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Basic explanation for knock and detonation

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alasdair12
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Re: Basic explanation for knock and detonation

Postby alasdair12 » August 5th, 2010, 1:38 pm

Inside the combustion chamber, as the flame front spreads out from the spark plug, a series of reactions take place in the gases ahead of the flame front. Detonation when the air/fuel mixture in the cylinder explodes, instead of burning rapidly.

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_spool_
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Re: Basic explanation for knock and detonation

Postby _spool_ » August 24th, 2010, 4:58 pm

13 GHOST wrote:What is pre-detonation is it same as detonation


There is no such thing as pre-detonation, whoever told you that misspoke, its common to confuse pre-ignition and detonation.

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Lucian-2nr
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Re: Basic explanation for knock and detonation

Postby Lucian-2nr » August 29th, 2010, 6:09 pm

Nice Info!

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Re: Basic explanation for knock and detonation

Postby jonesz0310 » April 2nd, 2011, 10:03 pm

Hi. I have a 2006 Isuzu Dmax 3.0. My vehicle is making a LOUD knocking noise. Mechanics are a lil baffled as to what the problem could be. It is believed it could either be a fuel problem or a problem with the bottom half of the engine. Check were made to the head, i already bought new injectors and the sump pan was removed and the bottom half was checked, everything seems normal. It was thought that the noise was caused by the connecting rod, but the noise is loudest at idle and remains constant when accelerating (100km etc). Does anyone have any other suggestions?

Chaim
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Re: Basic explanation for knock and detonation

Postby Chaim » January 26th, 2012, 6:23 am

Hello everyone.
I'm new to the Trini forums...
but usually you won't even hear the knock.

DIS1
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Re: Basic explanation for knock and detonation

Postby DIS1 » April 12th, 2012, 9:18 am

Nice thread.........X2 knows what he is talking about. For those who want some protection from Knock and detonation when building turbo/N/A hybrids I can offer Thermal coatings.
If you doubt the ability of these products check out my FB page Dow Fabrication and look at the video.

ase_tt
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Re: Basic explanation for knock and detonation

Postby ase_tt » July 11th, 2012, 11:17 pm

i have a ford focus mk2 that pings and runs on premium, only mod i have is a cone filter the metal kind.... any advise where to begin looking...

What i noticed is after an oil change and new plugs...car runs great for about a week, and then its back to the pinking/pinging

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Re: Basic explanation for knock and detonation

Postby Sundar » November 21st, 2012, 1:12 pm

ase_tt wrote:i have a ford focus mk2 that pings and runs on premium, only mod i have is a cone filter the metal kind.... any advise where to begin looking...

What i noticed is after an oil change and new plugs...car runs great for about a week, and then its back to the pinking/pinging


are you running 'hot' plugs or 'cold plugs? if you not sure there is a article on this site that explains it.

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Re: Basic explanation for knock and detonation

Postby ase_tt » November 22nd, 2012, 6:33 pm

i dunno, but im using the original ford plugs

kaushalsingh
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Re: Basic explanation for knock and detonation

Postby kaushalsingh » December 9th, 2012, 5:02 am

Thanks for sharing such explanation...It is a basic explanation but very helpful :)
Learned some basic and helpful things through this thread...
Keep posting

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X2
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Re: Basic explanation for knock and detonation

Postby X2 » December 9th, 2012, 9:33 am

Chaim wrote:Hello everyone.
I'm new to the Trini forums...
but usually you won't even hear the knock.



For the most part that is true.. with all the sound deadening in the car cabin plus how densely packed the engine bay is, often you won't hear it... but the loud stuff you can hear when listening for it... if it's loud enough to hear... it's knocking/pinging pretty badly.

Serious enthusiasts and tuners may take the time to make a 'Det-can'... basically a DIY detonation hearing device that allows you to use it like a stethoscope to listen to the engine.

Regarding the ford... they tend to ping... use an octane booster to increase octane... I suspect the timing maps are a bit aggressive (ignition timing)... which will keep the combustion chamber hot enough to encourage pinging or rattling. My Focus did it for years...even slightly so on premium.

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thegtiman
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Re: Basic explanation for knock and detonation

Postby thegtiman » December 21st, 2012, 8:57 pm

X2 wrote:
Chaim wrote:Hello everyone.
I'm new to the Trini forums...
but usually you won't even hear the knock.



For the most part that is true.. with all the sound deadening in the car cabin plus how densely packed the engine bay is, often you won't hear it... but the loud stuff you can hear when listening for it... if it's loud enough to hear... it's knocking/pinging pretty badly.

Serious enthusiasts and tuners may take the time to make a 'Det-can'... basically a DIY detonation hearing device that allows you to use it like a stethoscope to listen to the engine.

Regarding the ford... they tend to ping... use an octane booster to increase octane... I suspect the timing maps are a bit aggressive (ignition timing)... which will keep the combustion chamber hot enough to encourage pinging or rattling. My Focus did it for years...even slightly so on premium.


Audible det, although not always distructive can be heard at ~ 6kHz. In a modern car you can hear this with the windows down and low road speeds after a transient from low engine speed and high load. In a buzzy track vehicle, you can use det cans to detect det and make corrections to the calibration just retarded from the det limit if less than MBT.

The C307 Ford Focus, with its 1.6 Sigma fixed cam engine (and FN Auto for TnT?) is calibrated for 95 RON with reduced performance on lesser RON fuels. On tip ins you are likely to have some knock activity, which will be corrected until the next tip in.

LyonTuner1
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Re: Basic explanation for knock and detonation

Postby LyonTuner1 » December 12th, 2016, 7:50 am

Well that makes a lot of sense. Thanks for posting!

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