I was wondering, for daily highway driving, what are premium gas' advantages and disadvantages (other than paying 20-30 cents more per gallon). I filled my tank up with premium last night and it seemed to me that when I accelerate while on the 5th gear, i get better acceleration.
Tell me your opinions.
It'll help reduce the weight of your wallet and because of that you can experience faster times with the butt dyno. There is no need for it in a stock J-body.
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yeap no need for it, THE ONLY reason it would help is sometimes gas companies put extra additives in the higher grades of gas to clean the engine and fuel system.
The other reason why I tried is because I have been having sputter problems when I accelerate. I change the fuel pump, the serpentine belt, put synthetic oil but i still was having the same problem. The mechanic said that I might have problems with my fuel delivery system or the fuel wasn't flowing the way it should. Since I have been driving with Premium Gas, it seems to help but again, It could be just me too.
the only point to premium gas if for in engines with higher combustion pressures to prevent pre-detonation from increased cylinder pressures, for example from super/turbo chargers, or if you were to install high compression pistons. this is because when higher pressure exists in a cylinder it increases the temperature or the air fuel mixture and can cause it to explode rather than burn before its supposed to. High octane fuel can also be used if an engine will be under a heavy load for an extended period of time example towing a trailer because this will increase operating temperature. So unless your towing a u-haul or have a supercharger or turbo charger it is not needed. The only benefit i can think of is that high octane fuel has more detergents in it so it might have more self cleaning properties. other than that it can actually cause your engine to run less efficently because it high octane fuels are made to resist burning more than regular octane. answer any questions?
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Thanks for the great information guys
Any gain you think you feel in your head is false.
Yellowcav is right, higher octane gas is harded to ignite. Lower octane is much more volatile gas with a more violent explosion so to speak. Higher octane gas is basically taking the potency out of the gas. You want to run the LOWEST octane you can without causing detonation.
I think in a lot of cases you will find the quality of premium gas is better than regular stuff. That might only be around here, but I can absolutely tell a difference between running 89 octane and 93 octane in my 99 z24. Start up and initial idle are far and away better on 93 octane than the other stuff. My car is sorta modded though and probably north of 10.0:1 compression also.
And the difference of just having newer fresher gas in the tank.
^^^ actually thats wrong...
you could fill up with gas that has been sitting in the pump, and your next fill up could be the same gas still sitting in the same pump. You don't know how new or old it is, you just know when you put it in your car.
edit = typos
Edited 1 time(s). Last edited Sunday, March 08, 2009 2:08 PM
sputtering could be a coil going out as well.
premium is good for turbo/boosted engines ... but it can also permit the car's computer to advance timing, where it might otherwise see knock. for example, 2500rpm and accelerating slightly. people will notice this when towing, or going up hills. not likely to make a different in the upper RPM IMO .. unless your car is experiencing knock, and if it is there are other ways to fix that w/o lightening your wallet on every fillup
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Actually the L61 stock ECM pulls some timing which you gain back running mid-grades.
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Youll see beter performance with midgrade. premium is a waste.
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these scans were made on regular gasoline (87)
take note of the retard (3rd group from the top, red line)
this is on a STOCK car, with STOCK tune
low grade = 4-6degrees of knock retard. I now run premium and see less than 1 degree, although I'm taking another scan soon to double check.
higher grade means more advance, meaning more power.
unnecessary on a stock jbody? I disagree. It seems GM's lame version of reduced timing is making the knock sensor too sensitive. Either that or I have some other issue on my 04.
Again, a follow up scan is coming when the weather gets warmer outside (50-60degrees) but I see significantly less kR when running premium fuel.
less knock is good! my motor loves me!
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like its been said before, higher octane helps reduce detonation in higher compression motors (either due to displacement differences or adding some form of boost). from what I was also told by a good mechanic friend of mine, higher octane also burns cooler, slightly reducing operating temps (not enough to see on your gauges, but he said even a lil bit helps). i used to run 93 before gas went up over $3/gal for the temps argument alone, but from a performance stand-point, I never noticed a drastic change. aweosme charts tho, Skwirl
I have a similar issue right now.. my car seems to not just sputter, but completely hiccup if I go full throttle at lower RPMs (under 2500 or so). now, I believe this is due to a fueling issue. I installed a Walbro fuel pump and tossed the factory "accordian" feedline for a rubber hi-pressure line.. problem being that the line is too fat, and when the pump canister is compressed down, it kinks the line, cutting fuel.. so much so, that the car wouldnt even start. now, we trimmed the line down as much as humanly possible and the car will start and run fine, and if I punch it at a higher RPM, I dont notice any cutting out.... just a lil thought to throw in for you
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DaFlyinSkwir(LS61) /PJ/ OEM+ wrote:these scans were made on regular gasoline (87)
take note of the retard (3rd group from the top, red line)
this is on a STOCK car, with STOCK tune
low grade = 4-6degrees of knock retard. I now run premium and see less than 1 degree, although I'm taking another scan soon to double check.
higher grade means more advance, meaning more power.
unnecessary on a stock jbody? I disagree. It seems GM's lame version of reduced timing is making the knock sensor too sensitive. Either that or I have some other issue on my 04.
Again, a follow up scan is coming when the weather gets warmer outside (50-60degrees) but I see significantly less kR when running premium fuel.
Haha, somebody finally proved this.
I too was having 4-5 degrees of knock which was reducing my power and backing off the timing.
I did this while at the track datalogging the information similar to PJ.
Once I added premium to the tank, the knock went down to 1 or 2 degrees or less with much better response from the engine than previously.
Times improved too with the addition of premium.
Even with the daily driver that I have, I've experimented with gas grades only to come back to using premium with it too.
The daily drives so much better with smoother idle and better top end response.
Nice to see somebody with visual proof and dispell the 'your butt dyno lies' replies.
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Newbie member since 1999
Thank you Dave and JBO! 
the funny thing is, I didn't take those logs for this.. that was during my testing of the PE delay feature, and how it truly works. I didn't even notice how much kR I was getting until after making the post (PE delay myth investigated)
I run premium now all the time. It just doesn't sit right that I'm getting almost 6 degrees of knock because of running cheap gas.
How much kR is too much? Skwirl do you get better gas mileage with the premium? Premium is all I used to run in my car before I decided I was just wasting money. I figured I didn't need it due to high compression. I even made a thread about it. Hell if I can find it now.
okay question, when i push the gas pedal my car revs a little for like a half second then starts moving, is that the timing problem you were having that the premium gas solved?
Doug wrote:okay question, when i push the gas pedal my car revs a little for like a half second then starts moving, is that the timing problem you were having that the premium gas solved?
Probably not.
I was only having issues with knock with full throttle acceleration whether it was on the street or at the track.
I'm not sure of your condition and would think that it's other issues.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
yeah idk it's weird. i should probably get it tuned or something. and get the tranny looked at. and now my radiator is leaking coolant at 73k. stupid.
Doug wrote:okay question, when i push the gas pedal my car revs a little for like a half second then starts moving, is that the timing problem you were having that the premium gas solved?
it could be the trans downshifting? I don't really know.
Doug wrote:okay question, when i push the gas pedal my car revs a little for like a half second then starts moving, is that the timing problem you were having that the premium gas solved?
pretty sure thats just the lag you get when you've got an automatic tranny.
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