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  1. #1

    Default Boosted lt1, high compression and timing

    Currently running a Dual intercooler D1SC. I've hit 13psi on the dyno with mild tuning.
    The bottom end is forged but not specific to boost.
    I'm pretty sure the tuner was being very conservative and he also tunes ls1 engines so I'm sure that has some weight.

    When boost starts its around 19 degrees of timing and up top it's at 14degrees. 10.5 AFR.

    We gained some power going to 11.5 afr. But kinda disappointed.

    I run stepped headers and 2OTL. He claims the exhaust is choking the car. It could be a restriction but I've seen single 3" muffler car pushing well over 500 wheel hp.

    I believe a lot is lost is lost not only in AFR but also timing.

    What do we typically run timing wise for 13psi of boost? Also mention I'm on 11 to 1 compression.

    I really feel like the car would like more timing and thats where I'm missing my power output.

    I've read people say 17-20 degrees sometimes more.

    I dont mind flying close to the sun as they say but also dont want to get burned yet.

    Also need to mention I'm set up for e85 as well.

    So In short what type of timing should I consider with my set up with and without e85.

    Thank you
    Bobby

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  3. #2

    Default

    I have a 9.5 scr 383ci on 93 pump that I run 15psi at 19* with 11.5afr

    Its an auto so dyno numbers are meh, 571-658rwhp area depending on type of dyno.
    Correlation does not imply causation.

    Una salus victis nullam sperare salutem

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  5. #3
    Pr0jekt Turb0?


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    Ryan
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    1993 Camaro Z28
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    Default

    Just be aware that nomercy being at 9.5 versus yours being at 11 CR is a significant difference in terms of boost/timing tolerances.
    -Ryan
    93 Z28 M28

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  7. #4

    Default

    Z28 I understand thank you. My buddy said evey 1 compression difference is like 1 psi of boost.

    From research I believe the car can take 17-19 over 14.

    3-5 would yield the results I was expecting vs what i got.

    I've done NA tunes and some nitrous but boosted is new to me so I'm more researching before I turn it up.

    Thank you

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  9. #5
    Pr0jekt Turb0?


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    @MoeHorsePower You still around to give a high level input to him? I'd pull up the tune you helped me reconfigure but I don't have access to that laptop anymore. I don't recall the timing curve because it was so long ago but I remember you telling me that the base tune I was given by another company had WAY too much timing in it.
    -Ryan
    93 Z28 M28

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  11. #6
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    Default

    How much HP is it making and how much were you expecting, you didn't say. Just curious.
    Nolan
    '94 Z28 Bone stock,4l60e
    '97 SS SLP,T56,385 stroker,AFR210,XFI292,NO traction til top of 3rd gear.
    '57 Chevy 3100 p/u LT1/T56

  12. #7

    Default

    JOATMON I copy pasted my original post from another post I made and yes I forgot that information there as well lol

    Car made 400rwhp. I was expecting at the least 500rwhp on 93 even with the 3" catback having some restriction (might do a cutout).

    The car is mechanically sound, unfortunately we had to stop tuning bc of an oil issue but even so the tuner was very reluctant to add anymore timing. He does LS cars so I'm sure he made some basis of tuning the timing off that as well. Even tho the bottom end wasnt build specifically for boost bc I never thought I would ever go boost it still has forged parts but I know theres more to it when it comes down to aspects like rings etc.

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  14. #8
    Pr0jekt Turb0?


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    Quote Originally Posted by anniversaryss View Post
    JOATMON I copy pasted my original post from another post I made and yes I forgot that information there as well lol

    Car made 400rwhp. I was expecting at the least 500rwhp on 93 even with the 3" catback having some restriction (might do a cutout).

    The car is mechanically sound, unfortunately we had to stop tuning bc of an oil issue but even so the tuner was very reluctant to add anymore timing. He does LS cars so I'm sure he made some basis of tuning the timing off that as well. Even tho the bottom end wasnt build specifically for boost bc I never thought I would ever go boost it still has forged parts but I know theres more to it when it comes down to aspects like rings etc.
    Are you stock heads/cam/intake manifold? If so, there is a lot of power left on the table there. Personal opinion but 10.5 AFR is really rich to me, even for boosted.
    -Ryan
    93 Z28 M28

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  16. #9

    Default

    When boost starts its around 19 degrees of timing and up top it's at 14degrees. 10.5 AFR.
    At what RPM? what the torque at that RPM

    We gained some power going to 11.5 afr. But kinda disappointed.
    You can run .77 to .80 Lambda on E, but remember, just because you are running E doesnt mean you can turn up the timing, Ive seen cars make 20+ HP on E and some that made none.

    I run stepped headers and 2OTL. He claims the exhaust is choking the car. It could be a restriction but I've seen single 3" muffler car pushing well over 500 wheel hp.
    I made 722 WHP on a 3" exhaust

    I believe a lot is lost is lost not only in AFR but also timing.

    What do we typically run timing wise for 13psi of boost? Also mention I'm on 11 to 1 compression.
    On a low compression motor, usually around 20 to 21 degrees of timing, with your compression, Id run 18-19 degrees

    I've read people say 17-20 degrees sometimes more.
    Its always better to run more boost than timing but in your case, more boost will eventually run into ring butting.

    Clearances make all the difference, those that get away with more timing could mean there is more clearance between the piston and cylinder walls.

    I would pull the plugs at peak torque and see what they read then go from there, take baby steps.

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  18. #10

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    @MoeHorsePower

    I don't have the dyno graph unfortunately but from some logs I have on hptuners it typically enters boost around 2800-3000rpm. Up around 5800 I'm at 10.6 psi so around 6500 is where I assume I hit 13psi. As for how much torque im unsure as well.

    I haven't introduced E to the system yet. Running of 93 at the moment. But I am set up for flex.

    722 on a 3" exhaust is great news for me. Good to hear. Alleviates some stress about the set up. Not that its optimal. I went back to the 2OTL bc it originally came on the car and I liked it. I also wanted to tone it down.

    As far as timing goes 18-19 is where I figured I'd stop adding timing. I've heard and seen people make quite a bit if power of a few degrees of timing.
    Maybe that 4-5 degrees is where I'm losing the power. I've had my suspicion and that's what brings me here.

    I have no plans on running more than 13psi. Honestly I was looking at 10-11 but they shipped me the wrong pulley and I went with it.

    Plug reading is somthing I need to do. I understand completely. The weather is kinda sucky and my season is coming to an end unfortunately so I'm kinda in the information gathering state right now.

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