Thoughts on VANOS and (Lean?) Spool Strategy

Discussion in 'Advanced Tuning | Coding' started by Jeffman, Aug 8, 2017.

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  1. Jeffman

    Jeffman Corporal

    205
    I think this topic is worthy of a new thread. I've copied the following discussion from a previous thread.

    My max spool rpm is currently set at 2750 rpm with my Vanos Spool Inlet / Exhaust table values overlapping (equaling) the moving warm VANOS Inlet / Exhaust table values at 2750 rpm. I currently have lean spool enabled for my stock turbo / OEM catted DP exhaust setup. Right now I have no cowl or engine cover on to help hear spool up and diagnose operation of my Forge Diverter Valves. [SIDEBAR: I had a lot of fluttering on the yellow springs when shifting 3rd-4th WOT. I added a shim to each one to tense the Yellow springs a bit more with no real improvement. I then went up to the blue springs (23-30 psi) and they seem to hold pressure better and release the pressure more crisply.]
    During lean spool up I hear lots of swooshing / filling the intake at a Lambda target of about 16.0...
    So I'm wondering:
    1. Maybe I'm better off reducing my max spool RPM and eliminating lean spool? The theory being that I'd need less air spooling richer and thus achieving faster spool up to hit the max part of the torque curve sooner (at a lower RPM) if I disable lean spool.
    2. But on the other hand, lean spool is intended to generate hotter exhaust gas which is intended to speed up the spool process.
    3. I think it was Brad or RSL on the other forum who recommended the VANOS / spool strategy I mentioned above to generate nice amounts of torque below spool max rpm. Is this strategy still considered to be sound?

    Any thoughts on whether or not to use lean spool for stock turbos / stock exhaust setups running 93 octane and 23 psi?
     
  2. Idahospool

    Idahospool Specialist

    16:1 seems really lean to me. Lean spool was intended for stock boost levels. I think at 23lbs ur pushing to far and probably pissing off those cats. The risk doesnt seem worth the reward. Have u tried running richer to see if it affects ur spool time. Ur cylinder temps would appreciate it
     
  3. Idahospool

    Idahospool Specialist

    On ur fluttering, are u gerting throttle closers ar that time?
     
  4. Jeffman

    Jeffman Corporal

    205
    Thanks, Idaho.
    I'll try turning off lean spool and see if there's a difference.

    Nope. No throttle closures at all.
     
  5. Idahospool

    Idahospool Specialist

    Any difference on spool time? U planning on getting catless downpipes? Hows timing look on 23psi on 93oct? Im tuning my wifes 335xi at the moment but im only targeting 150 load value with 91oct. Intake temps get too high. Downpipes, intercooler and fuel pump showed up this week so should be pushing a little more by this weekend
     
  6. Jeffman

    Jeffman Corporal

    205
    I just turned off lean spool but I'm also training my transmission on xHP Stage 3 right now. I'll be able to do some pulls in the next day or so and will let you know.
    Not planning to do downpipes anytime soon.
     
  7. all4bspinnin

    all4bspinnin Lurker

    15
    135i TT
    The stock VANOS spool mode values work fairly well for stock turbos. On a stock turbo car i run spool mode out to 3000. For vanos moving int/exh I use values similar to spool mode in that rpm range and then make sure i blend it in the transition range when it leaves spool mode for a smooth tune.

    For larger turbo cars i'll rescale the rpm axis to better suit the spool characteristics of the turbo and blend/scale the main vanos moving tables accordingly.
     
  8. all4bspinnin

    all4bspinnin Lurker

    15
    135i TT
    On a side note, I dont like running lean spool unless the car is on at least e40+. On pump i'll keep it lean (low 14 afrs) and then richen up as peak torque approaches. 99% of the time, i disable lean spool
     
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  9. Jeffman

    Jeffman Corporal

    205
    Thanks, All4.
    I simply disabled lean spool and I'm much happier with results. There's a whole lot less "air whooshing" sound which makes sense. My spool AFR target is now 14.3...with lean spool on it was 16.0 so the turbos needed to generate more air, apparently. The tune feels smoother in the trnasition. I'm also easily hitting my target 24-25 psi boost at max Torque but I think that's partly the higher permitted Torque values by the xHP Stage 3 TCU map (that's a separate topic - how to adjust the ECU and TCU maps together for best results). Here are three runs from yesterday (93 oct / 81F). First run is 3rd gear only. Interestingly, no timing pulls at all in first run, but the next two included shifting into 4th and see lots of ECU (not TCU) timing pulls, especially after the gear change - possible an IAT effect.
    http://datazap.me/u/jeffman/xhp-sta...2-no-lean-spool?log=0&data=2-6-14&zoom=32-108

    I'm currently have about 1 year / 6K miles on my NGK 95770 plugs gapped to 0.022. I am very hopefully these timing pulls will be eliminated after I ininstall the PR ignition system and new 95770 plugs gapped to 0.031 as suggested by Justin/V8 in a recent post.
     
  10. Jeffman

    Jeffman Corporal

    205
    The timing pull effect is pretty stark between the back-to-back run 1 (3rd gear only) and run 2 (3rd-4th). Here are two screen shots of only timing data and rpm of all six cylinders from the runs.

    Run 1 - 3rd gear only - no timing pulls
    IMG_2440.PNG

    Run 2 - 3rd-4th - lots of small timing pulls before and after shift
    IMG_2439.PNG

    Hopefully the Precision Raceworks ignition will help prevent all these timing pulls. If I had the time and were very methodical I'd do the PR coil swap with the existing plugs to prove this point. But I'm planning to install it with new 95770's gapped to 0.031 for hopefully even more powa!
     

    Attached Files:

  11. Idahospool

    Idahospool Specialist

    I would log your IAT. May be getting too hot for 93oct. Your running 93 only, no meth? I noticed your STFT's are getting high in some spots, no that its affecting your timing. I'm still learning too, so don't take my word as gospel. Are you using a 3.5 bar map sensor with sensor scaling?
     
  12. Jeffman

    Jeffman Corporal

    205
    I changed my logging parameters and will log IATs. My STFTs have been high ever since I started playing with E85 4-5 years ago and needed to increase my scalars to compensate. Yes, I'm running N20 3.5 bar TMAP with scaling. Happy to post my IJEOS bin here.
     
  13. Idahospool

    Idahospool Specialist

    Ya id like to take a look at your bin. Just recently started digging into sensor scaling. Post a log with IAT, would like to see what theyre getting to. What intercooler are u using? Are u still using factory knock settings?
     
  14. Jeffman

    Jeffman Corporal

    205
    IATs we're about 110-115F that day.
    HELIX intercooler. I'll post the bin later tonight when I'm on my tuning laptop. Haven't changed the factory knock settings.
     
  15. Idahospool

    Idahospool Specialist

    Thats not bad, maybe it is your coils. U in idaho hahaha? If so u can borrow my PR coils
     
  16. Idahospool

    Idahospool Specialist

    Judging by your atmospheric pressure ur not in idaho
     
  17. Jeffman

    Jeffman Corporal

    205
    This system won't allow me to upload my *.bin file to this post. PM me your email and I'll send you my IJEOS bin I used for the above logs. Requires MHD MBoost license option, obviously and TMAP. I flashed it only with the following MHD options:
    OEM catted downpipes
    Linear throttle
    3.5 bar TMAP
     
  18. RSL

    RSL Lurker

    14
    If doing a custom bin, why not just add the flash-time options directly to the bin? I'd be REALLY surprised if coils do anything to alleviate timing corrections, but in for results.
     
  19. Jeffman

    Jeffman Corporal

    205
    (Flash time redundancy.)
    You're probably right about coils not fixing timing corrections. Compression-based ignition versus spark-based ignition. Duh.
    Get me some ethanol to suppress the compression-based ignition!
     
  20. Idahospool

    Idahospool Specialist

    I was just thinkin the same thing.
     

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