Is this true?

[Last_Z]

I posted at LS1 board that my Z28 has a persistent pinging above 5k RPMs. James, a dealer for the predator tuner said the following:

quote:

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I would recommend BP/Amoco, Shell, Mobil, or Sunoco fuels. Stay away from Chevron, or other brands with a lot of additives in them.

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I know this is not the whole thread, but he makes sound as if a gasoline like Chevron with a lot of additives can cause pinging or a car like mine to run lean or whathave you. Is this true?
Rick


BTW: the car is a 02 Z28....it doesn't seem to burn oil through the PCV, a common problem in LS1s that causes pinging, the car is almost stock with only an SLP Lid and an opened lower air box. A/F ratio is 12:1-12.5:1. Does any body have any ideas?

[ September 23, 2003, 07:25 AM: Message edited by: BOBISTHEOILGUY ]

 

[Pablo]

I have found Chevron to prevent pinging in my turbo. What's his science?

 

[FowVay]

I agree with Pablo, I think Chevron sells one of the very best gasolines on the market. It is recommended exclusively by my local BMW Car club of America chapter due to it's ability to keep valves clean.

 

[Chris]

It is the best gas in America! Now you know the guy at the dealer is not the sharpest tool in the shed.

 

[alexiskai]

So what should I do if the closest Chevron station is 30 miles away?

Who else is good with additives?

 

[Last_Z]

quote:

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Originally posted by Pablo:
I have found Chevron to prevent pinging in my turbo. What's his science?

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This is how he explained it:

quote:

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Yes it does! Their premium grade has 2 times the detergents as their regular unleaded. In order to add these detergents, you must take out more raw fuel to do such. In turn this takes away from the fuel's ability to suppress detonation. My friend works for Chevron, and he gives me all the inside info.

I have a friend with an '01 SS M6, and we've successfully cured his pinging problem he had by switching from Chevron to Shell, or BP/Amoco (we don't get Mobil or Sunoco here).

Shell actually has reformulated all their fuels recently to have less additives in them. BP/Amoco is the same fuel now (Amoco), and Mobil and Sunoco have always been high quality fuels.

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Sounds like it "might" make sense, but I just don't know. Any gasoline blenders out there?
Rick

 

[MolaKule]

quote:

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Their premium grade has 2 times the detergents as their regular unleaded. In order to add these detergents, you must take out more raw fuel to do such. In turn this takes away from the fuel's ability to suppress detonation.

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The logic escapapes me.

Not a fuel blender per se, but detonation prevention is attained by raising octane level which allows a more even flame front to spread from the plugs.

Let's say I have 1 Liter of raw fuel, and I add 0.1 L of octane improver. Now suppose I add some fuel system detergents which results in an increase in volume of another 0.5 L. I then have 1.6 Liters of blended fuel. Where did I remove fuel in order to increase octane and detergency?

 

[alexiskai]

I think he's thinking you're keeping the volume constant. So if X ml of gas goes into the cylinder every time, some proportion of X is fuel and some is additives. If you increase the amount of additives, the ratio of additives to fuel in any given milliliter will go up and thus the amount of fuel going into the cylinder will go down. But this assumes that the engine will not compensate by shifting the air/fuel ratio more toward fuel. And it still doesn't explain what this has to do with detonation.

 

[Shannow]

If the additives were non-combustible, then you'd be running lean. Super lean, and no pinging anyway. But only on open loop, not closed loop. Mileage would be attrocious.

But the additives are combustible, and to get the octane rating to pass the testing, the overall package must have whatever the advertised octane rating is.

 

[hannaco]

Well, I once worked for a "custom" refiner. We made gas for all of the dealers in the area. The only difference between the different brands was the additive packages. Shell at that time used by far the most additives by volume. Chevron, like the others used more additives in their premium grades than their regular gas.
Needless to say, I do not understand his argument. The additives are usually blended into one of the blend stocks used in the gas. The additives are then added to the tanker truck at the loading rack at the time of sale. It is not as if the gas was getting diluted.
One would think that more octane improver's, and detergents would be a good thing.

 

[RussellA]

Could this difference be ethanol related? I know blending ethanol varies by both brand, region, and season. Isn't ethanol supposed to reduce pinging? I think Chevron only uses ethanol where legally required. Just a thought.

 

[Pablo]

I just ran a tank of Shell. Not scientific, but MPG went down and pinging went up. Back to Chevron.

 

[shortyb]

One thing to consider, that may or may not pertain, is how are these addititives are used up in the combustion process. I know that on my Xterra where 93 Amoco was used religiously since new, caused some of the extra adds to precipitate out as CC deposits. The manual calls for 87. This in turn raised the compression slightly causing a need for higher octane, thus causing more deposits etc. A vicious circle. After a single use of a fairly aggressive CC/injector cleaner, I noticed very slight pinging using the same fuel from the same station. After some head scratching and discussion with a knowledgable analyst, he theorized that the cleaner only took off a portion of the deposits and left an uneven surface on the piston crowns. This would definately interfere with the flame front propogation. A subsequent inspection with a borescope confirmed the suspicion and a switch to 87, with less addititives, was made. After my next UOA, I'll start a Fuel Power regimen to finish the clean-up. Long story short, some brands, and even different grades of the same brand, contain varying amounts of addititives. I suppose it may take some experimentation to settle on what "flavor" an engine likes.

[ August 12, 2003, 01:05 PM: Message edited by: shortyb ]

 

[MNgopher]

Taking a statement from one gasoline market and spreading it across the country is not correct.

Reality is that the gasoline you buy in your market under a brand name may be completely different than the gasoline sold under the same brand name in another marrket, short of additive packages.

In my market, four refiners supply over 90% of the fuel. Three have direct ties to a brand (BP/Amoco, Marathon Ashland, and Holiday), while there are at least 15 major brands sold in the market, not to mention the independants. Where does their gas come from? The same suppliers of the three brands above, with different additive packs.

Thus, an Amoco gas here is not the same as an Amoco gas there.

Work around the local brands and see which one eliminates the ping. You have then found the correct fuel to use in your market.

The talk of additives displacing gasoline are laughable at best. The ratios of additives to raw gasoline and ethanol are so small that its impact is nearly negligible.

 

[sbc350gearhead]

I use shell gasoline exclusively in my vehicles except when I am somewhere where it is not available. In most of those instances, I use chevron if available (chevron is not available where I live). I have never experienced any problems with either chevron or shell, however, I have experienced problems with BP.

[ August 12, 2003, 04:57 PM: Message edited by: sbc350gearhead ]

 

[Last_Z]

From Shell's site:

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Prior to developing the new fuel, Shell conducted extensive consumer research, which revealed that drivers value the time and money saved as a result of improved fuel economy. The new formulation reduces friction between moving parts inside an engine, such as pistons and rings, so they slide more easily inside cylinders. This helps the engine run more efficiently and use less fuel. In addition, the new Shell formulation has significantly more detergent than gasolines at minimum EPA detergency requirements to help protect against the build-up of harmful carbon deposits inside the engine. A clean engine not only performs better, but also produces fewer emissions

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They just added more detergents. Where did he get the "low detergency" from?
Rick

 

[Last_Z]

Hey guys;
I wanted to bring this post back to the top for the same reason I started it.
James, a Diablo Tuner dealer said the following today:

quote:

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DiabloSport tested all the known brands of fuel at one time and found that those brands they tested were the best. In the addendum to the '03 Gas Truck Predators, the manual says to use BP/Amoco (same gas now, btw), Mobil, or Sunoco. The new reformulated Shell is also an excellent choice. Stay away from Chevron (the Techron sux), and Exxon, IMHO.

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What do you make of this. He still claims that Chevron sux.
Rick

 

[Pablo]

His opinion. Period.

 

[Les]

I work in the second largest refinery in the U.S. (BP - old Amoco refinery) Gas formulation not only changes throughout the year but it varies from one market to the other. For instance, one market might have lower sulfur levels than another. Octane in the gasoline leaving the refinery is kept very close to advertised levels. If it is supposed to be 93, it usually ships out as 93.1 - 93.3. You can't ship it out too high because the ingredients that boost octane are expensive and if the octane is too high takes away from the bottom line for the refinery. (Octane giveaway) You can't ship it out too low in octane because it is tested at the other end of the pipeline and they won't accept it as premium. As an addendum, Chevron's additive package is pretty good, we, when we were still Amoco used to use some of it. Not now though.

Les

 

[BOBISTHEOILGUY]

Detergents in gasolines are a big part of gasoline. Epa requires that a min of detergents be used in all gasolines which is known as the Lowest Additive Concentration (LAC).

Gasolines contain unstable components that can lead to deposit formation in the high temperature areas of the induction system, as many of you have seen when looking in one. The detergent additives are used in gas to reduce or eliminate deposit formation in the critical fuel delivery system components.

By reducing or eliminating these deposits , this can lead to improved engine power, better driveablility, improved fuel economy and reduced emissions. In most cases , gas marketers use these additives to differentiate their gas from each other.

Deposits also form in the higher temp conditions of the combustion chamber as well. The formation of these deposits can be influenced by the composition of the gas and the type of detergent additives used. Combustion chamber deposits (CCD) can result in increased Octane number requirement and increased NOx emissions.

Ok, Octane is a measure of the ability of a gas to resist knock. The antiknock value or a gas can be measured in two standard lab engine tests. Both use the same single cyl variable compression ratio engine attached to dynamometer. Different operating conditions characterize each method.

The D2699 measure the research Octane Number(RON) of gas and the D2700 measures the motor octane number(MON). Both tests, the engine compression ratio is adjusted to produce a measured level of knock with the test fuel. This gas is compared with the primary reference fuels producing slightly higher and slightly lower levels of knock. The octane number of the test fuel is determined by interpolating between the two primary reference fuels that bracket the test sample.

Of the two procedures, the MON test is more sever, correlating with high speed, high temp, part throttle conditions in a vehicle. The MON for most gas is lower than the less severe Ron test, which primarily correlates to a gasolines ability to resist run on or dieseling. The difference between the two ratings, (RON-MON) is called the sensitivity for the gas.

Some markets rate gas by the antiknock index(AKI) which is the average of the RON and MON values. (R+M)/2.

In the U.S. gas octane values are posted as AKI values on gas pumps. Other markets choose to express oct value as RON or MON only.

A vehicles octane requirement does not remain constant over its life. As the vehicle ages, octane number requirement(ONR) can increase from 1-13 octane numbers due to deposit buildup on the intake valves and in the combustion chambers. This is where deteregents come into play, and if you are able to run an engine on the lower octane with minimal knocking, then you're engine isn't having the deposit buildup as bad.

So, those that are having to step up their octane, are having more build up. Which ultimatly carbon on the valves, will cause excessive valves stem/guide wear giving a premature failure on the engine.

So, is additives needed? You bet.