What octane to run
 

Newly swapped newly rebuilt 6.0 LQ4, 799 heads, WS6 Store high lift ASA. Its in a 3400lb Nova. I am new to the LS deal and always ran 93 in my SBC due to the compression ratio. Do I need to continue with 93? Headed to the tuner in a week or so and want to be right when I get there.

If it's a stock rebuild with the LQ4 pistons then run the same fuel as a stock LQ4, The 799 heads aren't an upgrade other than a slight bump in compression but not enough to really change anything. I wouldn't run the lowest you can find at the pump but depending on what's available in your area you could run 89-91.

You should be fine with mid-grade. It'll depend in part on the final tune though so see what the tuner recommends based on what he sees from the knock sensors.

Thanks guys. I have a half tank of 93 and I'll see what the tuner tells me.

Worst case you run premium which you already were anyway. My car calls for 91 but mid-grade around me is 89 so I just run the 93 and don't have to worry about it.

Lord internet, don't do this today.............

Dude, you can run whatever fuel you want. The stock program has two timing tables, one called low octane, one called high octane. The computer uses some kinda voodoo algorithm to decide which one or blend of the two to use. What we as tuners typically do is ask the customer what fuel they want to run, then lock both tables into the same number so the computer loses the ability to pull power/change timing. Depending on application and customer preference, WOT can be locked in anywhere between lower to upper 20s. For pump 93 on an LS1 I generally go to 28ish. Carb motors can handle more. For an LQ4, I think you'd end up around 24/26 due to slightly lower compression.

Depending on your elevation you can get by in lower octane without knocking.