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

[Mudsport96]

Okay finally got around to getting the timing tables looked at. Been a bad week around here.
Okay first up is low octane timing for an LQ4 and I have a generic cell chosen 4400rpm and .60 g/sec air flow

 

[Mudsport96]

Next is the same tune but the high octane timing

 

[Mudsport96]

I'm having trouble with the site and posting more pictures. It says parsing failed... whatever that means. I'll try to get the LQ9 stuff up later. But the timing g difference between low and high octane for the same 4400 rpm and. 60 g/sec cell is 10 degrees of timing.

 

[Mudsport96]

Ok let's try again today.
P59 computer has the rows and columns reversed for some reason but here is an LQ9 low and high octane table set.

Almost 10 degrees of timing difference in the selected cell and anyone can look over the rest of those maps and see what timing for a given rpm/air flow volume each table calls for. So yes you can see more power with 91/93. And it is POSSIBLE to get better mpgs with it too. But cost offset of 87 to 91 you most likely will not recoup the money spent.

 

[Marky Dissod]

Almost 10 degrees of timing difference in the selected cell and anyone can look over the rest of those maps and see what timing for a given rpm/air flow volume each table calls for.

So yes you can see more power with 91/93.
And it is POSSIBLE to get better mpgs with it too.
But cost offset of 87 to 91 you most likely will not recoup the money spent.

Your last 4 posts are GM OE tables of two 6.0L V8s, yes?
I'm sure a significant portion would be interested in the 6.2L V8 tables, as in,
Is the low octane table enough to protect a 6.2L from spark knock on 87? Something like that.

I'm more interested in whether or not aftermarket improvements to the spark tables can improve MpGs, as in,
can the cost of a pcm / ecm tune be recouped by the MpG savings?

 

[Mudsport96]

Your last 4 posts are GM OE tables of two 6.0L V8s, yes?
I'm sure a significant portion would be interested in the 6.2L V8 tables, as in,
Is the low octane table enough to protect a 6.2L from spark knock on 87? Something like that.

I'm more interested in whether or not aftermarket improvements to the spark tables can improve MpGs, as in,
can the cost of a pcm / ecm tune be recouped by the MpG savings?

Yes those are the gen 3 6.0 engines.
I don't have the software for the newer computers that the 6.2s use.
As for the aftermarket tuning for a mpg standpoint alone.
A '19 5.3 z71 my coworker tuned with hptuners picked up 2 mpg after a transmission only tune. He did no engine changes, but strictly shift points and shift completion time changes. Taking out 70 percent of the torque management and "sliding" feel of the shifts. And allows 6th gear at a lower road speed when not in tow/Haul mode.
So yes a tune will pick up mpg. But it may not necessarily be on the engine side of things.

 

[Marky Dissod]

Yes those are the gen 3 6.0L engines ...
... As for the aftermarket tuning for a MpG standpoint alone:
A '19 5.3L Z71 my coworker tuned with hptuners picked up 2MpG after a tcm only tune.
He did no engine changes, but strictly shift points and shift completion time changes.
Taking out 70 percent of the torque management and "sliding" feel of the shifts. And allows 6th gear at a lower road speed when not in Tow / Haul mode.
So yes a tune will pick up MpG. But it may not necessarily be on the engine side of things.

Sounds like what you're saying is:
'even a 'tcm-only' tune will improve MpG regardless of octane used'.

And yet the majority of GMT800 & GMT900 owners have not yet bothered to get tuned ...

I don't have the software for the newer computers that the 6.2Ls use.

Is it just that the 6.2L definition files have not yet become available?
'cause I would not mind detuning the spark tables for an L92 / L9H / L94 so that idiots can use 87 octane without breaking the 6.2L V8 that I'm hoping to transplant in my Tahoe someday ...

 

[Scottydoggs]

high octane modded 5.3

stock 53 high octane

i gained 4-5 mpg on this modded timing all local. running 93 only. if i ran 87 it got knock retard. trans is tuned too.

when timing file was modded and on 93 i got 10-12 mpg local. back to stock timing and 87 im seeing 6-7 all local. im not on the hwy to much. but it was getting around 17-18 on long trips all hwy.

 

[Mudsport96]

Sounds like what you're saying is:
'even a 'tcm-only' tune will improve MpG regardless of octane used'.

And yet the majority of GMT800 & GMT900 owners have not yet bothered to get tuned ...Is it just that the 6.2L definition files have not yet become available?

You have to remember that GM isn't always tuning for the best mpg or best power for the truck and general car lines. They are trying to get you a vehicle that does "well enough " and will make it out of the warranty period...and that is all. The Corvette and other performance vehicles will get more aggressive tunes, but not the bread and butter cars. Most people don't care enough to get a tune. They take the kids to soccer and go to bingo on Sunday. They aren't really caring about a better shift of a couple mpg they may gain.

'cause I would not mind detuning the spark tables for an L92 / L9H / L94 so that idiots can use 87 octane without breaking the 6.2L V8 that I'm hoping to transplant in my Tahoe someday ...

It is the generation of computer software that the entire truck line. The E38 style pcm is a generation after the P59(2003-2007ish) and 2 generations after the P01(1997ish-2002). I have open source software put together by enthusiasts so it is a little limited. But more expensive stuff like hptuners and efi live can do the stuff you are wanting to do.

 

[Marky Dissod]

Most people don't care enough to get a tune. They take the kids to soccer and go to bingo on Sunday.
They aren't really caring about a better shift or a couple MpG they may gain.

Indeed.
... but a couple MpG helps defray the cost of the tune ...
... so does a TCC or a transmission that lasts longer because line pressures were improved and TCC lockup was addressed ...
... or an engine that lasts longer because Engine Half@$$ or Cylinder Confusion was disabled,
or because overheat mitigation protocols were made to activate at 230F instead of AFTER the engine already overheated ...