Real Benefits to 91/93 Octane in a regular LQ4???

[SilverSport]

anyone really seeing benefits to using 91/93 octane in their regular LQ4/6.0 V8???

I have not been one of those that believed higher octane on vehicles that don't recommend/require it got any benefits...I've owned vehicle that did recommend/require it and always used it in those vehicles but tried in other vehicles, I saw no benefit...

as a test I tried a full tank (currently) of 93 octane and noticed what I believe is a slightly better or smoother running of the 6.0 and definitely no ping when under load...I will also add that the ping happens so infrequently as to not be a big plus but I noticed it yesterday driving on the expressway...MPGs might be 1 MPG better...

that said, I am not convinced this isn't the "placebo effect" I am experiencing as it is only 3/4 of a tank in but...

what say all of you???...I just drive my 2005 Yukon Denali, never tow, rarely have more than me and maybe one other so...

please feel free to share your thoughts and experiences...'round ChicagoLand it is about $1.00 more a gallon for 93, 89 isn't worth the cost or effort and mostly, 87 seems just fine but for what I've mentioned above

thanks,

Bill

 

[Joseph Garcia]

There is an active thread here that discusses this issue ad nauseum, which you can view. Make some popcorn first, so that you do not starve to death while reading through the thread.

Many varying opinions and many facts, but definitely not a consensus of opinions, though.

 

[SilverSport]

Thanks

 

[Scottydoggs]

if you own a tuner (i own one, so its way to easy to play around) i ran 93 only in my 5.3, added some timing across the board and felt more power, and got better mpg. once 93 went back up to over 4 bucks a gallon. i tuned it back to stock and run 87 now. that first tank of 87 sucked so bad with the loss of power.

 

[Mudsport96]

If you are able to look at the factory tunes with a program like HP Tuners or even TunerPro, you can see the big difference in the "High Octane " and "Low Octane " timing tables. Now the ecm has no way of knowing what Octane you have put in the tank. But it watches the knock sensors and from what I understand it floats between the High and Low tables as it sees knock. If it sees no knock it will stay on the more aggressive timing table. Thus, the POSSIBILITY of better mpg. I saw this with my father's 2002 LQ4 2500 truck. It would consistently get better mpgs on premium... but not better enough to warrant always running the more expensive fuel.

If I remember after work tomorrow, I'll pull up a set of high and low timing tables for an LQ4. Not sure I have one for an LQ9, but I'll look. But I'll post them and you can see the difference.

 

[tom3]

Watching one of those Engine Masters dyno session on Motor Trend TV the other day. They tested gas from 87 to racing 116 octanes and E85. Blueprint HiPo 6.0 with EFI. Saw about 3 HP difference from the lowest to highest octane and that was with tuning for timing and AF ratios. No real advantage in any of the fuels. I was pretty surprised at all that.

 

[SilverSport]

I've seen the Engine Masters episode as well as the Car and Driver tests...yesterday I did a bit of driving on the expressway and entering or passing still heard the slight pinging when under heavier load...I feel no additional "power"...I still believe that without a tune I won't see much of a benefit and certainly nothing to justify $1.00 more a gallon...

thanks so much for the advice you've shared here...it is appreciated

Bill

 

[drdave81]

It's not so much a power gain by running premium as a power loss by not running premium. As stated above, the PCM adjusts timing based on input received from the knock sensors. The higher octane, the more resistant it is to detonation, which can damage an engine. A higher compression engine will be more susceptible to spark knock (detonation), so that is why premium is recommended/required. Using a lower octane fuel can result in more spark knock, which will remove timing and cause less power. It may or may not be noticeable, but if you were able to look at data logs and live data, you would absolutely see it. It can also have an impact on MPGs. You can contact any tuner and they will confirm this. I'm sure blackbear performance on here would be a great one to reach out to as they tune these vehicles daily, for years.

 

[tom3]

And worth noting that most tests are at wide open throttle with air/fuel ratios at 12.5 : 1 or so. Running at part throttle at a much leaner mixture in real world conditions the higher octane might, or should, be worthwhile at the higher cost? I've always run at least mid grade gas in our recent GM motors with the higher compression.

 

[Marky Dissod]

I've seen the Engine Masters episode as well as the Car and Driver tests ... yesterday I did a bit of driving on the expressway and entering or passing still heard the slight pinging when under heavier load ... I feel no additional "power"... I still believe that without a tune I won't see much of a benefit and certainly nothing to justify $1.00 more a gallon ...

thanks so much for the advice you've shared here ... it is appreciated

Pessimistically, 1 gal of gas equals 10 stop'n'go miles. Optimistically, as much as 25 highway.
So a 25 gallon tank (never run it bone dry) should cover between 250 and 625 miles.
Price of 91 / 93 in NYC is about 30% higher than the price of 87.
250 * 1.3 = 325 miles ... 625 * 1.3 = 812 miles

If 91 / 93 doesn't improve mileage by enough to offset its additional cost, then save your money.

 

[homesick]

Pessimistically, 1 gal of gas equals 10 stop'n'go miles. Optimistically, as much as 25 highway.
So a 25 gallon tank (never run it bone dry) should cover between 250 and 625 miles.
Price of 91 / 93 in NYC is about 30% higher than the price of 87.
250 * 1.3 = 325 miles ... 625 * 1.3 = 812 miles

If 91 / 93 doesn't improve mileage by enough to offset its additional cost, then save your money.

This sounds like good advice, if you're willing to ignore post 8.

joe

 

[Mudsport96]

It has been one hell of a day so I won't be going through tune tables tonight. Had to run 2.5 hours to the kids place at college to remove and replace a frozen caliper on the Silverado, then pads and rotor. Then drive 2.5 hours back. I'm shot. I'll try to get them up tomorrow

 

[Marky Dissod]

This sounds like good advice, if you're willing to ignore post 8.

Oh, but I am.
1. GM designed spec'd built and tuned every 4.8L and 5.3L specifically for 87 octane; same goes for the LQ4,
and most of GM's other 6.0L V8s.
2. Too many are reticent / averse to having their pcms / ecms & tcms tuned.
They fail to appreciate how easy it is to tune an LQ9 or any other 6.0L or 6.2L to operate safely with 87 -
even without more burst knock or power enrichment.
(No one should operate any engine that recommends 91 using 87, PRIOR to the 87 tuning,
except as gently as possible until 91 or E85 can be used - no towing / hauling / racing / hooning on 87!).
3. Even many tuners understandably hesitate to de-tune an engine from 91 to 87.
It's so much easier to simply lean back on the standard disclaimers and tell 'em to keep using 91.

 

[SilverSport]

I keep track of my MPGs for every fill up...at best I saw less than 1 MPG using 93 octane over 87 and 93 is usually about $1.00 more per gallon (best I had found was .85 cents)...

I agree with those that say my 6.0, without a tune will see little benefit in using a higher octane gasoline than recommended by GM which is 87

I appreciate the feedback from everyone and may consider getting a tune, Blackbear or otherwise but for now, 87 Top Tier for me...

Bill

 

[drdave81]

I keep track of my MPGs for every fill up...at best I saw less than 1 MPG using 93 octane over 87 and 93 is usually about $1.00 more per gallon (best I had found was .85 cents)...

I agree with those that say my 6.0, without a tune will see little benefit in using a higher octane gasoline than recommended by GM which is 87

I appreciate the feedback from everyone and may consider getting a tune, Blackbear or otherwise but for now, 87 Top Tier for me...

Bill

I have an LQ4, tuned from Blackbear and usually just run their 87/89 tune. They provide you with both an 87/89 tune and a 91+ tune. So you can swap between the two.

They're finishing up a tune for me now on an LQ9, so I am curious to see if they give me both files for that engine as well, or only a 91+ tune since it is higher compression. But the LQ4, you will get both since the LQ4 could run on 87.

 

[SilverSport]

thanks for sharing your experience...

Bill

 

[SilverSport]

6.0 what grade fuel

Picking up an 04 Escalade with the 6.0 V8, what is the correct grade fuel to run? Some people say 87 is fine, then others say it runs like crap, just want to run what's best for it Sent from my iPhone using Tapatalk

www.tahoeyukonforum.com

this may be helpful for anyone wondering as I was...

Bill

 

[91RS]

Higher octane is to prevent spark knock (also known as pre-ignition). That's it. That is the only benefit. If the vehicle doesn't require or recommend it, it is a waste of money. You will not get more power and you will not get more fuel economy.

Gasoline explained - octane in depth - U.S. Energy Information Administration (EIA)

An introduction to gasoline octane, why octane is important, and how it is measured.

www.eia.gov

 

[petethepug]

My neighbor uses two violent car cooling fans in series plumbed into the intake.

12V70W DC brushless Turbo Fan PWM Speed Regulation high Power Violent car Cooling Blower Motor/Motor (Color : Black Fan)
https://a.co/d/32RPchM

 

[Mudsport96]

Higher octane is to prevent spark knock (also known as pre-ignition). That's it. That is the only benefit. If the vehicle doesn't require or recommend it, it is a waste of money. You will not get more power and you will not get more fuel economy.

Gasoline explained - octane in depth - U.S. Energy Information Administration (EIA)

An introduction to gasoline octane, why octane is important, and how it is measured.

www.eia.gov

I'm so glad you worded it fuel economy. Because yes you can get better mpgs. But, if it isn't enough mpgs to offset the higher price of the higher octane, the economy part isn't there.