I was out of gas and the only gas station around me was very expensive so i decided to fill it with 87. It was shell gas which is not known to be good gas to begin with. Well to my surprise my car is running much BETTER now. It pulls a lot harder and i am not getting knock. My car was tuned twice for 93 octane and i have never put anything but that in it. Can anyone explain why its working so well?

 

I've always been told to use Shell... I had to put 89 in a few months ago, because 93 was sold out, and I could tell that it was a little sluggish and idled a little wrong.

Where do you typically fuel up?

 

i usually use sonoco or bp because i did a dyno test twice and both times when i used shell gas i got knock. When i used other gases i didnt get knock.

 

i used to use strictly shell until i has knock on my dyno run. i try to get BP everytime now even though my town only has shell.

 

the only reason it could be running better is because higher octane ratings take more energy to ignite and the burn speed could be different could be in your head though not sure

 

i am thinking it has to be in my head, but today i raced a stock gxp and it looked like it was standing still yet i have recently raced a monte ss that was stock and that kept up well.....idk maybe i got a really good batch of gas?? cause the car isnt pinging either

 

No. all Octane does is raise the temp required to fire it initially. It allows more timing/compression before cylinder temps can ignite it on their own (ala Diesel). The spark is hot enough to fire any Octane gas available and once the reaction starts, it is exothermic (obviously) and the flame front will progress at the same speed. It takes heat to ignite, one might make the argument that it takes more energy to fire initially, but you could have an atomic bomb fire off in it if the temps stayed low enough and it would not fire. Conversely, you could have the tiniest amount of spark energy imaginable (within reason) and it would ignite the mixture.

 

just telling you what i have read it takes more initial spark energy to run higher octane which is why it can be detrimental to use high octane gas in cars that work perfectly fine on regular. just maybe his car because of heatsoak or some other reason has the retard set so that it runs fine on 87 and because it takes less spark energy to ignite the coil saturation stays better....

 

same here... read that higher octane burns slower than lower octane...

so maybe that's the difference he's feeling with using the lower octane gas, cuz it's burning/flashing faster???

 

I use whatever gas station nearby. I'm not picky. Typically I go to Mobil or Wawa(for you Northeastern'ers). I originally used 89 for the first 3k miles or so, now have used 92/93 ever since. Buddy of mine has had an 06 Imp SS since brand new and has never used anything other than 87.

 

Just because it said it was 87 doesn’t make it 87. When I was N/A and tuned for 93 the wife put 87 in and the car ran like crap.

 

I think it's funny you heard that Shell is crap, I've generally heard that Shell is some of the best gas available, along with Chevron.

 

The only theoretical advantage of lower Octane gas is that Octane boosters are real good at what they do, but crappy as a fuel. Ethenol blends kick *** as an Octane booster, but they have waaaay lower energy content per volume. So....gasoline that has lower Octane (aka less boosting additives) will have more chemical energy potential per weight. I doubt you could measure it, as the boosters are a tiny portion of the mixture, but, in theory, it should give better mileage.

 

Shell is **** gas... causes a lot of KR... definitely NOT one of the better gases available...

 

Shell has always been top rated. I use 93 octane Shell V-Power exclusively.

http://www.toptiergas.com/retailers.html

 

yeah, don't believe that top-tier listing... they PAID to be on that list....

log your knock retard on that shell crap...

I, as well as MANY MANY MANY MANY MANY MANY others had a BUNCH of KR... and after switching off of shell gas, it went away...

I wouldn't run that **** in my lawn mower...

 

It'll run fine on regular. If you lug the engine though, you might feel a surging effect.

 

I have always used shell and never have I had a problem with the gas.

 

shell for sure is much worse gas i have dyno results to prove the kr

 

Thanks for the info. My other choices are BP or Marathon w/STP.
Whadda ya think?