[ZLRob]

Originally Posted by hawk02

If you compare the OEM airbox on the Cadillac CT5-V Blackwing to the one on the ZL1, the Blackwing has an additional inlet near the passenger-side front fender. I’ve always suspected that extra airflow contributes to its ~18 hp advantage with the LT4—along with the wideband O2 sensor helping keep fueling in the optimal range.

You’ve confirmed what I suspected—and clearly, the Cadillac engineers felt the engine needed to breath better.

The other change is the intake tube is hard plastic instead of the rubbery tube used on the ZL1. No worries about collapsing under WOT.

It's crazy just how many refinements Cadillac made after the fact the Camaro rolled out. They were worth merit too because the results definitely speak for themselves.

Originally Posted by SpeZ

Hmm, my 2019 ZL1 SC750 from Callaway just has the stock airbox with a green filter.

Actually at WOT the barometric pressure drops up to 1.5 PSI which means the supercharger creates a vacuum in the intake.
This leads to high wear of my LT5 TB which usually only lasts 1-2 seasons each time before it starts dropping off throttle body codes at WOT.

The main restriction is caused by the air filter. The surface is just not large enough.
A cone intake like rotofab offers a lot more filter surface.

For sure doing cuts in the stock airbox allows to suck in more air through the restriction. I see it as 1 main restriction from the filter and another smaller restriction by the small opening.

106 Hz to be fair does not sound like alot to be honest.

I might gonna try this anyway, if I fixed my fender liner. Which basically is barely there anymore.

Can you share what exactly you did on your stock intake?
I did already cut out all the grids from the lower half. Worried about the upper half in terms of MAF reading with changed airflow.
I am considering cutting the lower half like in the first post of this thread.

106 Hz doesn't sound like a lot I agree, but when you are talking about frequency changes up top even a little goes a long way. The mod I did followed Hawk's and the only thing I did was go further than his cuts but not as far as EDF went on this box to preserve some of the boxes structural integrity. I didn't take a photo of the box but I took a photo of just how much I took off. It looks ugly, but I cleaned up the box once I finished my cuts, mostly at the ribs. Used a Dremel 3000 with the cut off wheel and a straight drill type cutting tool to dig into the plastic ribs. Then a small grinding stone to trim and smooth the remaining portion of the ribs which were exposed.

Originally Posted by hawk02

No doubt the OEM paper filter is more restrictive than an oiled panel or cone, but my hesitation is how much a different filter alters the MAF signal due to changes in airflow quality. GM calibrated the MAF around the stock paper element, so changing that can shift the transfer function.

Turbulence clearly matters—otherwise GM wouldn’t have designed the airbox with a diverter/straightener ahead of the MAF. In my experience, a higher-flow filter might pick up a bit on the top end, but it can cost some mid-range torque if the MAF readings get skewed.

Of course, once you’re tuning, that concern largely goes away.

Yeah and so for the filter itself, I am not too sure who makes the green filter or what it's airflow properties are, but I am and have been using an AEM DryFlow filter. It has proven to make the most airflow over the years between them, K&N, AFe, and definitely the paper stock one. I even proved it myself on another application years ago measuring between factory and the AEM, so using it on the Camaro when I first got it was no contest between it and the stock paper filter.