Race Fuels

[Xtraction]

I was at work today and happened to meet a guy that races a Yamaha R1. I walked passed his bike and noticed a very attractive scent...RACE FUEL!!! I talked to the guy for a while and he enlightened me with some very interesting information about race fuels. He actually uses a "race fuel" of only 92 octane. So...I have a couple of questions for you all. What effect does an extremely high octane fuel have on your engines power output, would you rather run 92 octane or 104+, and why? I'm just curious to see what everyones take on fuel is. This will be a learning experience...so stay tuned!

P.S. His 92 octane "Race Fuel" costs $12 per gallon.

 

[MyTGSX]

Never heard of a 92 octane "race fuel" but anything is possible.


the octane rating is the amount of impurities in the fuel, the higher the octane
the less impurities. which means it resists knocking or pre-ignition which we know
is bad.*******added to this with a more correct info******

Most times you can get some unleaded high test stuff(around here 104 unleaded is as high as it goes) but you can get leaded race gas much higher (I've run 120 octane) but it's bad on the O2's.

or he was mixing 87 with some 104 ( 2 gal 87 with 1 gal 104 gets ya 92.6 octane)

 

[xveganxcowboyx]

the octane rating is the amount of impurities in the fuel, the higher the octane
the less impurities. which means it resists knocking or pre-ignition which we know
is bad.

My understanding is it's sort of the other way around. Lower octane is a more combustible 'pure' fuel. I guess I've never heard a great explanation on why it's more combustible. Shorter carbon chains?

I don't really understand 92 octane 'race fuel.' The point of race fuel is a higher resistance to combustion which equals higher boost levels without knocking.

And if it was available/affordable I would run higher octane with higher boost. As it stands, pump gas can make decent power if set-up right. I'll just have to live with that.

 

[Gary 420A RS]

i use nothing but 87 octane race fuel unleaded. race fuel i guess would be anything other than the average found at pump stations. there is the occasional 100, 103 octane found and that would be considered race fuel. or c16 which would equal about 117 or so octane which is like 9 dollars a gallon.


p.s. the whole 87 octane thing was a joke. over and out.

 

[TJGoSurf]

Yes a lower octane race fuel is used, but since 87 is available everywhere it is actually lower. But it is used by rotary race teams, they need a quick combustable fuel due to their increased size in the combustion chamber. But they are also running n/a.

I cant see a practical reason it being used in a motorcycle.

 

[Turbo Demon]

It must suck to live in hickville. Well, I actually live in hillbillyville, and we have 93 octane at the pump. I think the bike guy was pulling your chain homes.

 

[Xtraction]

Here's what I know about fuel and the combustion process. Higher octain fuels simply act as a flame retardent. If you ran a given set-up on 92 octane and made 400hp with no pinging then used 104 octane with the same set-up you would actually lose power. When the air/fuel mixture combusts inside the cylinder you have one "flame front" that travles in one direction. Under extreme pressures and heat or hot spots inside the cylinder the air/fule mixture can detonate prematurely which causes two flame fronts (one from the spontaneous combustion and one from the spark) traveling in opposite directions which in turn collide with each other. This process is an uncontrolled explosion...bad detonation. Higher octane fuel acts as a retardent that keeps the fuel from combusting until the spark ignites it. The ideal fuel for maximum power is the lowest octane that you can run without getting knock because anything higher is simply retarding the explosion which limits power output. Don't believe me...try it! Use 1/8 of a tank of 92 octane on the dyno and then fill her up with 104...you'll be amazed. Higher octane fuel will NOT make more power under the same conditions as long as you're not pinging in the first place. Thanks and good luck!

 

[Gary 420A RS]

Yes a lower octane race fuel is used, but since 87 is available everywhere it is actually lower. But it is used by rotary race teams, they need a quick combustable fuel due to their increased size in the combustion chamber. But they are also running n/a.

I cant see a practical reason it being used in a motorcycle.

do you know what your saying?

 

[Thomas91169]

i think hes sort of onto something.

a quicker combusting fuel is needed for higher revving motors, such as a R1 which can see 16000rpm. at those high of rpm's, you want things to combust faster to keep with the rpm's. if you have a fuel that doesnt want to combust fast enough(like a higher octane) than youre going to lose power.

i could and more likey am wrong, but thats how i would think of it. maybe its just a purer fuel at the same octane, making for better combustion. anyways, if hes paying 12 bucks a gallon for some 87 octane, he either doesnt know jack shit, or knows more than we think.

 

[Thomas91169]

Here's what I know about fuel and the combustion process. Higher octain fuels simply act as a flame retardent. If you ran a given set-up on 92 octane and made 400hp with no pinging then used 104 octane with the same set-up you would actually lose power. When the air/fuel mixture combusts inside the cylinder you have one "flame front" that travles in one direction. Under extreme pressures and heat or hot spots inside the cylinder the air/fule mixture can detonate prematurely which causes two flame fronts (one from the spontaneous combustion and one from the spark) traveling in opposite directions which in turn collide with each other. This process is an uncontrolled explosion...bad detonation. Higher octane fuel acts as a retardent that keeps the fuel from combusting until the spark ignites it. The ideal fuel for maximum power is the lowest octane that you can run without getting knock because anything higher is simply retarding the explosion which limits power output. Don't believe me...try it! Use 1/8 of a tank of 92 octane on the dyno and then fill her up with 104...you'll be amazed. Higher octane fuel will NOT make more power under the same conditions as long as you're not pinging in the first place. Please give me some good reputation points by rating this helpfull if it is. Only being able to post in the Newbie section sucks big nutz. I might be a newbie to this forum but I'm not a newbie to DSM's. Thanks and good luck!

indeed. this goes for most cars. if you can run a car on 87 octane, slapping 93 into it isnt going to do jack shit.

most people run higher octane so they can upp the timing and/or run forced induction. higher octane is less prone to detonation, thus more advance can be added, thus increasing power while not changing anything else but timing and the fuel used.

which is why nobody dynoes their car on pump, then race gas, without any other changes, cause it wont make a difference. they might dyno pump to get a baseline, then dyno race gas with more boost/timing.

up until i got my tuner/chip for my stang, i ran 87 octane. now with my chip and added timing, i run 91. if i go back to 87 with the same tune, ill get shitloads of knock and predetonation.

 

[TJGoSurf]

do you know what your saying?

Yes I do. Its not a difficult concept, the "combustion chamber" in a rotary is about 5" long and 2" wide. I can explain it more in detail if you want.

 

[pnishr]

In a motorcycle because they run high static compression ratios...

 

[MyTGSX]

Found this and it's worded very well


In general terms the octane number of a gasoline is a measure of its antiknock quality or ability to resist detonation during combustion.

By using high octane gasoline, we are attempting to prevent engine knock. Engine knock is the premature and spontaneous ignition of gasoline. In effect the fuel EXPLODES rather than BURNS, and this results in incomplete combustion, a loss of power and (over time) engine damage. When this happens, you hear an audible "knock" or "ping", sometimes referred to as detonation. Detonation may vary from a faint noise on light acceleration to a constant, deep hammering noise while driving at speed.

Octane requirements are dictated by the following three engine operating factors:
- Cylinder Pressure,
- Spark Advance, and
- Engine Temperature.

Also, engine deposits can affect all of these factors, and produce engine knock where it otherwise would not exist.

Modern engines do a good job of controlling the spark advance and to some extent engine temperature. Cylinder pressure is less well controlled and is more dependent on the environment (the engine’s compression ratio, the altitude where you’re operating and the throttle position). But things get real exciting when you go to maximum power output at WOT (Wide Open Throttle). That's when bad things can happen fast. That is typically one of two times when you need maximum gasoline octane to prevent engine knock. The other is lugging your engine when engine temperatures are high.

Anything you do to increase any or all of these three factors will increase your engine’s octane requirement. So, if you put a turbo-charger on you car, you will increase cylinder pressure. If you’re driving a loaded car up a steep grade at high speeds, you will increase the engine’s temperature (but also slowly decrease the cylinder pressure due to ever higher elevation).

Because many OEMs (Original Equipment Manufacturers) are conservative, their stated octane requirement for their vehicles are frequently based on a series of very strenuous tests on the engine dynamometer that are in all likelihood never seen in the real world. In effect they have you driving at WOT (maximum power) for several hours at a time. The last I checked, all Highway Patrols kind of frown on that.