Hardware modifications GM style...

[1project2many]

You make the injectors progressive the same way they were on the LT5/ZR1 engine. When the TPS indicates the secondaries are about to open, bring a 2nd injector driver on line which fires the secondary injectors in parallel with the primaries.

[Six_Shooter]

That would be the first TBI Quadrajet! That is exactly how the Quadrajet carburator works.

You could open the throttle blades more on the big ones to prevent puddling? But how would you make injectors progressive? Holly did it! There old progressive four barrel had rear injectors turn on later... I found this out using a progresive Holly four barel on a GM system, when the secondaries opened the motor was flooded. Then I looked in at idle and they were filling up! We changed out the progresive linkage and it worked fine. The injector delay must be in the Holly ECM...

That is the exact reason the linkage is 1:1 between each pair of throttle plates. ;)

You make the injectors progressive the same way they were on the LT5/ZR1 engine. When the TPS indicates the secondaries are about to open, bring a 2nd injector driver on line which fires the secondary injectors in parallel with the primaries.

That's pretty much what I have in mind, though it would be an external controller, until I can learn how to write code for ECMs.

[1project2many]

The ZR5 box was external. It was triggered with a digital output from the ecm... it turned on above a specific TPS and turned off below a specific TPS.

[EagleMark]

The ZR5 box was external. It was triggered with a digital output from the ecm... it turned on above a specific TPS and turned off below a specific TPS.

Interesting! So it was just like a module wired into ecm?

[1project2many]

Found diagrams to double check. ECM engaged relays on power side of injectors to bring them online. Secondary injectors shared driver with primary injectors. 1228331 /1990 LT5 wiring diagrams thanks to "Tyler Townsley" of corvetteforum.com:
http://www.sirgalahad.org/tyler/misc/90ecm1.jpg
http://www.sirgalahad.org/tyler/misc/90ecm2.jpg
http://www.sirgalahad.org/tyler/misc/90ecm157.jpg
http://www.sirgalahad.org/tyler/misc/90ecm158.jpg
http://www.sirgalahad.org/tyler/misc/90ecm159.jpg
http://www.sirgalahad.org/tyler/misc/90ecm160.jpg
http://www.sirgalahad.org/tyler/misc/90ecm161.jpg

[dave w]

An electronics idea I have to get the secondary injectors to work progressively is a 555 timer IC ( http://www.ti.com/lit/ds/symlink/lm555.pdf ) to turn on the secondary injectors based on the pulse with of the primary injectors. Something similar to a watch dog timer?

dave w

[1project2many]

If you can distinguish between AE (fuel delivered due to air density change in plenum) and load based fuel (fuel delivered due to air mass delivered to cylinder) you might have a workable approach. I found a copy of LT1 / 8051 code hanging around thirdgen. If the fueling routines could be worked out (no apparent AE tables) and duplicated in the P4 then you might be able to use a very simple circuit to follow the primary injector.

[gregs78cam]

you could build or buy one of these, wired to the secondarys, and just use a relay to put power to it when the secondary blades open.

http://www.jbperf.com/p&h_board/

[EagleMark]

I found a copy of LT1 / 8051 code hanging around thirdgen.

I'd like a copy of that please!

[1project2many]

Haha! I think you posted in the thread it was in! I need to find the link as I forgot to save it on my pc last night.

[EagleMark]

I've got one a guy did but it is in several pieces and not completed. One of these days I'd like to learn this but the time it would take is probably not going to happen unless there's a dissesembler and commenter button?