89 Octane Fuel vs 93 Octane

For the 2010 season, we ran 87 pump in our 600RRs...usually came from the last station before we pulled into the track.

 

I think often Suzuki's and Hondas are spec'd @ 87, my Kawi's are 91+

 

For 2011 did ya upgrade to 89?

We ran pump 87-91 in the Moriwaki and SV650.

 

We splurged on 93! The MD definately likes the expensive chit

 

First off octane is averaged between "motor" and "research" octane numbers, motor is derived from observing when pre-ignition and detonation occur in a test bed engine and is the gold standard so to speak.
The other number is projected from the multiple chemical's blended into "gasoline" and their known reaction properties and is considered somewhat less trustworthy in terms of predicting detonation and pinging/spark knock.
You can have a mix of 87 average with high motor number and a low research octane number that will resist detonation and spark knock to a high level while the same 87 average blended with lots of research and less motor numbers will ping like hell.
In addition, octane measures the burn speed of the fuel, high compression engines must have slower burning fuel or bad things happen but slow burning fuel in a lower compression engine does not make as much power as the faster burning version so if your engine is rated at 87, run 87 not 93 and vice-versa.
Factors like volitility rating and the latent rate of evaporation come into play as well around the time of seasonal weather changes because gasoline is made far in advance of when it is consumed by the public and the oil companys have to guess in the summer if the fall/winter/spring is going to be colder or warmer than predicted in order to blend in cold start and hot idle properties that match the climates the vehicles using it are subjected to.
If they blend up a few million gallons of cold weather fuel and summer comes early, lots of engines are going to have trouble coping with fuel designed to burn at below freezing temps and likewise if they predict the opposite, hot weather fuel will be very hard to start on sub-freezing mornings.

I guess I should add that if we are talking about race bikes, you should probably blend higher octane race fuel with pump gas or do something other than run low octane fuel under full load high rpm conditions.

 

Yea, what he ^ said.:up:

 

After 2 pages of debate we still don't know what kind of engine this is going in.

L454- If it's a diesel, don't run either 89 or 93, run diesel. If your engine requires 90 octane, talk to your tuner and ask for it to be tuned to 93 and let it ride. If you want to try to get every 1/10 horsepower out of it, tune it to 93 then to a blend of 89/93 and see which makes the most power. Go w/ the best. If your tuner does not know, find a new one.

To the others- Thanks for the interesting info.
The big post helped clear some things up.

My favorite statement from the driving public w/ a car req 87 octane is this. "every third or fourth tank of fuel, I run the high dollar 93 to clean my engine out."

 

There is something to running the 93 once and a while.
All fuel contains waxy gunk called olefins which clog up injectors and gum up valve stems and guides.
Used to be the oil co's would evenly (more or less) distribute the olefins equally between the three grades but now they stuff it all in the lowest grade resulting in next to none in the 93.
I reccommend BG "44k" to clean fuel systems, it really works and is harmless to fuel pumps/screens etc..

 

Well it's not really the 93 part, it's the additives part that comes only in the high octane some providers offer. Chevrons 'Techron' and Shells 'V-Power' are a couple examples of an additive complex that actually DO help clean out fuel systems. Without those additives, it's sort of a moot point.

 

It's both, they really do remove some of if not most of the olefins from the 93, the cool part is they put them back in the lowest grade so they don't lose money from the lost bulk.
When they tell you they include special additives that clean your valves, what they don't mention is that the crap they leave in the fuel in the first place causes them to have to add the cleaning chemicals.

 

I vaguely remember hearing/reading somewhere that the API test bed engine was some kind of Edwardian flathead, glow tube ignition, wick carbureted relic kept in a mahogany cabinet with brass fittings. Maybe that isn't the case now, or it never was, anyone know?

 

Regardless of where you buy gasoline in the USA all pump fuel of all grades must contain a minimum specification of detergents by law.

A better method to cleaning out the system than a dubious "premium" gas is to use a fuel system cleaner. Techron is the most recommended but any PEA additive is good. None of which has a thing to do with the OP but it's great stuff to chat about.:up:

One thing I've found is marinas still sell fuel with zero ethanol. That might be something to consider since ethanol definitely robs gasoline of power. Might be worth taking a couple jugs to your local marina to fill up before the track.

 

It's going in a GSXR 600 with a stock motor running a Bazzaz as a piggyback. Didn't know the extent of debate I would set off.

 

It is indeed, I've seen one, it was designed by the famed Ricardo of WWII aircraft engine fame.
It has a "viewing window" in the combustion chamber where different burn colors can be observed while changes to jetting, spark timing and even compression via movable combustion chamber adaptors while running.
Google Ricardo, he is the father of many of the designs we take for granted today and his very early work pre WWII is amazing considering he tinkered up his stuff in his basement.

 

So did we decide if there is more power or not with the octane rating? I forgot.

 

Max power lives where as much fuel as possible burns as fast as possible without pre-ignition/detonation.
Matching fuel burn speed to cyl pressure is the key.

 

100% agreed. Every engine is different.

 

tunersricebowl I agree with of few things you've said, disagree on others.

I agree that what we see at the pump is the average of RON and MON (R + M /2) also know as Anti Knock Index (AKI), however both RON and MON are obtained from testing the fuel in an engine. Feel free to google it.

Regarding your statement above, I have to say that octane does not measure burn speed, however it does have an impact in burn speed. Fuels with high octane rating, excluding additives, are composed of Hydrocarbons (HC's) with stronger molecular bonds. These bonds require more energy to break, therefore, slower burning speeds with higher octane fuels.

Can you please answer why an engine with high compression must burn fuel slower?

In regards to volatility, for the most part I agree. I'm not sure I agree with you on how the way oil companies handle the seasonal changes. They are smart enough to now what fuel type they need to send up north and they need to send south.

A little more on volatility:
If you look at VP's fuel specifications you will see RVP (Reed Vapor Pressure) and Destilation, this indicates the fuels volatility

RVP indicates how much gasoline evaporates at room temperature (I don't remember if it is room temperature or a standard temperature). The higher RVP the easier it is for fuel to vaporize. This is very important for cold starting (winter temperatures) because liquid gasoline doesn't ignite, gasoline with high RVP is used in northern states for better cold starting performance. Destilation data gives you information on the state of the fuel vs temperature. As fuel travels down the intake into the combustion chamber, heat is transfered to the liquid fuel from all the surfaces and hotter gases on its way. The fuel's temperature rise changes liquid fuel into an ignitable gas, this is also why fuel has a cooling effect. Once fuel is in the chamber, any remaining liquid fuel will be converted into vapors from the heat of combustion. You can see that excess liquid fuel in the chamber will suck heat away from combustion resulting in lower combstion temperatures which results in loss of power, this is one of the resons why too rich is not good for power.

Another very important factor in fuel is it's Heating Value, wich tells you how much potential energy is in it.


Regarding Olefins: Olefins are a type of Hydrocarbon with a double Carbon to Carbon bond, let me google that for you http://lmgtfy.com/?q=Olefins

I agree with your comment above, but if you burn too fast, you would need to retard your ignition right?

Let me also say that is pretty cool you got to see the test engine.

A general comment about octane. Spark ignition engines thermodynamic efficiency is directly related to the engines compression ratio. For this reason, we want to increase compression ratio, but because increasing compression we get knock, we must use fuel that are more resistant to knock even though they burn slower. It's all a compromise, we can squeeze more out of the fuel by compressing it more than what loose by burning it slower.

 

Wow there is some seriously bad advice here. Although most street bikes can get away with using regular (87 octane) 93 is NEVER a bad idea, especially on some of the newer high compression engines. Detonation will blow your motor, trying to "squeak by" with the lowest octane possible is a great way to grenade your engine. You always want some buffer, some room for tuning error, bad gas, or anomalies with cold, hot, and humid weather. Running too close to the edge of your fuel's octane is a huge reason why many track guys blow their engines. A lot of people don't realize that when you advance ignition timing, you want to also increase your octane as well. Not doing this can spell disaster. If you tune a bike on a dyno and find that it can make maximum power on 87 instead of 93 (highly unlikely unless your tuner is smoking the crack) then go for it. Its all about how the tune is setup, if it is a shitty tune, you might want to use 93 for longevity. If the tune is spot on, then you don't need to worry about detonation or preignition so you may get away with 87 with good results...if you are just using a PCV with no ignition module, chances are 87 is probably OK. Once you start getting into changing the ignition maps (especially with factory race ECU's or hacked ECU's that can also change maps for the secondary throttle bodies or exhaust valves), higher octane is really a good idea (i.e. necessary!). Bottom line: you can use higher octane, but you won't gain any power/torque from it unless your ECU (or piggy back) is tuned for it. You usually won't lose much performance by using a higher octane either, however you may potentially prevent an explosion between your legs. Tuning motorcycles for max power/torque isn't easy because they lack knock sensors. Instead you have to learn to read the dyno curves (and pray it doesn't pop) or be proficient with the det cans.

 

Most of what has been said here is not 100% correct...