is my compressor too small?

[NMB2]

Think about what you're doing by reducing the BTDC timing. Starting the burn later gives it less time in the cylinder before the exhaust valve opens. This means more combustion energy is exiting the cylinder and making its way to the turbine - quicker spool. :ft:

Inversely, this is why advancing the timing is usually accompanied by a reduction in EGT; you are capturing more of the burn in the cylinder.

My advancing of the timing gave me higher EGT when getting into it, because it wouldn't spool the turbo like I do now....

That being said.... I change up the exhaust parts.... and am able to spool it normally and hit the same boost I am now, but @ 8.5* where the engine should be.

How is 30psi @ 8.5* going to make more power than 30psi @ 6*, if the 6* produces more combustion energy.

Sorry if I am missing something, I'm just trying to understand my issues specifically.

 

[Amish Elegance]

Ok, my lower EGT comment has some caveats. With advanced timing, I observe lower cruising EGT. But at a dead matt, the slower spool in some applications gives the EGT time to build. It is far easier to get the turbo lit and keep the egt's down as opposed to spiking and trying to cool it down from a peak.

I digress...

In your scenarios below, neither produce more combustion energy. By injecting it earlier you are keeping more of that energy in the cylinder before the exhaust valve opens thus the cylinder has opportunity to better harness this combustion energy.

By retarding the timing, the burn starts later and more energy is still present when the exhaust valve opens. This energy/heat excites the turbine and improves spool.

The perfect timing is a balance between harnessing this energy in the cylinder and utilizing it to drive the turbine on your turbocharger.

 

[NMB2]

Ok, my lower EGT comment has some caveats. With advanced timing, I observe lower cruising EGT. But at a dead matt, the slower spool in some applications gives the EGT time to build. It is far easier to get the turbo lit and keep the egt's down as opposed to spiking and trying to cool it down from a peak.

I digress...

In your scenarios below, neither produce more combustion energy. By injecting it earlier you are keeping more of that energy in the cylinder before the exhaust valve opens thus the cylinder has opportunity to better harness this combustion energy.

By retarding the timing, the burn starts later and more energy is still present when the exhaust valve opens. This energy/heat excites the turbine and improves spool.

The perfect timing is a balance between harnessing this energy in the cylinder and utilizing it to drive the turbine on your turbocharger.

This makes perfect sense to me, I just needed it broken down so I could visualize it. It is along the lines of what I was picturing, but was having a hard time wording it.

I feel confident that switching to a 68/12 exhaust side is the right choice now.

Thanks for everyone's help, I will update in a few weeks after I get the truck back from body shop, and get the charger swapped.

EDIT:

On another note, I'm guessing I will see a mileage increase being able to advance the timing too. Currently I get 13-14mpg no matter what. Empty, towing, granny driving, romping on it... doesn't seem to matter.