H8 ECU Tuning (Timing Specific)

Posted by kiddsm95, May 7, 2010
Tuning & Engine Management - 4G63 EPROMS, ECU, MAF, knock, EGT, wideband, datalogging, fuel trims, etc. Read this Forum's Strict Guidelines.

  1. kiddsm95

    kiddsm95 Proven Member

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    I'm running an H8 flashable ECU and I noticed that my torque curve isn't climbing as fast as it did in the past. Is there a way to increase low range torque and make the turbo spool quicker by changing the timing values? Increase timing perhaps?
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  2. JayRolla

    JayRolla Proven Member

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    Increasing timing in the lower rpm range should give you some more tq down low and of coarse turning up some boost. Ive read a lot in the past that lowing timing raises heat and helps spool the turbo but when lowing timiing when boost hits at low rpms can make the car feel sluggish.
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  3. rstchris

    rstchris Proven Member

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    You can utilize fuel and timing to help spool. Just log wot and maybe 75% throttle where you want better response and pull a tad bit of fuel and add a bit of timing while watching for knock. Lowering timing for more boost is for launch control where you don't need to make power, only boost then when you come off the 2step all the timing comes back and you are at 100% power. If you are looking for low rpm power you will need to add timing. I added about 5* to the whole low load part of my low oct. map and the car feels way more peppy at light throttle off boost.
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  4. Ceddy

    Ceddy Proven Member

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    More advance will give you more HP/Torque.

    You can recreate "Lean Spool" like the Evos have, run 12.5 AFR during SpoolUp, then 11.0 AFR at WOT. (Or whatever AFRs your car can handle)
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  5. kiddsm95

    kiddsm95 Proven Member

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    You only added timing to the low octane map? :confused: I thought the intent of the low oct map was so the car can revert to it for safety reasons. Please do explain.

    So lean AFR's at spool up, and leave the timing as is?
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  6. JayRolla

    JayRolla Proven Member

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    If you research online about spool up there are so many mixed answers. You see the subaru guys say they like rich afr's at spool up and the evo guys say lean. Lots of people say using cam gears to tune the lift to allow more heat to escape to the turbo. Some say lower timing to cause more heat for spool and others say add lots of timing.

    I myself dont look at the spool that much but more of what makes more tq. I hit around 17* when boost starts to build and slowly rises to around 22* at redline. My car seems to love it. The minimal difference you will get from tuning is not going to be enough to really notice the turbo spooling faster.
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  7. Ceddy

    Ceddy Proven Member

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    There are many different theorys/practices for AFR tuning.

    For a Lean Spool type of map:

    Idle - 14.7
    Spool - 12.5
    WOT - 11.0

    This replicates the Lean Spool feature the Evos have had since the Evo5.
    I think the theory behind it is by running lean you have more power and faster spool, but since it is only for a short period of time it won't heat things up enough to cause knock, and the rich AFR at WOT will cool things back down.

    If you can add more timing with out knocking during spool up, it will help. But you want to aim for zero or very low knock. If you start knocking during spool up it will cascade into the rest of the pull, and you will start to bog out from pulled timing and it will ruin the whole pull.


    You should keep the Low Octane map stockish, as a safety feature in case you get bad gas, have a bad tune, or heat soak your intercooler or something.
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