adam728 said:
This is about the 20th time this week that I have seen someone replying about how crappy gas is now days. Any proof, or references, or anything?
Below are a couple of reference papers I have on my hard drive. They are worth the cost if you are really interested in the subject. ($14/paper direct from the SAE) There are plenty more references out there on the EPA federal website, and some states publish local fuel quality data as well. Pump fuel is just a really poor for high rpm engine purposes, and old pump fuel only makes things more complicated. The basic quality of fuels may actually have improved over the last 15 years based on data from some long term studies. The problem is during that time the basic makeup of the fuel's distillation curve, and carbon/hydrogen ratios of the components used to blend pump fuel were being designed for engines with long pre-heated intake tracts running in a very narrow, and by comparison low rpm range. So even if there is less trash in the fuel, it's suitability for
our purposes hasn't taken a turn for the worse. These fuels also seem to be less stable during long term storage than they were years ago. Given that we have no idea how old the fuel is before we even pump it into a gas can, it's silly to think you can "know" how long fuel will sit.
If your fuel is going to sit for extended periods of time it's advisable to keep it consistently cool(or cold) and dry along with adding stabilizer to the fuel. Stabilzers won't stop the fuel from going flat and boiling off the low ends which aid starting warmup and throttle response, but it will help keep the fuel from oxidizing to the point where it will clog jets, or turn completely.
Fresh fuel is cheaper and easier in the long run. ;)
SAE paper # 2004-28-0054
Gasoline Quality and Its Effects on Intake System Deposits
Abstract:
Gasoline can oxidize during storage giving rise to formation of gums, which cause deposit formation in the intake system of engines, affecting the performance, drivability and emissions characteristics of the vehicles. To evaluate the deposit-forming tendency of gasoline, a small-scale engine test method using a modern technology gasoline engine, was developed and reported in SAE paper 2001-28-0039. Further work has been done in this area to demonstrate the ability of the test method to distinguish between different qualities of fuels. Data on the performance of different base fuels and various commercial deposit control additives, with regard to their effect on the deposit forming propensity and cleanliness characteristics, in the engine combustion chamber and intake systems is reported. In order to investigate the effect of prolonged storage of gasoline on deposit-forming tendency tests were conducted with base fuel samples stored over a period of two years. Results of the tests show that during prolonged storage, lighter fractions of olefins evaporates and remaining gasoline oxidizes giving rise to the formation of gums and gum precursors that can increase the deposit-forming tendency.
SAE paper # 1999-01-3584
An analysis of 1996-98 gasoline quality in the United States
Abstract:
The importance of the fuel in providing improved vehicle performance and reduced emissions has become widely recognized, especially in the past ten years. In 1998 an SAE paper was presented providing a systematic analyses of 1996 United States gasoline quality. This paper extends the methodology of that paper to include the impact of fuel composition on evaporative emissions, and it provides analyses of gasoline quality for the years of 1996, 1997 and 1998.