0411 to 97 L29, decision time

[Scott-m]

I have a 97 K3500 with 230k on the L29 7.4l. I bought a 99 L29 complete engine to build and swap in. I have ported and flowed the heads (290 cfm on intakes), had the cam reground for more lift, tighter lsa and more advance (from -6 deg to -2), And matched and ported the dreadful stock intake manifold. It's also getting Comp Cams springs and adjustable valvetrain, stainless headers, and 29 lb/hr injectors. I haven't bought the injectors yet, so maybe you can help me find ones with tuning data available.

I recently received a 12200411 ecm from ebay with warranty and pre-loaded with a 2001 L31 express van program. I got the van vin from the gmt400 forum, so there might be hundreds of ecm's out there with the exact same vin. Will that be a problem with credits and 'licensing'? I will be buying an Hp tuning system, but I have some questions for you guys first:

1. The stock manifold is a giant intake-air heater, apparently designed to flow as little of that hot air as possible. Unfortunately, I need it to stay emissions legal in the phoenix area. So initially I will run it on the new engine and stay with the conventional L31 Maf-based program. But someday I would love to play with a real intake, like the Edelbrock Pro Flo 4 (Victor Jr efi manifold with a throttle body the size of a toilet, which I just happen to have). Such a manifold would require a speed-density os. Should I buy the mvpi2 pro version for sd tuning? Or can the regular mvpi2 handle it?

2. Spark mapping is cool and all, but isn't it an unnecessary complication? Why not just stab in a vacuum advance Msd dist and 6AL box? It would certainly simplify things with the Pro flo intake and speed density. Can ignition in the 0411 be completely turned off?

3. I have an obd2 plug and 2 pairs of red/blue connectors, one pair is to build a bench tuning harness. The obd2 port has wires in pins 2, 4, 5, and 16. Can someone post the pin connections needed to build a bench harness?


Thanks a bunch in advance! Scott

[5FDP]

1. Either would run it for speed density. The MPVI2 Pro makes it easier for adding in extra stuff like a wideband sensor, which you will require. There are other ways to log the wideband sensor but the PRO makes it easier.

2. I would take modern EFI spark tables over a vacuum distributor anyday for modern engines like this. We have complete control over everything. Think of all the stuff you lose out on. You'll have zero control over spark if your coolant temps are too cold, too hot. If your intake air temps go through the roof. You also won't be able to pull power away if there is spark knock. And no, you can't just turn the ignition system off in the computer.

[Scott-m]

Ok thanks. Here's how bad the port match is, before and after. Does anyone have the bench harness pin out?

[blindsquirrel]

That is... nothing. At least not on anything that isn't being used in high-buck competitive class racing. Street driven engines spend 95% or more of their lives below 2500 RPM.

Hell, I've seen rectangle port BBC heads used with oval port manifolds, and oval port heads used with rectangle port manifolds. Outside of a flowbench you'd never know. Carry on if you're just OCD and it bugs you but don't be disappointed when you can't feel the extra three HP in the seat of the pants.

[Scott-m]

Actually I have flow benched it. The work I did on the stock manifold added over 10 cfm at .500 lift. And I am ocd..

[Oleblu]

Been running the edelbrock 29135 super Victor on my L31 daily street truck for years. Very happy with the results from 2500-6500rpm. Never really spin my factory bottom end higher than that. See sig for setup details.

I Completely agree with 5FDP manipulation of ignition advance tables is less time consuming than changing out HEI springs and weights. With many more advantages. Even in a race only application.

Buy an mpvi2 pro, or find someone selling an older mpvi pro unit. Start your OCD tuning experience. Im interested in the outcome of this.

[Scott-m]

And the Victor Jr efi mani I mentioned earlier flowed over 40 cfm better than the modified stock one. Every cfm is roughly 2 ft-lb at peak torque, so it will make a difference that can be felt. That's why I want to figure out speed density tuning, so I can run that victor jr.

[Scott-m]

Thanks oleblu, I am here to pick brains, at least those of people wanting to be helpful! Are you running maf or speed density? I have sent lex a couple pm's on gmt400 over the last month and have not heard back. I need the 0411 to 97 k3500 pinout sheet and a pinout to make a bench load/tune harness. I will pay handsomely..

PS: Those 906 vortec heads work great. Is it still pulling at 6500?

[Oleblu]

It's been speed density for years. With a dedicated wideband. this cam and spring setup peak torque is at 4K give or take. and it stops making power around 5900. Cam installed 2 degrees retarded. With a cloyes adjustable single roller set. I shift from 1st around 6300 if I feel like stretching it out Obviously losing major tq by that point.

[blindsquirrel]

Tuning in SD is no different than anything else, you collect error data and then apply it to the table. Nothing that you wouldn't need to do no matter what kind of intake manifold.

[Scott-m]

It's been speed density for years. With a dedicated wideband. this cam and spring setup peak torque is at 4K give or take. and it stops making power around 5900. Cam installed 2 degrees retarded. With a cloyes adjustable single roller set. I shift from 1st around 6300 if I feel like stretching it out Obviously losing major tq by that point.

Great info! I need to keep the stock manifold to pass phx emissions, because they check under the hood for obviously-not-stock hardware, no matter how clean the exhaust reads. But the stock maf will be a restriction even with the stock intake, so I will be quite happy to eliminate it from the start. Does your 0411 read the wideband in closed loop?

[Fast4.7]

Put a carb bonnet on the TB and hook it up to a 4" MAF. I run almost entirely on MAF especially on big cammed stuff. I hate speed density with a passion especially with big cams that have unstable idle vacuum. The MAF signal is much more stable than MAP on a bigger than stock cam.

[Scott-m]

I did a lot of work in the intake to try to improve the horrible dog-leg flow path. I broke through in a couple places, so I buried the outside in weld. Besides the poor flow path, the intake is designed with no regard to air temp control. The second pic shows the runner that feeds cyls 2 and 4. Notice how it shares the wall with the damn coolant passage! That makes me sick. I'm going to try to reduce heat infiltration into the manifold, starting with an oil deflector for the underside with thin stainless sheet metal. I bought a thermally insulating 2 part epoxy coating to paint the manifold with inside and out to hopefully add insulation. I am going to build it up with several layers in the area of the coolant passage. Of course I want to document any changes, good or bad. I found this 12vdc thermocouple monitor on Omega, part number DP7005, and I happen to have a bunch of new and used thermocouples. I'm going to drill a 1/16" hole in the number 2 runner of the old engine for the tc, and find out exactly how hot the air is. Will there be any improvement with the coated new manifold? I hope to see a 40 deg reduction in air temp just above the injector.

[MelaniePayne]

Looking back on your post from 2 years ago, you were really diving deep into the tuning world with your L29 project. Your dedication to the details is impressive, from porting the heads to selecting the right injectors. It sounds like you had a solid plan for keeping it emissions legal while also prepping for some serious performance upgrades.
The ECM decision is a crucial one and it seems you had quite the puzzle with the 0411 swap. If the thought of choosing between the mvpi2 versions or the ignition setup had you at a crossroads, a flip coin might've been just the thing to cut through the indecision.

[blindsquirrel]

Looking back on your post from 2 years ago, you were really diving deep into the tuning world with your L29 project. Your dedication to the details is impressive, from porting the heads to selecting the right injectors. It sounds like you had a solid plan for keeping it emissions legal while also prepping for some serious performance upgrades.

Thank you for this extremely informative AI-generated pseudotext. The formatting of your username is also a dead giveaway - FirstnameLastname, each capitalized, no space in between. This is spam-in-waiting, it will be edited 3 days from now to add a link to some lame stupid mobile clicker game.

[Scott-m]

Ha wow a nice bump, ai spam or not! It took exactly 1 year to swap in the new engine, and it drove for the first time just last weekend! The heads finished up with 102cc chamber volume after unshrouding, matching, polishing and flat milling .020" for an actual comp ratio of 9.08:1. I put in 5-O racing 29 lb Bosch injectors, went with a comp cams 212/218 110lsa cam, full adjustable comp valvetrain, and built tig-welded stainless headers and exhaust back to a magnaflow muffler. Did the 0411 conversion successfully and had Black Bear do a best-guess tune on the 0411, and they nailed it. So far no code for crank position relearn or cam retard. The headers make it sound like a hot rod that has some compression and normal cam (it does, now..).

The credit card has recovered nicely, so I do still want to buy an Hp pro setup. Where do you recommend buying it? Direct? Ebay vendors?