Paul wrote,
>Is the Holley sequential??? I thought it was more of an electronic carb
>set-up. He wants to use the Holley ECU with port injection and a
>throttle body, in closed loop. I'm not too familiar with the ProJection
>system though. I realise you rolled your own Jarrid, but what would you
>recommend as a "proper sequencial or phase sequencial ECU" that is
>available off the shelf?
Well the Holley system uses a speed density TBI "Throttle body injection"
system, that is essentially an electric carb.
I know little of the details of what sits in your friends specific
controller,
but that particular controller is available in 1 and 2 injector apps.
The original 1.8 to 2.5 liter GM J type application used a single
injector, single throttle TBI, which incorperated the TPS, manifold pressure
and fuel pressure regulator in one unit.
Your friend has taken that injection controller and adapted it to
drive 4 injectors, which as I said before, I assume that they are all
wired in parallel. This actually is not too bad a thing to do, but thats
another discussion.
The holley system is available in 1, 2 and 4 injector models, supplying
bolt on TBIs for OEM TBI replacement, as well as bolt on TBI to
replace 2 and 4 bbl carbs.
The controller really could care less that it is driving port type
injectors, over the TBI type injectors, once the reasons for which
are again for another discusion time.
If he has a 2 injector driver, the driver alternates between the two
injectors, to allow the pressure regulator a more balanced
opperation, and thus better pressure control.
This can be used to contol two sets of two injectors, in what is called
phased sequencial, where like phased cyls are injected at the same
time, but alternate with the opposite phase.
On the alpine, 1 and 4 are like phases, and 2 and 3 are the other like
phases. Each injector driver will drive its two injectors, and all is well.
The problem now becomes, how do I tune this beast.
The stock mapping is for a very annemic engine, and for the most
part the only way to tune these things is to range the sizes of injectors
to your applications sort of like changing jets. When you get close
enough, then the thing can be tweaked in with a few pots on the
controller.
This works marginally in mild performance apps, and generally
doesnt work well with any level of performance mods, because
of the need for mapping that is not provided.
>As it is he has the "1&2bbl" (aka 1 or 2 injectors) ECU driving four
>injectors so it's delivering more fuel than the ECU thinks it is.
The above statement is not nessessarily true. TBI injectors are pretty
big, typically about 50 or 60 lbs per hour each. The port injectors are
between 15 and 50, but typically 100 to 120 BHP cars use 19 lb/hr
injectors. 19*4=76, which if its driving the alpine to higher RPMs,
may result in about the correct level of fuel usage.
If you have a few thousand dls laying around, a really good system
for aftermarket EFI is electromotive.
They have there own web page if you want to gawk.
I have experience in dealing with these systems, and are very
flexible and allow you to map the system via laptop.
Also, as a matter of potential interest, I have been contracted
to design a low cost fuel injection controller for a MFGR of
forklift engines.
The project is nearly complete, and my partner is considering
automotive applications as well, provided that the industrial
engine people dont object (which they should not).
Jarrid Gross
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 10:18:47 CDT