Suedes Car Club

General => General Discussion => Topic started by: parker on August 28, 2007 11:02 am

Title: engine knocking ?
Post by: parker 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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Title: RE: engine knocking ?
Post by: racerjohnson 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.

Title: RE: engine knocking ?
Post by: Ricola on August 28, 2007 9:47 pm

It's a bad thing.

Title: RE: engine knocking ?
Post by: AdamNDebbie 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

Title: RE: engine knocking ?
Post by: racerjohnson on September 05, 2007 1:30 pm

detonation sounds like popcorn popping in a microwave