SCT Tuning with a high octane gas

[SVT Lightning2003]

Hi, first thread. long time reader as a guest.
I have an 03 Lightning, mod'ed up with the usual stuff before the internals get done. i have it dyno tuned for 91 octane pump gas and for 94 octane pump gas from the shop. my research on the use of the sct x3 that i have for the truck has shown that using a higher octane fuel will allow me to change the settings on the global spark by as much a +4 for the use of higher octane fuels. we have a local shop (afd petroleum) that makes the race fuels for the local circuit up to 120octane and i think higher for special applications. they do have pumps at the facility though that pump sl99 fuel at a mere $3.24 litre.
my question is easy i think but i thought i would ask the group before using it in my truck.

if i program the truck with the 94 octane program and then add a +4 to the global spark thus allowing me in theory (according to research) to run at 98 octane (99 actual) without losing the benefits of a higher octane fuel, will the result be the tune be what i need for driving using the program settings at 94 on the 99 fuel?
OR
Should i book an entirely new dyno appointment and have it completely re-tuned at the 99 octane level which the truck will be running on from now on?

 

[01yellercobra]

I think you have to take into account what the stoich is for the race fuels as well. I know some of them require a different A/F. Similar to gas vs E85. At least in my research. Ideally I would get a tune written for the gas you plan on running. But you could always try adding the spark after mixing fuel and listening for detonation. I wouldn't add all 4 degrees at once though. I'd work up to it.

 

[SVT Lightning2003]

thank you. i'll be fueling today starting with 1/2 tank to test with. i think adding 1 deg at a time is a good idea.

 

[BigPoppa]

I'm very leery of using global spark adders, but if you want to go that route, stick with slo984now's advice and only bump it a degree at a time.

 

[SVT Lightning2003]

i'm currently at +3 global spark with no issues. i borrowed a mechanics stethoscope to monitor for ping noises. its running strong so i may not go to +4, no need to max it out.

 

[decipha]

log your spark advance at wot and post back here, that will determine if its safe or not

also need to know how much boost its making

 

[01yellercobra]

i'm currently at +3 global spark with no issues. i borrowed a mechanics stethoscope to monitor for ping noises. its running strong so i may not go to +4, no need to max it out.

Unless you're using the stethoscope at WOT I don't think it's going to help. That's where you need to be mindful.