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Thread: Timing between Pilot and Main event

  1. #1
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    Pilot Timing Feedback

    So the Rom for the 325hp 04.5-07 has a minimum of 250uS between the pilot and main event. I created a timing calculator that dynamically generates the main timing event based off Fuel pressure/duration/%btdc, then calculates the suggested Pilot timing duration adds it on top of the main event, Adding the 250uS timing to the mix when it generates it.

    When i look at stock vs my outcome the WOT map looks mint, runs mint... BUT im wondering, has anyone given any thought as to not the minimum timing between events without overlap, but the optimal timing between events...

    Im looking for something in degrees or in uS from research before i start testing it on my own...

    Its simple to add it into the calculator as a factor of time or timing... so if i dont get feedback i can add in both of them and the Tuners can change it themselves... but if there is an optimal duration between events then that would obviously make it easier to program in now, then later....

    Once i get feedback ill move the sheet to hp tuners forum as it will help a lot..

    Reason behind the inquiry is im almost thinking i have to look at this as three separate entities... (Idles/start moving)(cruise)(WOT)...

    Any feedback from others would speed up the calculator..




    Update but left the initial question - Pilot timing is not based off TDC which was my initial thought, it is based of the SOI or Start of Injection of the Main Pulse. Logging is also based off SOI of the main event and not the TDC of the motor. My mistake, good feedback "eventually" Will be removing the pilot timing out of the calculator because now it really isnt needed. New feedback would be your thoughts around Pilot timing in general.
    Last edited by Bamofo; 02-10-2016 at 07:39 PM. Reason: Corrected but left the initial Thought

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    Quote Originally Posted by Bamofo View Post
    When i look at stock vs my outcome the WOT map looks mint, runs mint... BUT im wondering, has anyone given any thought as to not the minimum timing between events without overlap, but the optimal timing between events...

    Im looking for something in degrees or in uS from research before i start testing it on my own...
    Wouldn't that just depend on valve events/camshaft duration? Pilot Injection generally takes place as the piston begins its travel up the cylinder bore shortly after BDC to let the fuel and air begin to mix to help with ignition delay. Not sure if it is a "tolerance" of what a factory injector was intended? Or if they used a formula of Time of Ignition delay against cylinder pressure? Im not an engineer but, may have to be trial and error.
    1961 C-10 5.3 NV3500

    2007 NNBS ECSB 4.8

  3. #3
    From what I have noticed is the truck likes more pilot timing in the low to no load regions like idle and coasting, then get it tighter to the main as load increases like light to mid acceleration. WOT pilot is pretty much shut off so I don't know what would be optimal in that scenario. This is on an early 04, so a later truck without the re-entrant style pistons may like something completely different.

    Quote Originally Posted by mcfarlnd View Post
    Wouldn't that just depend on valve events/camshaft duration? Pilot Injection generally takes place as the piston begins its travel up the cylinder bore shortly after BDC to let the fuel and air begin to mix to help with ignition delay. Not sure if it is a "tolerance" of what a factory injector was intended? Or if they used a formula of Time of Ignition delay against cylinder pressure? Im not an engineer but, may have to be trial and error.
    Pilot Injection happens a lot closer to TDC than BDC

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    Any chance you could share your calculator??

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    Tuner 2007 5.9's Avatar
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    I think I speak for most of the tuners out there...we dont mess with Pilot to Main and Main to Post min timing.
    Les Szmidt
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    TDC? Wouldn't that defeat the purpose of pilot (pre) injection? I am now confused.
    1961 C-10 5.3 NV3500

    2007 NNBS ECSB 4.8

  7. #7
    Quote Originally Posted by mcfarlnd View Post
    TDC? Wouldn't that defeat the purpose of pilot (pre) injection? I am now confused.
    The pilot needs to be injected into the cylinder when there is enough heat to ignite it, too early and the fuel will pool and ignite all at once when the compression does create enough heat. This causes a cylinder pressure spike early in the compression stroke that we all hear as rattle. If you inject the pilot too late, there is not adequate time between shots to burn the entire pilot and it basically just becomes part of the main injection event.

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    Quote Originally Posted by 2007 5.9 View Post
    I think I speak for most of the tuners out there...we dont mess with Pilot to Main and Main to Post min timing.

    Im not interested in that either. Im interested in making sure at a minimum i never hit that wall or overlap the pilot injection into the main event.

    What im looking for is if anyone has insight into how much of a (time period or degree) is needed as a minimum, ideal, or optimal setting for these Dodges, specifically the model/year range stated in the original.



    We cant have a great tool to map out main injection and then stab in the dark by adding timing or duration to the pre injection to make it it work half decent..

    Any feedback i can add to my tool?

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    Quote Originally Posted by Kill View Post
    The pilot needs to be injected into the cylinder when there is enough heat to ignite it, too early and the fuel will pool and ignite all at once when the compression does create enough heat. This causes a cylinder pressure spike early in the compression stroke that we all hear as rattle. If you inject the pilot too late, there is not adequate time between shots to burn the entire pilot and it basically just becomes part of the main injection event.
    100% agree. Now i just need to figure out what that is, either by testing or someone filling me in.

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    Quote Originally Posted by muz79 View Post
    Any chance you could share your calculator??
    just working with the hp tuner guys before i publish it. I dont want to violate any policy they may have....

    But yes i expect it up over the next day.

    Using the pilot table maybe as a reference of minimum timing the pilot event needs to be in order to prevent overlap until i figure out what the real answer is...

    Hopefully someone in the community will share so we can automate a lot of the guessing.

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    Quote Originally Posted by Bamofo View Post
    Im not interested in that either. Im interested in making sure at a minimum i never hit that wall or overlap the pilot injection into the main event.

    What im looking for is if anyone has insight into how much of a (time period or degree) is needed as a minimum, ideal, or optimal setting for these Dodges, specifically the model/year range stated in the original.



    We cant have a great tool to map out main injection and then stab in the dark by adding timing or duration to the pre injection to make it it work half decent..

    Any feedback i can add to my tool?
    So you are looking for a value to not go below with pilot timing?
    Les Szmidt
    Silver Bullet Tuning
    HP Tuners BETA Tester for 2003-2005 Cummins
    [email protected]

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    Here's two articles that I've been referencing if it helps:
    http://www.tytlabs.com/english/revie...3_009hotta.pdf

    And:
    http://www.ecm2015.hu/papers/P2-21.pdf

    In the second paper, read about the micro seconds and how it relates to crank angle at 1500rpm. It gives you SOME idea of the relationship between time and crank angle degrees. I was referencing both articles to learn more about close pilot to main shot.

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    Quote Originally Posted by muz79 View Post
    Here's two articles that I've been referencing if it helps:
    http://www.tytlabs.com/english/revie...3_009hotta.pdf

    And:
    http://www.ecm2015.hu/papers/P2-21.pdf

    In the second paper, read about the micro seconds and how it relates to crank angle at 1500rpm. It gives you SOME idea of the relationship between time and crank angle degrees. I was referencing both articles to learn more about close pilot to main shot.
    Yup all my tables reference the RPM scaling that is in the target Timing map (pilot/Main) Event and calculate the timing dynamically. meaning im not hiding some math off to the side that references a bogus Timing map like i saw some of the other calculators doing.

    The equation is always the same for RPM vs Degree's per second. You just have to change it in your math to encorporate what the tuning software is using, in HP Tuners i see uS used so i did all the conversion for Degrees/uS...

    I will read them anyways it will definitely help either way. Keep them coming!

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    Quote Originally Posted by 2007 5.9 View Post
    So you are looking for a value to not go below with pilot timing?
    well thats what it does now...

    What im looking for now is since it shows you the minimum pilot timing you can run based off your pilot duration/pilot mm3 mess. The calculator creates off to the side an RPM vs mm3 so it can be referenced back into Degrees BTDC.

    What i would really like is to know is if there is an ideal duration between the pilot to main that people use or target, if its that minimum timing + 10 degrees (tested it yesterday and it worked oookk...) but that again is stabbing in the dark.

    Do you have any feedback of what you would do if you knew the minimum pilot timing you had to run to not overlap?

    Thats where im going with it....

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    Ok I'm going to try to understand...the min pilot to main value is what the ecm goes off of.

    You can't have overlap because of this value...

    250uS from the time EOI pilot main can begin...but since most tunes have pilot timing far out in from of main until you dump pilot....there is almost no physical way to have anything close to hitting the min limiter UNLESS your actually trying to run say 1* of pilot and have main set at 0*

    If what I'm saying isint making sense, then I'll sit back until I can understand what you're asking better
    Les Szmidt
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    HP Tuners BETA Tester for 2003-2005 Cummins
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    What I've read, 250 micro seconds between events is pretty darn close!! In the article above, it states that 400 micro seconds is 3.6 degrees crank angle BTDC @ 1500rpm
    Last edited by muz79; 02-10-2016 at 02:30 PM.

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    Quote Originally Posted by 2007 5.9 View Post
    Ok I'm going to try to understand...the min pilot to main value is what the ecm goes off of.

    You can't have overlap because of this value...

    250uS from the time EOI pilot main can begin...but since most tunes have pilot timing far out in from of main until you dump pilot....there is almost no physical way to have anything close to hitting the min limiter UNLESS your actually trying to run say 1* of pilot and have main set at 0*

    If what I'm saying isint making sense, then I'll sit back until I can understand what you're asking better


    I think you're getting it. But i believe the answer we are going to get back from everyone is that we dont care enough about the pilot event, or turn it off, etc... or at least not as much as we do about the main event, which makes sense. Im just wondering if there is a trick i haven't thought of to have pre injection on to keep the motor quiet, but do it in a strategic way that also helps the main event be more effiecient, make more power, overall use less fuel when Pilot injection is on.. instead of just blowing the pre injection event whenever the stock table says/smoothed out/randomly changed... Its less about making power and more about keeping pre-injection on.. When we talk about 3000+ RPM the duration the pre injection even will run almost hits the main event btw... from what my calculator is showing..

    But i think the feedback will probably be turn it off up top.. which is fine.. im just wondering if we are saying that because we haven't tested it enough, or its too hard... or there is no equation behind % before main injection event starts...

    I just want to be as complete as possible with what im doing..

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    Quote Originally Posted by muz79 View Post
    What I've read, 250 micro seconds between events is pretty darn close!! In the article above, it states that 400 micro seconds is 3.6 degrees crank angle BTDC @ 1500rpm
    yes the equation for figuring out angle/uS in uS is as followed.


    ((Current RPM*6)/1000000)

    The point of this isnt to find the minimum timing between pilot and Main event.

    The purpose of this thread is two things

    1) Make sure your never hitting an overlap with your pilot
    2) Strategically spray the pilot event in a way that benefits the main event for what your doing at that time (Idle/Cruise/WOT)

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    Gotcha. My (limited) research had been looking into the relationship between pilot and main in an effort to maximize fuel economy. I looked at BSFC charts in that toyota article and have decided to run a CLOSE pilot at low load only, phasing pilot out gradually into the medium load areas so that it is gone at high load, disregarding noise, HC and NOx factors.

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    Quote Originally Posted by muz79 View Post
    Gotcha. My (limited) research had been looking into the relationship between pilot and main in an effort to maximize fuel economy. I looked at BSFC charts in that toyota article and have decided to run a CLOSE pilot at low load only, phasing pilot out gradually into the medium load areas so that it is gone at high load, disregarding noise, HC and NOx factors.
    when i use the 250uS the truck lobes bad... you need it close plus some timing... im just looking for something better then "close" :-)