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.

[HAWAIIZR-1]

Originally Posted by XfireZ51

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.

Dom,

Thanks for all the info and explanation. I wish I could have had those bungs put in the header collector before ceramic coating; how about in the pipes right after the collector since I'm not running any cats? I don't mind the shop punching holes in those pipes and welding in bungs. I'll measure to see how far away from the stock O2 sensor location.
Craig

[HAWAIIZR-1]

Originally Posted by LGAFF

out in the country/corn fields this morning on the way to work.....stopped revd it to 3K dropped the clutch and the car did a water box style burnout without using the brake, just sat and smoke the tires....lovin the car...

Every Z needs porting and cams...

I totally agree, now you need tires like me. I'm going with Nitto NT05Rs in the rear; I can't get any traction now.

[LGAFF]

could the variance also be slight differences in open and closing of cams vs injector pulse????

[XfireZ51]

Originally Posted by HAWAIIZR-1

Dom,

Thanks for all the info and explanation. I wish I could have had those bungs put in the header collector before ceramic coating; how about in the pipes right after the collector since I'm not running any cats? I don't mind the shop punching holes in those pipes and welding in bungs. I'll measure to see how far away from the stock O2 sensor location.
Craig

Craig, you could do that. Not optimum BUT after all we measure AFR at the tailpipe on the dyno, so it won't be too far off.

[Blue Flame Restorations]

[QUOTE=LGAFF;145015]out in the country/corn fields this morning on the way to work.....stopped revd it to 3K dropped the clutch and the car did a water box style burnout without using the brake, just sat and smoke the tires....lovin the car...

Every Z needs porting and cams...[/QUOTE]

Oh yeahhhhhhhhh.................

[XfireZ51]

Originally Posted by LGAFF

could the variance also be slight differences in open and closing of cams vs injector pulse????

Unlikely this would create a consistent L/R, leaner/richer situation. BTW, the L98s and LT motors had same split blm issue. Fuel comes from one side and crosses over to the other.

[XfireZ51]

Originally Posted by LGAFF

out in the country/corn fields this morning on the way to work.....stopped revd it to 3K dropped the clutch and the car did a water box style burnout without using the brake, just sat and smoke the tires....lovin the car...

Every Z needs porting and cams...

Lee,

You're just having too much gdamn fun! =D>

[Ccmano]

Really a shame most of the photos of this great old thread have been lost. Especially since I might be going down this road shortly. Good info here especially from the perspective of a novice LT5 builder. Lee any chance some of these photos could be resurrected?
H

[WVZR-1]

I just went through the first several pages of this thread and there wasn't a snapshot that wasn't available. I saw nothing that had been 'blitzed'. I've been using the Chrome extension by Jesse for quite a long while and I actually thought I was a little 'late to the party'. His most recent update to the extension looks to be early Jan but I'm very sure I was using his or another long before that.

I've had no PB locks for I'd guess 10 - 12 weeks maybe more. It's been a long time.

I only came to the thread because I saw a 'recent' post!!