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Thread: End of Injection Timing Open Discussion

  1. #16
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    Quote Originally Posted by Terminal_Crazy View Post
    So which end does does the #60 540 end up on the chart on the std timing diagram?

    Mitch
    $60 is at the end of power cycle on graph.

    If you count After TDC it will be at 180* ATDC
    If you count Before TDC it will be at 540* BTDC[720-180]

    SO the math will be after TDC counts from 0 to 720.
    Before TDC will be [720 - degrees after TDC]

    0* is at the start of power cycle and 720* is at the end of compression cycle. That should be norm for timing chart.



    What that bothers you may be that the EoiT target is inverted.

    From left to right
    0-720 degress = $80- $00 target value in table

  2. #17
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kur4o View Post
    That could explain the difference in b-body, the iron heads get hotter and evaporate the fuel much quicker.
    If I had to guess I'd say just the opposite - the b body cams have less / no overlap. Whatever the case, that's the reason I'd love to see a scope capture on an f-body or y-body because I'm fairly certain 96 decimal / 0x60 puts the end of injection at the bottom of the intake stroke.

    Quote Originally Posted by Terminal_Crazy View Post
    So which end does does the #60 540 end up on the chart on the std timing diagram?
    I'm not sure if this was aimed at me, but I believe this is what your EoIT_List.txt should look like. I think you're focusing on semantics more than you should - the EOIT value is identifying where the spray stops on any given cylinder, and each cylinder fires once every 720 crankshaft degrees.

    Edit: another way to look at it, 720 degrees from the perspective of eoit is the same as 0 degrees. It just depends on which way you want to visualize it - from a degree wheel perspective or the way the ecu keeps track of it.
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  3. #18
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by Terminal_Crazy View Post
    Neither the 180 or 270 is anywhere near the EVC point but are before the intake opens.
    I could be dead wrong, but... while there's no-one I would want to disagree with less than kur4o, I'd be willing to stake a wager that 0x60 is at the bottom of the intake stroke and the F and Y body calibrations are essentially spraying fuel right into the open cylinder at normal operating temps. I can see no reason why we'd want that fuel sitting in the intake port. The maximum value for the table of 6F (by my estimation at midpoint of the compression stroke) lends validity to this notion - there's no point in spraying fuel after the intake valve is closed.

    Read Rocko350's post here it seems pretty clear he's talking about starting to spray fuel after the exhaust valve closes.

    Another thing I caught from Rocko350 that's interesting is the idea of using a FLIR camera to compare header tube temps.

  4. #19
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    We have two hypotesis for $60.
    First is $60 is at 180* or end of power stoke.
    If we assume that aluminium heads run colder than iron that lines perfect. More time needed for the fuel to evaporate, since the intake valve is colder.
    Also the stock settings for cold startup, also lines up. The setting is $20 which is end of intake stroke. At subzero temps of the heads and fuel, the time the fuel will evaporate is unknown, so the spray is while the intake valve is open direct in the cylinder. At this point there will be alot of unburned fuel in the exhaust, and that could be the reason for low AFRs settings at cold startup.


    The max 6f could be for pcm to resyncronize the first pulse. The counter goes to zero and than starts at $80, It might need one pulse to syncronize again at $70.

    We are not sure where the zero point is at also. So all of the assumptions might be wrong.
    A new scope chart to confirm the settings will be great.


    I know for sure that the combustion mixture must be well mixed air with evaporated fuel. Liquid fuel don`t burn well[if at all] and can wash down the oil film on the cylinder wall.
    Higher fuel temperature and pressure with good spray pattern injectors can atomize fuel better, so it evaporates before hitting anything.

  5. #20
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    Eoi spreadsheet here if anyone is interested in calculating eoi verses valve events https://pcmhacking.net/forums/download/file.php?id=9851

  6. #21
    Fuel Injected! Terminal_Crazy's Avatar
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    I inverted my chart because 0x50 lined up at 270 degrees as per Kur4o’s scan.
    720 - ( 450) = 270
    My initial thoughts were the same as spfautsch.

    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  7. #22
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kur4o View Post
    The counter goes to zero and than starts at $80,
    This is about the only piece of info that compels me to think your initial hypothesis could be the correct one.

    Quote Originally Posted by kur4o View Post
    We are not sure where the zero point is at also. So all of the assumptions might be wrong.
    A new scope chart to confirm the settings will be great.
    I've PM'd vilefly to join the discussion in case he might be able to do another capture. If not I can utilize one of the open inputs on the diy-ltcc to get a picture of what's happening while adjusting the slider. But I'm out of commission and will be for at least a month, possibly two or three. I also lack the connectors as well as time to build a bench test rig.

  8. #23
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    Hi Folks

    As per my previous post here is the generic data I have on Injector timing.

    1: From the Lucas site, there is the start point for testing, used on Formula 5000's etc

    2: There is a Generic PDF on the subject

    3: The Chart I developed when tuning the Triumph TR6 with a very radical cam(For a 2700cc engine that is)

    I chose to display it over the top of a chart I borrowed from the internet. You can see the STD triumph Cam there and the revised method Triumph used to set it up on later cars and what I ended up with for the rad cam.

    The triumph is limited by the Teeth driving the metering unit where it has about half what the Cosworths have. So not as flexible as an electronic sequential where we can(IDEALLY) get it perfectly matched to the cam.

    Also shown are the Cosworth DFV F1 timing and Cosworth BDG timing.

    What I think would be ideal is to have a similar chart as a page in EEHACK where you enter the cam timing at zero and .050 lift and it draws to scale(horizontal) the events so people can see what the differences are, perhaps
    even showing two camshafts at once Dotted and Full lines for comparison(Just a thought)

    A line would represent the current EOIT point that matches the slider position and the BOIT point would be shown calculated from the Pulse Width, MAYBE?

    Cheers
    Kevin
    Wellington
    new Zealand
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  9. #24
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kevinodb1 View Post
    What I think would be ideal is to have a similar chart as a page in EEHACK where you enter the cam timing at zero and .050 lift and it draws to scale(horizontal) the events so people can see what the differences are, perhaps
    even showing two camshafts at once Dotted and Full lines for comparison(Just a thought)
    No offense, but there are all sorts of cam timing calculators on the internet so I'd hate to see someone spend the time to adding such functionality to eehack. Reinventing the wheel, so to speak.

    On the subject of EOIT - though I still intend to employ the scientific method and measure it objectively, after a lot of reading and searching I'm beginning to think kur4o's initial hypothesis that $60 is going to be spraying fuel on a closed intake valve is likely the correct one. Yesterday a copy of one of Banish's books arrived at my door and I absorbed it while taking breaks from working on my diy flywheel balancer. Though there were no groundbreaking pieces of news in it for me, he mentions the fuel film in the intake port extensively and how critical a role it plays in fueling calculations. He also made the statement that almost all OE sequential systems inject on the back of a closed intake valve. Many of the pros here should know or at least know of Greg - apparently he works as an OEM calibrator for one of the big three.

    At any rate, if this is the case with $EE Terminal_Crazy's test seemed to indicate better results through longer evaporation time (well before the exhaust valve closes). The cam overlap stuff everyone is mentioning is putting the injection event after the exhaust valve closes. So I think more investigation and experimentation on the subject is warranted. After spending a week worth of my life (20 minutes at a time) in my garage last winter with my eyes watering, I'd very much like to reduce exhaust smell at idle.

  10. #25
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    Hi Spfautsch

    I see your point, it is some extra coding....

    BUT anyone coming to use EEHACK for the first time will not be able to work out what its all about without something like that, it would make it better tool on the dyno.

    Also helping to clarify(FOR OTHERS) exactly the issues that are still being clarified in this post.

    In terms of timing of the Injection, one also needs to take into account the period the fuel takes from the injectors to go down the manifold, port and transit the valve area, on an LT1/4 its not that long, but on a Formula 5000 with the injectors way up in the intake trumpets its more significant.

    That time is dependent on port flow speed Feet/Sec and hence revs and throttle openings.

    The TR6 was initially injecting fuel into the cylinder when both valves were open on the overlap, it was pouring gas out the back and was virtually un-drivable. The revised position has made it suitable for even a daily driver, although a very sporty one!

    So depending on Injection start to when fuel first arrives into the cylinder and gets to the exhaust valve is, I believe, a key point to consider in the timing equation.

    Not withstanding the Lucas advice is that at fairly high revs the timing seems to not matter as much as long as its within a certain range.

    Cheers
    Kevin

  11. #26
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    Quote Originally Posted by spfautsch View Post
    On the subject of EOIT - though I still intend to employ the scientific method and measure it objectively, after a lot of reading and searching I'm beginning to think kur4o's initial hypothesis that $60 is going to be spraying fuel on a closed intake valve is likely the correct one. Yesterday a copy of one of Banish's books arrived at my door and I absorbed it while taking breaks from working on my diy flywheel balancer. Though there were no groundbreaking pieces of news in it for me, he mentions the fuel film in the intake port extensively and how critical a role it plays in fueling calculations. He also made the statement that almost all OE sequential systems inject on the back of a closed intake valve. Many of the pros here should know or at least know of Greg - apparently he works as an OEM calibrator for one of the big three.

    At any rate, if this is the case with $EE Terminal_Crazy's test seemed to indicate better results through longer evaporation time (well before the exhaust valve closes). The cam overlap stuff everyone is mentioning is putting the injection event after the exhaust valve closes. So I think more investigation and experimentation on the subject is warranted. After spending a week worth of my life (20 minutes at a time) in my garage last winter with my eyes watering, I'd very much like to reduce exhaust smell at idle.
    I'm still not convinced from which side we are counting from :-)
    Sometime before the Intake opens seems to the normally accepted position as far as I can tell.
    i think this thread
    https://forum.hptuners.com/showthrea...ight=injection
    has a comment on it by Greg Banish about the intake being closed.
    This has lots of info
    https://forum.hptuners.com/showthrea...ing-what/page1
    which is where I got the notion of the calculation being subtracted from the NEXT TDC (on compression).
    720 - (6x90=540) == 180 which is a little before the intake opens.

    I had presumed the place for it would be whilst the intake was open and piston descending pulling in the charge.

    I don't know why the "Split" would increase with that though unless it's a symptom of my issue.

    Just looked. I'm seeing the same Injector issue again. Hmm...

    Mitch
    Last edited by Terminal_Crazy; 12-30-2018 at 03:53 PM.
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  12. #27
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    Hi Mitch

    I see you are in Lancashire, anywhere near Burnley, thats where my dad came from!

    I think the implication of the delay for the fuel from the injector to getting into the cylinder, based on airflow and some inertia of the fuel from the injector, means that one can start injecting before the exhaust valve closes on the basis the fuel will arrive into the cylinder, just before it does...

    That will/should give better drive-ability because you are linking injector timing to the cam events, better economy as well, that also probably co-insides with good, if not max, intake airflow speed as well.

    Cheers

    Kevin

  13. #28
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    Does anyone know at what Degrees the intake valve opens on a stock 94 LT1. I can't find any type of cam card for a stock cam. The cam I have now opens at 15.5* BTDC. But the eoit tabe is still stock

  14. #29
    Fuel Injected! Terminal_Crazy's Avatar
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    Quote Originally Posted by kevinodb1 View Post
    Hi Mitch

    I see you are in Lancashire, anywhere near Burnley, thats where my dad came from!
    Hi, Yes, I live about 40 miles away but have worked in and around Burnley.

    Quote Originally Posted by kevinodb1 View Post
    I think the implication of the delay for the fuel from the injector to getting into the cylinder, based on airflow and some inertia of the fuel from the injector, means that one can start injecting before the exhaust valve closes on the basis the fuel will arrive into the cylinder, just before it does...

    That will/should give better drive-ability because you are linking injector timing to the cam events, better economy as well, that also probably co-insides with good, if not max, intake airflow speed as well.

    Cheers
    Kevin
    Re reading Greg Banish's book, Most factories spray onto the back of the intake valve before it opens to help "vapourise" the liquid fuel.
    The issue we have is with incdreased overlap, you can blow this out the exhaust rather than into the cyclinder.

    I'd like to see some more attempts from people testing and logging results frfom changing the EoIT.


    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  15. #30
    Fuel Injected! Terminal_Crazy's Avatar
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    Quote Originally Posted by Stroked 388 View Post
    Does anyone know at what Degrees the intake valve opens on a stock 94 LT1. I can't find any type of cam card for a stock cam. The cam I have now opens at 15.5* BTDC. But the eoit tabe is still stock
    I couldn't find anything definitive when i looked. Some figures contradicted themselves a little.
    This is what I found.



    Lloyd Elliott @ 0.006 @.050 Lobe Lift Lift 1.5 Lift 1.6 Lobe Sep Intake CL IVO btdc IVC abdc EVO bbdc EVC atdc Overlap Adv
    Hi lift emission ~275/281 223/231 .610 .594 112 109.5 28.5 66.5 77.5 28.5 56.5 3
    Comp Cam Card Spec 275/285 223/231 .381 .371 112 108 3 39 51 0 (0.050 figures)

    1 249-07-466-8 XFI 268 CAM LT1/LT4 93-96 268/276 218/224 .357/.354 .570 .565 113 109 25 63 75 21 46.0


    92 vette 205/207 .451 .450 117

    Stock LT1 1993-95 Vette & F bodies 202/207 .450 .460 .480 .491 116 22.5 (guess at 252/257 duration)
    1996/97 F Bodies 205/207 .447 .459 .477 .490 117
    LT4 203/210 .446 .449 .476 .479 115


    (It probably needs to viewed in a non proportional font like in wordpad)

    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

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