Informative gasoline article
Informative gasoline article
A friend of mine sent me this from his Volvo website, he figured the Q guys would like it.http://www.faqs.org/faqs/autos....html
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Mayhem_J30
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Great article.
I was just in a gas discussion on another board and thought you guys might find this interesting.
Hard, empirical research has borne out time and again that a well-tuned late-model engine (OBDII) runs best on fuel within specifications made by the manufacturer. Running higher octane fuel is almost always a waste of money, no matter what the seat of your pants or your brother-in-law the mechanic says. Engines without knock sensors, older engines with carbon deposits, and engines with the effective compression ratio modified (i.e., supercharged) will need the premium stuff. Run the lowest octane the manufacturer recommends. If it doesn't knock under load, stay with it. I love it when a car owner says that he "treats" his new vehicle to a tank of premium. The only treat in that situation is going to the oil company.
This link is below is pretty interesting. One of the things they did was put 87 octane in a new BMW M3 and compared the results. Read this link in depth.
There are three pages total: http://www.caranddriver.com/xp/Caranddr ... 111_featur e_gasoline.xml
I was just in a gas discussion on another board and thought you guys might find this interesting.
Hard, empirical research has borne out time and again that a well-tuned late-model engine (OBDII) runs best on fuel within specifications made by the manufacturer. Running higher octane fuel is almost always a waste of money, no matter what the seat of your pants or your brother-in-law the mechanic says. Engines without knock sensors, older engines with carbon deposits, and engines with the effective compression ratio modified (i.e., supercharged) will need the premium stuff. Run the lowest octane the manufacturer recommends. If it doesn't knock under load, stay with it. I love it when a car owner says that he "treats" his new vehicle to a tank of premium. The only treat in that situation is going to the oil company.
This link is below is pretty interesting. One of the things they did was put 87 octane in a new BMW M3 and compared the results. Read this link in depth.
There are three pages total: http://www.caranddriver.com/xp/Caranddr ... 111_featur e_gasoline.xml
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Q45tech
- Moderator
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
"Cheapskates burning regular in cars designed to run on premium fuel can expect to trim performance by about the same percent they save at the pump.".......20 cent saving up to 10-12% power decrease!
So on a 4 valve per cylinder engine designed for premium using regular could result in a 6-10-12% power loss and roughly the same increase in acceleration time.It all depends on how closely the engineers tuned to squeeze every HP out. ................NISSAN SQUEEZES PRETTY HARD!
The comments about mediocre engines not being able to use [take advantage of] premium is a fallacy since you could advance initial timing by 3 degrees and then the knock sensors would become active obviously less so with Premium. so you could increase power by at least 3%! But not without adjustments.
What one has to be careful of is HOW IS THE OCTANE RATING CREATED.......is the 93 octane a lower btu oxygenated fuel which will provide less heat than a non oxygenated regular.BOTH ETHANOL and MTBE have a much higher antiknock rating than the best gasoline.
". Since adding oxygenate increases octane, refiners adjust the octane of the gasoline portion so that the octane of the finished oxygenated gasoline will be the same as the octane of the conventional gasoline it replaces. The adjustment involves substituting lower-octane gasoline components for higher-octane components. Since some of the higher octane components, particularly aromatics, have higher energy contents, the adjustment lowers the energy content of the gasoline. The additional decrease in energy content is about 0.5 percent.
So, since oxygenated gasolines contain 3.5 percent less energy, they would be expected to yield a proportional reduction in fuel economy.http://www.chevron.com/prodser...shtml
In the past [before oxygenates] Regular might have had 2-3% more BTU but the knock sensitivity prevented you from using it so a mid blend might have created the best of both worlds ----in the last 6-7 years who knows.
BTU created by the fuel is what yields power as long as none of it is wasted in a pressure peak [knock] before the piston is in the correct position [after TDC] to create the max downward force [BMEP].
These are tests the ETHANOL LOBBY would not like to see published.
Note that magazine test don't specify the fuel type they test with and many times SMART engineers will supply the fuel for their brand of car..........just part of making your car look good!Hey you can use carogenic additives in the tank that will blend and even supplement an almost empty tank in case the mags run thru the first tank you supplied
A system that would analyse the fuel in the tank for MTBE or Ethanol would allow the ignition timing to be set correctly!SAAB and others are using after spark ionization and peak pressure measurements to optimize ignition. Fine tuning for the max peak to occur at the correct 16--17--18 degrees ATDC is one thing but if the fuel is low in BTU [preburnt = oxygenated] there is nothing you can do about it.
So on a 4 valve per cylinder engine designed for premium using regular could result in a 6-10-12% power loss and roughly the same increase in acceleration time.It all depends on how closely the engineers tuned to squeeze every HP out. ................NISSAN SQUEEZES PRETTY HARD!
The comments about mediocre engines not being able to use [take advantage of] premium is a fallacy since you could advance initial timing by 3 degrees and then the knock sensors would become active obviously less so with Premium. so you could increase power by at least 3%! But not without adjustments.
What one has to be careful of is HOW IS THE OCTANE RATING CREATED.......is the 93 octane a lower btu oxygenated fuel which will provide less heat than a non oxygenated regular.BOTH ETHANOL and MTBE have a much higher antiknock rating than the best gasoline.
". Since adding oxygenate increases octane, refiners adjust the octane of the gasoline portion so that the octane of the finished oxygenated gasoline will be the same as the octane of the conventional gasoline it replaces. The adjustment involves substituting lower-octane gasoline components for higher-octane components. Since some of the higher octane components, particularly aromatics, have higher energy contents, the adjustment lowers the energy content of the gasoline. The additional decrease in energy content is about 0.5 percent.
So, since oxygenated gasolines contain 3.5 percent less energy, they would be expected to yield a proportional reduction in fuel economy.http://www.chevron.com/prodser...shtml
In the past [before oxygenates] Regular might have had 2-3% more BTU but the knock sensitivity prevented you from using it so a mid blend might have created the best of both worlds ----in the last 6-7 years who knows.
BTU created by the fuel is what yields power as long as none of it is wasted in a pressure peak [knock] before the piston is in the correct position [after TDC] to create the max downward force [BMEP].
These are tests the ETHANOL LOBBY would not like to see published.
Note that magazine test don't specify the fuel type they test with and many times SMART engineers will supply the fuel for their brand of car..........just part of making your car look good!Hey you can use carogenic additives in the tank that will blend and even supplement an almost empty tank in case the mags run thru the first tank you supplied
A system that would analyse the fuel in the tank for MTBE or Ethanol would allow the ignition timing to be set correctly!SAAB and others are using after spark ionization and peak pressure measurements to optimize ignition. Fine tuning for the max peak to occur at the correct 16--17--18 degrees ATDC is one thing but if the fuel is low in BTU [preburnt = oxygenated] there is nothing you can do about it.