Gasoline

[N03 4ME]

Hi all,
Just curious of what you all feel is the best gasoline to use in a new GT.
Does one brand differ much from the other?
Is there a performance/gas mileage difference from 87 to 89 octance or brand?
Thanks for your input..

[420nitro]

Originally posted by N03 4ME
Hi all,
Just curious of what you all feel is the best gasoline to use in a new GT.
Does one brand differ much from the other?
Is there a performance/gas mileage difference from 87 to 89 octance or brand?
Thanks for your input..

Yes, generally the Mobil, B.P, Shell, etc gas stations are better then the Speedways and the "Uncle Al's" gas station. (If you even have those?)
Hope this helps.

[surfbeast]

Basically all gas is the same. If you live in the N.E. all the gas comes through the same pipeline and is pumped to a transfer station. Gas is refined to a certain spec so Exxon dosn't care if they get some of BP's refined fuel. They even ship the extra unleaded right behind the regular. The part of the fuel that gets mixed up, say, ( 89 / 92 ) is pumped off and sold as a feul blend. It is at the transfer station that the individual suppliers add their additives. The additives is what makes up the difference, not the gasoline itself. There is no milage difference in fuel octane ratings. The higher octane may burn cleaner but will not make your GT run better or stonger unless you have a power adder,chip or timing advance. The octane rating is just a measure of how much compression or time it takes for the fuel to burn ( can't remember wich ). If you are running a new GT then just put in 89 octane from a good brand station. Like the last post said, don't buy from a cheap station, you may get water, debris etc.. from the fuel they sell.

Sorry about the leghth, it is really boring here today, SNOWED IN

[N03 4ME]

Thanks guys,
I assume that here in Southern California, all the brand names are the same as well.
The marketing makes you wonder sometimes between Chevron Unocal, etc.

From the last post, I am taking that because 89 octane burns a little bit cleaner, there will be less crap going through the system.


Thanks again!

[GodStang]

I have been told that putting the wrong octane in your car can over time mess it up. The different Octanes burn at different rates. If one burns faster than what you are supposed to using than it will be burned before the piston is in the right spot. Just what I have been told.

[surfbeast]

remember, the gas is the same but the fuel you pump into your car has been altered by the oil company at the main transfer station ( the place it is pumped into trucks ). Each co. has it's own special formula, that is what they are advertising as being diffrent from the other guys. I notice that Sunnoco 94 or BP 93 runs best in my car, although it may just be all in my head.

[xxxBlakexxx]

There are three issues with gassoline: Octane, additives, and quality. Quality refers to how much sediment and water is present. Pretty much these days, all octane ratings have the same additives.

Calulating octane is a pretty complex chemical equation. But what is generally means is how much potential energy the fuel has. Higher octane fuels need more compression before they will ignite and then you get more work or energy from them.

Low octane gas in a high compression motor will cause knock. This is when the fuel ignites prior to spark. Moden cars have knock sensors that I think will advance spark if knock is sensed so that the engine is not damaged. You will loose power.

Using high octane gas in a car designed for low octane (lower compression) I believe will result in fuel not being burned, thus leaving depsosits.

Check out this link too for more info:

http://auto.howstuffworks.com/question90.htm

[N03 4ME]

Blake,
That makes good sense to me. The questions that come to my mind then are:
1. Is 89 or 91 rated octane going to leave deposits in a stock GT due to the compression?
2. If the stock GT compression is high enough, then I should get better performance from 89 or 91 octane.
3. If one uses too high an octane and deposits are left, then what happens to the deposits? How are they removed if at all. What are long term effect.
4. Who is putting the better quality fuel at the pumps?
It appears that using the wrong octane rating whether too high or too low could have a negative impact.

I must be reading too far into this huh..

[bigred90gt]

Try this over at Rice Haters Club. There is some useful info there.

[96_4.6]

MAn now you got me scared, I run a 96 gt with the mods listed in my sig and I always run 89 and now I'm scared

[420nitro]

Originally posted by 96_4.6
MAn now you got me scared, I run a 96 gt with the mods listed in my sig and I always run 89 and now I'm scared

Always listen for pinging sounds or detention, no matter what octane you run. You should be ok though.

[xxxBlakexxx]

OK, guys, let me take a step back on this to try to clear up some confusion. Here are some fuel basics:

1 - Always use the fuel octane rating recomended by the manual! There are no hidden secrets here.

2 - Pining is not really a problem. A ping is a slight knock. All cars will ping a little at full throttle especially when it is hot outside. This ping is the caused by increased pressures in the cycliner head due to the high load.

3 - Dirty cyclender heads can also cause knock or ping due to cabon deposits actually reducing the head volume. This will raise pressure and result in pre-mature ignition.

4 - Think of octane as meaning "resistance to knock". Knock is when fuel ignites too soon. It can be destructive to a motor if it takes place for a long time. Modern cars have "knock sensors" which will detect knock and alter the engine situation...timing and/or fuel (I believe) to reduce the knock. They work to an extent.

5 - 87 Octane gas ignites at lower pressure/temp and burns slower. 93 Octane gas ignites at higher p/t and burns faster.

6 - When high octane fuel is used with a high compresson engine you can make more power because of the added compression. This products more work. The high octane fuel simply allows you to take advantage of the high pressure. Make sense?

7 - If a high octane rated engine uses low octane gas, the fuel will ignite early resulting in knock. Ultimately, this will mean that the car will loose power.

8 - If a lower octane rated engine uses high octane gas, the fuel will not be able to ignite properly. However, you will not really loose or gain performance. Most of the unspent fuel should pass out the exhaust and the detergents should keep the car clean.

9 - ALL fuels are really the same! Except for the octane rating. All the gas companies could merge, and it would not make a difference. The industry is tighly regulated by the feds. All fuel quality is the same. PERIOD. Gas is like milk. Milk is also tightly regulated by the feds. All 2% is the same. All 1% is the same etc... Just like octane. Make sense? What might be different is the pump station. Old tanks will have more water and sediment at the bottom of the tank. Try to avoid getting fuel when a fuel truck is present...it stirs the tank up. And, if you get any dirt, the dispersants in the fuel should move it out.

10 - If you are worried, use a fuel injector cleaner every so often. Ford does NOT recomend their use, however. So do not tell Ford that you used one if ever a warenty issue. How do they work? Most of them have ingredients that make the head burn hotter in order to burn-out deposits. The higher heat can damage the engine.

11 - Do not under estimate the power of octane. I have seen studies where a basic Honda engine has been used to produce 750 hp by doing nothing more than changing spark timing, adding race fuel, and increasing compression. However, the intense heat, would blow up the motor quickly.

Ok. I hope this helps. This subject can be really confusing as the industry has allowed society to pay for gas for years that we don't really need. You can use a chip program to take advantage of higher octane fuel. The chip will alter the spark timing, but without increasing pressure, you will not get a huge advantage. Chip companies claim 15 - 20 hp increase. Increasing pressure even a little can result in much, much more hp than that.

[420nitro]

question for XXXblakeXXX
And I am not trying to be a smart ***..legit question

You stated that low octane (87) burns slower then lets say a higher octane (93).
I thought it was the other way around?

When we advance are timing on a cars,....example from stock 10 degrees btc and advance it to 16 degrees btc wouldn't you need gas that burns slower?

I thought when we purchased a higher octane fuel we were getting a gas that would not pre-ignite and burn a little slower to allow the piston to reach t.d.c to fire???

If I am wrong then cool, I stand corrected, but it has been a f-up day for me and nothin seems right. lol
Thanks

[xxxBlakexxx]

Ooops! Typo. High octane fuel burns slower than low octane fuel. Thanks 420...too much "high, low...this that" discussion. Should have proof read better. That should also answer your second question.

Your third question: If the car is set up properly, ignition already should be occuring at TDC. Using too low an Octane will cause early ignition. So if ignition is already at TDC, then there is no benefit with using higher octane.

Keep in mind that there are many variables that affect pressure in the cyclinder. Not the least of which are atmospheric conditions. We have no control over things like humidy, temp, and altitude. As a result, engine computers are really quite sophisticated in order to take into account all of these factors.

There are instances when you are getting early ignition due to these factors as well as high engine load (full throttle, up hill, towing, ...) when using the recomended octane rating. This is what causes ping. In these cases, going to a higher octane fuel helps address this problem in the EXACT way that you described in your post.

I have an '02 Suburban. When I am towing my boat on a long trip, I always go with 89 octane instead of 87. If I don't, I get a small amount of ping when going up hills and we have a lot of them in Eastern PA.

Please, there are no stupid questions. If I don't know the answer, I know where to find them.

Blake

[420nitro]

cool thanks, I was like damn I am so confused..lol..
But anyway cool thanks I used to have an 02' Avalanche and know went to a 03' Silverado with a diesel..no more pinging just alot of knocking...lol

[xxxBlakexxx]

That's a good one!

[SleeperGT]

Blake,
Maybe I'm in a foul mood tonight, so please excuse me, but I am actually offended by your advice because you're putting peoples motors and wallets in jeopardy. Particularly # 2 about pinging. By stating that pinging is nothing to worry about, you have demonstrated that you really don't know what you are talking about and are discrediting this website as a source of good information. I won't even go into your other equally wrong comments with one exception concerning octane and power (# 8 on your list). You will lose power running too much octane for a mildly to moderately modified Mustang (I have the time slips to prove this). Street Mustangs should run at the lowest octane levels possible without encountering ANY detonation, as you will lose power with too much octane, maybe not noticed on the street, but you will see it at the track. A car should never ping, and detonation has the very good chance of destroying your motor, especially if you ignore it and proceed to hammer it while detonating. Mustangs do not have the ability to know what octane is in the car and adjust to generate more or less power and to prevent detonation. I'm hoping you were confusing other cars which do have this capability but Mustangs do not.

[xxxBlakexxx]

Every single car on the road can ping. Don't confuse ping with Knock.

[xxxBlakexxx]

Sleeper (which is what I should be doing right now), The bottom line (which we both seem to agree), use the octane fuel that is recommended and you won't have any problems.

I have also heard many drivers mention slower track times when higher octane fuel is used. This is a tough claim to make unless you can repeat the test multiple times in the exact same conditions (atmospheric and other). There are really too many factors, including the human ones. I would venture to say that there are equally as many folks who thought their times were better with high octane fuel. Maybe with them, it is just a "self-fulfilling prophecy."

I tried to distinguish between a ping and a knock. Pinging probably happens more often than you think.

I have seen lots of studies done on internal combustion engines when it comes to fuel usage. There was one that was done at either the University of Wisconsin or Michigan (I forget which one). I will see if I can find it and email to you or post it.

[420nitro]

I have also heard that if you run to much octane it will slow the car down.
I will tell you what. The next time I race my car (Spring) I will test this theory.
I suppose to run the car on pump gas on motor, and 116 on spray. I will just make a pass on motor with 116 and see what happens. Sorry about the Spring thing but its a lttle cold out here with this white stuff on the ground.
Later