MySunset350Z

iTrader: (23)

i have been filling up using 93 octane, but a few days ago i stopped at a gas station that i dont usually stop at and i saw a fourth nozzle.

it said 105 octane. it was a bit steep on the price too.
anyway i was just wondering what is 105 octane, and what would it do if i put it in my car??

would the engine be able to handle that high on an octane?
what if i mix the 2 octane levels?

looking for some more info on this high of octane for my Z....

peace

Z350Maniac

the octane level is basically a rating for how many hydrocarbons (I believe that is the word I am looking for. PLEASE feel free to correct me if I am mistaken.) the gasoline has per unit. The higher the more fuel efficient, but also the hotter the fuel burns. Most people believe a myth that using higher octane gas helps the engine run better and produces more power. This is not true for n/a engines that do not utilize a large amount of 'breathing' power (forced induction) By using a higher octane gas such as 105 (BTW WHERE in Detroit was this station I would like to know of a few places where I can buy racing fuel for later on when the car can utilize it best. I live in Sterling Heights.) in a n/a engine meant to use lower octane, you run the risk of causing detonation in the engine as the compression of this gas when not mixed with the proper amount of air creates an unstable combustion and produces DAMAGING detonation. Unless you are using some form of FI (T/C, S/C or n2o) then using a higher octane gas would be a beneficial idea for you to get more power from the engine. Hope this helps.

Jason

I'm sorry, but you have this backwards. If you use a lower octane gas then you risk detonation. Higher octane fuel is more resistant to detonation.

You could run 105 octane fuel in your Z, but it would be of no benefit.

Typically 100+ octane fuel is used in race applications. If you have forced induction and plan to turn up your boost at the track, get high octane. If you want to build a n/a race engine that runs that has a high compression ratio, run high octane. Etc.

This is why the Z needs 91 octane now; it's a fairly high compression engine.

Z350Maniac

thanks for the correction, I knew it was one way or the other, I usually get them mixed up.

MySunset350Z

iTrader: (23)

thanks for the info

i might put a few gallons or so in just to try it out...

by the way the gas station was on 7mile west of john r.....not sure the exact location...or the name of the gas station. ill post an exact spot when i put a few gallons in my car. the only reason i was in that area was because im on a football team that plays near the armory in that area. i was VERY low on gas heading back home.

would mixing cause a problem?

Z350Maniac

I've heard different opinions on mixing, some good some bad. I wouldn't do it personally in case it could cause problems.

Rob Nance

Mixing would not cause a problem, but a common misconception is that they mix to create an average octane. Kind of like how some people think they can put 93 and 87 in and get 90 octane by putting half and half, it doesn't work like that. Like others have said, the octane rating isn't like a combustibility scale, it's a bit more complex than that.

Ben Davis

Higher octane is more RESISTANT to nock or pre detonation....

The biggermisconception is this: Lower octane gas actually burn quicker! THe benifit of hogh octane is that you can increase CR and advance ignition timing cause ti is such a slow and controlled burn (slow maning a fer milliseconds slower) that you can start it early and get a VERY stable and predictabe combustion cycle. On a COLD COLD DAY you will actually make more power on lower octane. Using high octane will be no good cause you dont have the ignition timing, plugs, gap, or CR to make use of it. But it will never HURT your motor unless you go leaded.

Ben

AndyB

Ben is dead on here. The octane number on the pump is LITERALLY defined as the fuel's ability to resist knocking. The (R+M)/2 tells you how they measure it. It says they take the average of "research octane" and "motor octane" ratings.

Research octane is a chemical test. Motor octane is exactly what it sounds like. They run the fuel in a tightly specified motor. Then they advance the timing until it knocks. Where it knocks is the "motor octane" reading.

I spent nearly 2 years working on a system to replace simulate octane motors and replace them with an infrared instruments (NIR). Octane is controlled very carefully at a refinerly (belnding station). If the octane is too low for the label they are breaking the law. If the octane is too high they are "giving away" octane. They usually try to get "just a little above" the sticker value so they are legal but not giving it away.