Non-ethanol vs octane

[EAM 17806]

How can you have run Top Tier gasoline since 1977 when the Top Tier designation was only introduced in 2004?

DAN;  You're correct, Top Tier gas was started in 2004 and that's all I use in all my 4 cars today. Prior to 2004 whatever 87 octane was I was using in the 76 and all was just perfect.  EAM

[GregoryAlan]

The way octane boosters are labeled are a bit misleading. When a bottle says it will boost octane by up to 4 points, it won't take 87 and boost it up to 91, it will boost it to 87.4.

There is a bevvy of discussions about this on Bob is the Oil Guy forums.

Exactly...
Be careful of 'boosts' that are TEL [lead] substitutes and additives...


http://www.overkillgarage.com/what-is-octane-supreme.html

[chrisntam]

How can you have run Top Tier gasoline since 1977 when the Top Tier designation was only introduced in 2004?

I would just assume "name brand" like Shell, Mobil, Esso, Enco, Exxon, Sinclair, Texaco, etc. as opposed to "discount" gasses.

What are some of the older name brands I missed?

I use 93 octane from Costco (ethanol is included) in my 10:1 '70, no issues.  I make sure to run it often though.  It don't take long to go through a tank of gas.

[hornetball]

Just to add another data point:

I use pump 93 in the '74 Eldo and make sure to drive the car once a week to keep the gas fresh.  The only ethanol free around here is 87.

During my refresh, I rebuilt the heads due to valvetrain damage and also replaced the cam (Competition Cam 252H) and timing gear/chain (Cloyes roller).  When I pulled the heads, I discovered that the engine was a '71-73 engine (you can tell by looking at the piston tops -- mine had the "soapdish" shape).

So, this should be an 8.5:1 engine and should be perfectly happy with 87, but for some reason it pinged with 87 and even pinged a bit with 89.  Due to the rebuilt heads, there is no carbon to speak of.  The heads would have been decked a bit during the rebuild, but not enough to significantly raise compression (I think).  Timing is carefully set to factory specs.  I really can't explain why it needs the premium, but it does.  ??

["Cadillac Kid" Greg Surfas 15364]

Just a reminder that all "gasolines" are not the same.  Automotive gasoline is a blend of chemicals that have been refined from crude oil


Gasoline is a refined product of petroleum consisting of a mixture of hydrocarbons, additives, and
blending agents. The composition of gasolines varies widely, depending on the crude oils used, the
refinery processes available, the overall balance of product demand, and the product specifications.
The typical composition of gasoline hydrocarbons (% volume) is as follows: 4-8% alkanes; 2-5%
alkenes; 25-40% isoalkanes; 3-7% cycloalkanes; l-4% cycloalkenes; and 20-50% total aromatics
(0.5-2.5% benzene) (IARC 1989). Additives and blending agents are added to the hydrocarbon
mixture to improve the performance and stability of gasoline . These
compounds include anti-knock agents, anti-oxidants, metal deactivators, lead scavengers, anti-rust
agents, anti-icing agents, upper-cylinder lubricants, detergents, and dyes . At the end of the production process, finished gasoline typically contains more than 150 separate compounds although as many as 1,000 compounds have been identified in some blends.

That said is is apparent why there is a great deal of disparity between their performance be it mileage, power produced and anti knock characteristics in what might be similar engines/

Cheaper "bargain" brands will blend their products using the most economical blend of these chemicals while the major brands tend to go to consistency of performance.
Although most gasoline pumps are placarded "May contain up to 10% Ethanol", this amount also is quite variable.
Motto is: Find a gasoline your car runs well on and stick to it.
Greg Surfas

by the way, of course I cut and pasted that text on the chemical composition. I am a mechanical engineer, not a Chemical one.

[walt chomosh #23510]

hornetball,
  You set your initial timing but remember that your vacuum and centrifugal advance should be set correctly. If you can find someone in your area with a distributor machine talk to them. The exact and correct distributor advance chart will be in your shop manual. Having the advance set correctly is one of the most important tuning devices in a motor to make it happy.....then there's you timing chain and gears.....walt...tulsa,ok

[35-709]

hornetball,
  You set your initial timing but remember that your vacuum and centrifugal advance should be set correctly. If you can find someone in your area with a distributor machine talk to them. The exact and correct distributor advance chart will be in your shop manual. Having the advance set correctly is one of the most important tuning devices in a motor to make it happy.....then there's you timing chain and gears.....walt...tulsa,ok

Absolutely, been there done that with replacement vacuum advances.  The set screw in the adjustable one I put on Big Red's 472 had to be backed out completely to bring the vacuum advance numbers to what they should be.  Had lots of trouble with pinging before I set it up correctly.

[impalamansgarage]

I run 89 non-ethanol in my '71 472 without issue.  Are your choices only 87 non-eth. or 93?  If 89 or 90 is available and closer that should do well.  I am running 10 degrees BTDC for timing (factory is 8 for '71s). Being able to use non-ethanol is important enough to me that if I had to run 87 non-eth., I would set the timing back to 8 degrees, or even 6, to eliminate the pinging.  The last little bit of performance would not be as important to me as being able to run non-eth., my car is a cruiser and that 472 has plenty of power.

All I have close by is 87 non-ethanol.

[impalamansgarage]

The 71-73 engines I have been into had a lot more carbon build up than 74-76's did.  I'm not sure if that had anything due to the design of the heads and huge piston dishes compared to the later ones or if the ones I saw just happened to be the ones that were only driven to church on Sundays.   

Yeah I just finished cleaning carbon from my valve stems. They were pretty nasty.
Waiting on a couple of parts and then I'll have her back together in a few days hopefully.

[impalamansgarage]

The way octane boosters are labeled are a bit misleading. When a bottle says it will boost octane by up to 4 points, it won't take 87 and boost it up to 91, it will boost it to 87.4.

There is a bevvy of discussions about this on Bob is the Oil Guy forums.

Now THAT is interesting. Will do more research. Thank you.

[jdemerson]

hornetball,
  You set your initial timing but remember that your vacuum and centrifugal advance should be set correctly. If you can find someone in your area with a distributor machine talk to them. The exact and correct distributor advance chart will be in your shop manual. Having the advance set correctly is one of the most important tuning devices in a motor to make it happy.....then there's you timing chain and gears.....walt...tulsa,ok

Amen!  I learned this the hard way a few years ago, from an old-timer who really knows old cars and who lets me work with him in his repair shop. After the advance was right, the gasoline mileage improved quite dramatically (from 10 average to 14 average) also.

I use 91 octane ethanol-free, which is about 30 cents or 40 cents more than regular. I will never go back as long as I can get 91-octane ethanol-free. It's been posted here many times, but do check out  https://www.pure-gas.org/ for your state; you may be surprised....

John Emerson
1952 Cadillac Sedan 6219X  (which hates ethanol more than it likes high octane)