Octane requirements

[ZRXMAX]

I am new here and the 01 Busa I bought recently came with nothing, not even an owners manual.

Having said that... All this talk about which octane rating and what is good for the Busa has me a bit perplexed. It is well known that flame propagation that touches the top of a piston is what can damage a motor. Generally speaking the lower the octane rating the faster the fuel will burn. Fuels that burn to fast and allow the flame front to touch the top of the piston are more likely to create engine damage if used for a period of time. Head design has much to do with burn rates and an engines ability to handle a wide range of fuels. The Hayabusa, like most other sport bikes has one of the best head designs going. I can't understand why 87 octane has been recommended by so many people here.
Their has to be a reason for this widespread belief in 87 octane being the best for the Hayabusa.

Does anybody have documented imformation they can share here that reveals the details concerning the use of 87 octane vs higher octane fuels ?

 

[Sloto200]

87 is recommeded because its what the owners manual suggests. I've used it for over a year with no problems. You want to pay more at the pump, be our guest and use premium but you wont gain any advantage using it, you will just be spending more money...

 

[Gunnybusa]

I have used 87 for the last 4 years on both my 02 and 06. The temps range from the 40's to the 120's here and I have NEVER had any issues with 87.

 

[ZRXMAX]

(Sloto200 @ Nov. 26 2006,08) 87 is recommeded because its what the owners manual suggests.  I've used it for over a year with no problems.  You want to pay more at the pump, be our guest and use premium but you wont gain any advantage using it, you will just be spending more money...

My question doesn't have anything to do with a performance advantage. What Iam looking for the solid reasoning behind the recommendation. I am not arguing with the manual, I want to know the scientific version of the answer. That answer is out there for those that understand the dynamics of combustion, fuel blends, and head design. The head in the Hayabusa is practically identical to other sportbike head designs... Some of those other bikes with similar compression ratios use premium fuel... so... why is our requirments different ?

 

[runeight]

I switch every now and then. 87 or the next higher grade but I would say most everyone here uses 87.

runeight...

 

[semi]

no scientific answers coming from me...i ride the same way i live- flying by the seat of my pants...anyway, i guess i am one of the few who run premium...the two times i ran regular it felt like my bike was chugging? at low rpm's

this is just my guess and uneducated opinion but i think the bike gets used to and accomodates itself to what it regularly experiences to a certain level...this could all be hogwash brought on be my over-emotional connection to Lucy

i think the only way you are going to get the answers you are looking for is if someone like GPW keeps records over a given length of time on some of the bikes he services in his new shop (free ad

)

good luck

 

[Sloto200]

thought it delt with the fact that the busa engine wasnt a high compression engine like the 1000 or the 600 that recommends premium...

 

[Professor]

(ZRXMAX @ Nov. 26 2006,10:49)

(Sloto200 @ Nov. 26 2006,08

) 87 is recommeded because its what the owners manual suggests.  I've used it for over a year with no problems.  You want to pay more at the pump, be our guest and use premium but you wont gain any advantage using it, you will just be spending more money...

My question doesn't have anything to do with a performance advantage.  What Iam looking for the solid reasoning behind the recommendation.  I am not arguing with the manual, I want to know the scientific version of the answer.  That answer is out there for those that understand the dynamics of combustion, fuel blends, and head design.  The head in the Hayabusa is practically identical to other sportbike head designs...  Some of those other bikes with similar compression ratios use premium fuel...  so... why is our requirments different ?

ZRXMAX

One of the things you didn’t mention that affect the engines ability to burn lower octane fuel without detonation and pre-ignition is camshaft timing. The valve timing can have an impact on peak pressure. Higher octane gasoline is also slower burning with all other factors being the same. This slower burn can lower performance. Lower octane gasoline also has a very slight less BTU per pound rating. The BTU per pound is the amount of energy given off. This may be due to some of the additives that bring up the octane rating.

One of the favored fuels some of the builders use to get maximum horsepower out of the stock Hayabusa engines is VP MR9 which is only 87 octane. However we are talking about an oxygenated racing fuel in this case. Never the less it is still putting out more power (do to the oxygen properties of the fuel) and only needing 87 octane.

I had seen a few threads some time ago in which the HP numbers went up with 87 vs 91 or 93 octane PUMP gas. I personally picked up my ¼ mile MPH when I went to using my 87 octane lawn mower gas in the same day. Never went back to 91.
Read through some of the threads with an open mind. You will even find a few statements from Johnny Cheese telling people they will pick up some HP with 87 octane. I am sure this some from some dyno testing.

Octane is clearly not an indication of the amount of power that is available in the fuel. This is where several make mistakes.

 

[Wag]

When I first got my Busa, I used 91 octane. Then someone here stated that the Busa compression ratio is really quite low and that 97 octane is better for the engine.

I tried it and saw an immediate improvement in gas mileage and in power. Something like going from 33 mpg to about 36, typically. I've never gone back to high octane. It just does not do the Busa engine any good, apparently.

If you're interested in a scientific approach, you can't get better than your own experimentation. Try it yourself and see what you get. Bear in mind that gas mileage is not the only factor which determines how well an engine will run but it's a fairly good bet that if the mileage drops off on you, then something is definitely wrong.

Do two or three tanks of each octane and measure the results on the third tank. That way, you can be relatively certain that one fuel is not contaminating the results for the other fuel.

Report back your findings and call yourself the best scientist you can ask for!

--Wag--

 

[DonnieF]

You guys are on the right track , compression is the main factor that determines octane needed. But another variable i havent seen any of you guys say yet is the heat range of the spark plugs. Factories tune there motors on the safe side. The Hayabusa's compression ratio of 11:1 and the spark plug heat range suzuki engineers chose for there engine combination needs no more then 87 octane. Like ZRXMax said ,the more the octane rating the slower the burn , when you slow the burn you need hotter plugs and vise versa. Now you could go up a few heat ranges on the plugs with 93 octane and see a slight improvement , but is it really worth it trying different plugs and fuel with several engine or chassis dyno pulls just to gain a 1/2 hp ... are you really at that level yet??? Also you can index the spark plugs and get a little more power but again are you really at that level where it will matter???

Everything stated above only applies to N/A motors , when a power adder is introduced the rules change again , but thats another topic for another day.

 

[heavybusa]

 

[ZRXMAX]

Since I have owned the bike a few weeks all I can say is this about fuel milage. After hearing how low the mpg is when riders are getting heavy on the throttle, I was suprised to get 38 mpg on the last tank. That occured under normal conditions where I spare only a few horses some of the time !

Why own a Busa if your not going to be "the torque of the town" on a regular basis ? In other words... I got 38 mpg and never gave gas milage a thought... life is to short to spare the throttle, isn't it ?

Will see what I can do about a milage check with different octanes... It will be a very unscientific test unless the conditons are controlled... every route is different imho...

 

[BA BUSA]

 

[camaro69_4542003]

Simple answer is heat determines what octane is to be used. Peak horsepower is obtained at the lowest octane that doesnt ping or detonate before the combustion is actually spost to take place. A higher octane requires more heat to burn fully. When running a higher octane will give you better fuel mileage at the cost of the engine actually running in a lean condition during burn. This is caused because a stock hayabusa engine cant fully burn a higher octane than 87. It puts unburned fuel molecules into the exhaust that couldnt be burned. Hince your O2 sensors are tricked into thinking the bike is running rich and causes less fuel to be delivered into the engine. Heat can be from ignition advance , compression , spark ect... Running a highest octane in a stock hayabusa over a long term could actually cause carbon buildup inside the engine on the valves and so forth. Fuels are hydrocarbons they have no oxygen of their own. they are hydrogen and carbon molecules which when spark is added in vapor form or a mist form the heat seperates the fuel into usable hydrogen and has a byproduct of carbon. Carbon is added to make the fuel more stable since pure hydrogen must be kept at extremly low temperatues since it is very violatile. Engines only comvert about 30% at best of the rest is lost to heat which exits out the exhaust. Head design has play into compression mainly. combustion chamber size can change the actual compression of an engine , same as adding a head gasket thats different from stock size can effect compression ratio. Thats about as simply scientific i can get i could go into chemical properties and start showing math that explains it but figured this would be better lol. ALSO i almost forgot to mention this , running lean will allow a slight advantage to power , since again your running at only what you can burn the catch is this will cause serious engine wear and tear and cause unnessary risk and damage over time to the engine itself as in pistons and valves along with other engine components also can gum up o2 sensors alot faster and cause failure to other sensors on the bike. Same applys to cars and any other combustion engine

 

[camaro69_4542003]

I also forgot to mention all fuels actually burn at the same rate if heat demands are sufficent. It doesnt burn slower or faster , or even hotter really. The way gas works is power not really rate of burn any fuel will burn at the same rate just not fully be able to burn. Kinda like 2 fuses on a firework , they can both burn at the same speed just one may take more heat to light it to burn.

 

[Professor]

(camaro69_4542003 @ Nov. 27 2006,00:16) Hince your O2 sensors are tricked into thinking the bike is running rich and causes less fuel to be delivered into the engine.

If you are running a US spec Hayabusa, I don't think you are going to find an 02 sensor on it.

 

[jjbusa]

87 with a lil bit of U4 mixxed but thats for the nights i want the extra oomff not that its not enough already but im a big guy

 

[mountainmotor]

Just a note to make sure everyone is on the same page with the term " flame propagation .

# 3 onward will help . Remember Suzuki uses the Twin Swirl combustion chamber .

http://www.erc.wisc.edu/modelin....005.pdf

Spark plug heat ranges is one of the most mis-understood topics I see . Instead of going into it myself , here's a link with much info on the subject and how heat is either added or reduced by use of the internal core . They spark the same for all intents and purposes but transfer heat differently according to internal design .

Click heat range .

http://www.ngk.com/search_char.asp?seenWarning=1&manufacturerID=1

The Busa has less than the advertised 11-1 static compression and the ECU does not give the engine any spark advance until around 4000-4200 rpm in lower gears from what I have observed. There's but two of the reasons it can run on 87 octane . Aluminum alloy head , combustion chamber efficiency factors in .

Bump the compression to 12.26 and it will spark knock under heavy load in lower RPM's and hi ambient temperature when the ECU gives the engine some more timing with 87 octane in the tank. Thats with a little more pressure bleed from increased valve overlap added as well . 91 octane was the easy fix .

 

[dadofthree]

87

 

[NightCrawler]

The manual says MINIMUM 87 octane ... not suggested or required.

Long story short, the Busa runs just fine with regular oil, but some of us use synthetic. You know, the good stuff.