I have a stock style 5.3 with a 76mm turbo going though a csu e85 blow through. I was curious as to what total timing you guys have at 20psi.I have mine at 18 total at 20psi and was wondering if that is a good setting or not..I am running a carb and its on e85 as well.This does not go through a intercooler its straight from turbo to hat..thanks in advance

 

Let the plugs tell you.

 

When I ran my BT on 93, 12-13 lbs boost, IC'er, the plugs liked 22 degrees-not the same setup as yours, but seemed with a BT it liked timing more than FI.

 

I wouldn't start out at 18* and 20lbs personally... Especially without an intercooler.

For example my twin 76mm (non-intercooled) 5.3 at 10:1 runs 14* at 15lbs. This gets me the somewhat “HOT” strap reading below. IMO you want to be about half way down the strap for a conservative "safe" tune. You can defiantly sneak up on the tune after that and get closer to the bend like in my pic if you are racing it. I add timing after 6k and I run "na timing" up to 4-5psi.

Another good point is indicated timing may not be actual timing. 18* on your setup may only be 12* on my setup. The crank/cam positioning can vary. If both parties don’t have the timing sync’d and spot on perfect with the exact same air fuel ratios in every cylinder, same charge temps, loads, weights… etc etc… Then listening to another person telling you what timing to run can cost you an engine.

If your already at 20lbs I’d pop a new plug in the leanest looking cylinder and see what 12* looks like on the plug strap.