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Thread: setting B3618 PE AFR with cam and supporting mods

  1. #1
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    Default setting B3618 PE AFR with cam and supporting mods

    Ive been doing some searching on two very important tables (spark and PE fueling)

    I do not see much info recommendations on tuning or setting these up. about the most i see even with Google searching is some tuners or experienced people with a dyno will briefly touch on this as if its a super top secret formula only letting out a ideal max spark or AFR.... Don't get me wrong I know not every person wants to give out info they make a living on but for the rest of us why not? isn't this why we buy the tuning programs? (to make a better tune and understand how and why changes are made)


    With that said and since modified tunes are not around to dissect and note proven changes maybe this thread can spark some interest or even some knowledge on how a guy at home with no dyno can properly figure out how to make the PE scale and to avoid leaving a good deal of HP on the table or worse run it too lean.

    I have a highly recommended book on tuning that I was reading off and on for some time now and from what I'm understanding on a NA ls1 max power would be achieved with a Lambda of 0.91 ( 13.17:1 ) but this could leave you on the edge of shortening the engine life. Also in the book they chose run between 0.82-0.86 Lambda to allow a safe WOT tune. In the example they had stepped the AFR at different RPMs.

    My question is how do you know where to make these steps? I can only guess you need a dyno and significant experience to know where the steps are made.


    So this leaves me here wondering what I should do short of having this taken to a "Tuner" which was what I thought I could avoid.
    Last edited by myws6formula; May 27th, 2013 at 11:04 AM.
    Since this is a tuning site.... LS1 swap, 224/228 .588/.588 114+1 , LS6 intake , Ported TB, LS6 Valley cover (huge difference in oil usage!) 36# grand prix injectors, SLP Thirdgen dual air box cold air, Stage 2.5 Ported PRC ls6 heads, Hawks ls1 1 5/8 swap long tubes, SLP Thirdgen Catback t56, spec 3 clutch, S60 street 3.73 rear. LC-1 WB , Roadrunner

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    What I did very recently was to get my base maps very close. Make sure the PE table set safely with say at least EQ set to 1.18 across the RPM range and then log a couple of 100% throttle runs in 3rd and 4th gear. Being cautious by keeping an eye on the wide band gauge (hopefully you have one!) for the first couple of runs and stop if the AFR is rising above 13:1.

    By looking back at the log, monitoring AFR & RPM (and KR) I could see where the AFR was lean in the RPM range. I adjusted the PE table to try to get a fairly flat AFR across the RPM when doing the 3rd & 4th gear runs again. I was aiming for an AFR of between 12.5 - 12.8. Doing that I only saw a 0.4 KR on a couple of occasions myself and increased PE at those places.

    I don't have my tablet with me curently I can't post the values but it basically stayed at 1.18 EQ then stepped up to 1.19 then 1.20 as RPM went up.

    I was using the spark table from "LS1-M6 Base Tune.tun" posted on the forum as it appeared to have sensible spark values. The one thing I changed though before making the runs was to reduce the spark from 27 down to 24 at around 4000 RPM and stepped that back up to 27 as RPM increased to 6200 RPM.

    That was purely based on having read that the LS engines work with 24 at peak torque and 27 at pek RPM just as a starting guide.

    Click image for larger version. 

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    Last edited by bimbleuk; May 27th, 2013 at 09:42 PM.

  3. #3
    Joe (Moderator) joecar's Avatar
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    Normally Aspirated:

    Set PE to whatever it takes to avoid going lean at load during tuning (without being so rich that you're washing cylinder wall oil into the crankcase)...

    [ do not just set PE to Lambda 0.91 without testing as this may increase combustion chamber temps and may allow detonation/knock ]

    then if you're driving on the street set it to Lambda 0.86 (12.6 AFR) which is suitable for good peak torque and cooling the combustion cambers (if your airmass model is correct);

    then if you have access to a dyno, find out what Lambda and spark advance produces the best peak torque...and then lean it a little as you go from peak torque to peak power to see if you can improve on power (but stay on the richer side of power-vs-lambda, and avoid detonation/knock at all costs)...

    this "tuned" PE would be suitable for drag racing (short intense load), but would not be suitable for road racing (long intense load) where you want the richer peak torque lambda thru-out to provide combustion chamber cooling.

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    thanks guys, also how consistant / accurate is the hp pid? saying its 4th gear pulls in a 6spd on the same stretch of road. not talking about how much hp im making but more of a improvement monitor
    Last edited by myws6formula; May 28th, 2013 at 09:44 AM.
    Since this is a tuning site.... LS1 swap, 224/228 .588/.588 114+1 , LS6 intake , Ported TB, LS6 Valley cover (huge difference in oil usage!) 36# grand prix injectors, SLP Thirdgen dual air box cold air, Stage 2.5 Ported PRC ls6 heads, Hawks ls1 1 5/8 swap long tubes, SLP Thirdgen Catback t56, spec 3 clutch, S60 street 3.73 rear. LC-1 WB , Roadrunner

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    HPTuner Experiments

    Check this link and setup the "Street Dyno" log and I think you'll find that a better way to compare mods on the road.

  6. #6
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by myws6formula View Post
    thanks guys, also how consistant / accurate is the hp pid? saying its 4th gear pulls in a 6spd on the same stretch of road. not talking about how much hp im making but more of a improvement monitor
    The FWHP pid is a guestimate by the PCM based on factory stock tables.

    The RWHP pid is limited due to insufficient sampling rate, but can yield interesting results if used vary carefully in controlled driving/road conditions (but will not match dyno results).

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    Lifetime Member BLK02WS6's Avatar
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    An experienced tuner can get a good safe street tune based on experience - but the only right way to correctly optimize the tune througout the RPM range is on a dyno. I have tuned hundreds of LS engines, and I could give you a really good starting point based on that experience, but the only way I could find out what your particular setup wants for fueling and spark would be to put it on a dyno. Starting off with a good safe starting point, you would want to make small changes in fueling and spark (only one at a time) and see what effect it has on torque and power. Also, keep in mind, all of this discussion is assuming you already have the actual AFR corrected to the targeted AFR by tuning the VE and MAF tables in using a wideband... If you want to post up your tune, I'm sure some of us can make some recommendations to help you get going.
    GM EFI Tuner
    02 WS6 9.41 @ 143 MPH 3675#, drag radials, pump gas, through the mufflers - sold


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    that would be great. I'm tuning with a wideband and its pretty close right now but I want to hit some more cells before I blend it. same with my MAF table
    Since this is a tuning site.... LS1 swap, 224/228 .588/.588 114+1 , LS6 intake , Ported TB, LS6 Valley cover (huge difference in oil usage!) 36# grand prix injectors, SLP Thirdgen dual air box cold air, Stage 2.5 Ported PRC ls6 heads, Hawks ls1 1 5/8 swap long tubes, SLP Thirdgen Catback t56, spec 3 clutch, S60 street 3.73 rear. LC-1 WB , Roadrunner

  9. #9
    Joe (Moderator) joecar's Avatar
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    +1 post tune/logs.

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    Log_0004.efiSunday_may_19th_160Thermo_36inj_G.tun


    I was having issues with my wideband and found the issue but now at WOT i notice the fuel ratio commanded vs what the WB is reporting seems off. the WB seems to toggle rich lean at WOT If it was fuel pressure I wouldn't think i would see such a fast change
    Since this is a tuning site.... LS1 swap, 224/228 .588/.588 114+1 , LS6 intake , Ported TB, LS6 Valley cover (huge difference in oil usage!) 36# grand prix injectors, SLP Thirdgen dual air box cold air, Stage 2.5 Ported PRC ls6 heads, Hawks ls1 1 5/8 swap long tubes, SLP Thirdgen Catback t56, spec 3 clutch, S60 street 3.73 rear. LC-1 WB , Roadrunner

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