coolguycooz

I live in California (state of 91 **** gas). I was just wondering if different gas stations would cause you to knock more or less?

I know i remember an article in motor trend a while back they did a test on gas stations in california. Shell had the highest BET rating, and thats what i have been using.

I was wondering if somebody picks up any less knock with one perticular gas station over another.

Throw in your 2 cents.

Ralph

iTrader: (19)

I've tried shell vs 76.. can't tell a difference really.

cpoevo

iTrader: (1)

I use Costco or 76. I tried Chevron once and the car ran like crap.

C6C6CH3vo

iTrader: (9)

The true anti - knock value for fuel between seller to seller, despite Octane # claimed, differs greatly, even throughout the year. It all boils down to the fuel's pressure of combustion and rate of burn, the RON whatever + whatever method is a lousy and potentially corrupt way to guage the quality but works most of the time.

You just have to get gas from the right people by experience and with caution (don't get gas from some run down station with crackhead employs)

RazorLab

iTrader: (8)

76 has been the best gas overall here in California for as long as I have been messing around with turbocharged cars.

Evo_Jay

iTrader: (17)

+1
I've seen a dyno proving 76 is better then Shell or Chevron.

Also, Shiv, one of the best tuners (and a CA tuner), recommends 76.

nj1266

iTrader: (6)

Tuning Technologies also recommends 76 gas. I have been using 76 since I got my car tuned. Since June I have only used 93 octane.

Today I logged the AFR/timing/knock on an 05 EVO 8 that ran 91 octane gas and saw the same AFR spikes that I used to get when I ran 91 octane on my car. After I started using 93 octane regularly the spikes in the AFR log went away.

coolguycooz

so your AFR was actually unstable with a lower octane gas?

can somebody explain to me why that is? i thought the stochimetric ratio was based only on the amount of air to amount of fuel ratio??

how does octane rating cause that to change? would it have something to do with the speed of the burn ? causing a different reading?

nj1266

iTrader: (6)

I asked the vp of engineering @ innovate this question and he told me that because the 91 octane gas in CA is such low quality gas, the spark plugs were having a hard time lighting up the air/fuel mixture. When that happens you get spikes in the AFR. That ran normally and I was only able to detect the spikes @ WOT when logging.

So far I have had two Evos shwoing these symptoms, mine and the one I logged yesterday. I recommend to anyone in CA to use 93 octane if they have a gas station that sells 100 octane gas.

Cannonballer

iTrader: (3)

I switched over to Shell after observing a much lower know count than I got with 76 gas.

Nogi

Here in the NW, I've had the best consistency with 76 (92oct). I lived in Vega$ for a year or so and had the best success with 76 there as well - bonus: they have GT100 on a few pumps.

I used to use Shell as an alternative but it was hit and miss (no pun) for quality. This was after I discovered that running my fuel level too low was causing my fuel pump (evo viii) to run lean.