Brands of gas: which to use, which to avoid:

Sunoco 100 is designed for cars, and is unleaded. Airplanes using 100 octane gas use LL as described below since their engines are designed for low lead gas. Do not put 100LL into your car!!. Will screw up the cats eventually, and if you have a late model (355, 360), will cause the engine malfunction light to come on as the sensors get screwed up.

For those geniuses I recently met who were going to the airport to get some "jet fuel" I tried to explain that it is basically kerosene but they were determined to give it a shot. The gene pool has no lifeguards.

In answer to 911's question- I need 100 octane to run a 360CH car. If I start out at 94 I will have a shorter way to go using octane booster to get to approx. 100. It will run on 97-98 (even 93 in a pinch), but it doesn't like it.

 

100LL avgas is only "low lead" compared to older avgas. 100LL has more lead than regular leaded auto gas.

 

One must be quite cautious with additives. The lead boosters had us doing valve jobs on an untold number of Jag 12 cylinder cars when it would send a glob through and stick a valve open. Until I track down what the cause of this little problem was (http://ferrarichat.com/forum/showthread.php?t=23286) I am having my customers stop using all octane boosters and fuel additives.
Dave

 

Dave- I thought octane boosters had no lead, but used toluene (as stated below, and as I remember so well from organic chemistry) to boost octane. Wouldn't lead in an additive ruin the catalytic converters, to say nothing of the problems you mentioned?

 

True to all. I was making a point in general with a few additives we have seen used. Tolulene is some nasty stuff! Used to run it in high concentrations in the race cars. One could always tell who followed who. The tailing driver always looked like his eyes were bleeding.
I still do not know what melted all of the rubber in the fuel pumps, but will find out in short order. I have the remainder of the rubber out being tested.
Dave

 

I only use Shell for no reason other than they sponsor the F1 team. I am such a sheep.

 

As long as it's not Trinitrotoluene!

 

Just takes nitric acid and ~140 C to make it. Not a recommended back yard project.

Ah, the stuff you learn in organic chemistry.

 

California varies, from 91 octane to 92 octane pending area and gas station. I've run it all (Chevron, Mobil, Shell, Union 76) and even Unocal 100 octane (noticed NO difference in performance, gas mileage, etc.)

However, I did get a bad tank of gas from a Shell station. Put premium in, and the minute I left, pinging like crazy. I didn't know anything about pinging at the time (no, no damage done) until later that night. Needless to say, I will a) never fill from Shell again, and b) never from that particular station.

I remember the next day I was visiting Mr. Leno (yeah, that one), and I mentioned I got a bad tank of gas of which my wife rolled her eyes. He said there is no such thing as a bad tank of gas. He thought I let the gas too low, and introduced air bubbles in my fuel system. When I explained everything, he said "you got a bad tank of gas" and proceeded with some jokes. At least it shut my wife up about bad gas.

 

I have a question for the crew ...

would not a modern car with all the computers, solenoids and analyzers and such read the combustion gasses along with a few thousand other things and then adjust the running of the vehicle to try to mimic the prefered characteristics of design regardless of octane, as long as the octane is above the minimum recommended?

Modern computerized cars:

I have always been told that if a car maker recommends 87 octane unleaded that there would be no difference in the performance of the vehicle if one fills the tank with 93 octane. The reasons given by the mechanic is that the vehicle will change the timing or whatever to adjust the performance and emissions to closely approximate the same numbers as it would have made with 87 octane?

In other words, if someone put 100 octane in a 360 would the performance of the vehicle be better? More power, faster acceleration etc.?

Your thoughts?
Best wishes

 

In general, the modern systems will retard timing (etc.) to deal with lower octane gas, thus robbing performance. There was an article in road and track where they tried to make the cars work the other way around: they wanted to know if they put in higher octane than spec called for, would the car perform better. They found some cars ran the same, but a few performed better. I seem to recall they were turbos.

 

The 360 Challenge car has a motor identical to the 360 modena/spider. Yet the specification is 100 octane for the Challenge, and 93 for the road cars.

This leads me to believe that the software for the Challenge car is different, and allows it to take advantage of the higher octane. I do know that the SD-2 unit has different programming for the street and Challenge cars, so the ECUs and their performance are different.

I'm not sure that the stock ECU on any car would take advantage of higher octane gas without some reprogramming.

 

I have a friend who owns a Calif Exxon distributorship. He says the gas in his trucks is coming from a common tank, to which the additive is then placed. Multiple brands are filling from the same gas source, then adding their own additives.

No doubt some bias here, but he feels the additives and turnover at stations does matter.

steve

 

Funny, I posted a NYTimes article on this same topic a couple of days ago.

http://ferrarichat.com/forum/showthread.php?t=24149

 

Back in February of '74 I got a tank of bad fuel that nearly had us break down on a frozen winter's night on I-74 (when our son was six or so weeks old). I almost destroyed my engine/drivetrain as I drove on til we reached a closed gas station. As the town was small, the first person we met knew the owner and got him to come help us. If you've never had bad fuel, count your blessings. Needless to say, never bought fuel at that station again.