ethanol resistant; we're getting there, but inertia in cleaning out old stock is a financial question.  Again, getting replacement seals, etc. certified and ethanol resistant (and traceable...counterfeit parts are not just discovered for commercial jets...it's a problem for general aviation too....) for use in aircraft is part of that issue.

Third is that there is just one manufacturer of TEL (tetraethyl lead) in the UK.  One.  TEL is a nasty chemical.  Transport is an issue.  Remnants in the ground are long-lasting.  It's UGLY with a silent F.  The sooner it's gone, the better.  That being said...it's up to the federal government (in the US), the DoD, and the invested interests to make progress to get rid of it.  The amount in 100LL avgas is minimal, but, it's still there. 

FWIW, if you are near a general aviation airport...many of them will be happy to sell you 5 gallons in a jerry can that you can use to fill your europa tank and be assured that the gas will be just fine next spring.  Been doing that for years...and believe or not...the car runs just fine on avgas.

[Clifton]

We're using it (here in the US) because of the FAA aircraft certification standards (which haven't been updated in decades for large swaths of the fleet) for the airframe/engine combinations.

FWIW, if you are near a general aviation airport...many of them will be happy to sell you 5 gallons in a jerry can that you can use to fill your europa tank and be assured that the gas will be just fine next spring.  Been doing that for years...and believe or not...the car runs just fine on avgas.

Bad for me not for thee. If lead were that bad it wouldn't be used. I have a pilot friend that tells me the same stories about plane engines being more special.

I live next to a Scottsdale airport. When I road raced pre 2008 and went through fuel on a weekend I would go for avgas, they would let me pull up to the pump with my race jugs to fill. Much cheaper that Turbo Blue that was sold at the track. It wouldn't be worth the trouble for a street car.

[cazman]

I have been using non-ethanol 90 sold around here with some octane boost added. No pinging and no gel.

I have searched, but have not found a good evaluation of octane boosters. They seem to range from cheap to expensive, with not much explanation of the differences, but they all seem to work.

[BDA]

When Dave Bean dyno'ed my engine, he included Moroso in the fuel. He also used very cold plugs. I suspect that he did both of those things to ensure that detonation would not be a problem. I plugs probably three heat ranges warmer and only use premium fuel. No pings and it runs fine.

I realize that my engine is different from everybody else's but I doubt the octane requirement for a TC motor (stock North American motors had 9.5:1 compression) would be any higher than for my BDA (10.5:1 compression). I think if your ignition is set properly and you're not running too lean, you shouldn't have a problem using premium.

[dakazman]

Fellow Lotus Fans, I am getting old. I remember a time when gasoline (petrol) had lead in it for lubrication. Another sign of my age is that I can admit I don't know everything to my wife. She knows everything (almost) but can't answer my question. I hope that you can. Woodstock, my 1970 Lotus Europa S2 is nearing the point that I can fill the gas tank and start the engine break in process. I have googled a fair amount but need a definitive answer on leaded vs unleaded and what octane gas to put in the tank. I admit I'm a little embarrassed to ask. I know you all will have the answer for me. Thanks. Woodstock and Robbart

   Well Woodstock, First of all, Congratulations. 
    Secondly, have you asked ALEXA,   she knows THINGS.... 
 
                  Sorry but i had to get that out.
     I am also an owner of a 70 S2 0453R, That I recently ran for the first time. I used a separate temporary gas tank that motorcycle shops have only mine was a modified lawnmower tank. I can only say if you're going to run it everyday use high test or the best octane level they sell locally. get the carbs and you trained on your babies moods.  Sorry for the un-scientific answer.


Dakazman
 
   

 

[Richard48Y]

All the octane boosters I have found are expensive and of questionable utility.
I can get 100 octane race gas locally for about the same cost.
I am hoping to be able to run 50/50 alcohol free gas and 100LL avgas.
This what I did for an overbuilt FIAT 850 and it worked great.
Having to brew my gas is one reason I must have two fuel tanks.
The big downside here is that even with two tanks longer distances become an issue.

[kram350kram]

Moroso at one time sold tetra ethyl lead additive in quarts. Used it when road racing in the mid 70’s. Rubber gloves, no splashing, etc…. worked well. At the time we ran supreme pump gas with the Moroso, as racing fuel was too costly for most. Anyway, static compression ratio is not dynamic running compression. What fuel octane you think you require in your engine, based on static compression calculations i.e. 10.5 to 1, is usually not as high an octane as you think you need to avoid detonation. Valve timing events dictate the running dynamic compression which is much lower that static compression, so for most street engines pump gas is adequate. In my book, the long term storage of ethanol laced fuel and its impact on older systems is more of a concern than detonation suppression. Reading you plugs should be on your list of things to check before spending dollars on fuel boosters, race gas, avgas, etc.

[cazman]

As I mentioned, I use the non-ethanol. I also have had to many problems in the past with ethanol and I would like to reduce the variables on the Strombergs.

For me the Amsoil Octane Boost is what I settled on because my hardware store sells it and Amsoil usually makes good stuff. I figure it costs just under than $1.00/gal extra. Seems like good insurance and just keep a bottle in car at all times, as I have had to fill up in strange places before. I have 10.25:1 compression with a sprint cam. If I go up a long hill without the additive, I can make it ping.

[Pfreen]

Rick,
That is so interesting about the ping.  I have also have 10.25/1 cr.  I cc'd the engine to measure each chamber and then made them the same 10.25/1 cr.
I have never heard ping from my engine.  I have the Hitachi SU carb.  I have an exhaust O2 sensor so I know it goes to about 12:1 af at wide open throttle and at all speeds.  I have the maximum spark advance set at 37 degrees, and have run the no ethanol and 10% ethanol (90 and 93 RON).  No octane booster.
So, our differences make me wonder why the difference?

[cazman]

Paul,

The hills around here are steep and long. I can usually make it ping going up in a higher gear than I probably should. So I think that I could always avoid pinging if I am watching gears, but since I go to the track with it too I like the insurance.

I am thinking of installing a O2 sensor.