50/50 gas?

[n811]

What is 50/50 gas? What are you mixing? At 11:1 do you need anything more than pump gas? I am going to do a 416 kit and was told pump gas at 11:1 will be fine. Is this untrue?

[400exrider707]

50/50 race gas/pump gas. At 11:1 you can run straight pump.;)

[pigpin]

a random site

http://www.faqs.org/faqs/autos/gasoline-faq/part3/section-1.html

[n811]

will race gas give you any power gains? or will it "ping" with lower compression?

[pigpin]

yea it will give u gains, thats it purpose, and "ping" will happen when you dont have enough octane, but everybody i know with 11:1 compression, be cars, bikes, qauds, run pump gas, and do fine, but you can always run race gas, its addictive becouse the power gain, but expensive!!!

[250X_project]

Originally posted by pigpin
yea it will give u gains, thats it purpose.....you can always run race gas, its addictive becouse the power gain, but expensive!!!

There should be no power gains from a higher than necessary octane. If anything, it would hinder performance. The higher the octane, the harder it is to burn. The only gain felt would be the bump in compression.

[rooster300ex]

I know my 300ex with TT101 performs a tad better then a tank of 89,91 or 93 and its only 11:1.

I usually run about (pump)60/40(race gas) of 93/101. When soembody is talking about 50/50 they are running some kind of race gas in regular pump gas.

[underpowered]

Originally posted by pigpin
yea it will give u gains, thats it purpose, and "ping" will happen when you dont have enough octane, but everybody i know with 11:1 compression, be cars, bikes, qauds, run pump gas, and do fine, but you can always run race gas, its addictive becouse the power gain, but expensive!!!

actually not. race fuel will not give you more power. like 250X_project said running higher than needed octane can actually hurt performance. race fuel is to deal with higher comp ratio's, not give power gains. the only gains you would get from a race fuel is by running an oxy gas, which is oxygen enriched gas so you jsut burn more fuel since the gas has oxygen in it. by burning the extra fuel, you get a power gain. but normal race fuel will not give you any power gains.

[GPracer2500]

Originally posted by 250X_project
...The higher the octane, the harder it is to burn...

This isn't quite correct. Higher octane fuels are harder to explode, they are not necessarily any harder to burn. You may be asking yourself, what's the difference--burning, exploding....same thing, right? Not by a long shot.

When everything is working normally, the mixture inside the combustion chamber does not explode, it burns. The technical term for burn = deflagration (good for our engines). The technical term for explode = detonation (bad for our engines). Higher octane fuels are more resistent to exploding (deto). But octane rating in and of itself has NO IMPACT on its burning characteristics.

The idea that higher octane fuels are harder for the engine to burn and therefore might produce less power is a myth. Some racing fuels may not be well matched to stock engines. But if a racing fuel produces less power than a pump fuel, octane rating is not the culprit. Some other specification of the fuel would be responsible. When it comes to fuel, it seems octane rating is all anyone ever cares about. But there is a whole slew of other specifications that can be equally important to consider.

I have yet to see a single instance of a high octane fuel hurting performance in an ATV engine as long as the jetting has been adjusted for the fuel. Always comfirm jetting when switching fuels--different fuels require different jetting.

[CDCHONDAS]

or- octane is the resistancy to spontaniously combust under compression, for say a diesel engine fires only by compression, there are no spark plugs, but when you put air under pressure with fuel it can spontaneously combust the fuel without spark. on a high compression engine without high octane the fuel/air mix will ignite before the sparkplug fires, which is predetonation. a higher level octane would raise the resistancy to spontaniously combust letting the engine fire at the correct time. higher compression higher octane. going high in the octane isnt going to really hurt anything just make sure to check the jetting like said above also rejet if you try running an oxygenated fuel.

[GPracer2500]

FYI, "predetonation" is a nonsense word. There are two types of abnormal combustion: pre-ignition and detonation. ;)

[n811]

So, what are the symptoms of pre-ignition? and what is it telling you to do? is it jetting or wrong gas for the compression? can you hear it happening?

[rooster300ex]

Originally posted by n811
So, what are the symptoms of pre-ignition? and what is it telling you to do? is it jetting or wrong gas for the compression? can you hear it happening?

Yes if its bad enough you can hear it. It will be a ping or knock sound usually when the engine is underload. GPracer2500 can explain it in the right terms way better then I can, but I can say i'm smater because of em.

[400exrider707]

Here... I stole it from GPracer2500...

Well, they are two completely different things. What can make things confusing is that one can lead to another and both can occur at the same time. But one doesn't always lead to another and they don't always occur at the same time.

Deto always occurs after the air fuel mixture is ignited and has begun to burn. This ignition source is usually/normally the spark plug firing. The plug fires, the mixture begins to burn, but before the mixture at the edges of the combustion chamber has a chance to burn (if conditions are just right) it explodes violently instead of burning. That is detonation--when some of the a/f mixture explodes rather than burns. Burning (deflagration) and exploding (detonation) are not the same thing.

Pre-ignition is simply when the a/f mixture is ignited and begins to burn (deflagrate) well before the spark plug fires. Deflagration is usually a normal occurance. But what makes it abnormal in the case of pre-ignition is that it's happening at the wrong time.

Deto is the wrong kind of combustion (deflagration is the good kind, detonation is the bad kind). With pre-ignition it is the right kind of combustion but it happens at the wrong time.

Most engines can withstand a certain amount of mild detonation without sudden, catostrophic damage. Deto also usually provides an audible warning that it is happening. Pre-ignition can destroy an engine in a second or two. I'm not aware of an engine that can withstand a continuous pre-ignition condition for any period of time. Deto is somewhat common while pre-ignition is comparatively rare.