I will post a log later today, but this is more in theory of a discussion
I put my car on the dyno finally, and hooked up a sensor to log my pre-turbo exhaust pressure. Car was dialed up to 14psi, 19psi, and finally 22psi, 6266 twin turbo, 392 forged motor.
The exhaust back pressure was pretty much rock steady at right around 2:1, but right near 6200rpms or so I got a big spike of back pressure (went from 35psi to around 41psi), but at the same time my boost pressure started falling off, fading from 19 down to 17.5 to 18psi, but the car also went pig rich going from around 0.72 to 0.66 in a matter of a few hundred rpms.
I am trying to figure out exactly which is the cart and which is the horse. I know rich means higher exhaust temps and more back pressure, so initially I am trying to figure out if my tune is somehow allowing cat overtemp to kick in (car is catless), and how I can monitor for it. Would the commanded lambda show the change in fueling?
I could have simply hit the wall on flow of this T3 0.82 AR setup, which I know is small, but is how Hellion sets up the kit. But strangely I got the SAME exact spike in manifold pressure at the same rpm at 14psi, 19psi, and 22psi of boost, always spikes over 2:1 in that spot. Leads me to believe its not really a flow issue, maybe a wastegate issue?
I didn't get a chance to play with the fueling to see if it would help back pressure, but for sure my VE table doesn't have some big spike there and should be no reason why its going rich. Leads me to believe the rich spot is from high back pressure, gates getting blown open, boost falling, power falling off, way too much fuel.
Open to thoughts.
I had posted a few months back about my shitty spool I thought I had. Showed it clearly on the dyno how lazy this setup is. WOT at 2600rpms in 4th, didn't hit peak boost until 5000rpms.
Diablo Tune 1_3 Bar_v.hpt