Sunoco 94 octane

8570 Views 47 Replies 20 Participants Last post by wytltng, Jul 9, 2010

CapriSSish

Discussion Starter · Oct 24, 2009

So Sunoco has decided to drop Ultra 94 in this area (Dayton, Ohio) I have been running it the whole time since I've been modding the Caprice and ain't sure what is the next best fuel I can or should be running. The next best "pump gas" is either Sunoco 93 or BP 93.
Have I been wasting my time trying to get 94 and will I loose any power with 93 octane?
Anybody had experience with this situation? Thoughts, Ideas?
I'm not running any cats and the track sells real race gas and I could "add" a few gallons to the tank but I sure wouldn't run it "straight"

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SSandman

· #21 · Oct 24, 2009

KW Baraka said:
It does that by......ok.......ready for this.......burning slower .

KW

No, not necessarily. Could it be possible that a given fuel can resist spontaneous combustion at a specific compression level, thus being able to be used in a high compression motor; but have the same rate of 'burn' from start to finish as a lower octane fuel (when both are tested at the same compression, one that is within the lesser octanes fuels ability to resist detonation).

Being that 'octane rating' does not actually mean the amount of octane in a fuel, it only means how that fuel compares to a percent of iso-octane and heptane mixture in regards to how much pressure it can resist before spontaneous combustion, it seems that you can have a variety of different ways of making a say '105 octane' mix and because of this there could be varying characteristics in the rate of burn.

I don't really know that for sure, im just sayin. I would really like a chemists explanation. I might try to seek one out.

94SSman

· #22 · Oct 24, 2009

I have been wondering about fuel as well. A local station here sells leaded race fuel. My car was tuned on a mix of about 5 gallons 93 octane and race fuel. Would it hurt to run leaded fuel with my setup? It's a low compression 383 LT4 with a Procharger.

KW Baraka

· #23 · Oct 24, 2009

SSandman said:
.......Could it be possible that a given fuel can resist spontaneous combustion at a specific compression level, thus being able to be used in a high compression motor; but have the same rate of 'burn' from start to finish as a lower octane fuel......

I'm not smart enough to say that it's not possible.

But from all that I've read......I'll say that your supposition doesn't make sense.....since ignition and burn (combustion) rate is supposedly tied to octane rating.

KW

KW Baraka

· #24 · Oct 24, 2009

94SSman said:
.......A local station here sells leaded race fuel...........Would it hurt to run leaded fuel with my setup.........

Depends if if you consider clogged cats, ruined O2 sensors and a very rich A/F ratio as a 'hurt' or not.......because that's what leaded fuel will do to your car.

That's why car manufacturers will tell you to not run leaded fuel in cars with cats.

KW

SSandman

· #25 · Oct 24, 2009

KW Baraka said:
I'm not smart enough to say that it's not possible.

But from all that I've read......I'll say that your supposition doesn't make sense.....since ignition and burn (combustion) rate is supposedly tied to octane rating.

KW

If octane rating somehow takes into account the 'speed' of the burn somehow, some way, then I am definitely wrong, but all I can find are generalized descriptions of how the octane rating system works and most of them just say something along the lines of 'a fuels ability to resist detonation as compared to mix of iso-octane and heptane'.

question is, can a distinction be made between the ability to resist detonation and the rate of burn or is it one and the same. Can you have two fuels that both resist the same amount of pressure before spontaneous combustion, but one burns faster or slower than the other? Or is the speed of burn the only contributing factor as to WHY the fuel resists a particular amount of heat/pressure before spontaneous combustion. I am in the same boat as you, I don't know nearly enough about chemistry to understand. I am curious though!
btw, when did you turn 90?

94SS man, to add to what KW said, I would also say that if your tuner tuned the car on a mix of race fuel and 94, and you are now driving the car on pump gas...that could be a problem in and of itself if your tuner didn't leave a lot of leeway for pump gas. There are plenty of unleaded race fuels out there if you wish to run it, it's just a little harder to find than leaded. I know my shop only sells leaded but shops that build a lot of imports may have a supply/supplier for unleaded.

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Moose LT1 9C1

· #26 · Oct 24, 2009

My motor is 13.8:1 and I run C-16 in it.

117 Octane MON.

Good up to 17:1 compression.

Bob with 3 Bs

· #27 · Oct 24, 2009

KW Baraka said:
It's not about the 'explosion' as you incorrectly phrased it.KW

ex-plode (verb) 1. to expand with force and noise because of rapid chemical change or decomposition.

I guess you're aware of the expansion and force, but it's that bit about noise that really gives it away, don't you think? Or do you not have mufflers?

Granted, burn rates change with some higher octane fuels. My point about 'slow' burn rates is whether or not the difference between varieties of unleaded pump gas (and even the lower octane race fuels) is enough to make a difference in performance. Given the relatively low RPM potential of the common pushrod V8, I seriously doubt it. If you have info from real science guys, I'd be very interested in seeing it. Thanks.

Bob with 3 Bs

· #28 · Oct 24, 2009

Mean SS said:
you get knock when it explodes what you want is "rapid flame propagation"

You get knock when it explodes before the spark ignites it.

Moose LT1 9C1

· #29 · Oct 25, 2009

Bob with 3 Bs said:
You get knock when it explodes before the spark ignites it.

Pre-Ignition, as it were

SSandman

· #30 · Oct 25, 2009 (Edited)

just to clear it up for some

pre-ignition is just that, the fuel igniting BEFORE ignition ever occurs.

detonation aka ping aka knock is when the fuel does not burn nicely in a cascading fashion with the oncoming flame front, but instead it starts spontaneously combusting as the flame front moves (i.e; lets say fuel at the end of the line starts to burn before it's turn). But this all happens AFTER the spark plug shoots spark.

detonation=bad
preignition=very bad

I think the bottom line of this thread is,

1)leaded fuel=NO GOOD FOR COMPUTER CONTROLLED CARS WITH 02 SENSORS
2)high octane WONT give you an increase in performance IF your car is tuned for a lower octane UNLESS you are seeing knock retard from an overly aggressive tune

that pretty much states it. It's pretty simple really. If you have an aggressive tune and a high compression motor, hook it up to a scanner when you run and see if you are getting any knock retard. Run the car with some high octane UNLEADED if you wish and see if knock count goes down and knock retard goes away. If so, using race gas is a benefit for you. For most of the guys on this forum I would gather, using higher octane fuel than what they are tuned for would be useless as most guys here aren't pushing the limits of pump-gasable dynamic compression or super aggressive timing curves.

If you aren't geting knock retard but you think you can get more out of your car by using race gas, put some in and have it tuned. If you can get more power before she pings with the race gas, then you've found a reason for it. But as many already know (but yet some MECHANICS I have met STILL don't get) putting high octane fuel in your bolt ons, stock motored car is going to do NOTHING.

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Bob with 3 Bs

· #31 · Oct 25, 2009

SSandman said:
just to clear it up for some

pre-ignition is just that, the fuel igniting BEFORE ignition ever occurs.

detonation aka ping aka knock is when the fuel does not burn nicely in a cascading fashion with the oncoming flame front, but instead it starts spontaneously combusting as the flame front moves (i.e; lets say fuel at the end of the line starts to burn before it's turn). But this all happens AFTER the spark plug shoots spark.

Yes. Non-controlled ignition before or after the spark plug fires is unwanted. Good clarification.

SSandman said:
detonation=bad
preignition=very bad
beer=good

Better?

SSandman said:
I think the bottom line of this thread is,

1)leaded fuel=NO GOOD FOR COMPUTER CONTROLLED CARS WITH 02 SENSORS
2)high octane WONT give you an increase in performance IF your car is tuned for a lower octane UNLESS you are seeing knock retard from an overly aggressive tune

that pretty much states it. It's pretty simple really. If you have an aggressive tune and a high compression motor, hook it up to a scanner when you run and see if you are getting any knock retard. Run the car with some high octane UNLEADED if you wish and see if knock count goes down and knock retard goes away. If so, using race gas is a benefit for you. For most of the guys on this forum I would gather, using higher octane fuel than what they are tuned for would be useless as most guys here aren't pushing the limits of pump-gasable dynamic compression or super aggressive timing curves.

If you aren't geting knock retard but you think you can get more out of your car by using race gas, put some in and have it tuned. If you can get more power before she pings with the race gas, then you've found a reason for it. But as many already know (but yet some MECHANICS I have met STILL don't get) putting high octane fuel in your bolt ons, stock motored car is going to do NOTHING.

I'm with you on this. However, some race fuels will burn more completely, giving a power increase even without the benefit of more aggressive tuning.

KW Baraka

· #32 · Oct 25, 2009

SSandman said:
........question is, can a distinction be made between the ability to resist detonation and the rate of burn or is it one and the same. Can you have two fuels that both resist the same amount of pressure before spontaneous combustion, but one burns faster or slower than the other..........

I really don't think that's possible......at least not without extreme expense.

SSandman said:
........btw, when did you turn 90? ...........

This Forum will never know my true age or birthdate.

Identity theft, yada ......

Bob with 3 Bs said:
ex-plode (verb) 1. to expand with force and noise because of rapid chemical change or decomposition.

I guess you're aware of the expansion and force, but it's that bit about noise that really gives it away, don't you think........

Burning fuel = expansion of gases = the need to blow off (through exhaust ports). See......you don't need 'explosions' to do what you discribe.

Explosions in your engine would be an enormously bad thing; to the extent that your engine wouldn't last.......at all. The only 'explosions' I know of is the improper consumption of fuel; as in, pre-ignition.

Properly ignited fuel in an engine's combustion chamber will NOT 'explode'; it will burn. That's why it's called a "combustion chamber".

Bob with 3 Bs said:
.......However, some race fuels will burn more completely, giving a power increase even without the benefit of more aggressive tuning.

Yeah........right.

KW

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Bob with 3 Bs

· #33 · Oct 26, 2009

KW Baraka said:
I really don't think that's possible......at least not without extreme expense.

If your definition of extreme includes the difference between pump and race fuel, sure.

KW Baraka said:
Burning fuel = expansion of gases = the need to blow off (through exhaust ports). See......you don't need 'explosions' to do what you discribe.

Explosions in your engine would be an enormously bad thing; to the extent that your engine wouldn't last.......at all. The only 'explosions' I know of is the improper consumption of fuel; as in, pre-ignition.

Properly ignited fuel in an engine's combustion chamber will NOT 'explode'; it will burn. That's why it's called a "combustion chamber".

You're going to argue that an event that meets the requirements of being defined as an explosion is not an explosion? Well, uh...don't let insignificant little things like facts cloud your opinion.

KW Baraka said:
Yeah........right.

KW

Do I detect a whiff of sarcasm here? The following was taken from this article. http://www.hotrod.com/techarticles/fuel_octane_rating_comparison/index.html Yes, things in Hot Rod are often dubious, but this seemed to be legit.

… we discovered that our presumption that higher-octane fuels burn slower than lower-octane fuels (and therefore require more ignition lead) is largely incorrect. There are too many other fuel-formulation issues at work to assign a general rule about octane. Race fuel tends to have a more powerful formulation than pump gas, regardless of octane rating, because it is denser and can release more power and heat.

Thanks for the debate, Kev. It's been interesting to say the least.

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snakey5138999

· #34 · Oct 26, 2009

The thing with higher octane fuel is that it burns slower, which in hand burns more complete. Something how the higher octane fuel ignites faster and hotter than lesser octane fuels, which is how it burns more complete.

I can agree with wasting money, but as said, Slower more complete use of fuel can also help in fuel economy slightly. It also burns much cleaner than lower octane fuels as well.

SSandman

· #35 · Oct 26, 2009

snakey5138999 said:
The thing with higher octane fuel is that it burns slower, which in hand burns more complete. Something how the higher octane fuel ignites faster and hotter than lesser octane fuels, which is how it burns more complete.

I can agree with wasting money, but as said, Slower more complete use of fuel can also help in fuel economy slightly. It also burns much cleaner than lower octane fuels as well.

you may want to read the last few pages of debate, along with the quote Bob with 3 B's pointed out from Hotrod magazine. The 'burns slower' thing may not necessarily be true. Maybe it is, maybe it isn't. But one thing we can all agree on is that race fuel WILL either A) burn more completely or B) give off more energy as Hotrod states it. But either way, I don't think anyone will see much of a gain from this on a street car with a tune that works on pump gas. Maybe if you're looking for every last half of a tenth it's worth trying though.

KW Baraka

· #36 · Oct 26, 2009

Bob with 3 Bs said:
If your definition of extreme includes the difference between pump and race fuel, sure......

No......I'm saying......a lot more difference than that......I'm thinking something with a much higher degree of 'formualtion' than race fuel.

Bob with 3 Bs said:
.......You're going to argue that an event that meets the requirements of being defined as an explosion is not an explosion.........

In this case........yes. Because the proper state of fuel consumption in an engine's combustion chamber is not by way of 'explosions', it's by way of 'burn'. Which, BTW, also meets the 'requirements' of your 'explosion' definition.

Bob with 3 Bs said:
......Do I detect a whiff of sarcasm here........

No......skepticism......HRM not withstanding.

KW

Bob with 3 Bs

· #37 · Oct 27, 2009

KW Baraka said:
No......I'm saying......a lot more difference than that......I'm thinking something with a much higher degree of 'formualtion' than race fuel.

Like what?

KW Baraka said:
In this case........yes. Because the proper state of fuel consumption in an engine's combustion chamber is not by way of 'explosions', it's by way of 'burn'. Which, BTW, also meets the 'requirements' of your 'explosion' definition.

Except for the noise. Get it? It goes boom. Rapid burn (aka 'combustion') plus noise makes it an explosion by definition. It looks like a duck, it walks like a duck and it quacks like a duck, but it's not a duck?

KW Baraka said:
No......skepticism......HRM not withstanding.

No? You replied with a sarcastic remark. To convey skepticism, you'd have to say something such as, "I'm skeptical," or "I doubt that." Do you have your own personal dictionary that the rest of us don't have access to? Geez, I'm getting a headache...

Bob with 3 Bs

· #38 · Oct 27, 2009

SSandman said:
I never really got the idea that race fuel 'burns slower'. Higher octane resists detonation better than lower octane, that is what octane is essentially a measure of. But how does that have any affect on burn speed? I always figured perhaps this is flatout untrue, as octane rating itself, as defined, has nothing to do with burn speed, but maybe lead vs unleaded affects the burn speed?

SSandman said:
No, not necessarily. Could it be possible that a given fuel can resist spontaneous combustion at a specific compression level, thus being able to be used in a high compression motor; but have the same rate of 'burn' from start to finish as a lower octane fuel (when both are tested at the same compression, one that is within the lesser octanes fuels ability to resist detonation).

Being that 'octane rating' does not actually mean the amount of octane in a fuel, it only means how that fuel compares to a percent of iso-octane and heptane mixture in regards to how much pressure it can resist before spontaneous combustion, it seems that you can have a variety of different ways of making a say '105 octane' mix and because of this there could be varying characteristics in the rate of burn.

I don't really know that for sure, im just sayin. I would really like a chemists explanation. I might try to seek one out.

SSandman,

I'd wager the folks that make Rockett Brand fuels have some chemists working for them. They, as one would assume all other fuel makers, claim to adjust their formulations for maximum power given the customer's requirements. KW would probably argue this was written by their sales department and has no basis in fact or science (or that the sun sets in the east), but I'll take their word over his.
http://www.rockettbrand.com/techsup...letins/FlameSpeedOctaneAndHpRelationships.pdf

Bob

KW Baraka

· #39 · Oct 27, 2009 (Edited)

Bob with 3 Bs said:
Like what.......

Like what ain't readily available on the market.......and no, I'm still not talking about race fuel.

Bob with 3 Bs said:
......Except for the noise. Get it? It goes boom. Rapid burn (aka 'combustion') plus noise makes it an explosion by definition. It looks like a duck, it walks like a duck and it quacks like a duck, but it's not a duck......

When you burn large quantities of fuel in a confined space (combustion chamber) and then only allow the exhuast to escape that confined space for a short period of time (opened/closed exhaust valve) and futher allow the exhaust to escape through contructing tubes (headers & pipes), then yeah......you're gonna have noise!! But I've never heard my car go BOOM. Whatever. You'd be hard pressed to find an engine builder who will concede that several thousand 'explosions' are occurring safely in a properly running engine every minute of its operation, because that's not what happens

.

Bob with 3 Bs said:
......No? You replied with a sarcastic remark. To convey skepticism, you'd have to say something such as, "I'm skeptical," or "I doubt that." Do you have your own personal dictionary that the rest of us don't have access to? Geez, I'm getting a headache...

OK......let me put it this way with no sarcasm.......and no mere skepticism. As I see it, that hot rod magazine article is bullsh1t. Feel better, now?

Bob with 3 Bs said:
.......Rockett Brand fuels......KW would probably argue this was written by their sales department and has no basis in fact or science (or that the sun sets in the east), but I'll take their word over his.
http://www.rockettbrand.com/techsup...letins/FlameSpeedOctaneAndHpRelationships.pdf.......

Bob.....two quick points and a comment about this article;

1. You'll note that everything they wrote pertaining to fuel consumption spoke to fuel 'burn' or 'combustion'. Ask yourself why your so very trusted source speaks NOTHING to 'explosions' (I think your duck just died cwm3).

2. In stating that race fuel has a more complete 'burn' (damn that word

), they never/or superficially mentioned the primary factors involved.......increased compression and ignition timing. Put that fuel in a car tuned for 87 octane fuel and has 8.5:1 compression ratio and we'll see how 'complete' the fuel gets burned cwm2.

3. Yeah......a sales pitch is the best evidence ever conceived in bosltering an arguement.......the best evidence ever

.

KW

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Bob with 3 Bs

· #40 · Oct 28, 2009

KW Baraka said:
Like what ain't readily available on the market.......and no, I'm still not talking about race fuel.

So...It's a SECRET!

KW Baraka said:
When you burn large quantities of fuel in a confined space (combustion chamber) and then only allow the exhuast to escape that confined space for a short period of time (opened/closed exhaust valve) and futher allow the exhaust to escape through contructing tubes (headers & pipes), then yeah......you're gonna have noise!! But I've never heard my car go BOOM.

You're saying the noise emitting from and engine is simply the sound of exhaust gasses passing through various chambers, orifices and tubes? I am skeptical. I doubt that. That is BS!

KW Baraka said:
You'd be hard pressed to find an engine builder who will concede that several thousand 'explosions' are occurring safely in a properly running engine every minute of its operation, because that's not what happens .

Engine builders? I'd guess the majority would concede the point. Scientist, chemists, engineers? No problem. Can you find a prominent engine builder who'll back your supposition?

KW Baraka said:
OK......let me put it this way with no sarcasm.......and no mere skepticism. As I see it, that hot rod magazine article is bullsh1t. Feel better, now?

I found that article to be more believable than most magazine fodder because they're not hyping some product. Same engine, same dyno, different fuels, different outcomes. Can you show me something that contradicts their test results? Also, I'm feeling fine. Thanks for asking! <This is sarcasm.

KW Baraka said:
Bob.....two quick points and a comment about this article;

It's not an article. It's a sales flyer, but it addressed SSandman's questions.

KW Baraka said:
1. You'll note that everything they wrote pertaining to fuel consumption spoke to fuel 'burn' or 'combustion'. Ask yourself why your so very trusted source speaks NOTHING to 'explosions' (I think your duck just died cwm3).

Er...because it's not necessary? (What duck? I thought you said it wasn't a duck).

KW Baraka said:
2. In stating that race fuel has a more complete 'burn' (damn that word ), they never/or superficially mentioned the primary factors involved.......increased compression and ignition timing. Put that fuel in a car tuned for 87 octane fuel and has 8.5:1 compression ratio and we'll see how 'complete' the fuel gets burned cwm2.

Which fuel? They're talking about race fuels in general. Are you saying race fuel won't 'burn' in a low performance engine? Nice use of smilies, by the way. <More sarcasm? Could be.

What's your hard-on for the word burn? Fuels burn. Be it gunpowder, wood, gasoline, lighter fluid, C-4 or whatever, it burns. It's where the flames come from in fires and explosions. It's not exclusive to or separate from explosion, it's a part of the process.

From Wikipedia http://en.wikipedia.org/wiki/Explosion

"An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive" . Subsonic shockwaves are created by low explosives through the slower burning process known as deflagration."

Also from Wikipedia http://en.wikipedia.org/wiki/Deflagration

"Applications--
In engineering applications, deflagrations are easier to control than detonations. Consequently, they are better suited when the goal is to move an object (a bullet in a gun, or a piston in an internal combustion engine) with the force of the expanding gas. Typical examples of deflagrations are combustion of a gas-air mixture in a gas stove or a fuel-air mixture in an internal combustion engine, a rapid burning of a gunpowder in a firearm or pyrotechnic mixtures in fireworks."

In summary, fuel burns in an internal combustion engine via deflagration. Deflagration, along with detonation, is one of the two types of explosions.

KW Baraka said:
3. Yeah......a sales pitch is the best evidence ever conceived in bosltering an arguement.......the best evidence ever .

That flyer was intended to answer some of SSandman's questions and I'm not arguing with him. It seems I'm arguing with you, and your denial of the obvious is quite stunning.

Here are a few more items you can dispute.

http://dictionary.reference.com/browse/explosion definition 5.
http://auto.howstuffworks.com/engine1.htm
http://www.everything.com/understanding-internal-combustion-engine/
http://books.google.com/books?id=5LZFlCjG4CcC&dq=isbn:1557884005 Bottom of page 51, top of page 52

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