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Thread: Whats the "noisest" forged motor you've seen?

  1. #1
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    Whats the "noisest" forged motor you've seen?

    Still chasing down why my knock sensors are going off the chart under full throttle. Last test was with MS109 in the tank, knock sensor readings appeared near identical to 93 octane testing, which leads me to believe this isn't real knock. But i am occasionally pegging the sensors so I don't have much room to desensitize them. Want to hear from others with forged rotating assembles what they have seen over the years.

    To add to the noise its also a billet crank, which I have never tried to tune before.

    The attached log is a 3rd gear stab of the throttle.

    3rd Gear WOT (Startup Tune 8).hpl

  2. #2
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    Quote Originally Posted by 06300CSRT8 View Post
    Still chasing down why my knock sensors are going off the chart under full throttle. Last test was with MS109 in the tank, knock sensor readings appeared near identical to 93 octane testing, which leads me to believe this isn't real knock. But i am occasionally pegging the sensors so I don't have much room to desensitize them. Want to hear from others with forged rotating assembles what they have seen over the years.

    To add to the noise its also a billet crank, which I have never tried to tune before.

    The attached log is a 3rd gear stab of the throttle.

    3rd Gear WOT (Startup Tune 8).hpl
    Excuse my ignorance but why would a billet crank be different than a forged one?

  3. #3
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    Quote Originally Posted by 1bh View Post
    Excuse my ignorance but why would a billet crank be different than a forged one?
    harder metal? different sound resonance? could be part of what the sensors are "hearing" but not sure.
    Last edited by 06300CSRT8; 05-06-2019 at 01:02 PM.

  4. #4
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    Could it be a bad knock sensor?

    (edit: I see both are triggering, not likely)

    Do you hear anything?

  5. #5
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    Could be, I don't hear knock but this thing isn't a very "hearable" setup lol. 426ci stroker, 2.20 intake thitek heads, 2" primary headers to catless Corsa system, with a 4.5L whipple on top.

    The sensors seem normal under regular driving and idling, and bank to bank are pretty much matching. Would be hard for both sensors to be bad at the same time?

    These were the sensors on my last motor that blew apart the block, guess safer to replace, I have new sensors in the garage.

  6. #6
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    If you have sensors, might as well try them.

    Do you have a knock monitoring system with earphones?

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    Quote Originally Posted by spoolboy View Post
    If you have sensors, might as well try them.

    Do you have a knock monitoring system with earphones?
    No but you are not the first to recommend that, I started looking into them but just couldn't settle on a "good" one, the best one seemed to be made in Europe. Any recommendations?

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    I do not have one yet either.

    I keep seeing this one listed as good for the price:

    http://tunernerd.com/knock-monitor-pro/

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    Quote Originally Posted by spoolboy View Post
    I do not have one yet either.

    I keep seeing this one listed as good for the price:

    http://tunernerd.com/knock-monitor-pro/
    That's the one I kept coming across. I just ordered it, says 1-2 weeks. Ill report back if I wait that long before i turn off the sensors and send it, lol.

  10. #10
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    Before you send it, there are many recipes on the net for making something at home that will allow some manner of knock monitoring.

    I made one like this years ago and have no idea where it is now:

    http://www.autospeed.com/cms/article...-Part-2&A=0353

    I added a twist. I used a walkman that could record on tapes so I could replay it. That should tell you how long ago that was....

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    What pistons and p-b clearance are you running??

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    you sure you don't have a header or exhaust pipe connecting to the frame/subframe somewhere? even the most careful builds can get contact under load.... I've run into that a few times.

    Other things like noisy blowers or crappy A/C units have done it to me too..
    2018 Jeep Trackhawk - Blue

    What we do in life, Echos in eternity

  13. #13
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    Quote Originally Posted by lafrad View Post
    you sure you don't have a header or exhaust pipe connecting to the frame/subframe somewhere? even the most careful builds can get contact under load.... I've run into that a few times.

    Other things like noisy blowers or crappy A/C units have done it to me too..
    Can never be 100% sure, but the knock severity does change with load (4psi averages 2.5-3.0 volts on the knock sensors, 15psi averages 3.5-4.5v). Passenger side header is close to the frame rail, have bent it a bit trying to give some room, don't see it hitting.

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    Quote Originally Posted by Hemituna View Post
    What pistons and p-b clearance are you running??
    Mahle 2618 pistons. .005 piston to wall.

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    In my opinion, don't waste you time and money on an aftermarket knock detection setup. It's not going to magically tell you that there is knock. You have to establish a floor for noise, you have sensors now and can't establish it. You would have setup cylinder pressure measurements and purposely knock the motor to find where it really is and what it sounds like on your particular engine. I'd roll it old fashioned, get rid of them all together, read plugs, listen to the engine on a loaded dyno during pulls, watch power. If power is coming up as you give it timing and plugs look good keep going slowly. You start losing power back it off a degree or 2 and call it good. Ran plenty of boosted small blocks past 1k HP 15+ years ago with NO knock sensors. You just have to face the facts that a knock system for a FACTORY engine isn't going to do you any good at this point, and be confident in your tuning approach.

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    Quote Originally Posted by Blue Bee View Post
    In my opinion, don't waste you time and money on an aftermarket knock detection setup. It's not going to magically tell you that there is knock. You have to establish a floor for noise, you have sensors now and can't establish it. You would have setup cylinder pressure measurements and purposely knock the motor to find where it really is and what it sounds like on your particular engine. I'd roll it old fashioned, get rid of them all together, read plugs, listen to the engine on a loaded dyno during pulls, watch power. If power is coming up as you give it timing and plugs look good keep going slowly. You start losing power back it off a degree or 2 and call it good. Ran plenty of boosted small blocks past 1k HP 15+ years ago with NO knock sensors. You just have to face the facts that a knock system for a FACTORY engine isn't going to do you any good at this point, and be confident in your tuning approach.
    Thanks for this, its good to have someone reassure me taking this approach. I want so badly to do this, but cant get over the hump that this exact car had a different engine in it 8 months ago that worked perfectly fine with the knock system. So something about this new motor is different, and it bothers me. I have things in my mind that I am worried about, like wrong length pushrods, cracked flywheel, PTV clearances.

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    Quote Originally Posted by 06300CSRT8 View Post
    Thanks for this, its good to have someone reassure me taking this approach. I want so badly to do this, but cant get over the hump that this exact car had a different engine in it 8 months ago that worked perfectly fine with the knock system. So something about this new motor is different, and it bothers me. I have things in my mind that I am worried about, like wrong length pushrods, cracked flywheel, PTV clearances.
    What happens when you take out say, 5* of timing?

  18. #18
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    Quote Originally Posted by spoolboy View Post
    What happens when you take out say, 5* of timing?
    Car wont accelerate, only commanding 6-7* currently, knock takes me to zero, sits there like im sitting on a two step. I don't have 5 degrees to remove.

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    Quote Originally Posted by 06300CSRT8 View Post
    Mahle 2618 pistons. .005 piston to wall.
    ^^This^^^

    I get it all the time, is a pita tuning noisy built engines as the knock sensors are now useless.
    Simply is too much p-b clearance... if they aren't quiet at operating temp then it is too loose.
    We tried reducing clearance on our forged engines many years ago, half a thou at a time until the knock sensors worked again.
    Figured out that piston manufacturers specs are REALLY conservative and too much clearance is way safer for them than too little.
    We now routinely run half what they recommend and sometimes even less depending on material and manufacturer.
    Most guys/machinists have a heart attack hearing this, but it works...engines are quiet, dont burn oil, seal better and make real good power.
    And super easy to tune as knock sensors still work.
    Doesn't help your situation though...you will have to ignore the sensors and tune old skool style like blue bee suggested.

  20. #20
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    Quote Originally Posted by Hemituna View Post
    ^^This^^^

    I get it all the time, is a pita tuning noisy built engines as the knock sensors are now useless.
    Simply is too much p-b clearance... if they aren't quiet at operating temp then it is too loose.
    We tried reducing clearance on our forged engines many years ago, half a thou at a time until the knock sensors worked again.
    Figured out that piston manufacturers specs are REALLY conservative and too much clearance is way safer for them than too little.
    We now routinely run half what they recommend and sometimes even less depending on material and manufacturer.
    Most guys/machinists have a heart attack hearing this, but it works...engines are quiet, dont burn oil, seal better and make real good power.
    And super easy to tune as knock sensors still work.
    Doesn't help your situation though...you will have to ignore the sensors and tune old skool style like blue bee suggested.
    They are almost completely normal levels during idling and cruising. I get some sensor activity during first start up, for about 10 seconds, then go to normal levels. After that it is only under heavy load.

    I think I am onto something though, passenger side header is close to the frame rail.