And if so, do you notice the performance increase?

 

I htink it takes a long time for the stock ECU to adjust
Better gains if you run a map designed for the higher octane

 

Thanks.....but that was a typo....I meant 100 octane.

 

I've run the 100 octane. Noticeable improvement over the crappy 91 we get here in Cali. But it's overkill for the stock ECU. Sears Point sells 96 (50/50 mix of 100 &91) and I can't tell any difference between that and the straight 100. My advice, save some cash and top off with 100 when your tank is still 1/2 full. If you normally run 94 or therabouts, you may not feel any difference.

 

stock ECU's are programmed to run on 91 octane for allllllll street cars. (thanks to Cali). Running anything higher is overkill unless it is very warm/hot out all the time. Or you are tracking the car (where it will see higher than normal operating temps)

 

uh, it's not programed for 91, but if you look at the door or wherever it's meant to run higher RON at 94??

The car does run better when you give it more than 91 but I agree that pure 100 might not do much over the mix.

When the car starts it actually tests the octane through the initial sparking and then adjusts the timing i.e. pulling it back a little for 91.

That doesn't mean that it is meant to run at 91.

Nor does it mean that giving it more octane to match what the oem programming is set at without resorting to pulling back timing won't give more hp.

Regarding cold weather - colder weather = denser air = more hp and also less detonation, much like running higher octane or more boost.

If you're in a cold climate then the timing probably won't be retarded because you don't have detonation issues assuming the ecu learns this after the testing of the octane.

 

The manual & sticker on the car call for 93 (with a minimum of 90). As SPR said, the car retards the timing for less than 93 and you lose a little power. All other things being equal, it's unlikely you'll see any benefit from anything above ~95.

 

actually unless it's 110F or more, or you are faster than buckler or rohr, running 91 is just fine.

 

Good read guys . We get 94 here so I guess that will do. We can buy 100 here also, but like the thread says...probably won't see much if any difference

 

Hey Mooty that is not true at all. Even at say anything less than 70 degrees I notice a noticeable difference.

 

spr, interesting.
i got about 8000 track miles on the car. i can dupliate my time regardless which type of gas i used. i suppose if the driver is more capable than me, then the incremental difference can be felt. i can't feel it in my car, so i cheap out on 91oct. YMMV.

 

Don't know what YMMV means but the result is probably 5-10hp if that. Now is that really going to increase your time? Is what you ate for breakfast more likely to change the time? Probably. I never said it would make you faster around the track certis paribus, only that it does actually produce a different result.

 

YMMV = your mileage may vary.

that it does actually produce a different result.
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got you. yes, there SHOULD be some differences with different fuel. just that not everyone may feel it.

 

Actually higher octane combusts slower and is thus less prone to detonation.

 

The more resistant the fuel is to ignition from the heat of compression, the higher its octane rating. This doesn't mean it combusts slower, it means it combusts later when exposed to a given level of heat and pressure.