I spent some time researching volume vs velocity on tb and intakes and from what I have read over a few hours, it seems on a larger lower reving engine like ours, more air volume is key. On a higher reving engine over 6k rpm, more air velocity is key. I also started diving into velocity stacks and the theory behind them since the LF system uses velocity stacks. So my thinking is w/ a 95mm tb on the LF system, its getting the additional volume needed for the larger engine and the velocity stacks are actually increasing the air velocity, the best of both worlds. As Ive mentioned I did feel more top end power on the LF system, Im gonna call Mike at Soler performance and go over my ideas and thoughts w/ him since hes forgotten more about tb performance than I will ever know. Hes very knowledgeable. After reading all the articles Im leaning toward keeping the LF system but honestly think the key in making the gains is really in the tb and the intake, whether LF or a ported LT2 doesn't add a whole lot on top of the gains seen by just the tb. Someone tested a before and after on one of these threads and the intake was like 3-4 hp and the 15-20 hp was in the tb.

At this point, dealer is yanking my engine tomorrow to replace a bad cam phaser so Im praying the car comes back running ok and they dont mess it up, if not Im about done dealing w/ this issue and may sell it and buy something else as this has drug on for months w/ GM now. The next couple of days will be interesting.

 

Good luck with your repairs and please share what you learn from Mike at Soler! I think you have a pretty solid line of thinking here.

 

I did install a ported and polished Lt2 intake and added 95mm TB. Im installing my headers now with cats. (Pain in the ***)

 

Did you happen to dyno after those mods? What did your butt dyno think?

Seems the tb and intake make more power than headers but let us know how it all runs together!

 

I'll finish header install tomorrow. Gets dark fast, plus dealing with collecter studs kicked my ***.

 

My 23 has both of those codes, set off 3 days after installing an AFE cold air kit & Paragon Catback. Car has 600 miles on it.

 

Bigger TB on a fuel injected car will almost ALWAYS show hp gains at high rpm. It has zero to do with velocity that downstream from the heads.

The the reason you are getting a 174 cel is because the MAG expects a certain amount of airflow from the stock tb at specific throttle openings. When you just drop in a 95mm TB, the airmass isn't matching what the TPS is calling for. On my LS3 car, I needed quite a bit of tuning to get it to play nice with the larger throttle body. Basically, there are airflow limits in the ECM, larger throttle bodies can exceed those airflow limits and the ECM trips a code. I would be shocked if tuning wasn't a necessity.

Even stock, larger throttle bodies always showed a power increase--but often made throttle tip in less snooth. Even after tuning.