Switching octane

[bchaney]

So there is finally light at the end of the tunnel for my build and I'm hoping to have it in by the end of sept. I plan on switching to a higher octane gas - should I start filling up my ep with the higher octane now so when I swap everything is good to go?

[jimmyjames]

You need to tell us what the swap is first.
As for switching the octane of the gas now to get ready for the new motor; you can.
It's a safe move and the price is really negligible.
If you don't, start the new swap up and let it idle for a few hours.
You can also top off the tank with E85 to boost the octane as long as you don't put in more than 3-4 gallons as E85 will degrade fuel line components.

[bchaney]

It's a k24 block and I have TSX pistons so I know I'll need higher octane to run it.

I guess I'm just asking how you guys change your gas when you swap. Do you just start running higher octane before the swap? Or siphon out the old stuff?

[Lucid Moments]

I'd start about one tank full before you swap. So run your tank as close to empty as you are comfortable with, fill up with premium, then do that again and swap it. And to be honest that is very conservative.