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Old 04-04-2008, 12:25 AM   #1
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Default What knock sounds like (video)

So, I've read a lot of threads where someone says "as long as you know what knock sounds like." I read that and think to my self well ****, i have no idea what it sounds like, so naturally, i go to youtube and see if i can find it. I wanted to post this up so people would know what knock was like. Maybe i can save some a motor.



Now, like i said, i have never personally heard knock so i am assuming that this is knock. Please, someone, correct me if I'm wrong. I'm going on the fact that someone said it sounds like shaking pennies in a can.
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Old 04-04-2008, 12:29 AM   #2
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faint knock is very hard to hear, I can only see it on my op gauge. louder knock is very easy to hear, tust me you know it when you hear it, its like a animal is in your engine and freaking out banging everyhting trying to get out haha.
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Old 04-04-2008, 12:33 AM   #3
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Quote:
Originally Posted by cardriverx View Post
its like a animal is in your engine and freaking out banging everyhting trying to get out haha.
I will have to listen for animals when I finally boost. :
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Old 04-04-2008, 12:51 AM   #4
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http://forums.neons.org/viewtopic.ph...&highlight=det
this should help to hear that faint knock
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Old 04-04-2008, 09:53 AM   #5
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i hear the camera shaking in that video.....no knock.
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Old 04-04-2008, 10:57 AM   #6
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Originally Posted by hackerchris View Post
I will have to listen for animals when I finally boost. :
If you have a real oil pressure gauge, just use that. It freaks out bad when there is knock.
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Old 04-04-2008, 11:20 AM   #7
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Hell... My oil pressure gauge freaks out when there's oil pressure. (And yes, I cleaned the bloody contact)
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Old 04-04-2008, 11:20 AM   #8
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i hear the camera shaking in that video.....no knock.
Yeah, I was between that and random crap in the interior.
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Old 04-04-2008, 11:24 AM   #9
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he doesn't even get on the throttle, so unless he is the worst tuner in the world, he shouldn't have knock. but then again, he did post a video of said knock and labeled it "engine pinking". You know, when you're engine paints itself a shade of red.
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Old 04-04-2008, 11:26 AM   #10
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What about knock triggers the oil pressure to fluctuate?
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Old 04-04-2008, 11:30 AM   #11
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the 90-94 oil pressure sensors are carbon resistance sensors. As the carbon is compressed, the resistance changes. Detonation shock waves travel through the carbon sensors with massive changes in resistance that is indicated by the gauge needle flickering wildly to the left.
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Old 04-04-2008, 11:33 AM   #12
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i see, well then i guess i will have to find a better one :P
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Old 04-04-2008, 11:35 AM   #13
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Quote:
Originally Posted by Braineack View Post
the 90-94 oil pressure sensors are carbon resistance sensors. As the carbon is compressed, the resistance changes. Detonation shock waves travel through the carbon sensors with massive changes in resistance that is indicated by the gauge needle flickering wildly to the left.
Thats awesome. Makes me want one more now.

Was this intended in its design or just an accidental by product?
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Old 04-05-2008, 05:08 PM   #14
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Just bog the engine. Slow clutch till its nearly dead, no gas. It will knock.
Do it in someone elses car.
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Old 04-06-2008, 11:27 PM   #15
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I would never boost a car without det cans. They cost 15 dollars and 15 minutes.

Your brain is a better knock filter than any computer. Det cans amplify the actual vibrations of the block, it's not a digital or analogue reproduction. You will hear the knock, and any knock you don't hear will only be seen with a 10x magnifying glass in sunlight on new plugs.

I always have my det cans with me and just plug em in if I need to take a listen.



edit: I read that link and wonder why he folded the copper over itself like that, I've never done that. Seems like it would just insert some new harmonics into the system you might want to keep out? I also compared it to the almost never recommended air compressor hose to vacuum tubing. The stiffer hose transmitted the noise a little bit more loudly, it's not worth the cost at all.

6-10 feet of 3/4" vacuum tubing
1 3/4" plastic T (brass made no difference)
1 pair plastic over-ear hearing protectors
1 3/4" copper tube

Just slide the vacuum tubing into the copper and use a bead of silicone or rtv or whatever heat resistant sealant you have around.

Last edited by opek; 04-06-2008 at 11:41 PM.
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Old 04-06-2008, 11:42 PM   #16
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Quote:
Originally Posted by scfreshy View Post
Just bog the engine. Slow clutch till its nearly dead, no gas. It will knock.
Do it in someone elses car.
Knock or detonation is different from the valve noise you hear at low RPM in loaded conditions. I can only assume flex in the timing belt causes this? Maybe someone well educated can clear up the cause of the sound.
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Old 04-07-2008, 12:23 AM   #17
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Oh, I may be mistaken. I just always thought this was the same as detonation noise...
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Old 04-07-2008, 12:49 AM   #18
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http://www.streetrodstuff.com/Articl...ne/Detonation/

Well, if I cant post up a good video of it, I might as well link to a great article. So here it is.
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Old 04-07-2008, 01:01 AM   #19
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Quote:
Originally Posted by Braineack View Post
the 90-94 oil pressure sensors are carbon resistance sensors. As the carbon is compressed, the resistance changes. Detonation shock waves travel through the carbon sensors with massive changes in resistance that is indicated by the gauge needle flickering wildly to the left.
so flickering to the right is not knock at all?
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