87 vs 91 vs 93 Tune on LM7 5.3 w/ Mild Cam?
 

I have an early ('00) LM7 5.3 with a newly installed BTR Truck Torque cam, TBSS intake manifold, shorty headers (factory exhaust) and electric fans. I did these mild mods to gain additional power/torque when towing since this is an early, lower power 5.3. No more mods are planned. Tuners in my area are pushing me hard for a 93 tune but it's $0.85 more per gallon. 91 is $0.50 more per gallon.

Would an 87 or 91 tune net me enough gains to make my mods worthwhile? Would a 93 tune gain me better fuel economy along with more power/torque that would even out the added cost?

You spend all that money on mods to neuter it with regular gas? C'mon man.

It's going to cost you how much more per fill up? $15-$18?

We don't mod vehicles to save money.

cheap insurance running higher octane

You also blew some money on shorty headers and a TBSS intake on a 5.3, wouldn't say those are the greatest mods.

Personally I would consider 91 over 93 though. ONLY BECAUSE there are places in the US that don't have 93 gas and I am sure they have people modding cars and running 91 lol

I got a great deal on the parts but because you asked, $0.85 x 32.5 gal tank = an additional $27.63 per tank which is very significant.

You didn't even answer my original question :offtopic:

The headers and intake were very inexpensive and a fun project for me so it is what it is. Dumping on my mods when they're already done isn't helpful. :shrug:

In Virginia, where I am currently located, 91 is actually harder to find than 93. It's mostly 87, 89, and 93 here but Sunoco carries 91 so I can get it.

Nevertheless, I would still like someone with tuning experience considering these variables to chime in.

The 99-02 PCMs you can run a switch and be able to run 87 or 93 octane.
You could always get it tuned for 87 octane and get a feel for how it runs. Then later get it tuned for 93 octane.

My 2500HD i can get more timing with 93 octane but you cant tell a difference towing.

Oh wow, this is super interesting. Do you know of a write-up on installing a switch? Is this basically two separate tunes installed on the same PCM? Something else?

Only EFI Live does this.
Its a 2 wire setup and simple to do. It only works on the 512kb PCMs tho with COS5.


(J2,pin56)

Maybe if you ask your question a 3rd time someone will give you the answer you want.

https://www.performancetrucks.net/fo...-559977/page2/