Ya know you wouldn't have to make a injector controller if you set the main linkage to be progressive for both shafts. Know what I mean? Make the cable attach to the throttle lever only slightly ahead of the shaft centerline, instead of centering the arc of travel over the centerline. That way you have a slower opening at the beginning for better part throttle control, and faster opening at the end ...... progressive.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
Not that kind of progressive, the kind where the larger throttle plates stay closed until the smaller throttle plates are opened a certain amount at which point the larger throttle shafts open quickly. It does require the injectors to be progressive for the larger throttle plates, other wise the fuel puddles above those throttle plates and can cause stumble issues. It's been tried. ;)Originally Posted by gregs78cam
The man who says something is impossible, is usually interrupted by the man doing it.
Yea, somehow I missed that they were different size bores. You are right if you wanted the "secondaries" to be progressive. I was just suggesting you make them progressive together.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
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...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
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 is the exact reason the linkage is 1:1 between each pair of throttle plates. ;)
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.
The man who says something is impossible, is usually interrupted by the man doing it.
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?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
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
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.
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