V6 fuel switch 87 to a higher grade

[YodaOnCrack]

87 ethanol-free probably better than 91 with ethanol if you're going to spend the extra $$$$......The higher octane for the v6 equals wasted money

[bulls96]

my dealer just told me i am better off doing fuel treatments every so often than using a higher octane fuel...

any thoughts?

[chevyk1]

I have tried both in mine and noticed no difference except at the cashier.

[trekmanone]

Originally Posted by E.T.

It has been shown that timing is pulled with 87 octane. I'm actually curious as to whether midgrade is enough to avoid this?

newbie question, the term "timing pulled"?
Does that mean the spark advance is "pulled" lower than TDC (top dead center) at 87 octane and with 93 the spark advanced is higher on the piston cycle? Getting a new 2LT in a few weeks and wondering about gas choice.

[trekmanone]

Originally Posted by John Shields

I guess you failed to read my post. I never said anything about combustion, and I never said anything about performance. I use the higher level fuel because it's cleaner. The unleaded here is crap fuel and often times these stations mix their fuel with other substances. The higher level fuel is usually better quality gas. There was a big stink about this a couple years back when the news did an investigation into what some stations were doing around here with their Unleaded gas.

Last time I gassed up, I paid 2.53 per gallon of Premium where every other place around me was charging 2.85 for Premium and 2.65 for Unleaded. The place I went to (a Conoco, or some other such reputable place) was out of everything but Premium and gave everyone a deal. Along with that, a purchase of a car wash took another .10 off per gallon. Which it needed anyway.

You take your new Camaro through a car wash? Damn dude...

However, for the altitude of Denver, do they muck around with gas formulation for mile high city? Does the fuel/air ECM sensor figure it out correctly? You have pretty lean air at a mile.

I was wondering because I get about 5mph faster in my boat in winter than in summer (dense cold air vs humid air)

[trekmanone]

Originally Posted by CamaroMiami

100 is down here and expensive also.

In my 92 (V6) camaro, I use higher/better gas (91- 93) and have the feeling of a better benefit. I have no data to support more HP or anything. Just the gut/mental feeling and smile.

My current car, soon to be traded in on a new Camaro, has 5.3L V8. Texas has 87, 89, 93 octane. Pontiac recommended min 89 but performance would increase at 93.
I tracked 10 tanks of 93, same station, same day, almost same time (beginning of day when cooler) - mph. Then tried 10 tanks of 89 octane, almost same conditions.

No statistically difference in mph.

[trekmanone]

Originally Posted by usmc8411

The DI v6 runs off 87 but in my caddy it says use 91 for the most performance....which means it has probably 2 fuel maps....just like every other performance car. Difference being the v6 was designed for 87 and they probably just tweaked it a bit for 91 as opposed to the SS which was designed for 91 but also has a low octane map.

I dont know why people think higher octane is a better/cleaner gas. It just adds more anti-knock additives such as toulene.

Its not better gas. Adding certain amounts of toulene to 87 octane is (pretty much) the same thing as buying 91.

Another forum thread answered my question saying only the SS (V8) has the low & high octane tables and the V6 just has the timing pulled.

[GhostOutlaw]

I use 93 only, tried 87 twice, got really poor gas mileage on a 2LT.

Though the cold air is a killer now.

[shad2009]

if it's not tuned for a higher octane, you're just wasting money

[Lazerbrainz2k3]

Originally Posted by shad2009

if it's not tuned for a higher octane, you're just wasting money

If you're looking for more horsepower than the rating, yes it is a waste of money.

If you're looking to make the engine more efficient at reaching its full potential by limiting the timing pull, then common sense and some decent empirical evidence here seems to suggest there may be something to that theory. It all depends on what question is really being asked.

Do we know for certain which grade of gas was used to get the EPA rating? Maybe that's where the extra 8 hp for the 2011 V6!

[GretchenGotGrowl]

There's some dyno numbers that show a slight gain in HP from running high-octane gas. Greater timing usually means more power. You don't need a tune in the V6 because it automatically adjusts timing based on the knock sensors.

All that said, the best way to find out for oneself is to run a couple of tanks of 91/93 octane and see if YOU feel a difference in power, smoothness, MPG.

[E.T.]

Originally Posted by trekmanone

newbie question, the term "timing pulled"?
Does that mean the spark advance is "pulled" lower than TDC (top dead center) at 87 octane and with 93 the spark advanced is higher on the piston cycle? Getting a new 2LT in a few weeks and wondering about gas choice.

From: http://forums.rennlist.com/rennforum...ming-mean.html

Ignition timing refers to the point in the 720 degree cycle where the spark plug is ignited. Once the spark plug is fired, it ignites the air fuel mixture. The flame speeds away from the spark plug and requires some amount of time before it is fully burned. This is what pushes the piston down the bore. You need to ignite the spark plug before the piston reaches TDC to allow for maximum pressure. Ignite the spark plug too early and detonation occurs, ignite it too late and the piston speeds away from the flame. Pulling timing simply refers to the reduction of ignition timing from before tdc to a point closer to tdc. This can be done by any number of tables within an ECU and depending what the sensors are telling it.

There have been other posts on this site regarding this question, but I can't seem to find them at the moment. I don't know all the technical details of this stuff either, but basically, pulling timing = loss of power.

[mzdennis74]

Hey, there's a difference in the gas in this car, I have tried it and have noticed it. Hey, take a look at the new 5.0 mustang engine specs, it has vvt to and they state on the ford site with 87 it makes 402hp and 93 it makes 412 hp. The torque is different also by 4 or 5 lb. ft.

[chain777]

Yeah, but it isn't a 5.0, and Chevy never made such claims. I think you're reading too much into it.