ok to knocking on low rpm?

[normality78]

past weekened, drink teas with some drag runners back in JB. one of them mentioned its fine to have knocking on low rpm band but never on high rpm. how correct can he be?

 

[gohkokeng]

kinda new to me.......what's knocking on low RPM?

 

[Lopot]

I thought knocking is not good to your car no matter what rpm it is.

 

[normality78]

this is the reason why this thread was created. kekekeke

 

[gohkokeng]

wui tell me what is it all about la.....haha pls 10q

 

[alvinpck]

If the engine is running lean on low RPM, wouldn't it be leaner at higher RPM?

 

[nitrus]

Sorry noob question.. I also wanna know how exactly is "knocking" like ?

 

[xtremeleo]

alvikpck : dat isnt ALWIZ true, sum tuner set their engine up like dat to access the power quicker. i heard dat over advancing the ignition timing will do this, but on low rpm, the temp isnt as hot as in the higher revv range, so its considered okie.

but no matter what, when knock happens, there will be sum engine damage, even if they cant be detected. i wont allow dis to happen on my ride, no matter what

 

[normality78]

i heard dat over advancing the ignition timing will do this, but on low rpm, the temp isnt as hot as in the higher revv range, so its considered okie.

yup. this si exactly wat he said

 

[nitrus]

So may i know what is engine knocking ? Is it some loud knocking sound or car knocking vibration kind ?

 

[theorekz]

knocking is the pre-mature combustion of ur engine before the power strokes arrive...

correct me if i'm wrong.. cheers

 

[xtremeleo]

theorekz : dat is true, and once u can hear it, its bad imo. on the road, u'll mostly hear dis sound on those mitsu / proton engines, which make quite an irritatin sound. krik krik krik, sumthing like dat. y dont u try dis urself, put on high gear and cruise wit super slow speed, dat usually creeps the sound i described out.

 

[nitrus]

Ohh... So knocking is the "krik krik krik" sound ? Ok k .. Phew...

 

[1298]

For what I know, tuners don't set the ignition timing high up to the point where knocks will occur, but just lean out the air/fuel mixture a little bit so that the turbo will spool up faster.

Lean out the mixture in low rpm range is fine with accurate tuning but not make the engine knocks. It's totally different thing.

Cheers!

 

[xtremeleo]

1298 : i dont understand bro, so does this means dat knock and ping r two different things? ping usually is caused by overadvancing the ignition timing, and ive read sumwhere dat knock is the sound u hear when ping occurs, so i tot the two of them r the same thing, or at least caused by the same thing. guess i was wrong, ya

in charged engines, or at least in the one iam using, advancing the ignition timing in lower revv range wud give me better acceleration compared if i were to stay wit the factory setting. ignition timing in a charged engine is advanced during off boost, and retarded when boost kicks in, dats fundermental / logic. setting the afr lean at lower revv is okie, since, like the case of overadvancing ignition timing, the temp is considerably cool hence letting u set afr AND ignition timing as high as possibly, safely, means u shudnt let the engine knock (ping? iam a bit confused now, will confirm after reading more about dis)

in any case, my engine's std ecu wont let me to advance more den 10 degree, it will retard the ignition timing if i do advane more then dat. its sum kinda safety feature, safety indeed dat it wont let me have sum extra fun. hoho..

 

[1298]

xtremeleo, for what I know, "pinging" and "knocking" are more or less the same. Some with "tik tik tik" sound while some might have "tok tok tok" sound. Factory setting normally won't be in a optimum way but will make our engine run safe all the time, anytime.

To run with high ignition timing, fuel quality plays an important part. If you run your engine with, for example, methanol, then you will be fine to crank up more boost and advance the ignition timing.

However, there is no point to advance or retard the ignition timing if you are still using the stock ECU. It won't help much. Advance the timing, engine will knock during high RPM and will "boooom" anytime. Retard it, you won't have low rpm power. Unless you are using some kinda piggy back such as e-manage, or go standalone if budget allows.

Oh yea, 10 degree advance in ignition timing is kinda lot. You should be grateful your ECU is able to retard it automatically otherwise you might be busy looking for a new engine by now. Hahaa.

Cheers.

 

[kweng84]

if carb engine, can we tune the AFR until the fuel/air ratio ngam ngam that the knocking sound wont occured?? i tried with the tuning AFR and the knocking sound become less...so what actually causes the knocking sound? fuel too rich or too lean?

 

[Doink]

my cars all advanced timing for better pick up...so when low rpm i put more throttle the engine will have knocking...actually knocking is not good and a serious knocking can damage ur engine forever.slight knocking is usual for better performance...dont always drive with low rpm...at least maintain at 3k rpm.depends how u tune ur engine according to ur driving condition...

 

[normality78]

fark... im getting more confuse.....

1 more question. saying we advanced our ignition timing off boost. abit link back to my cam thread that i posted, can we use adjustable cam pulley to do something about it?

 

[xtremeleo]

normality, i may be able to explain about ping / knock, but these infos will confuse u more if u havent mastered the fundamental theories. hmm.. maybe mastered is too strong a word, but u have to know the fundamentals bro.

1298 : u may be able to run if u can lower ur combustion temperature down, say wit a set of water injector system. the trick is to lower the combustion chamber down, before combustion takes place in its stroke so dat the temperature inside the combustion chamber is alwiz in check witin the limits of the engine's internals AND to prevent PRE-IGNITION dat will give out those ping / knock sound. RON numbers r actually to show how a particular fuel wit certain compositions can avoid ping / preignition in gasoline engines, so using a higher RON wud definitely be better for advancing d ignition timing. our country 97 RON is more then enuff compared to 88 RON dat is recommended for my ride to operate at its optimum.

advacing ignition timing in a std engine is alowable, witin its limit. 10 degree isnt much compared to sum guy dat hit 23~30 degree (estimated, as i heard VTEC ignition system may advance as much as 40 degree when VTEC is activated, have to reconfirm dis wit any VTEC sifu) on his VTEC, i can hear his engine ping-ed while i watched his mech tune his ride using an emanage. crazy wei, orang takmau kalah kot.

doink : if u r using a proton, and want power, u dont have a choice except to advance the timing, rite? just be careful wit the consiquences bro, engine rebuild isnt cheap :)