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Author Topic: engine knocking ?  (Read 4181 times)

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parker

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engine knocking ?
« on: August 28, 2007 11:02 am »
Hai...i'm newbie..can anyone explain to me what is engine knocking ?? ive heard from people about this word many times , but i still dont understand..  :?

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Offline racerjohnson

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RE: engine knocking ?
« Reply #1 on: August 28, 2007 8:12 pm »
it is the sound your engine makes when it doesn't have enough oil and/or your engine clearences (piston to cylinder clearance and rod to crankshaft bearing clearance) is too loose.
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Ricola

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RE: engine knocking ?
« Reply #2 on: August 28, 2007 9:47 pm »
It's a bad thing.
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Offline AdamNDebbie

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RE: engine knocking ?
« Reply #3 on: September 04, 2007 2:30 am »
Engine Knocking is also caused by the early detonation of the fuel.  This occurs from having a low grade fuel in a motor with a higher compression ratio and the fuel detonates before the spark plug fires (Essentially becoming a diesel with really bad timing).  The effects can range from bent con-rods to damaged crank bearings to holes burnt into the top of the pistons.  It typically occurs under WOT (wide open throttle) at low rpm's in the presence of a high heat load, or when the motor is really lugging.  

Typically you want to use the following rule:
92 Octane: no higher than 10.5:1 compression ratio
98 Octane: no higher than 11:1 compression ratio
105 Octane:  no higher than 13:1 compression ratio
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Offline racerjohnson

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RE: engine knocking ?
« Reply #4 on: September 05, 2007 1:30 pm »
detonation sounds like popcorn popping in a microwave
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