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Thread: Opinions on these methods to lower knock and IDC's...

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    Spun Bearing Club '10 Feedback Score 0 O_ROD's Avatar
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    Opinions on these methods to lower knock and IDC's...

    Since the last track day, my datalogs haven't been sitting well with me. My IDC's are in the 130's and I had a few counts of knock up to 28! My 02's were reading .94v and .95v. The knock is pretty bad and feels like dropping an anchor behind the car when all the timing is pulled. This was all at 14psi w/ 9b's, BPU'd w/ a hotwired walbro

    Since then, I've decided to take action to find possible solutions for this. I've come up with 2 methods, I just need an opinion on which would be more suitable and effective.

    1. I bought an alchohol injection kit and was going to install that. This would give me a sure fire way to get the effected results I'm looking for...

    2. OR, sell the alchy kit and get an adjustable FPR and bump up my injectors. I'm running a hotwired Walbro w/ the stock FPR, my 360's seem to be pegged with those IDC's. I'm guessing bumping up the fuel pressure to 55psi would net me an extra 12% or so of injector flow.

    I'm wondering if my stock FPR is being overran and causing some issues... Some people have told me though at WOT the stock FPR won't cause any ill effects, it's only at idle and open loop you'll have driveability issues (w/ a hotwired walbro), which i haven't seen.

    I'm thinking out loud, but opinions on this would help me out...

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    Member Not Verified Feedback Score 4 (100%) dpartinvr4's Avatar
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    up your fuel pressure, you don't even need bigger injectors for 14lbs on 9b's

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    Spun Bearing Club '10 Feedback Score 0 O_ROD's Avatar
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    Quote Originally Posted by dpartinvr4 View Post
    up your fuel pressure, you don't even need bigger injectors for 14lbs on 9b's
    That's why I can't figure out why my idc's are so high. All my timing is being pulled and it sucks. 360's should be enough for the power I want.

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    Member Not Verified Feedback Score 4 (100%) dpartinvr4's Avatar
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    theres a thread on the "other site" that has a really good right up on what eache injector size is capable of at what psi of fuel pressure. .... i would start with upping your fuel pressure. that should solve your problem.

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    Forum User Not Verified Feedback Score 2 (100%) RealMcCoy's Avatar
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    If it's not going lean, reducing your IDC won't fix the knock issue. And without fuel control of some sort, raising the fuel pressure will cause more problems than you have now...

    I'd check for boost leaks that could be causing higher than normal IDC, I'd calculate the REAL IDC mathematically to see if you really have anything to be worried about, then I'd pour the water/meth to it and call it a day...


    Real Performance Automotive (541)816-4500 www.FB.com/RealPerformanceAuto

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    Banned Feedback Score 11 (100%) J. Fast's Avatar
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    Quote Originally Posted by dpartinvr4 View Post
    theres a thread on the "other site" that has a really good right up on what eache injector size is capable of at what psi of fuel pressure. ....
    Got a link? I'd like to see that.

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    Spun Bearing Club '10 Feedback Score 0 O_ROD's Avatar
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    Thanks for the helpful input. All parts are on there way for a new FPR set-up. I'm going to hold onto the meth injection for the time being and may play around with that as well. Gonna see just how low we can get these 9b's in the 12's before retiring them.

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    Quote Originally Posted by dpartinvr4 View Post
    up your fuel pressure, you don't even need bigger injectors for 14lbs on 9b's
    If it's true that you're running only 14psi on 9b's, then you might want to consider that fuel isn't your issue. .94/.95v on NB02 on 9b's shouldn't be knocking (unless of course you modified the stock timing from its' 5*).

    What coolant temps are you seeing during normal/wot driving?

    FWIW: I have 16Ts, running ~15.5psi with NB02 reading .93/.95v without knock but if I go to even 16psi my NB02 will read .91/.93v and I'll see a max of 5-7 counts of knock for maybe 200rpm then it's gone.

    * Evo8 MAF * TD04-16T * Delphi 780cc * FIPK * Full Custom Exhaust * Hotwired Supra FP * Megan CO *
    * GReddy FMIC * Nitto 555's * Avic Z3 * BlackStealths LCD/BC *** All else stock *

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    Spun Bearing Club '10 Feedback Score 0 O_ROD's Avatar
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    No boost leaks were present other than a slight leak where the injector meets the manifold. I pressure tested and That's been fixed.

    I no longer have the datalog but I think my coolant and intake temps were on the safe side. I remember thinking that might be the issue. My AC is deleted so the rad gets tons of fresh air. I also had air deflectors feeding into the engine bay where the ABS module used to sit. It was a fairly cool day as well.

    So before the season kicks off, I'll up the fuel pressure and check the base timing. I think you guys are right, it's not a fueling issue, but since I have a hotwired Walbro, I like the idea of having the stability/tuning ability of the AFPR.

    As for that link: Awesome thread, are those horsepower to injector estimates flywheel or WHP?
    Last edited by O_ROD; 03-16-2011 at 12:39 PM.

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