Pump gas quality

[Stratman]

I'm not sure if this has been covered, but I'd like to start a thread about pump gas quality from different stations. It is know that some parts of the world and even neighboring states only sell 91 octane. This may apply to the 91 octane crowd just the same from station to station.

As a tuner, there has always been an issue with knock in the 2.2 Daytona even with small amounts of boost or part throttle and low timing which may be from compression ratio or an oil intrusion problem in the cylinders, especially in very hot Texas weather. I live in Dallas area and it drives me crazy when the only place I can find 93 octane which makes all the knock go away is at a small 7 Eleven down the highway (which also gives me the worse gas mileage and best performance). I believe this is Citgo fuel, but not all 7 Eleven fuel in other places treat the Daytona with the same respect if it is tuned for the Citgo fuel.
If I have to fill up at the Texaco down the road, the car immediately starts retarding cylinders at part throttle which is uncontrollable until I start removing ignition timing. I've had the same experience with Cheveron and Shell fuels.

Does anyone else have this experience?
Is it possible these places are selling us 87 octane from the 93 octane pumps?
Is it just possible this Citgo fuel is designed to produce less gas mileage for more consumption?
What are your thoughts?

[contraption22]

Any time you increase octane (resistance to pre-ignition), you are going to lose energy (fuel mileage).

The lower the octane, the easier the fuel ignites, the faster it burns, the more energy per unit of volume.

I'm sure that there will be a thousand opinions in replies to this thread, but I don't think you will ever track down one particular brand that is better than the rest.

My advice for tuning on pump gas... tune VERY CONSERVATIVELY. Because there is such variation from station to station, you should never get close to a ragged edge tune on pump gas.

Race fuels and street legal performance fuels are made in small batches, shipped in sealed containers directly from the mfr, and are manufactured with much more control on the product.

[Keito]

I was going to start a thread like this.
My SRT-4 has not run as good this year as last year. I have a scan guage and
have been monitoring timing and retard for the last few days.
I can't compare to last year because I didn't notice lack of power then.
I have been using Shell exclusivly this year since my company moved next to the station.
I used to use Marathon only for the last few years, but thay only carry 92 octane,
since Shell still has 93 I figured it would be better.

[Stratman]

Hi Mike! How you been?

Conservative is a state of mind.
You may call me a little ate up. For the last 5 years I've had the laptop in the car and tune almost daily chasing issues. This post can be a good answer for people who are looking for a decent place to get fuel from the other people in the same areas who have found good fuels. There should also be people on the list who may also have some insight to different manufacturers fuel refining (maybe).

[Stratman]

There is a correction. The 7 Eleven near me at Beltline and Highway 175 in Seagoville, TX carries Citgo fuel. Good pump gas for performance tuning.

[Juggy]

Any time you increase octane (resistance to pre-ignition), you are going to lose energy (fuel mileage).

The lower the octane, the easier the fuel ignites, the faster it burns, the more energy per unit of volume.

so why do lots of V8 cars get better fuel mileage on mid grade or premi as opposed to regular??

[Stratman]

so why do lots of V8 cars get better fuel mileage on mid grade or premi as opposed to regular??

I'm quite sure it depends on the vehicle and the factory tune. I had a 96 Thunderbird with that had the nasty 4.6 Ford knock/pinging that was unbelievable and the same was found that MPG was a little better with higher octane.

[fishcleaner]

stick to gas stations that are always busy, they have a higher turn around rate and you get fresher gas.

[Stratman]

stick to gas stations that are always busy, they have a higher turn around rate and you get fresher gas.

The Texaco where I get the bad knock causing fuel is the busiest station around.

[BadAssPerformance]

Any time you increase octane (resistance to pre-ignition), you are going to lose energy (fuel mileage).

The lower the octane, the easier the fuel ignites, the faster it burns, the more energy per unit of volume.

so why do lots of V8 cars get better fuel mileage on mid grade or premi as opposed to regular??

I'm quite sure it depends on the vehicle and the factory tune. I had a 96 Thunderbird with that had the nasty 4.6 Ford knock/pinging that was unbelievable and the same was found that MPG was a little better with higher octane.

Yes it depends on how the car is calibtrated. Also, newer cars can re-calibrate to make use of the higher octane more efficiently.

I'm sure that there will be a thousand opinions in replies to this thread, but I don't think you will ever track down one particular brand that is better than the rest.

My advice for tuning on pump gas... tune VERY CONSERVATIVELY. Because there is such variation from station to station, you should never get close to a ragged edge tune on pump gas.

Race fuels and street legal performance fuels are made in small batches, shipped in sealed containers directly from the mfr, and are manufactured with much more control on the product.

I said this in a thread the other day... this is why I use race gas, you know what you're getting.

[strang3majik]

Believe it or not, BP actually has some of the highest quality gas along with Sunoco.

What you want to watch is a lot of the cheaper/off brand places (Wal-Mart for instance). What they do is get gas at cheaper rates from whatever company, and the reason it is cheaper is because it is close to its expiration date (yes, gas has an expiration date as well).
So, avoid places like that as they are more prone to have water intrusion, especially now with this ethanol crap.

And, just so you know the mileage difference between ethanol vs. non-ethanol... With non-ethanol in my truck, I got 400 miles out of a tank with 50 miles of that tank being city driving, the rest was highway, 75mph. With ethanol laden gas, I got 305miles average out of a tank, and thats all highway 75mph. So, tell me this ethanol stuff is good for the enviroment and our pocket books
My truck also seemed to run better with non-ethanol as well.

But, what gas stations do is have Regular and Premium. All 89 (Mid Grade) is, is a 50/50 mixture of Regular and Premium.

Also, according to Hot Rod Magazine, mixing leaded and unleaded gas actually raises the octane rating higher than that of the highest number (something like, 100 leaded and 93 unleaded will net you around 102 octane).

[BadAssPerformance]

The "up to 10% ethanol" in gas is also a major variable to deal with... just like E85 "up to 85% ethanol" ... you want more variables, start mixing gas and race gas together.

[Stratman]

And, just so you know the mileage difference between ethanol vs. non-ethanol... With non-ethanol in my truck, I got 400 miles out of a tank with 50 miles of that tank being city driving, the rest was highway, 75mph. With ethanol laden gas, I got 305miles average out of a tank, and thats all highway 75mph. So, tell me this ethanol stuff is good for the enviroment and our pocket books
My truck also seemed to run better with non-ethanol as well.

It takes roughly 1.5 times more Ethanol to burn stoich than gasoline.

The "up to 10% ethanol" in gas is also a major variable to deal with... just like E85 "up to 85% ethanol" ... you want more variables, start mixing gas and race gas together.

I used to mix leaded with unleaded on the CSX when I was racing. The only problem I use to experience was the 112 leaded race gas not mixing well and getting used up leaving mostly unleaded pump in the tank. There has been days at the track (when mixing) pushing 24-26 psi when it would start sucking up the unleaded fuel as the tank got lower. Has taken out the head gasket and made me lose a really good race with a 500+HP Z06!

http://www.turbofreak.com/vids/2-9-08z06vscsx.wmv

[contraption22]

so why do lots of V8 cars get better fuel mileage on mid grade or premi as opposed to regular??

I'm quite sure it depends on the vehicle and the factory tune. I had a 96 Thunderbird with that had the nasty 4.6 Ford knock/pinging that was unbelievable and the same was found that MPG was a little better with higher octane.

If a car is intended to run on premium fuel from the factory, then you should run it on premium fuel for best performance/economy. Preigniton is detrimental to performance and economy. An older car without knock detection will just ping and ping and ping and that will rob power and economy. On a newer car with knock detection, the computer will retard ignition timing to prevent knock and that will reduce power and economy.

The same would be true for an engine that has carbon buildup, or some other condition or defect that would lower the knock threshold.

[Dusty_Duster]

Just because a station has a particular brand name on their sign does not mean they are selling that brand of gasoline. A Shell, BP, Sunoco, and Amoco on the same block probably all get their fuels from the same supplier.

[ShadowFromHell]

All un branded stations (mom and pop) buy whatever is cheapest to dump in their tanks. Branded stations like Shell, BP, Texaco, ect use their own brand of fuel. But, it is mostly whatever is cheapest with their additive pack. I always put branded gas in my turbo cars for this reason. But in my neon or the wifes car, I buy what is cheapest.

My dad has drove fuel tankers for YEARS, and that where I got this info from. But, sometimes you get shady gas stations that want 87 dumped into their 91 tanks. My dad said he has been asked to do this by station owners way more then once...

[Stratman]

My dad has drove fuel tankers for YEARS, and that where I got this info from. But, sometimes you get shady gas stations that want 87 dumped into their 91 tanks. My dad said he has been asked to do this by station owners way more then once...

That is the situation I am worried about with this particular Texaco down the road.

[spiro440]

Just to mix up things up a bit. Has anybody used octane boosters?
When at the track I use race fuel but when I,m just driving around I use premium 94 and NOS maxracing octane booster (advertise 60 point increase). I'm using an s60 cal.
I usualy only use low boost setting but at the occasion when I chase down an srt-8 or 370z I will flip the switch. I do admit that I am not confortable doing it this way, but so far... all is good (fingers crossed).

What do you guy's think?
Here is a good read on the topic and easy to understand tables at the end.

http://www.europeancarweb.com/tech/0...ted/index.html

[cordes]

Just to mix up things up a bit. Has anybody used octane boosters?
When at the track I use race fuel but when I,m just driving around I use premium 94 and NOS maxracing octane booster (advertise 60 point increase). I'm using an s60 cal.
I usualy only use low boost setting but at the occasion when I chase down an srt-8 or 370z I will flip the switch. I do admit that I am not confortable doing it this way, but so far... all is good (fingers crossed).

What do you guy's think?
Here is a good read on the topic and easy to understand tables at the end.

http://www.europeancarweb.com/tech/0...ted/index.html

With the cost of Toluene or Xylene being what it is, you may as well run race gas IMO.

Also, most all the fuels in a given area come from a couple different "racks". From what I have been told by the guys who drop the gas at the stations, there is virtually no difference in any of them. It's all in the quality of the containment system at the station.

[spiro440]

With the cost of Toluene or Xylene being what it is, you may as well run race gas IMO.

Also, most all the fuels in a given area come from a couple different "racks". From what I have been told by the guys who drop the gas at the stations, there is virtually no difference in any of them. It's all in the quality of the containment system at the station.

A bottle of the stuff is sold for 15$ and treats 15 gallons.That brings it to about 6$/gallon up here. Race fuel goes for 20$/gallon. I don't think the diffenrence in price is justifiable but I do agree and have heard the same from the drivers who deliver to the gas stations. Which brings us back to adding a bottle to bring it up 6 octane numbers to reach 100. According to the research. Now is it good or detrimental to the engine??? I realy would like to know!