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Thread: ATDC retarded timing

  1. #1
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    ATDC retarded timing

    All, (couldn't find anything on this)
    I was wondering... is there any reason to retain factory timing that was ATDC outside of the low-rev and low-rpm (LR&LR) areas?
    Could (should?) anything that was ATDC outside of LR&LR areas be considered automatic candidates to be at least be moved up to TDC? (ignoring Pre1/2 EOI).
    My initial thoughts are that there should be no downsides.

    Would appreciate your $0.02.
    Ian B
    '15 Holden VF SSVR L77
    '19 Ford Ranger PX3 3.2TD

  2. #2
    Advanced Tuner projectlnf's Avatar
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    Emissions is all I can think of. None of my timing maps on my 6.0 powerstroke are negatives anymore, but I have no emissions on mine so I have no cat or dpf to clog.





    Quote Originally Posted by VFL77 View Post
    All, (couldn't find anything on this)
    I was wondering... is there any reason to retain factory timing that was ATDC outside of the low-rev and low-rpm (LR&LR) areas?
    Could (should?) anything that was ATDC outside of LR&LR areas be considered automatic candidates to be at least be moved up to TDC? (ignoring Pre1/2 EOI).
    My initial thoughts are that there should be no downsides.

    Would appreciate your $0.02.
    2003 Ford excursion 6.0 psd
    No limit intake
    Straight pipe
    Blue spring update
    Studded
    EGR delete
    KC billet single plane compressor wheel
    Self Tuned

  3. #3
    Advanced Tuner JaegerWrenching's Avatar
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    Quote Originally Posted by VFL77 View Post
    All, (couldn't find anything on this)
    I was wondering... is there any reason to retain factory timing that was ATDC outside of the low-rev and low-rpm (LR&LR) areas?
    Could (should?) anything that was ATDC outside of LR&LR areas be considered automatic candidates to be at least be moved up to TDC? (ignoring Pre1/2 EOI).
    My initial thoughts are that there should be no downsides.

    Would appreciate your $0.02.
    As injectors get bigger and bigger in modern stock trucks, less timing is required. These newer 17+fords have a good size stock injector and can make upwards of 700+ with only 1650us. On older dodge trucks some guys were zingin it to 3000us and only making 450hp. Those are two vastly different timing amounts required. Granted some of that shorter pw if from produced from higher pressures, it actually plays into requiring even less timing from the better fuel atomization. So times are changing and with it the timing requirements and old school positive timing the world goes with it IMO. Now older worn out injectors and worn engines both tend to like more advance relative to newer, that stays true. Nonetheless I hate to give a number as many things determine where it should be set and the way you worded your question the specific area RPM wise and fuel amount wise is very vague, but a rough number is 2400RPM and 50mg/stroke should be getting into positive. Below that your turbo spool area will determine how the rest of your timing map is developed.

  4. #4
    Advanced Tuner projectlnf's Avatar
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    I know negative timing will spool the turbo faster. But as for power you would want more positive correct?





    Quote Originally Posted by JaegerWrenching View Post
    As injectors get bigger and bigger in modern stock trucks, less timing is required. These newer 17+fords have a good size stock injector and can make upwards of 700+ with only 1650us. On older dodge trucks some guys were zingin it to 3000us and only making 450hp. Those are two vastly different timing amounts required. Granted some of that shorter pw if from produced from higher pressures, it actually plays into requiring even less timing from the better fuel atomization. So times are changing and with it the timing requirements and old school positive timing the world goes with it IMO. Now older worn out injectors and worn engines both tend to like more advance relative to newer, that stays true. Nonetheless I hate to give a number as many things determine where it should be set and the way you worded your question the specific area RPM wise and fuel amount wise is very vague, but a rough number is 2400RPM and 50mg/stroke should be getting into positive. Below that your turbo spool area will determine how the rest of your timing map is developed.
    2003 Ford excursion 6.0 psd
    No limit intake
    Straight pipe
    Blue spring update
    Studded
    EGR delete
    KC billet single plane compressor wheel
    Self Tuned

  5. #5
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    Quote Originally Posted by projectlnf View Post
    ...But as for power you would want more positive correct?
    Well, that's the thing isn't it, do you? As JW said with modern hardware the accepted tuning approach might not be so relevant. Certainly the tuning methods that discuss a 50:50 BTDC:ATDC injection method seems to be missing the point that fuel injected BTDC has the potential to decrease power (depending on ignition point) and is generally pursued to try and squeeze the required fuel in before the piston has travelled too far down its stroke.

    I know the desired peak pressure point is about 12-14 ATDC, so for example if an injection period takes 7 deg CA, then to me SOI point should be around 2-4 deg ATDC even allowing a few degrees for ignition delay. So to me, the EOI point is the critical timing aspect, not SOI (which is what we see in tables). My (misplaced?) simplistic logic is that you want your injection period to always be in the 0-14 degree ATDC window if injection hardware allows. The next item (to me) becomes what is the maximum angle ATDC (and BTDC I guess) that injection should be allowed, to fit the required fuel in if we have maxed fuel pressure out, and if we haven't maxed fuel pressure out, what 'angle of injection^' should we aim for?.
    ^ - I know people like to talk in uS for injection period, but it seems more useful to me to talk in the angle through which injection occurs as this negates (mostly) the engines RPM, or am I missing something?

    Thanks both, for reminding that timing also affects turbo spool (and EGT) that also plays its part when producing power. This raises other tuning questions for me, but I'll try and keep this thread on-topic.
    Ian B
    '15 Holden VF SSVR L77
    '19 Ford Ranger PX3 3.2TD

  6. #6
    Advanced Tuner projectlnf's Avatar
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    I agree with everything.

    I learned a 50/50 burn is the ideal for power. But for me I hear hesitant when I get over 6-7 degrees (mainly in cruising areas)

    The calculator I have shows me in my tunes I?m actually running a 30/70 burn which EGT?s and power are perfect for me. Smoke output is pretty much non existent. But I have done testing I left everything in my tunes the same but went back to a stock timing map. Egts we?re significantly higher and power output was horrible. I feel a 50/50 burn would add to much timing under certain instances

    Typically I run 2 degrees in mid range and cruise I?m seeing 5ish.

    Wot I see 4-8 and I no issues. I logged an innovative tune and tried to map out what timing was during certain loads and conditions and pretty much ?copied? it in a sense. It taught me a lot.

    I have seen timing maps that run out to 12-14 in cruising areas which for me with my fueling would be 80/20 burn almost



    Quote Originally Posted by VFL77 View Post
    Well, that's the thing isn't it, do you? As JW said with modern hardware the accepted tuning approach might not be so relevant. Certainly the tuning methods that discuss a 50:50 BTDC:ATDC injection method seems to be missing the point that fuel injected BTDC has the potential to decrease power (depending on ignition point) and is generally pursued to try and squeeze the required fuel in before the piston has travelled too far down its stroke.

    I know the desired peak pressure point is about 12-14 ATDC, so for example if an injection period takes 7 deg CA, then to me SOI point should be around 2-4 deg ATDC even allowing a few degrees for ignition delay. So to me, the EOI point is the critical timing aspect, not SOI (which is what we see in tables). My (misplaced?) simplistic logic is that you want your injection period to always be in the 0-14 degree ATDC window if injection hardware allows. The next item (to me) becomes what is the maximum angle ATDC (and BTDC I guess) that injection should be allowed, to fit the required fuel in if we have maxed fuel pressure out, and if we haven't maxed fuel pressure out, what 'angle of injection^' should we aim for?.
    ^ - I know people like to talk in uS for injection period, but it seems more useful to me to talk in the angle through which injection occurs as this negates (mostly) the engines RPM, or am I missing something?

    Thanks both, for reminding that timing also affects turbo spool (and EGT) that also plays its part when producing power. This raises other tuning questions for me, but I'll try and keep this thread on-topic.
    2003 Ford excursion 6.0 psd
    No limit intake
    Straight pipe
    Blue spring update
    Studded
    EGR delete
    KC billet single plane compressor wheel
    Self Tuned

  7. #7
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    Quote Originally Posted by projectlnf View Post
    I agree with everything.
    Thanks. :-)
    Quote Originally Posted by projectlnf View Post
    The calculator I have shows me in my tunes ...
    I think this is an important step. You do need to create a calculator to better understand the injection periods if you want to include timing in your actions and not just throw in more Fuel and FuelPressure which is the anecdotal approach I've seen. I've created a calculator, but it does get fairly clunky with the SID209 given it operates across 4 (that I know of) fuel/timing/pressure/TTQ/InjConf table sets by default during Normal operational temp running (plus Regen maps). There is the option to lock certain InjConfigs in, but there is no option to lock in a 'MAP' (The SID209 has a lot of similarity with the recent 6.7TD EDC17 but has 5 MAPs instead of 4 and swings between MAPs 3&4 during normal operation, and appears to drop back to MAP2 for regen activity)
    Quote Originally Posted by projectlnf View Post
    I?m actually running a 30/70 burn ...
    I'm not locked onto the concept of a specific ratio because I think it fails to allow for load based ignition delay, but your info is really helpful.[/quote]
    Quote Originally Posted by projectlnf View Post
    I logged an innovative tune and tried to map out what timing was during certain loads and conditions and pretty much ?copied? it in a sense. It taught me a lot.
    I have a commercial tune to look at and I was disappointed to see that all they did was stick more fuel into the same injection periods and didn't adjust anything else. I guess it suited their purpose but I wouldn't use it or recommend it because I don't like the underlying tune it is based on.
    Quote Originally Posted by projectlnf View Post
    I have seen timing maps that run out to 12-14 in cruising areas which for me with my fuelling would be 80/20 burn almost
    Yeah, I think this is the more difficult area to be smart with. At lower load, ignition delay increases so timing needs to be advanced to compensate, but by how much?. At the moment I'm thinking cylinder airmass and Driver Demand might be useful guides here.

    Appreciate the feedback. Hopefully others will chime in with experience and random thoughts.
    Ian B
    '15 Holden VF SSVR L77
    '19 Ford Ranger PX3 3.2TD

  8. #8
    Advanced Tuner projectlnf's Avatar
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    I haven?t had a chance to look at a commercial tune but I have logged plenty.

    I am not really 100% on shooting for a specific burn rate but I have seen my truck just feel good at a 30/70ish burn. But the only way I can calculate is after the fact. My calculator goes by the log and not the tune. I was in the midst of making one but the PW tables in my ficm honestly do not match what I see in the log.


    Quote Originally Posted by VFL77 View Post
    Thanks. :-)
    I think this is an important step. You do need to create a calculator to better understand the injection periods if you want to include timing in your actions and not just throw in more Fuel and FuelPressure which is the anecdotal approach I've seen. I've created a calculator, but it does get fairly clunky with the SID209 given it operates across 4 (that I know of) fuel/timing/pressure/TTQ/InjConf table sets by default during Normal operational temp running (plus Regen maps). There is the option to lock certain InjConfigs in, but there is no option to lock in a 'MAP' (The SID209 has a lot of similarity with the recent 6.7TD EDC17 but has 5 MAPs instead of 4 and swings between MAPs 3&4 during normal operation, and appears to drop back to MAP2 for regen activity)
    I'm not locked onto the concept of a specific ratio because I think it fails to allow for load based ignition delay, but your info is really helpful.
    I have a commercial tune to look at and I was disappointed to see that all they did was stick more fuel into the same injection periods and didn't adjust anything else. I guess it suited their purpose but I wouldn't use it or recommend it because I don't like the underlying tune it is based on.
    Yeah, I think this is the more difficult area to be smart with. At lower load, ignition delay increases so timing needs to be advanced to compensate, but by how much?. At the moment I'm thinking cylinder airmass and Driver Demand might be useful guides here.

    Appreciate the feedback. Hopefully others will chime in with experience and random thoughts.[/QUOTE]
    2003 Ford excursion 6.0 psd
    No limit intake
    Straight pipe
    Blue spring update
    Studded
    EGR delete
    KC billet single plane compressor wheel
    Self Tuned

  9. #9
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    i bumped a few degrees into mine just to see what happens and seen some good results. better economy and felt alot stronger in the higher torque areas but mine is also tuned so fueling in the high torque areas has been increased. something i want to play with more but dont really have the time

  10. #10
    Advanced Tuner projectlnf's Avatar
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    Mine has been bumped in fueling also. Mine feels similar to the street tunes from most big name tuners. But trans I?m still working on. Shifts kinda softer than I like but I?m getting it closer as time goes on.

    But as for timing my timing maps are drastically different than stock timings. Amazing power down low and decent up top (more for safety)

    Mid range is where I?m lacking which is also a work in progress.



    Quote Originally Posted by h41ry View Post
    i bumped a few degrees into mine just to see what happens and seen some good results. better economy and felt alot stronger in the higher torque areas but mine is also tuned so fueling in the high torque areas has been increased. something i want to play with more but dont really have the time
    2003 Ford excursion 6.0 psd
    No limit intake
    Straight pipe
    Blue spring update
    Studded
    EGR delete
    KC billet single plane compressor wheel
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  11. #11
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    It is due to emissions and engine longevity. The more you advance timing at low engine speed Cylinder pressure and temps rise higher and NOX production is increased as well as of course stress on the internals due to the increased CP. EGTs will decrease which can actually decrease turbine speed. Of course with advanced timing the engine will be more responsive and torquey.
    Last edited by SuperchargedPSD; 2 Weeks Ago at 01:35 AM.

  12. #12
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    Anyone had any luck with building a calculator?

    I've tried adapting a couple, seem to run out of time with work though.

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    I have started one for the SID209 but no-one would understand it.
    It's complex because:
    • there are at least 3 active sets (trees?) of tables during normal up to temp operation (5 total)
    • HPT does not show which table set is active...
    • an active set of tables can have sub-tables
    • There are many inputs into the active table (fuel, timing, inject conf, Trq2Ffuel, Fuel Pressure and probably others I've forgotten)
    • Tables of a particular description do not always have matching axes
    • Some referenced values (injection pulsewidth) have to be interpolated for both pressure and duration
    • There can be multiple input tables for a given situation

    Consequently, you can't realistically create a calculator for all map sets easily (The GM Duramax calculators are super simple in comparison). Then you need to decide which map sets are relevant to you, and build a calculator for this.
    For me I focused on map sets 4&5, EngineMode=0, 70C+ ECT, and InjConfigs 2&5. I figured in all other circumstances the factory setting was adequate (and known to work).

    From all this I could now work out injection duration (ms) crank angle (CA degrees) and crank angle travel (CA duration). I know when injection starts, and finishes. But this has to be done for Pre2, Pre1 and Main injection (post injection is not relevant to the chosen map sets) and referenced to each other to show if there is overlap occurring at times (there is sometimes). (Oh, you have to create some foundation engine motion reference tables, too)

    So, once that's all done I ended up with a spreadsheet for table sets 4&5 (MAPs4&5) InjConf 2&5. The FuelQty+Timing sheets have ~24 tables (7 are input) to create a picture of what's happening for that EngMode+InjConfig+MAP. There are 4 of these that are actively used and switched between during normal hot engine operation [that I can tell]. You could make all these the same for simplicity (but that's not my style). I specifically wanted to capture EOI info (we already know SOI) and duration to know when injection needs to stop (to stop wasted fuel and just generating high temps). The upshot of all this, is that it looks (unsurprisingly) like the injectors are well matched to fuel pressure and the turbo is sized spot-on for these needs. It looks like [to me] there's about 12% overhead available for fuel and ~5% for air while trying to stay above an AFR of 20:1 (my minimum for the 3.2) technically.

    I DO KNOW if I gave the calculator to someone else, it would need an hour to walk through the tables, how some were created (because a different factory tune will require interpolation recreation), how they get used, and why I have some info that I have included (like piston position). I don't have the time to explain this (unless someone is paying) so my recommendation is have a go and try and do something that you will understand.

    To encourage you, here's a piccy of some output table info that interests me but might not be of interest to [most] others.
    2022.01.14 16.09 02.jpg

    hth,
    Ian B
    '15 Holden VF SSVR L77
    '19 Ford Ranger PX3 3.2TD

  14. #14
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    Thanks Ian,

    Very inspiring, if I find some time I'll see if I can build one for the PX1, lucky for me map mode 0 is the only mode ever active due to lack of dpf etc. My major issue is working out the excel spreadsheet formulas.