http://www.edelbrock.com/automotive_...efi_main.shtml

Ever notice that they use a factory TBI computer for the MPFI conversion? I would think that it just overheats the injector drivers. Wonder if they are low impedence...

 

Yes.
No, they're high impedence.

 

MATH! put the injectors in series and measure. Do they react correctly? NO. Does any edelbrock kit work correctly ALL the time? (or ever?) NO!

 

It seems really wrong. I'm suprised that a company would do that. Figured if the TBI computer would support 8 injectors, then it would be common around here. Wonder if it just overheat/fry the ecm. I thought lingenfelter had success with the same setup though....

 

I've run my GTA with peak and hold injector drivers (on my company's ECU, not GM), and I was surprised to not see any problems. I measured the sense resistor too to make sure it was actually peaking and holding. I didn't run it for many days like that though, so not sure what the long term effects are, and I don't recall having it on the dyno then either.

It shouldn't burn up the drivers. They're used to peaking and holding. 4 Saturated injectors are about the same as 1 peak and hold.

I'm not sure how the injectors react. They should open just the same (as saturated) almost (maybe not get fully opened), but maybe the spring pressure could close them when about 1/4th the normal current is flowing through the coils. It might depend on the injector brand.

 

Check out my post in this thread https://www.thirdgen.org/techbb2/sho...ghlight=lm1949 . I illustrated the electronic theory behind the use of P/H drivers to drive saturated injectors. There is no magic or risk of failure if look at closely. However, firing a PFI setup with a TBI firing strategy is a whole other issue and the reason the Edelbrock setup sux. HTH

 

As far as firing strategy goes, might look at some of the later Truck Hacs, and there's a flag in some for *batch fire mode*. There's also been a posting about shorting a pin on the memcal for invoking Batch fire.

I haven't really looked at all of that, but if someone's interested there's data out there.

 

Soon I'm going to test one of the Edel MPFI manifolds as a wet flow.

 

What, does tbi fire both banks at once? me confused

 

In synchronous mode, TBI alternately fires one injector every DRP and PFI fires all injectors every crank revolution or every 4 DRP's for a V-8. In asynchronous mode, both TBI and PFI fire all injectors at a fixed rate or frequency if you will independant of DRP frequency (RPM). HTH