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Thread: Built LNF ZFR6758 e85 low power

  1. #1
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    Built LNF ZFR6758 e85 low power

    I've recently gotten my car together and running, I was feeling great about it on the street until I took it to the track last weekend and was only trapping 115, tuner thinks the "MAF is reading a little low" and "the boost pressure is low for the WG duty cycle %". With that speed and weight at 3100, calculates to about 350hp and I'm certain the car is 75-100hp shy of what it should be at this point.

    I think I need a second opinion because he's going strait to a mechanical issue, granted, I've done the work on my end. Good relative compression, about 2%-5% cylinder leakage with piston TDC on compression. Plugs looked good, Boost leak test was great @30psi. No metal in filter after break-in change. Car runs flawlessly with no issues at start-up, CEL of any kind, no oil or coolant consumption.

    Mods-
    Gen 3 block
    Wiseco pistons molnar rods
    Cat-5 ported head, supertech springs, stage 2 zzp cams
    ZFR 6758
    zzp lt1 pump AEM 340 in-tank, Opel injectors.
    split second 5th injector (not setup)
    All zzp bolt-ons.

    I have yet to check the WG valve on the turbo, I do have a forge bpv, I don't recall which spring is in it. Normal driving the car is very responsive, It feels very similar to when my previous setup was 440whp 405wtq just driving around slow.

    I included the latest edit from him and one of my logs from that day.

    Thanks for your input!
    Attached Files Attached Files
    Last edited by BlueDevilCSSTC; 1 Day Ago at 10:24 PM.

  2. #2
    check if the bushing of the wastegate flaps stud is loose, i've seen this on early revisions of the ZFR housings, meanwhile the put a little tig weld spot on so it can't move.
    if this was happening, wastegate wasn't closing correctly

  3. #3
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    I wiggled the WG flap, it has maybe a half-mill of radial play. I pulled off the rod and moved the valve around loosely and it seemed ok, hard to tell without taking off the O2 housing for sure though. It's definitely an earlier turbo with some miles on it but I'm not convinced this is the major issue. Anyway, I reinstalled the actuator and adjusted the rod for proper tension. I may drive it tomorrow and see what happens.

    What exactly do you mean by weld a spot on? Do you mean on the end of the shaft that controls the valve?

    Another thought I had was the intake boot. I have the ZZP fendwell 3" intake and that boot just barely fits on the inlet of the turbo, I had never fought a silicon boot more that this one. I could squeeze it fairly easily with my hand just before the compressor. Would it be possible it could be collapsing and causing an upper rpm restriction? I have never heard of this before but it's just a thought.

    Had some back and fourth with my tuner today, he was asking about the ported head, he was curious if the short side of the intake runners were reduced, Josh at Cat-5 ensured me that he did not do that, I don't really think I could be losing this much power from the ported head.

  4. #4
    Senior Tuner cobaltssoverbooster's Avatar
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    Coupler collapse on the inlet side is a real thing. Just run without the intake on to test that theory.
    If you alter the short side radius without the right flow equipment you can do some major harm. I lost over 130 hp and ruined a head by fucking with that short turn radius a little too much.

  5. #5
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    Interesting. How exactly will the car run ok without the MAF from the intake near the filter? I think I'm going to get a camera mounted in there and watch how it responds. That's a little concerning that you did in fact loose that much power from the ported head. Josh hasn't had any issues with LNF's before so I really really hope that isn't the issue in this case.

  6. #6
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    IMG_1241.jpg

    I went through some of your older threads and looked for what my waste gate preload needs to be, I definitely made the wrong adjustments before I went to drive the car tonight. Looks like I need to do ~3-4mm instead of the 0 I did tonight

    I also found a post where you were talking a bit more about the ported head. I didn't get any super close pictures of the intake ports on mine but I do have 1 decent one. It's obviously not as good as a close video but I guess I just have to trust that Josh did not take any metal out from the short side.

    If this waste gate adjustment doesn't really liven up the power, I'm not sure exactly what needs to be done short of swapping out for a stock head which I will do everything I can to not resort to that solution.
    Last edited by BlueDevilCSSTC; 1 Day Ago at 10:19 PM.

  7. #7
    Senior Tuner cobaltssoverbooster's Avatar
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    the car can run without the maf but it requires some table settings to be set up as defaults. in order to operate correctly. basically has a fit and forces the maf to be custom calibrated for the default.
    you could also just remove the air filter and run straight open pipe with the maf still in. the filter usually causes the inlet vacuum condition and then the coupler collapses due to the vacuum. remove the restriction and see if you make power.
    maybe you could mount a gopro or some recording device to watch the coupler. get creative.
    2000 Ford Mustang - Top Sportsman