LT5 Assembly Project

[XfireZ51]

Originally Posted by HAWAIIZR-1

Dom,
What do you recommend for someone wanting to add WB O2 to their car and do you need to install dual bungs and have dual O2 sensors?
Thanks,
Craig

Well the O2 should be as close to the exhaust ports as possible but in the collector not an individual primary tube. Its nice to have 2 WBs, one for each bank, altho we currently have no way of "trimming" fuel for the individual bank. With 2 WBs you basically take the middle of the road route just like you do with part throttle. The final fueling becomes a compromise. However, the disparity in the L/R banks becomes less pronounced at WOT than it is at idle. That's why choosing something like 12.7-12.8 is a safe choice and why you want your cruising BLMs to be a bit on the rich side to begin with, ie 124 or so.
I suspect the split BLM issue is due to the difference in distance fuel needs to travel between left and right rails. Typically we see D/S bank as leaner than P/S. I would plug the fuel line directly to the back of each fuel rail and then to the regulator. When i had my Xfire, one of the mods was to re-route the fuel from "in-series" to parallel plumbing for each TB. I once measured a .5psi drop in fuel pressure between the TBs with the fuel line in series. That FP drop was enough to make Chevrolet specify different size injectors for front and rear TBs. The front TB used a 62# @10.5psi while the rear used a 65#@10.5psi to make up for the differential FP. However, parallel plumbing made the engine run sooo much smoother.