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Thread: Tech talk: Why 2v heads need more advance than 4v heads.

  1. #76
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    Quote Originally Posted by 5mall5nail5 View Post
    No, I am lying about M50 idle figures.
    You tell me.In that thread there are many M50 maps published:
    http://forums.bimmerforums.com/forum....php?t=1655079
    For the lazy guys I will take the freedom to quote Gunny:
    Quote Originally Posted by gstuning View Post
    As discussed in another thread there seems to be some lacking information regarding the values related to M50 based engines.


    Please post your ignition table and the relevant information related to it.

    Engine : M50 Non vanos, ARP and MLS
    Turbo : Borg Warner S257 (57mm compressor, 63mm turbine)
    Exhaust : "3
    Load strategy : Speed density
    Fuel : 98ron / 91mon

    This table was thrown together being considered safe. It worked a treat was run to 1bar boost.



    just for kicks here is the cars VE table.

    And after that it ,of course,your table:
    Quote Originally Posted by 5mall5nail5 View Post
    I know

    I'd have to pull the latest map in the car but its not running much more timing. I literally took my conservative street tune to the dyno and did pulls. I think I added .5 degrees up top and the clutch let go. I was running around 300 kPA for 685 rwhp with a timing map not to dissimilar from the above.

    Edit: Actually, I pulled my timing map from before the dyno (like 2 weeks before I think) and ... its even more conservative lol:



    I think I had it up to about 10 advance under the 315 kPA column when the clutch let go.

    Imagine how much power is left on the table. I run about 22 psi on the street. The truth is its fast as is so I have a hard time tuning timing on the street. Make some edits if you want!
    I still dont see 9 degree at idle,but that is probably because I cant read maps.FYI my M20 runs best at 13 degree for what it is worth.

  2. #77
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    Quote Originally Posted by bawareca View Post
    You tell me.In that thread there are many M50 maps published:
    http://forums.bimmerforums.com/forum....php?t=1655079
    For the lazy guys I will take the freedom to quote Gunny:


    And after that it ,of course,your table:

    I still dont see 9 degree at idle,but that is probably because I cant read maps.FYI my M20 runs best at 13 degree for what it is worth.
    You're looking at an 8.5:1 CR M50 on my map. You failed to quote the one with 12 deg of idle advance (also 8.5:1).

    The map you quoted from Gunni is a stock motor with a 0.140" thick MLS which drops the engine to like 8.8:1 CR and KILLS the efficiency (kills squish and quench). It is noted that head spacer motors require more timing than low compression motors (with proper pistons vs thick gaskets).

    Do more researching!

    (If you notice in my table there you will see 8 degrees of timing at 300 kPA vs Otis' 19 - 20 degrees).

    I am not sure why you're fighting this - it's dictated by physics lol.

    A stock M20 requires much more advance than a stock M50. You can't use head spacer gasket timing maps. Thought that would be painfully obvious?
    Last edited by 5mall5nail5; 03-18-2012 at 02:32 AM.

  3. #78
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    Quote Originally Posted by 5mall5nail5 View Post
    Hardly.

    There's no use arguing with the clueless. Hopefully the rest of the forum will find this thread useful. The two of you are hopeless. Well, I should say the one is hopeless the other one is intentionally trolling.
    Thanks,I knew it's coming.After posted maps in which there is no 9 at idle you are going further with the insults,but looks like it is normal for you.I continue to enjoy your TECH TALK thread Even in your other map there is no 9* at idle,and I believe it was your primary map.And even if take your time to read your quoted post you will find that you wrote that your timing at full load is what it is because your clutch gave away,so you should open another thread about clutch limited engines
    If you are tired dont bother to make any more excuses and calls on the laws of physics,I am sure most guys reading that thread know what your next post will be.The only interesting for me is when I will be promoted from hopeless to troll

  4. #79
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    Quote Originally Posted by bawareca View Post
    Thanks,I knew it's coming.After posted maps in which there is no 9 at idle you are going further with the insults,but looks like it is normal for you.I continue to enjoy your TECH TALK thread Even in your other map there is no 9* at idle,and I believe it was your primary map.And even if take your time to read your quoted post you will find that you wrote that your timing at full load is what it is because your clutch gave away,so you should open another thread about clutch limited engines
    If you are tired dont bother to make any more excuses and calls on the laws of physics,I am sure most guys reading that thread know what your next post will be.The only interesting for me is when I will be promoted from hopeless to troll
    I'd post a map from a stock M50 but you still won't get it, whats the point?

    Gunni confirmed. Are you going to argue with him too?


    Oh... weird...



    Image Date: 2007-01-05 22:03:17 (no TZ)
    Orientation: Normal
    Color Space: sRGB
    GPS Coordinate: undefined, undefined
    Software: Adobe Photoshop CS2 Windows


    Date created, so you don't try and say I just made it

    From my 200k mile M50 Non-Vanos MegaSquirt setup w/ stock compression. That's odd... looks like 9 degrees of advance...
    Last edited by 5mall5nail5; 03-18-2012 at 02:54 AM.

  5. #80
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    Quote Originally Posted by 5mall5nail5 View Post
    I'd post a map from a stock M50 but you still won't get it, whats the point?

    Gunni confirmed. Are you going to argue with him too?


    Oh... weird...



    Image Date: 2007-01-05 22:03:17 (no TZ)
    Orientation: Normal
    Color Space: sRGB
    GPS Coordinate: undefined, undefined
    Software: Adobe Photoshop CS2 Windows


    Date created, so you don't try and say I just made it

    From my 200k mile M50 Non-Vanos MegaSquirt setup w/ stock compression. That's odd... looks like 9 degrees of advance...
    Why should i argue with Gunni?I fully agree with his opinion written a few pages earlier.
    If i see a map with 13 degree difference between 2 adjacent fields i would think it should be a shitty tunning,hopeless tuner or all of the above.And that map is what it is not because of the M50 is so efficient,but because your 200 k+ engine is knock(or clutch ) limited.8 degree @10 psi is not a sign of efficient engine.But at least you are trying to be instrumental now.

  6. #81
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    Quote Originally Posted by bawareca View Post
    Why should i argue with Gunni?I fully agree with his opinion written a few pages earlier.
    If i see a map with 13 degree difference between 2 adjacent fields i would think it should be a shitty tunning,hopeless tuner or all of the above.And that map is what it is not because of the M50 is so efficient,but because your 200 k+ engine is knock(or clutch ) limited.8 degree @10 psi is not a sign of efficient engine.But at least you are trying to be instrumental now.
    Thats a basemap I create for people to get started. The out of boost portion runs the car proper.

    I feel bad that you're so lost

    Run my DTA map in your M20. There's no difference, right?

  7. #82
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    Quote Originally Posted by bawareca View Post
    Why should i argue with Gunni?I fully agree with his opinion written a few pages earlier.
    If i see a map with 13 degree difference between 2 adjacent fields i would think it should be a shitty tunning,hopeless tuner or all of the above.And that map is what it is not because of the M50 is so efficient,but because your 200 k+ engine is knock(or clutch ) limited.8 degree @10 psi is not a sign of efficient engine.But at least you are trying to be instrumental now.
    Ignition timing is not all about hitting MBT all the time, at low loads and engine speeds this can cause a very obnoxious KICK when the throttle is opened up and the torque is quadruppled from say 30kpa slow 1st gear@1750rpm driving to something like 70kpa. Alot of people get improved drivability with less ignition below 2000rpm.

    Those ignition values for idle are not the final output value anyway, the VEMS I use adjusts ignition constantly to maintain steady idle, I may want to have the base line a little higher to control the de-acceleration of the engine entering idle, then when its at just above the idle target the ecu pulls out a few degrees and it smoothly comes down to the idle speed . Itīs also about emissions as well. 10deg is a general all purpose all around ideal starting point for ignition at idle for a pent roof head. Throttle angle also have ALOT to do with what ignition angle you need for idle, for instance if your missing a ICV but require excellent cold starting behaviour and higher idle speeds like a choke would give, then when itīs warm the ignition is the only thing that can pull the engine speed down to normal idle.

    Also please note the rpm scale in Jonīs map, it goes from 1200 to 2000rpm,

    Ignition at idle it not really something to discuss in this thread as there are really the most variables in play to affect final timing.

    High load (being equal mass flow) is the only comparable situation between two engines, who would also have to have the same compression ratio and plug heat range for absolute ignition values to become comparable. Overall itīs not a excersise in exact scrutineering as what I wrote in my first post are the reasons.

    Burn efficiency between the two is negligable btw.

    Whoever has the higher turblence intensity after the ignition delay will have a higher flame propogation speed.
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  8. #83
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    Quote Originally Posted by DarkSideofWill View Post
    Define "the same work".
    Quote Originally Posted by SiGmA View Post
    Power output.
    Even though BMEP is the same if *TORQUE* output is the same between two different engines of the same output, turbo M20 and turbo M50 at the same torque output are going to be very different engines. The M20 will need more boost to get the same mass flow of mixture into the chambers. Because of the higher boost, it will have higher back pressure and be expending more energy to drive the turbo. The M20 will need a *higher* mass flow in order to achieve the same torque because it's putting more energy into the turbo.

    This difference becomes greater at higher RPM and power output as the M20 head becomes more of a restriction. Since the M20's running a higher mass flow at a higher boost and therefore higher temperature, *OF COURSE* it's going to accept less timing...


    That's why I asked... "The same work", using the physics definition of work, doesn't make any sense in his argument.

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    Don't you think that variable cam timing and thus variable dynamic compression ratios also play a major factor. The lsx tables I've studied get much less aggressive with a cam, because the dynamic compression ratio is raised.
    13.239 @ 105.67 with .000 R/T and 1.93 - 60' - 2007 350z - SOLD
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    Well, this thread has turned again!!

    I'm just going to stay out.
    This is my signature....

  11. #86
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    Quote Originally Posted by DarkSideofWill View Post
    Even though BMEP is the same if *TORQUE* output is the same between two different engines of the same output, turbo M20 and turbo M50 at the same torque output are going to be very different engines. The M20 will need more boost to get the same mass flow of mixture into the chambers. Because of the higher boost, it will have higher back pressure and be expending more energy to drive the turbo. The M20 will need a *higher* mass flow in order to achieve the same torque because it's putting more energy into the turbo.
    .
    Thats not exactly correct, you have no idea of the potential or actual backpressure as no mention has been made of turbo manifolds or turbines/turbos or exhaust system sizes. Your assuming.
    With great challenges comes great engineering.
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  12. #87
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    If that can't be assumed, then there is no valid comparison of any kind and this is all masturbation.

  13. #88
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    Quote Originally Posted by gstuning View Post

    High load (being equal mass flow) is the only comparable situation between two engines, who would also have to have the same compression ratio and plug heat range for absolute ignition values to become comparable. Overall itīs not a excersise in exact scrutineering as what I wrote in my first post are the reasons.
    [/B]
    The other thing everyone seems to be ignoring, that I alluded to in my first post, is that the burn rate changes SIGNIFICANTLY with AFR.

    What this means is that the timing map and fuel map are linked. A certain amount of timing advance is only optimal at a certain AFR.

    Even two identical motors with different fuel curves would have distinctly different spark maps (assuming each was optimized).

    There are lots of variables. Jon was just trying to present a general concept.
    That concept being that an engine with a centered plug will TYPICALLY require less spark advance, which is well proven and valid.

    In a general sense, this is worth keeping in mind for the average tuning noob when building their own map or comparing it to others.

    Amount of squish area, squish height, port design, AFR, rpm, type of fuel, etc etc also influence the required total advance. Nobody's arguing that I don't think.

    A faster burn is typically more efficient because it allows the pressure inside the combustion chamber to be focused to occur when the crank/rod angle are at the optimal position to convert that pressure into crankshaft rotation.

    This does ignore the thermal energy aspect but that's another issue.

  14. #89
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    Man, after reading this thread. I'm so lost on where to even begin to tune an MS.

    Or anything other than my current system.

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    Quote Originally Posted by BoostedE21 View Post
    Man, after reading this thread. I'm so lost on where to even begin to tune an MS.

    Or anything other than my current system.
    It's pretty easy to get roughed in - its just knowing that a 2v BMW head is going to take about 1.6 - 2.0x as much timing advance in general. This is all in general. I recently had someone IM me and say that they put an M20 timing map into an M50 application... so, this was to explain, basically, why that won't work.

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    Quote Originally Posted by 5mall5nail5 View Post
    It's pretty easy to get roughed in - its just knowing that a 2v BMW head is going to take about 1.6 - 2.0x as much timing advance in general. This is all in general. I recently had someone IM me and say that they put an M20 timing map into an M50 application... so, this was to explain, basically, why that won't work.
    Yeah, looking at those maps and tables, no idea what they are or mean. Other than the kpa values and such. My game boy EFI did not prepare me for when I change to MS.

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    Quote Originally Posted by BoostedE21 View Post
    Yeah, looking at those maps and tables, no idea what they are or mean. Other than the kpa values and such. My game boy EFI did not prepare me for when I change to MS.
    Your gameboy ECU is SO confusing. The traditional kPA vs RPM is much more conventional.

    Also, when "copying" maps - you MUST ensure that the original poster is running a true, correct crank sensor angle. For instance, if we looked at Jfdmas timing map for his M52 we'd be like wtf this looks like an m30 map. John admits to not really setting the crank angle proper and just "tuned the car for what it wanted" - so, we suspect his crank sensor was off.

    We now know an M50 non vanos is around an 84 - 86 crank angle and a VANOS (OBDI, OBDII) is 324 deg.

  18. #93
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    eh no need to make it confusing. Pretty much anything will run with an idle advance anywhere from 8-17 degrees, cruise to around 30, 100kpa to around 20, 200kpa around 15. From there you need to drive around with some det cans on.

    You should not be beating the car without some manner of knock detection, and preferably on a dyno, anyways.

    So an M50 doesn't have a normal 60-2 motronic trigger pattern?

  19. #94
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    Quote Originally Posted by Captain Bondo View Post
    eh no need to make it confusing. Pretty much anything will run with an idle advance anywhere from 8-17 degrees, cruise to around 30, 100kpa to around 20, 200kpa around 15. From there you need to drive around with some det cans on.

    You should not be beating the car without some manner of knock detection, and preferably on a dyno, anyways.

    So an M50 doesn't have a normal 60-2 motronic trigger pattern?
    All BMW motors other than the M10 have a 60-2 wheel. They moved the gap around.

  20. #95
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    Quote Originally Posted by 5mall5nail5 View Post
    Your gameboy ECU is SO confusing. The traditional kPA vs RPM is much more conventional.
    Really? I found it to be easy to tune. I put all of the values in Excel and saw my "map/tune". The maps posted above, I have no idea what they mean or how you tune it. I guess once I actually have it in my hands I can see and be better educated on it and won't be so intimidated.

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    Quote Originally Posted by BoostedE21 View Post
    Really? I found it to be easy to tune. I put all of the values in Excel and saw my "map/tune". The maps posted above, I have no idea what they mean or how you tune it. I guess once I actually have it in my hands I can see and be better educated on it and won't be so intimidated.
    Your map looks to be some sort of piggy back mode? Like I saw -5, -10, -15 degrees, and then like +5, +12...

    That is, if I am reading it right.

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    Quote Originally Posted by 5mall5nail5 View Post
    All BMW motors other than the M10 have a 60-2 wheel. They moved the gap around.
    Crazy, and good to know. I thought a 60 degree trigger angle was some sort of Bosch "standard" (All Volvo and VAG and SAAB motronic systems I am aware of with 60-2 have a 60 degree trigger angle- whioch makes sense and would be the normal sane thing to do). It would be very "BMW-esque" for them to decide they want to do it their own way, though. Typical.

  23. #98
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    Quote Originally Posted by Captain Bondo View Post
    Crazy, and good to know. I thought a 60 degree trigger angle was some sort of Bosch "standard" (All Volvo and VAG and SAAB motronic systems I am aware of with 60-2 have a 60 degree trigger angle- whioch makes sense and would be the normal sane thing to do). It would be very "BMW-esque" for them to decide they want to do it their own way, though. Typical.
    Well the OBD2 are Siemens units. But, still 60-2 wheels. It also depends on how the ECU counts. Some count from tooth 0 (first missing tooth). Some count from tooth #2 (first present tooth). But, they're different none the less. BMW also changed the cam triggers between various motors.

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    Dug up my old M10 spark map. Ran on 93 mixed with 100 octane.

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  25. #100
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    Quote Originally Posted by good & tight View Post
    Dug up my old M10 spark map. Ran on 93 mixed with 100 octane.

    Thanks Otis. Confirms the significant increase over 4v head timing (which I knew, but...).

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