I know I'm suppose to use it, but why? how does it relate to high compression engines? I just hate it when people tell me I don't have to use it and its all the same when I know I use 93 for a reason.
TIA,
Will

 

I'm no expert, but from what I've read in magazines while dropping friends off at the pool (that, I'm an expert at!) Octane is just a rating that describes a fuels resistance to detonation. We have to run "Premium" because it decreases our chance of preigniting or detonating in adverse conditions (ie. Houston, TX weather any time other than November-December). As far as BTU content goes, there's negligable difference between 87 and 93 octane that they sell here.

FWIW, I used to run 18psi on pump gas in my Eclipse. But if I threw in a gallon of Xylene (u can get that at any paint store for about $6/gallon) which helps raise the octane rating, I could turn up the boost to 23psi without timing backing out. Not sure if it was bad for the engine or not, but when I sold the car, it had about 160K miles on it and it ran fine.

 

You do not need to run 93 octane in your car. Whoever told you that you needed to is pulling your leg.

 

what about that little label at the bottom of the speedo that says "PREMIUM UNLEADED FUEL ONLY"...Ive always used it my gsr...

 

They just did a test in one of the magazines a month or two ago with a bunch of cars to see if premium fuel had any effect. The general gist of the story - if your manufacturer tells you to use it, it's probably a good idea.

 

the higher compression your motor has, the higher octane rating your car will need before it starts to detonate. I wouldn't go any lower then 91 octane with a stock b18c5 if it was me...

 

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

 

The Type R (and also the GS-R) are designed to use premium fuel (which is defined in the owner's manual as 91 octane).

If you use lower octane gasoline (less than 91), the ECU in the car will adjust the timing to compensate and avoid detonation, but you will get lower performance as a result.

Bottom line: CAN you use regular fuel without harming your car? Yes. SHOULD you use regular fuel? Well... you didn't really buy a Type R so that you could save a few cents on gas and have the performance of a base-model Integra, did you?

 

In simple terms, octane is a fire retardant that prevent the fuel from combustion during the compression cycle of the engine. High compression and forced inducted engines tend to produce extreme heat that may causes the fuel to combust prematurely (detonation) which can cause damage to the engine....high octane reduces the chance of premature combustion.

 

Oh, I'm not running that because someone told me to, thats just whats available at the pump as "Premium", so I use it like Honda says.

 

OK, I got this from http://www.howstuffworks.com

---------
The octane rating of gasoline tells you the amount that the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want have happening. Lower octane gas (like "regular" 87 octane gasoline) can handle the least amount of compression before igniting.

The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high performance engine" has a higher compression ratio and requires higher octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance". The disadvantage is that the gasoline for your engine costs more.

The name "octane" comes from the following fact. When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has 5, hexane has 6, heptane has 7 and octane has 8 carbons chained together.

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. 87 octane gasoline is gasoline that contains 87% octane and 13% heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.

During WWI, it was discovered that you can add a chemical called tetraethyl lead to gasoline and significantly improve its octane rating. Cheaper grades of gasoline could be made usable by adding this chemical. This led to the widespread use of "ethyl" or "leaded" gasoline. Unfortunately, the side effects of adding lead to gasoline are: 1) the fact that lead clogs a catalytic converter and renders it inoperable within minutes, and 2) the fact that the earth became covered in a thin layer of lead, and lead is toxic to many living things (including humans). When lead was banned, gasoline got more expensive because refineries could not boost the octane ratings of cheaper grades any more. Airplanes are still allowed to use leaded gasoline, and octane ratings of 115 are commonly used in super-high-performance piston airplane engines (jets burn kerosene, by the way).
------------- http://www.howstuffworks.com

 

Weird coincidence, I went to bed tonight and started reading Forza magazine (the Ferrari monthly magazine and yes I am a Tifosi) and there is a multi-page article about this very topic. Here are some hightlights:

"Octane rating -- the pricipal quality that distinguishes premium gasoline from regular -- simply describes the chemical regulation of the speed at which combustion propogates from the spark plug through the fuel mixture. The higher the octane rating, the slower the flame spreads; the lower the octane rating the faster the flame spreads. If the flame spreads too quickly for the internal dynamics of a particular engine, pinging will be heard, especially during acceleration and up hills.

"Pinging is the sound of combustion that is veering more toward harsh explosion than properly controlled thermal expansion. Its sharp rattling noise is a result of excessively rapid combustion violently impacting the piston and radiating through reciprocating and fixed engine components -- and it has potential to be as harmful to an engine as it sounds...

"High octane gasoline is created from a refinery stream that possesses intrinsic molecular properties that facilitate the task of slowing flame propogation. In other words, it's more than regular gasoline with an octane-boosting additive package...

"Contemporary engine management systems use knock sensors to detect threshold detonation (the harbinger of pinging) and calibrate ignition and fuel injection timing to keep the engine on the verge of detonation -- the point at which the engine is most efficient.

"If you use low-octane gasoline in a high-performance engine equippd with a knock sensor, the computer will retard the timing to suit the specific octane at any given moment and, although the engine may run flawlessly, you will not be getting the best performance possible..."

 

just drop in a couple of moth ***** into ur tank...

 

speaking of octane, how about european and asian octane ratings? everyone talks about how there is 100RON gas in Japan. However, my friend who is in the chemistry field told me that the way octane is calculated in North America and the rest of the world is different. Apparently, octane calculation in the rest of the world yields higher numbers/ratings than in the US. Effectively, 100RON in Japan is equivalent to our 95 octane... which of course is still higher than what we get, but it's not that huge difference that we usually think it is... can anybody elaborate further?

 

THAT'S WHAT I SAID!!!

 

Americans use Octane = (RON+MON)/2.
The rest of the world (almost) use RON. RON > MON => RON>US Octane>MON.
RON = Research Octane Number
MON = Motor Octane Number

 

saw this post... freaked out because i thought min was 91 octane since day 1, dug out my owner's manual.... 91 octane *phew*

 

But will you get the advantage of using OCTANE 94, OCTANE 100 etc for a stock compression engine?

 

Sure, the ITR and other high comp engines can use higher than recomended octane ratings. However, on a stock B18c5, its a waste of money to put 101octane as there is a limit on what octane the ECU can adapt to. In terms of performance, it will do more harm too. The higher the octane rating the more additive it has. Less purity=less combustion energy.

 

Octane is like a vitamin -- reaching the essential level is critical; everything beyond that just gets hosed through the system...