S2000man01

iTrader: (1)

Here... so you know I'm not talking just "hearsay"

this was in a pdf i found at the american petroleum institute. here are some excerpts. i believe this was also hilighted on the service advisor web site.


WHAT IS OCTANE RATING?

Octane, by definition, is the resistance to burn or detonation. The higher the rating, the slower the burn when ignited during the compression burn cycle of the piston. The higher octane allows for better control of burning for high compression engines. So we want to match the correct octane rating of the gasoline to the engine design to ensure complete burning of the gasoline by the engine for maximum fuel economy and clean emissions.

I THOUGHT GASOLINE WITH HIGHER OCTANE REDUCED ENGINE KNOCK?

It did in older engines using carburetors to regulate air/gas mix They cannot as accurately regulate the air/fuel mix going into the engine as a computerized fuel injector. Carburetors need adjustment, as a part of regular maintenance, to keep the air/fuel mix as accurate as possible. So many times, these adjustments were not made regularly causing too much fuel to be mixed with the air. When this happened the gasoline would not burn completely soaking into carbon deposits. This would cause a premature ignition of the gasoline due to the intense heat in the engine cylinder creating "engine knock." When this happened, people would change to the higher octane/slower burning gasoline to resist the premature burn, thus minimizing the knocking problem. And it worked. Good solution.

However, since the middle to late 80’s, engines are designed to use fuel injectors with computers to accurately control the air/fuel mix under all types of temperature and environment concerns. However the accuracy of the fuel injectors and computers is based on using the recommended gasoline for that engine.

Most cars are designed to burn regular unleaded fuels with an octane rating of 87. If the vehicle needs a higher octane rating of 89-93, there is documentation in the owner’s manual, as well as possibly under the fuel gauge and by the fuel fill hole. Usually you will see this rating for high performance engines only.

WHAT IF I PREFER TO USE GASOLINE WITH HIGHER OCTANE RATINGS?

You can, but there are no real benefits, other than the gasoline manufacturers making more money off of you. When you use a fuel with a higher octane rating than your vehicle requires, you can send this unburned fuel into the emissions system. It can also collect in the catalytic converter. When you over stress any system, it can malfunction or not do what it was designed to do properly. In the early 90's, an early warning symptom was a rotten egg smell from the tailpipe. Easy fix, go back to using regular 87 octane gasoline. The rude odor usually disappears after several tanks of gasoline.

DOESN'T HIGHER OCTANE GASOLINE HAVE MORE CLEANING ADDITIVES THAT ARE GOOD FOR MY ENGINE?

No. Government regulations require that all gasoline contain basically the same amount of additives to clean the injectors and valves. The only differences are the type to help create the different octane ratings. All gasoline burns at the same rate, it is the additives that create the different octane ratings for the different types of engines.


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

And here's from the federal trade commission.
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

Derek-CEO

iTrader: (27)

how do u explain that honda et al are endorsing the new top tier gasoline?

gearbox

iTrader: (95)

Well you can buy the lower octane gas that is still part of the top tier program. The shell v-power (highest octane) has 5x more detergents, but the lower grades also have enough to meet the standard. I'm gonna keep using 89 to be safe, but stock civics only need 87.

Derek-CEO

iTrader: (27)

i thought vpower was the only top tier from shell?

i have been using premium in my V6 accord since day 1. dunno what to do now.

gearbox

iTrader: (95)

no 87 and 89 also contain 2x the additives required by the program. V-power has 5x the amount.

can someone explain how 91+ even works in our cars if it isn't able to burn? Does the ecu do something?

S2000man01

iTrader: (1)

let me explain what is happening.

Cars that do not have higher compression have a lower temperature of the mixture before ignition. (this is basic physics... the more you compress air/matter the hotter it gets) So in a car that does not have higher compression, honda builds the car from the factory with the appropriate timing for the recommended octane.

Higher octane gas burns LONGER since it is more resistant to detonation and heat. So the time it takes to burn through the mixture on 87 octane is LESS than what it takes to burn through a mixture with 93 octane.

if your car is setup for 87 octane (like the civic) the 93 octane will not have completely burned through the mixture by the time your combustion chamber has opened the exhaust valves and is scavanging the mixture. This gives the still burning mixture the not-so-great opportunity to burn through your valves since it now has an out and a re-introduction of oxygen via the open exhaust valves. This is what causes the buildup of crap on your valves and other parts which can lead to damage down the road. Also because the mixture did not finish burning, some of that fuel or unburned mixture can go through your exhaust and then settle in your catalytic converter, causing you to fail emissions and/or damage your cat.

So there are 2 keys to having a car that can run premium effectively without these issues. number 1, higher compression, which causes more heat, allowing the mixture to burn more efficiently and more thoroughly with less leftover contaminants.

number 2, advanced ignition timing and retarded exhaust valve timing, allowing the mixture more time to burn with closed valves.

going from 87 to 89 octane isn't too bad, but going from 87 to 93 can be harmful in the long run and cause a loss of power in the short run. (if your mixture burns all the way through, it gives you more power obviously)

Derek-CEO

iTrader: (27)

here is more good reading too

http://theoildrop.server101.com/ubb/...?ubb=forum;f=5

S2000man01

iTrader: (1)

oh as for the top tier question.

if shell sells "top tier" 93 octane gasoline, federal law states their regular 87 octane sold on the same pump MUST have the same amount of cleaning agents in it, which means the 87 octane must also meet the top tier standard. all gas under a brand of gasoline company must have the same amount of cleaning agents in them regardless of octane rating.

the FTC states this: As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car's engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.

this from the american petroleum institute:
Additives
Each major oil company typically adds its own proprietary additives to the basic recipe for gasoline in order to provide or enhance specific performance features. And, most important, each company provides the technical expertise to back its brand. They also must ensure that the additive package is contained in every gallon of gasoline sold under their brand name. Many customers buy branded gasoline because of this consistent quality. Deposit control additives, which are found in all gasoline by law, keep engines clean and make them run more efficiently. Deposits in carburetors or in fuel injectors, for example, can affect the engine’s overall air-fuel ratio as well as an individual cylinder air-fuel ratio, which in turn can affect fuel economy, emissions and driveability.

So, while the addatives and types of cleaning agents CAN vary from brand to brand, the amount of addatives and addative packages for each brand's 87-93 octane gas cannot. So if shell has top tier gas at a station, all of its gas by law, regardless of octane, must meet the top tier standards package of cleaning agents.

Stachmo

iTrader: (2)

what happens if you use a gasoline with a lesser octane rating than what the car is supposed to have? Example. My dad stopped using the premium 91 or 93 (I forget which one it is) on his Nissan Pathfinder and started using 87. What is this gonna do to his engine? Lose power since the gas is burning quicker than its supposed to?

Excal

iTrader: (2)

he answered that question already.

2K1Civic17"Gabe

iTrader: (9)

I use 91, thats the highest other than race fuel available at a pump. Im gonna try that 105 out sometime soon. maybe at the track

aznboysrfr

iTrader: (10)

you sure like to waste money

Jrfish007

iTrader: (3)

As long as the engine is made for 87, nothing will happen. He will have a tank 87+ octane, go through and then nothing, assuming the engine is made for 87 octane.

Jrfish007

iTrader: (3)

I shall quote the all knowledgable my self now:

This is about what S2000man01 said.

This is text book stuff, yes I have those text books. I'm a chemical engineer, chemical enginers purpose is to refine oil and work in the petroleum industry.

In the end, just use what gas your manual cars for. Detergents are nice, but your car doesn't require them to run nor will they give noticable power or anything of that nature nor will they clean you engine more (well maybe a little, but you'll never notice the difference). Listen to S2000man01, he knows what he's tlaking about here.

down_

Same here. i've been using 91 octane in my 03 civic since day one...i now have 50+ thousand miles on her and she still run's great....this hole post thread in based on the soul opinion of one biast person......if you want a "Real" scientific hypothisis and conclution research ALL of the products, w/ the Positives and Negetives....its obviouse by now that we all know the Definition of the word "Octane".....But all engines run diffrently, no matter if there the same generation engine or what have you....if you statement is true s2000 then why havnt i had any Significant powerloss, and why does my engine in all its technical specs. have minimal wear to it...........maybe its not the gasoline or the additives....maybe its the driving habbits of thouse who race to every red light. Everyone has ther own opinion on gasoline, you MIGHT be correct in your statment but only to a small degree, and even then Using a Lower quality Gasoline also Has its disadvantages, like deposits. ect. just because the goverment sets a standard, does not mean that that standard is correct....show me some prof. not the statments of biast persons..like the gasoline companys testemonies or even the Department of Energys Statments...........i wana see 3 engines 3 diffrent types of gasoline, and 3 diffent results then...and only then....will i stop "pissing away my money" You cant forget that 03+ civic ecu's have the ability to "learn" or compinsate for diffrent situations...........for example if you add and intake the ecu will compinsate for the add'd air in the mixture, and run the car more rich...its also possible that it can compinsate for the higher octane in the fuel , or another example...anyone w/ a vafcII can tell ya this......if you set your vafc to a certine point the ecu will reconize it ( given enought time like 2 months or somthin) and revert back to stock. hence the reason your cars dont feel as powerful as they origanly did when you put it on.


Edit: P.s After reading my own post it has come to me that it might seem alittle ummmm mean...i dont know..i didnt mean for it to come out that way but anyway...yea thats it..

Jrfish007

iTrader: (3)

Well, the idea that higher grade gas is bad for your car isn't really true. It's based on the fact that the higher octane burns slower, which is true, but you have to put things in perspective. There is about 2 order of magnitude bewteen the burn rate and piston velocity, so although it burns slowwer, it's like comparing which is faster than a civic, a SR-71 Blackbird (travels up to mach 4) or an F1 fighter jet (travels around mach 2), sure the Blackbird is faster, but both are way faster than the civic. So comparing 93 to 87, it really doesn't matter for burn time. In theory the 87 will give you a tad bit more power, but I doubt it's even enough to be noticable on a dyno.

Jrfish007

iTrader: (3)

I also think you are missing the bigger point S2000man is tring to make, the quality of gasoline is the same if they are from the same station (unless they have different pumps for each grade). If you buy 87 from shell, it will have the same cleaners and all that the 93 will.

If you want 3 different motors with three different grades of gas, you better be more specific and say all threerun on gas from the same company. My dad put 250,000 mile on his Accord with nothing but 87 and dino oil with out ever having anything cleaned in the fuel system, that far out does your 50,000 (his died from tranny problems, motor ran fine).

S2000man01

iTrader: (1)

Real quick here.

This is scientific fact, and jrfish007 is also backing me up on this. This is not my "biased opinion". Did you even READ the links I gave for both the Federal Trade Commission, howstuffworks.com, and the info from the American Petroleum Institute (the API is a non-profit unbaised organization)? All I did was summarize and explain in detail everything they said. So to say I'm "biased" and not telling you facts, is the same as saying the API and FTC federal agencies are biased and aren't telling you the facts. I don't know how else I can repeat myself 30 times over before you'll get that.

I ALSO gave you the technical reason WHY high octane gas is bad for your lower octane civic. I explained it exactly how it happens, with burn time and everything. And you just ignore that and throw it out as "biased opinion"?

As for your 50k+ miles on 91 octane, you have been losing power from day one. And the damage that occurs is not something that happens overnight. It occurs over time. In fact, go take apart the head of your civic. I bet your valves will be burnt to hell and have far more deposits of contaminants and crap in your engine head of a civic with the same miles that has been using 87 octane. I also wouldn't be surprised if you failed emissions within the next 25k miles as well as possibly have your catalytic converter go bad, ironically, right about the time your cat warranty expires.

Again, ignoring the problem at hand. As I already said, to adjust for higher octane gas you must ADVANCE your ignition timing and adjust your exhaust valve timing. Sorry but, all the changing of your a/f ratio in the world won't adjust for higher octane gas. All that does is change the mixture's a/f ratio. (duh)

Your ECU WILL NOT ADVANCE TIMING just because you put in higher octane gas. In fact, your ECU will not EVER advance timing. Because it can't.

A/F is adjusted for by the ECU or VAFC. But again, since higher octane gas burns longer, you need to adjust your ignition timing and exhaust valves for that. So your statement about the learning ECU of the civic is irrelevant, since it can't even physically do what needs to be done to run higher octane fuel.

(FYI, the civic ignition timing is 18 degrees. Advancing it to about 16 degrees and then retarding your exhaust valves slightly would probably be adequate to run premium fuel)

Derek-CEO

iTrader: (27)

ok, what about my V6 Accord? It has higher compression then civic right? What am I to do?

btw, my compression is 10.0 : 1 Civic EX is 9.9:1 so I guess it's not that big a diff.

S2000man01

iTrader: (1)

I would use regular 87 octane gas. I had a v6 6-speed accord and that's all i ever used in it as well. 89 might be ok too, but only go up to 89 if your engine is knocking on the 87.

to give you guys what I'm talking about with ignition timing and honda setting up your car for a certain octane, the civic's ignition timing is 18 degrees. The S2000, which requires premium, is 5 degrees. (the lower the number, the more advanced the timing is) Though I should note, the S2k can advance or retard the timing as much as 3 degrees either way, based upon several sensors. (load, vacuum, knock, etc)

gearbox

iTrader: (95)

i've used 89 for a year, but I still need to advance the timing at least 2 degrees if not more when I get the cam gear and tune it. Then I'm sure it'll be okay. I believe on our cars changing cam timing also changes the ignition timing.

S2000man01

iTrader: (1)

From what I know, cam timing and ignition timing are completely seperate. Cam timing is controlled by the cam gears and cams obviously. Ignition timing is controlled by the distributor.

gearbox

iTrader: (95)

Well I guess we'll find out when I get my cam gear in a few months (backorder sucks). Is there any truth to older cars needing premium to run better?

jttegx

iTrader: (3)

what is this "knock" suppose to mean? how do you know if its "knocking"?
does it happen when u use low grade fuel or something?

S2000man01

iTrader: (1)

yes, if the engine is carbeurated. since there is no EFI, the premium gas can help a carbeurated engine.

S2000man01

iTrader: (1)

well if you've ever heard your engine run under normal conditions, "knocking" would be described as a "knocking sound" coming from the top of your engine block. this is caused by pre-detonation. in other words, the mixture detonating before the ignition spark actually causes it to do so. it's louder than the normal engine sound by a slight bit as well.

it can happen if you get bad gas, but not from putting 87 octane in. assuming 87 is the minimum octane requirement.

if you put 87 in an S2000, you'd hear some knocking since it requires premium, for example.

Jrfish007

iTrader: (3)

That's true on the D16 because the rotor of the distributor was directly connected to the cam, it literally stayed in time with the cam, so if you adjusted the cam, you adjusted the timing. But the D17 doesn't have a distributor, it all electronically controlled through solid state relays and ignition coils. Changing your cam timing on a D17 won't affect the timing on the D17. I know it is electronically controlled, but I am not sure if the ECU controls it for the D17 or if it is a separate control system for the ignition.

Jrfish007

iTrader: (3)

Well, just go with what the manual says, and I think that is 87. Remember the civic may have a 9.9, but it can run 86. My Accord needs "regular" gas (I think that means 87)

http://www.hondanews.com/CatID2008?m...49831&mime=asc

the V6 falls under the same gas, I would think 87 is fine for either the Accord or Civic.

***Edit: Derek, is your Accord stock engine wise?

Jrfish007

iTrader: (3)

Yeah, like S2000man01 said, if carbureted. The problem with that is that the fuel is not aromatized properly in a carburetor (it's not spread out), specially because it has a wet manifold compared to a EFI car that has a dry manifold. So you get pockets of fuel with out air and pockets of air without fuel, this means you will pocket in areas that are very lean, hence they will cause detonation and blow the motor up eventually. Higher octane fuel can help in preventing this.

S2000man01

iTrader: (1)

Thanks for posting. I was unsure of whether the civic had a distributor but i know that the D17 ignition timing is not controlled by the cam gear, unlike the D16.