Going multi-port

Discussion in 'High Tech for Old Iron' started by uwasbuick, Feb 11, 2012.

  1. bammax

    bammax Well-Known Member

    Would it be possible to do what you guys want by hooking up the second set of injectors mechanically or electrically to only have them activate at a set throttle position?

    You could do it mechanically the way the nitrous guys use a switch on the throttle arm to activate the nozzles and injectors at 50% throttle.

    Maybe electrically you could build a 2 path circuit that runs to the injectors and when the flow demand of the first injector reaches a certain point it'll apply resistence to the circuit and the power will then switch to the second path which has lower resistence and powers the second injector. That's basically how the fuel guage and dummy lights work.

    In either situation the computer just powers the 1 injector and the power gets sent to the specific injector you want it to go to based on the wiring system you use. Kinda like how changing the plug wires on a 4-7 firing order swap changes the way the electricity is distributed without the distributor knowing anything is different.
     
  2. pmuller9

    pmuller9 Well-Known Member

    Bruce

    Sorry. Just noticed that no one has answered your question

    There are two separate issues, distributor phasing and electronic timing control.

    First: EDIS or Electronic Distributorless Ignition System and similar coil on plug systems.
    When the timing has to swing a large angle, example 10 degrees initial to 45 degrees with vacuum advance,
    the copper on the rotor will only be close to the contact on the cap for part of that angle.
    when at an extreme angle the spark will have to jump a greater distance than normal.
    The problem gets even worse when you use a large diameter distributor cap for better spark isolation.
    Also when you have high cylinder pressures the rotor needs to be phased so it points directly at the cap contact
    when the cylinder pressure is at its highest.
    Going distributorless solves this problem and also gets rid of a lot of plug wire length.

    In a distributor setup a single coil supplies all the spark and at high rpm the shorter time in between sparks
    may not allow the coils magnetic field to reach it max so spark output decreases.

    In a non distributor system, there are 4 or 8 separate coils that have plenty of time to charge and deliver maximum spark throughout the entire rpm range.

    As far as the electronic control part, you will find many threads and posts where there is a struggle to get
    mechanical advance to match the engine requirements and many others are settling for what they have
    because they don't want to mess with their distributor.

    With electronic control you simply change the points on a gragh or values in a table.

    Paul
     
    Last edited: Feb 22, 2012
  3. pmuller9

    pmuller9 Well-Known Member

    Good thinking.
    Switching to a second set of injectors is only half the problem.
    The other part of this is cutting the driver pulse to each set of injectors in half at the same time you cut in the second set of injectors so the amount of fuel being injected at the transition is the same.

    Example: Let's say when it is time to switch in the second set of injectors, the pulse width for the first injector is 5 msec. Now you cut in the second injector and cut the time in half, so you went from 1 injector squirting for 5 msec to 2 injectors squirting for 2.5 msec which is the same amount of fuel except in half the amount of time. Then the pulse width for both injectors can increase from that point as the need for more fuel increases.

    The proper timing for the crossover of the injectors and the injector pulse width can only be done safely with the software.
    It would be like having the nitrous solenoid come on before the gas solenoid if the transition wasn't controlled properly.

    Paul
     
  4. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    That's me right there. Very picky. I was never happy with the compromise between vacuum and mechanical advance on an overdrive'd engine. I got listings of GM vacuum cans that had listed rates for total vacuum added versus the amount of vacuum required to actually achieve total (like wanting 12* added, one can is at 8inHg another at 12inHg, etc), and in the end a lot of the part numbers were combined and the one I wanted wasn't available anymore. Then on the mechanical side, if I wanted 32* all in at 2500rpm, but I cruise at 2,000 rpm, and wanted 42* cruising, then I had to play a dance of various spring rates along with the vacuum can dance of the right vacuum levels when the engine is cruising, etc. Big headache. The EFI conversion let me crank at 5* (spins like the ignition is off), idle steady at a locked 23* and lean, then it retards the timing slightly just off idle as fuel is added (kinda like vacuum advance hooked to manifold vacuum), then I can run my 42* or adjust it easily while cruising and likewise on the WOT. On Drag Week after a pass I'd literally hot lap back to the staging lanes, and while waiting in line there (20 minutes?) I would review my datalog, adjust timing and/or fuel all while still sitting buckled up in the driver's seat. Can't beat that.
     
  5. supremeefi

    supremeefi supremeefi

    This is not a knock, just a fact. Most systems out there in this price range are pulse width, including yours and even the XFI. However a true VE based system takes that extra parameter and more accurately measures actual air intake under any condition and adjusts accordingly. Remember cold air is more dense, but hotter air moves faster enhancing pumping ability.
    And with the ability to curve your timing vs temp, when correct, you shouldn't have to recalibrate, for virtually any change in conditions.
     
  6. TheSilverBuick

    TheSilverBuick In the Middle of No Where


    I'm not changing for conditions, I'm making changes because it's never seen a dyno and I rarely ever get to the track, lets not confuse the two. That and when I left for Drag Week I only had 40 miles on the new roller cam/aluminum head/higher compression/new rear gear ratio combo, so I was figuring out what it wanted for fuel and timing when I got there on Test N Tune day, then I upgraded the injectors from 32lb/hr to ~44lb/hr (can't remember the rating at the moment) and did some guestimates at the change in required fuel and then required a bit more refining.
     
  7. sean Buick 76

    sean Buick 76 Buick Nut


    Keep in mind you can just use your megasquirt computer to control your timing. I am using a GM electronic Dist. controlled by the megasquirt 3 computer and still running a carb with the twin turbos. I can datalog everything from TPS, intake temps, exhaust temps, air fuel ratios on all 8 cylinders, etc still with a carb. Then I can tune the timing with the lap top, and use the info to tune the carb.

    I think you need a twin turbo setup on your car... Then you will no longer worry about anything other than getting away with driving WAY too fast LOL!!! Plus your MPG would be great when cruising!
     
  8. TheSilverBuick

    TheSilverBuick In the Middle of No Where


    Oh I definitely have the MSII controlling timing :TU: I only ran with the EFI with out timing controls for about a month before bumping up to a 7-pin HEI and then ultimately right off the pickup coil about two or three months later. I ran a Q-jet and standard HEI with the 5-spd in the car for about 12,000 miles. I swapped out three vacuum cans on it in that time and played with the advance springs as well.
     
  9. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    I just ran across this picture of when I was "Low-Tech for Old Iron" :pp Ran this way for around 12,000 miles, which was from March to September (got a nice drive from Ely to Fargo, ND and back that summer).
    [​IMG]
     
  10. sean Buick 76

    sean Buick 76 Buick Nut

    Cooler air requires more fuel per second than warmer air. Density of the air is dependent really only upon temperature unless using a power adder to add density (boost) to the air.

    If a system does not account for elevation then how can you take account of how at higher elevations the air lacks density due to the lack of atmospheric pressure. A vehicle typically runs faster at lower elevations unless using a power adder to get the density back up, even then great care must be taken to keep the intake air temps down.

    To me, if we are not accounting for things like the intake air temp, atmospheric pressure, and not measuring the exhaust temps. of each cylinder then why bother with a $3000 fuel injection system. If we want to tune each injector for each cylinder we need to have the ability to data log and make adjustments....

    Many aftermarket EFI systems claim to be "plug and play" although the real story is they are leaving a lot on the table in order to create a simplified product to sell for still top $. Sure they work well in most cases, but so does a carb. If I want an EFI system i want full command, not plug and play.

    On the other hand, I am a big fan of the simple EFI that allows users to tune and datalog properly... Systems like the Professional Products Powerjection 3 are great to swap on in place of a carb and be able to tune with a lap top AND not have to modify the intake, or add 25 wires like some MPFI kits. And one last thing, some of the simple EFI systems do not control timing, but that is not too bad, we can still just add a megasquirt computer to control the timing.
     
  11. BRUCE ROE

    BRUCE ROE Well-Known Member

    Thanks, I don't have to worry about phasing on a coil pack waste fire system.
    I would run the crank trigger system, and just keep an HEI cap around as a
    backup system. My current EDIS is on a carb engine.

    My question is, what would I be giving up, if the EFI system and the crank
    trigger system were completely independent? Bruce Roe
     
  12. pmuller9

    pmuller9 Well-Known Member

    Bruce

    Does the EDIS use a manifold vacuum reference to control timing the same as a vacuum advance on a distributor?

    Paul
     
  13. supremeefi

    supremeefi supremeefi

     
  14. Jim Blackwood

    Jim Blackwood Well-Known Member

    This software is buggy. The advanced reply window is all screwed up.

    Paul, the EDIS accepts a SAW (Spark Angle Word) signal to control timing advance. Without that is operates as a standalone ignitipn system locked at base time. Enough to drive on but that's about it. With an EFI system controlling the advance signal there isn't much limitation on what you can do in terms of inputs for rpm based and load based curves with temperature and baro compensations. It may respond fast enough to accept individual cylinder variations but I don't know if anyone has tested that or not.

    Jim
     
  15. pmuller9

    pmuller9 Well-Known Member

    Jim

    Thanks for that information and the answer to Bruce's question.

    Paul
     
  16. TheSilverBuick

    TheSilverBuick In the Middle of No Where


    The MSIII is in the mail =P I need to work on modifying an HEI distributor to be a cam sensor. Does anyone know if I grind all the teeth but one off each the pickup and the reluctor if that will be sufficient? It sounds good in my mind.... I have a spare HEI but I need to pin the advance weights mechanism. I just put new spark plug wires on the car last September so I want to stick with the HEI, otherwise I'd be grinding down all the lobes but one on the points distributor in the basement.
     
  17. pmuller9

    pmuller9 Well-Known Member

    Yea!! Congradulations on the MSIII.

    Grinding all the teeth off the reluctor but one will work.

    Since you are using the distributor to distribute spark there can be a conflict between when the MS3 needs the signal and the cap to rotor phasing.

    In our case with the Bigstuff3, the cam sync pulse was needed at 70 degrees BTDC but the rotor had to align with the distributor cap contact for cylinder #1 at 20 degrees BTDC.

    So we had to buy a replacement MSD Dist reluctor, grind off the original reluctor, grind off all teeth but one on the new reluctor,
    install a set screw in the new one, set it on the distributor shaft with the correct timing and finally spot weld it.

    I'm not sure what the timing for the cam sync pulse is for the MS3

    Paul
     
  18. Nothingface5384

    Nothingface5384 Detail To Oil - Car Care

    not to hijack the thread but does anyone need a nib fuelpressure regulator? i have two im needing to get rid of
     
  19. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Thanks for the heads up, I was thinking of looking up what the requirements were for the phasing/angle between the rotor point and the signal for #1, now I know I HAVE to. I have a little bit of play as my distributor's pickup coil "used" to be mounted on a vacuum advance so I can slide it with a range of ~20+ degrees. I know this was important in setting the trigger angle in the MegaSquirt when I was running off the stock pickup coil. Usually I'd set the engine to ~12* according to the timing tab, set the distributor to point just past the #1 tab, then rotate the pickup coil so the teeth all aligned, then set the MegaSquirt to 12* trigger angle, which the engine would always start (unless I was 180* out! =P) and then fine tune the trigger angle from there until it matched the timing light spot on.
     
  20. supremeefi

    supremeefi supremeefi

    Can you not change the injector timing/crank angle on the MSIII so you don't have to worry about phasing?
    You're using the distributor for a cam sync correct?
     

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