6.0 what grade fuel

[01ssreda4]

That may be true with a stock tune, which I also have access to , but I believe BlackBear Performance must optimize their tunes for the different octane levels. That's probably why I couldn't tell the difference, at least I assume. I did ask Justin at BB if I ran the 91+ tune with regular gas, would it cause problems. He said it would probably just suffer performance-wise. Are you saying the factory runs a dual tune or some kind of variable tune in the PCM? I don't see how that could be possible, but maybe a tune more likely based on the lowest octane.

Thats correct. It has 2 timing tables. It calls them "low octane" and "high octane". The high octane table has more timing advance. A common practice of tuners is to copy the high table to the low side so as the computer shifts between the two its actually shifting to the exact same table. Its a trick to keep one single table instead of two for consistent performance. Also, the tables, both of them, are conservative. And if the high table is conservative, then you could imagine how bad the low table is. I copy the high to low then add quite a bit of timing to the part and WOT regions....big difference in throttle feel and power. I also run 93. Remember, you still have knock sensors to retard timing if they sense pinging, but I have had none so far.

 

[hoe]

If your lq9 runs on 87 then it really isn't running right... yes they can handle mixed grades stock, but the stock tune is shit. Add a real professional dyno loaded tune not any trial homebrew tunes-ers. Then: You can have a significant amount more timing and fuel added in addition with quality fuel 93+... it's a whole different engine. Then run that on 87 and feel a 10hp difference.

Lq9 has flat top pistons and more compression to take advantage. Less tolerance for bad gas.

Lq4 has dished pistons and is more forgiving to 87 oct.

 

[Mechanic421]

My 05 denali pings on 89 .

 

[01ssreda4]

If your lq9 runs on 87 then it really isn't running right... yes they can handle mixed grades stock, but the stock tune is shit. Add a real professional dyno loaded tune not any trial homebrew tunes-ers. Then: You can have a significant amount more timing and fuel added in addition with quality fuel 93+... it's a whole different engine. Then run that on 87 and feel a 10hp difference.

You don't tune for a living do you? Cause you sound foolish.

My 05 denali pings on 89 .

Then you need a tune up or other routine maintenance.

 

[hoe]

I don't tune for a living. I pay a professional to do it right the first time. You sound like you think you know what you talk about.

 

[#1taho]

I am in Pennsylvania this weekend and put in 87. No pinging but I notice a drop in power.

 

[hoe]

In my 2500hd lq4 I even run 93. I notice in that truck It drinks 87 but sips 93. Considerable difference, and that's with a bone stock gm tune.

Actually all my 3 LS vehicles prefer premium. I notice a difference in all. And 1 of them is a 5.3.

In my lq9 I can notice a difference in 93 quality vs other gas stations 93. That's how sensitive they are to ocatane levels. It likes shell, chevron, texaco. Mostly gas with textron.

 

[#1taho]

In my 2500hd lq4 I even run 93. I notice in that truck It drinks 87 but sips 93. Considerable difference, and that's with a bone stock gm tune.

Actually all my 3 LS vehicles prefer premium. I notice a difference in all. And 1 of them is a 5.3.

This is the first I noticed it. I normally put 89 when I come over here. 89 is more equalit to 87 back home. With 89 it's the same as home. Don't know what it is.

 

[#1taho]

I also just noticed I drove 30 min after filling it and used 1/8 of a tank. That's a lot more than normal. When I leave this afternoon I will top off with 93.

 

[hoe]

It's quality of the same grades. Compare 93 grades at different stations as well. Example... If I use bp 93 it's like 87 from a shell. 93 from bp is nothing like she'll 93.

Also to fill up with 93 vs 87 maybe a 4$ overall difference. I don't get why some people try to save that and end up refilling almost twice as fast.

Post back with your results.