Shawnmack

A citgo station offers 100 octane fuel every tuesday for 3.99 I was thinking about trying it out to see how it does but is it safe to use in the Gs 300 without causing any pinging safe for the fuel injectors?

svt5150

Why? Its not a race car.

GSteg

iTrader: (15)

Higher octane generally help reduce pinging.


If anything, your car will most likely be more sluggish than with 91/93 octane.

The higher the octane, the harder it is to ignite. Your car is stock (engine wise) so the fuel will not be burned completely. Since it's harder to ignite, it wont be as explosive (which moves the pistons downward).

GS42NV

i thought higher octane fuel was easier to ignite? just an assumption, but when someone puts in a lower octane fuel the car will retard itself and allow more fuel to enter. this would make sense if lower octance fuel had a lower flash point thus needing additional fuel to offset the loss in energy. again, this is just a guess. if anything, putting in the higher octane fuel might possibly set off your O2 sensors because the exiting fuel could still be very rich. additionally, you might do damage to your spark plugs if those haven't been upgraded either.

just my $0.02

JeffTsai

iTrader: (1)

Higher octane fuel resists ignition up to a much higher temperature. Thats why in a vey high compression engine or a highly boosted engine will need a much higher octane fuel to run without damaging anything. Low octane fuel will ignite in race engines 80-90% into the upstroke, and thats a very bad thing!

How energy power which fuel has, the higher octane stuff has more power. If it resists ignition to a much higher compression and temperature, when it does ignite at the right time there is much more power on the downstroke.

As for putting 100octane in our cars, there shouldnt be any performance drop at all. The engine will just run at its full potential and not retard the timings. I mean think of this, most of the other countries outside of the US have 95, 100 , and 105 octane at all pumps. I've even seen 110 octane in a few places before. The GS was marketed to all those countries so I'm sure it will run the same if not better with the high octance fuel.

GSteg

iTrader: (15)

Other country uses different formula for octane measurements. I think japan's 100 octane is equivelent to the US's 93 or so. If I can find a link, I'll dig it up for you.


I remember a while back, someone took their Honda accord V6 (recommended at 87 octane) and put in 91 octane. Ran a few dyno test and actually lost power. He though the dyno was off so he put in 87 octane again, and made a bit more power, even though the next run was on a hotter day.

You get to the point where our cars do not have the kind of ignition and heat to fully make use of 100 octane. Perhaps you can start mixing 100 octane with 87 until u get 93 or so

GSteg

iTrader: (15)

The car's ignition has to retard timing because 87 octane is more explosive. Without retarding, the engine can start pinging and possibly detonate. I dont think the engine would allow more fuel into the engine if the ignition is retarded. It retards the timing for a reason. Having more of the problem (lower octane gas) would defeat the retard timing.

Then you have the Honda DOHC guys who advances their timing to get more power, but needs higher octane otherwise they'll run into the same detonation problem.

There shouldn't be any reason to use 100 octane on our cars though. Not unless you approach a stupidly high effective compression.