'97 Vortec to Holley EFI

[L31MaxExpress]

A little off topic, but are you using the wynjammer injectors? I've been using the 48lbs from them but haven't been able to find accurate specs to plug into the tune (flow rate, voltage offset, etc.). Makes tuning not quite as fun

Not sure who Wynjammer gets them from, mine are AUS Injection. Got them 2nd hand but new in the box from a guy that was going to build a L31 and decided to go with a supercharged LS. Mine seems to be running pretty well with only the flow rate changed to 48 lb/hr. I pulled 8° of timing out of my old tune and bumped the VE table and MAF table up 15% for a startup tune. Timing is low and it is rich at WOT and the long fuel trims are are pulling 10-20% across the board at the moment. When I get more time I will get some more miles on it and get it dialed in. I think they are merely stock injectors with enlarged internal porting and nozzle tips. I think the dead times and injector offsets and the like should be very factory MFI spider like. The standard spider and MFI spider have very different settings on the injector data yet GM sells them to retrofit. I used the settings out of an 05 Astro IIRC back when I had the GM upgrade MFI spider.

 

[L31MaxExpress]

@L31MaxExpress I didn't know of any examples of an 0411 swap with larger injectors in an MPFI spider. Good to know my theory is sound. Can you share your 383 specs? Specifically what cam and heads? How did you pass smog? In Texas they require an obd2 readout, but no sniffer. Can I tune the 0411 not to throw codes with a cam? I've been thinking a 212 to 218 intake duration at .050. Let me know if there's a better thread for all these questions. Nice build, and thanks for the pointers in my thread around installing stock front springs in the tahoe.

Cam is a custom grind 218/228 @ 0.050 on a 108 LSA and 106 ICL. 0.578 lift with 1.7 rockers. Rhoads V-Max lifters cold lashed at 0.014" off the bottom of their travel. Heads started out as Assault racing bare castings that were filled with good parts and ported by Lloyd Elliot. They flow nearly 300 cfm @ 0.600. Engine is 11:1 static compression and has 6" rods. Cranks at 225 psi.

Only changes between this video and it running currently are the modified L31 intake, AUS 48 lb/hr spider and bolted the vans factory dual 3" exhaust exhaust to the headers with the head pipes that Thorley provided with the headers. Has high flow cats and a dual 3" in/single 4" out muffler. It actuall idles even smoother now with the SFI and the weight of the factory bodied torque converter.

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[Awest623]

Not sure who Wynjammer gets them from, mine are AUS Injection. Got them 2nd hand but new in the box from a guy that was going to build a L31 and decided to go with a supercharged LS. Mine seems to be running pretty well with only the flow rate changed to 48 lb/hr. I pulled 8° of timing out of my old tune and bumped the VE table and MAF table up 15% for a startup tune. Timing is low and it is rich at WOT and the long fuel trims are are pulling 10-20% across the board at the moment. When I get more time I will get some more miles on it and get it dialed in. I think they are merely stock injectors with enlarged internal porting and nozzle tips. I think the dead times and injector offsets and the like should be very factory MFI spider like. The standard spider and MFI spider have very different settings on the injector data yet GM sells them to retrofit. I used the settings out of an 05 Astro IIRC back when I had the GM upgrade MFI spider.

Gotcha, I appreciate it

 

[Blubyu]

I am eyeballing a future project involving a 4bbl L31 intake and a Holley Terminator 4bbl kit with transmission control, and even adding in the Holley ignition parts if I don't feel like integrating the Vortec distributor. That should take care of the engine and the transmission control. What I don't know is what I'd lose if I pulled the existing ECM out of the truck in terms of body control etc. I assume not much, but hoping that the more familiar parties here could shed some light on what I'm overlooking before I start acquiring parts.

I'm in no hurry, the motor is relatively freshly rebuilt, sat at my parents place after we rebuilt and swapped in a 5.7 from a '97 burban and was only used for truck stuff for the last 6 or so years. I've recently re-acquired it and will be using it as my daily. I can hear it now, "It works, don't fix it!". I can't leave well enough alone. Plus, I have experience with Holley EFI and would like to fiddle with my own project for once. Maybe someone with a lot more sense will talk me out of it.

Makes two of us... I just ordered the HP EFI 4BBL MPFI SYSTEM for my 97 K1500. My engine is a 383 stroker, made 430 on the engine dyno, but from the very beginning, we have been fighting to keep it in fuel control since putting it in the truck. It never ran horrible but just never ran as good as it did on the dyno.