benefits of using 100 octane fuel on mirage?

[Dlareg]

hi, anyone have tried using 100 octane fuel on your mirage? are there any benefits?

[Daox]

The car is designed to use whatever fuel the owner's manual says (different countries use different rating systems so I won't say XX octane). Anything more probably won't do anything, anything less will likely result in a loss of peak power, but not necessarily much if any drop in mileage.

Also, welcome to the site!

[91cavgt]

I have personally experimented with 87 octane and 93 octane fuel here in the U.S. What I found is unless your car is packed full AND you are driving in VERY hot weather, you will experience a decrease in fuel economy.

Here is the technical reason why. Higher octane fuel does not burn hotter. Higher octane fuel burns at a slower pace which is what helps to prevent knock and detonation. In an ideal situation, you will use as low of an octane fuel as possible AS LONG AS there is no knock or detonation. Once you start running a higher octane fuel then you end up decreasing power. This is due to it taking longer to burn the air/fuel mixture which in turn causes the mixture to still be burning as the piston is traveling on the downward stroke.

In really hot conditions, and when the car is really loaded down, knock happens sooner. So, in these situations, a SLIGHT increase in fuel octane use will help to keep the engine running cooler and a potential SLIGHT rise in fuel economy.

I hope this helps to explain it.

[deleted user]

I put the cheapest regular (87 octane us spec) E10 gas I can buy.

regards
mech

[91cavgt]

I put the cheapest regular (87 octane us spec) E10 gas I can buy.

regards
mech

I do the same unless I have my car really loaded down in the summer. But then again, summers in Texas are brutal. I wish we had a no-ethanol gas station around here that I could try but no such luck.

[IchabodCrane]

Ethanol has similar effect of higher octane fuel....
Decreased power and cooler burn. So running 87 octane with ethanol should yield about the same result as high octane, ethanol free no?

[91cavgt]

Ethanol has similar effect of higher octane fuel....
Decreased power and cooler burn. So running 87 octane with ethanol should yield about the same result as high octane, ethanol free no?

Kind of. Ethanol has a very high octane rating, but it has a very low BTU content. When ethanol is mixed with gas to make 87 octane fuel, the ethanol is mixed with lower octane fuel so the end result is the same 87 octane rating (E85 has a true octane rating of 104 to 108 which is why turbocharged cars can be tuned to make so much power while running it). However, since ethanol has a lower BTU content, 87 octane E10 does not have the same BTU content as pure 87 octane gas. So you have to use more of the E10 gas to give you the same BTU content which is why fuel economy drops when using E10.

As a side note, diesel has a higher BTU content than what gasoline has. To go along with that, gasoline engines can only run effectively in the 18.0:1 to 10.0:1 air/fuel ratios while diesel engines can run from around 75.0:1 to 15.0:1 air fuel ratios which, combined with the higher BTU content, is why diesel engines can get such better fuel economy than gas engines.

[Dodger]

Octane Rating has nothing to do with quality of the fuel its 100% on how fast it burns cars with High compression engines need slower burning fuel (higher octane) to avoid knocking our cars require 87 octane running high octane fuel just gives the gas company's more of your money.

[debburyl]

Welcome

[debburyl]

To my knowledge the higher octane was for Bigger V8,s and if your car started pinging. So a smaller motor like the Mirage runs faster then a V8 so you don't need a higher Octain