87 octane better in the busa? Why?

[GMbusa]

Maybe theres a difference between cars and bikes with fuel grades. I've alway known to run the highest octane in my cars, i read that you get better performance with the lowest octane in the busa.
I can't understand this.

I'd appreciate any info on this matter.



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[GMbusa]

On the site elsewhere a guy asked what octane to run and i told him to run high test, Uh, sorry bout that.
So far in my 04' all i've ran is high test, i'll try the 87 next time.

But you gotta run 93 with a turbo on the bike,right?



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[Big E]

From reading from various boards. Seems like the big bore guys and turbo guys are running 93 octane. If your engine isnt knocking run on 87 octane

 

[UNDRPSI]

i would figure with a comp ratio af 11.0:1 you would want to run at LEAST 91 octane..... i could be wrong though..

on the turbo issue.. most definitely , you would need to use at least 91 . depending on the amnt of boost maybe more.

My tsi has a comp ratio of 9.5:1 along with 30lbs on a T-63 turbo....i need at least 100 with over 17lbs to be safe ... im running it really rich at 10.5 afr right now , im dynoing it next weekend t 30 lbs and will pull the afr to 11.5... hoping for 650+ whp.
It made 326whp at 12.8lbs.

JP

 

[Turbo-Torch]

Higher octane does NOT mean a bigger explosion and more power. All it does is stop detonation.
If the engine doesn't need the extra octane, buying premium is like flushing money down the toilet...although you look cool at the pump buying it

What's nice about the newer performance cars is that they can run on crappy 87 octane AND take advantage of 93. If you run 87 and the engine starts to "ping" the computer senses it and makes necessary timing changes. Engine runs safe but you have a decrease in power.
Next time you choose 93 and the computer eventually advances the timing just before detonation occures at that octane rating. Result is more power.

I have no idea if the Busa's ECM is that advanced?

I was quite surprised to see my Busa only needs 87 according to the manual. Simply amazing it can run that at such a high compression ratio.

Turbo's always require a high octane rating.
My 500T has 7.2:1 compression ratio and runs at 19.3 psi.
My 650T has 7.8:1 compression ratio and runs at 16.4 psi.
Those bikes need 93 octane to run safe.

 

[UNDRPSI]

thats kind of what i was thinking about the busa... kinda odd that they recommend 87

JP

 

[mcoyote]

AFAIK, the 'Busa runs fine on 87 octane pump gas. Mine has, anyway, with no (audible) knocking. The 'Busa has no knock sensor -- the only bike that I know if with a knock sensor is in fact the as yet unavailable BMW R1200GS.

If you use higher octane with stock compression, you're actually giving up power because combustion is slightly inhibited. I (think) I can tell the difference, epecially when they switch from winter to summer formulas at the pump.

 

[HayabusaEPT]

Actually 87 octane has more oxygen in it due to try to lower the emiisions on older veichles. Which we all know, use only 87...

 

[PACIFICBUSA]

aah....interesting...so I should be running 87 on my stocker instead of the 91 I have been puttin into it?

 

[busabrother]

yep

 

[EAKbusa]

87 is fine for the Busa's compression. Octane is basically a high pressure stabilizer and is simplified to say it is a particular length of carbon chain (eight actually hence the "oct" prefix). Know that gasoline allows a mix of different lengths including octane, however the higher the ratio of octane to the others the higher the octane number and the better the mix handles high compression. You see, other length chains actually will ignite on their own in the compression stroke which is bad news for a motor (knocking).

And if you wondered, all of the lenths of carbon chains are present in crude oil. It is then "distilled" by heat and the lengths seperate. How they are mixed and/or to what degree the lenghts are seperated determines what the end product is, be it gasoline, or diesel, or motor oil, or propane, or butane, etc. That is what refineries do. They distill crude oil to seperate it into usable compunds.

Long story short, you need high octane for high compression. Otherwise you are wasting your money.

 

[phatjoe]

thanks for the info fellas that was some good info

 

[busabrother]

EAK...... um WHy do you know so much??!!!

I should have stayed in school!!!

 

[EAKbusa]

EAK...... um WHy do you know so much??!!!

I should have stayed in school!!!  

He he. I am such a nerd, huh. Really I just love to read and love to learn about anything that interests me. I am very good at retaining technical information. I am no scientist nor do I pretend to be. I just read a lot. I am actually a manufacturing engineer by trade so I have "tech" in my blood. And you don;t have to be in school to learn. I have learned much more since I got out of school. The info is out there. get a book or check out the internet. HowThingsWork.com is my favorite place to kill time.

But you do not want to play me at Trivial Persuit. You will lose (smile).

 

[Rich]

Damn, I have been running 91 the whole time that I have had the bike. What about when running some nitrous as well?? Will 87 be fine while running that?

 

[FHL]

I am not sure. Nitrous makes you run rich and doesn't increase your compression ratio, but I don't know whether or not running rich means you need more octane.

 

[racrguy]

I am not sure. Nitrous makes you run rich and doesn't increase your compression ratio, but I don't know whether or not running rich means you need more octane.

correction: nitrous makes you run very lean, the chemical composition (for those of you who didn't know) is N2O which mean it has 2 atoms of Nitrogen and one atom of Oxygen and as you all should know oxygen is what engines use to burn, not gasoline, gasoline is just a catalyst to get the reaction started. When you introduce more oxygen into an engine without anymore fuel it makes a lean condition and will burn holes into the tops of the pistons because (besides the extreme temps made by a lean condition) it has nothing else to burn. Now i'm sure your wondering "why not just run pure oxygen into the motor instead of nitrous?" the answer to that is oxygen burns much to quickly and will detonate once it gets near it's flash point so the Nitrogen is thrown into the mixture to slow the combustion process down (and raise the flash point) to a non lethal level. You also must remember when you break apart molecules they take up more space, thus raising your "effective" compression ratio and what does exessive compression do? Causes detonation (read: baaaaaaad) and detonation will make your engine go boom bi@#*. And yes there are two kinds of compression ratios, the first one is the one which everyone knows of with the busas I beleive it's 11:1 called a static compression ratio, this compression ratio will never change without some sort of mechanical intervention, the other is the effective compression ratio which is what the engine actually sees right before the combustion takes place. So if you were to add some sort of power adder (other than naturally aspirated) it would raise the effective compression ratio therefore requiring one of two things, a higher octane gas to combat the higher temps and compression, or two a lower static compression ratio that way the effective compression ratio is not to high when compustion occurs Sorry if I made no sense it would be easier to explain if I was in person (unfortunately I'm not because some of you sound like really cool people)



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[FHL]

Yeah I stand corrected. I don't know if they make wet fogger kits for bikes but that's what you should use on a car. It adds fuel to the nitrous mixture to keep the engine running the right air/fuel ratio.

 

[DR1300R]

I am not sure. Nitrous makes you run rich and doesn't increase your compression ratio, but I don't know whether or not running rich means you need more octane.

correction: nitrous makes you run very lean, the chemical composition (for those of you who didn't know) is N2O which mean it has 2 atoms of Nitrogen and one atom of Oxygen and as you all should know oxygen is what engines use to burn, not gasoline, gasoline is just a catalyst to get the reaction started. When you introduce more oxygen into an engine without anymore fuel it makes a lean condition and will burn holes into the tops of the pistons because (besides the extreme temps made by a lean condition) it has nothing else to burn. Now i'm sure your wondering "why not just run pure oxygen into the motor instead of nitrous?" the answer to that is oxygen burns much to quickly and will detonate once it gets near it's flash point so the Nitrogen is thrown into the mixture to slow the combustion process down (and raise the flash point) to a non lethal level. You also must remember when you break apart molecules they take up more space, thus raising your "effective" compression ratio and what does exessive compression do? Causes detonation (read: baaaaaaad) and detonation will make your engine go boom bi@#*. And yes there are two kinds of compression ratios, the first one is the one which everyone knows of with the busas I beleive it's 11:1 called a static compression ratio, this compression ratio will never change without some sort of mechanical intervention, the other is the effective compression ratio which is what the engine actually sees right before the combustion takes place. So if you were to add some sort of power adder (other than naturally aspirated) it would raise the effective compression ratio therefore requiring one of two things, a higher octane gas to combat the higher temps and compression, or two a lower static compression ratio that way the effective compression ratio is not to high when compustion occurs Sorry if I made no sense it would be easier to explain if I was in person (unfortunately I'm not because some of you sound like really cool people)

WOW...and I thought eak was the smart one???LOL

 

[Bike382]

Racrguy nailed it. I have back to back runs using 99 octane (6 runs)race gas vs. 87 octane (6 runs)pump gas.

Result - Same day, same conditions, same rider (me) with an immediate 2-3 MPH increase in top speed with the lower octane. This was on a completely stock busa in the standing mile and was the only change I made that weekend. I have timing slips if needed. If you're stock, don't spend the extra at the pump, your paying more to decrease your power.