Knocklink Group Buy
Trending Topics
Scooby Regular
Joined: Jun 2003
Posts: 88
Likes: 0
what is a knock sensor, why would i need one and how much are they?
serious now, i'm a newbie AND i'm Welsh (poor bugger) so pleassseeeeee explain.
My scoob, which i should be picking up shortly has a blitz boost controller, apexi ECU, stainless zorst and induction kit etc....would i NEED a knock sensor?
Matt
serious now, i'm a newbie AND i'm Welsh (poor bugger) so pleassseeeeee explain.
My scoob, which i should be picking up shortly has a blitz boost controller, apexi ECU, stainless zorst and induction kit etc....would i NEED a knock sensor?
Matt
Scooby Regular
Joined: Nov 1999
Posts: 10,504
Likes: 1
From: Scotland, UK
Knock (aka detontation, "det", pinking) is caused when the fuel and air is burned before the piston gets to Top Dead Center (TDC). This can be before or after TDC and can easily burn a hole in the piston.
The spark timing can be directly related to engine knock or detonation because if the spark is initiated too early it will cause the detonation but if it is too late there will be a powerloss and poor fuel economy.
Also, if the engine has a high compression it could cause detonation because the higher compression can cause the mixture to ignite prematurely, therefore, causing engine knock.
For instance, if you remove the cyl. head/heads from your car and have the surface milled down a substantial amount you will most likely need to retard the timing of the ignition because the compression in the engine will be greater thus it could cause engine knock.
The spark timing can be directly related to engine knock or detonation because if the spark is initiated too early it will cause the detonation but if it is too late there will be a powerloss and poor fuel economy.
Also, if the engine has a high compression it could cause detonation because the higher compression can cause the mixture to ignite prematurely, therefore, causing engine knock.
For instance, if you remove the cyl. head/heads from your car and have the surface milled down a substantial amount you will most likely need to retard the timing of the ignition because the compression in the engine will be greater thus it could cause engine knock.
Trouble is, if it's knocking badly will the ECU adjust fast enough to stop it before it seriously damages your engine.
Since knock is the devil in Impreza engines, it's best to fit an external display to make sure it's not knocking at all or if it is, you can see when and do something about it before it gets terminal.
Stefan
Scooby Regular
Joined: Oct 2002
Posts: 4,313
Likes: 0
From: At Tescos Filling Up With 99 Octane!!!
Thread
Thread Starter
Forum
Replies
Last Post
Mattybr5@MB Developments
Full Cars Breaking For Spares
28
Dec 28, 2015 11:07 PM
Mattybr5@MB Developments
Full Cars Breaking For Spares
12
Nov 18, 2015 07:03 AM