4.3 multi-port fuel injection

[Donald Whisnant]

Ryan Harrell wrote:

> Donald Whisnant wrote:
>
>> I've just recently finished installing a '94 4.3 CMFI V6 into my '85 Grand
>> Prix -- And (even though it was a headache and a half to put in -- mainly
>> because the engine came out of a van instead of a truck) I've been very
>> well pleased with its power and performance in sort of a "stock" condition.
>> I also put on one of those 4L60E trannies too -- and with the way it is
>> presently geared (2.41 -- as designed for a non-od tranny) it will do 80-85
>> taching only 2000!!!
>> 
>> As for mods, I too would be interested in info on superchargers -- though
>> my question would be: How much height if any will it add to the intake??  I'm
>> already about maxed out on the Grand Prix -- any more and I'll have to add
>> a hood scoop....  ... So Ryan, let me know what you find out...
>> 
>> As for true port injection, I just bought another intake for the engine (I
>> paid $150 for the complete intake upper/lower halves, and all of the sensors
>> incl. map, tps, tuning valve, etc. -- a heck of a good deal when compared
>> with what the dealer wants for one!!!) ...  I plan to do some experimenting
>> with true port injection -- I plan to buy six injectors and do some machining
>> on the intake and see what I can't accomplish ...  I would also like to
>> add distribitorless ignition to it too --- I've thaught about using the
>> sensors and general hardware from a 3800 for that, but don't know yet what
>> problems I will get into...
>> 
>> Also, as for the eprom code, I'm in the process of completely disassembling
>> the entire eprom from the computer that came with my engine ...  After
>> figuring out exactly what processor they used, I wrote a code-seeking
>> disassembler and am now wading through piles of source code trying to
>> decipher all of the code and lookup tables (300+ pages!). ...  If anyone out
>> there has any hints, ideas, suggestions, port number pinouts, etc, let me
>> know...
>> 
>> Donald Whisnant
>> dewhisna at ix.netcom.com
>
>I don't exactly get what you mean about CMFI injection, so if you could 
>please elaborate I'd be able to help more.  As for the supercharger, 
>Accesseble Technologies, Inc. (913-338-2886) stated that their superchager 
>could be adapted to almost any application with some tinkering.  However they 
>state that they do not sell a kit (they became quite interested when I told 
>them that Vortec had one in development -- Hmm you never know).  I don't know 
>your level of superchager type knowledge, but the type I am talking about 
>installing is a centrifugal superchager.  This is a device that looks and 
>mounts (adds no height to the engine) similar to an air-conditioning 
>compressor, whose job is to force as much air into the injectors as possible 
>using a spinning propellor.  The air is compressed and sent to the injectors 
>via a hose.  What makes ATI's Procharger so special is that they offer a 
>special billet aluminum propellor that allows more airflow than Paxon or 
>Vortec.  This allows them to get up to 25 lbs. of boost versus 9 lbs. of 
>boost from steel propellors (Paxon and Vortec). Plus the blower is only 
>$2000.
>
>Because all the info on the Sequential Central Port Injection came from 
>mainly this list, could someone please describe how the air intake into the 
>engine is accomplished (how the plumbing is set up).  I'll probably end up 
>going to a dealership and looking at one.
>
>As far as technical info on the eprom, I have a friend who is a mechanic at a 
>GM dealership.  He might be able to get such info.  Being a novice programmer 
>(I only know basic BASIC), I wouldn't mind being sent the code that you 
>dissasembled.  But I need to know what language you are programming it in as 
>well as what programs you are using.  I'll try to be as much help as I can, 
>but I won't make any promises.
>
>I'd also like to hear more of your ideas concerning creating a true 
>port-injection system.  Could you please tell me what kind of intake you are 
>using.  Also, could everyone please elaborate on what mods you have done to 
>your own 4.3 such as boring the block, heads, cam, crankshaft, etc.  Finally, 
>I'd also like to know what works and what doesn't.  It would be nice to learn 
>from other's mistakes so that they will not be repeated.
>
>Ryan Harrell
>cyborne at murlin.com
>
>"Eat my dust", said the modified 4.3 to the IROC Camaro.
>

Sorry for the long post (and reposting -- I didn't want to loose anyone in
the conversation) ...  But Ryan: CMFI stands for Central Multi-port Fuel
Injection -- i.e. GM's term for their fuel injection system that has a single
injector and 6 poppet valves for fuel delievery ...  The intake I'm using is
the Vortec intake (not to be confused with Vortec superchargers) that GM
uses standard with the CMFI (or CFI, etc) system in some S-10 pickups,
Astro/Safari vans, and some Blazers...  The intake is a tuned intake with a
tuning valve that the computer opens/closes for making either a split plenum
or single plenum...  The intake runners converge to a single opening at the
front where the throttle valve is located...  ...  This is also the intake
type I plan to do the experimenting with to see if I can replace the 6 poppet
valves with 6 individual injectors, build my own computer system, and make
it a sequential port system...  The required Fuel pressure, for reference, on 
the '93 version of the poppets is a massive 65 psi... by the '94 release, they
dropped it to about 45-50 psi...  Versus a typical 35psi for many sequential
systems...  (for whatever difference that really makes)

As for languages used, the entire code that I'm disassembling from GMs 
computer is, of course, in the assembly language of the processor ...  And
my disassembler program I wrote in Borland Pascal (I emphasize the Borland
part, because I do make use of its object oriented capabilites --- "OOP"s the
ONLY way to program!)...  As for the disassembled code, since it is taking
so much time and effort, I don't plan to "give" it away -- but I can't
really sell it either (you know, copyrights and legalities with GM) ... So,
I will probably offer it either in whole or in part in exchange for either
other info or pieces and parts to play with...  ...  For example, I have one
person interested in the code for the LT1 GM computers -- which is my next
reverse engineering task  (since I want to do some modifying and
reprogramming on my '95 Formula Firebird) -- In exchange for some info about
the code and/or a system or method to do custom reprogramming, he has offered
in advance to provide me with several LT1 computer systems to play with...

As for the disassembler, supported copies of the executable file will be
given for similar information exchange --- it is a code-seeking disassembler
(i.e. it actively sorts out code versus data) and is targetted toward the
AS68xx assemblers written by Alan Baldwin at Kent State Univerity (those
assemblers are available from ftp to kent state, Circuit Cellar BBS, the CUG
distribution CDs, Programming Tech-Tools CD, and many other sources -- a 
real nice assembler/linker system)... I'm presently not releasing source code
on the disassembler because of the Generic Disassembler I'm working on (that
uses similar technology) to disassemble all microprocessors (with simple
additive opcode programming) as well as do emulation, chip-id, and many other
neat things that reverse engineers have longed for... ... For those
interested, I do have (or did last time I checked) have my older 6809
disassembler with source code posted on the Circuit Cellar BBS -- it too does
code-seeking...

Now back to the supercharge topic ... As for the ATI supercharger that you
mention, which you say will do up to 25 psi boost, with that type of boost
level, what problems are encountered with spark knocking/pre-detonation??
Most of the ones only doing 9-12psi boost encounter such problems starting
around 7-8psi... Reports I've heard say that the boost gains gets
depleted by having to retard the ignition to prevent the knocking... ...
So I guess what I'm asking is: what do they do so special to obtain that
high of a boost?  Is it in their cooling techniques, or what?

Donald Whisnant
dewhisna at ix.netcom.com