Engine knock

[billman]

I have a question for you guys: Can too small andvance induce knock?

I have a stroked RS2 with 8.25:1 CR and 7A camshafts and i am in the process of mapping the engine. Yesterday i could not get and 98+ fuel so i tanked 95 and thought that maybe is good to make a map for low octane fuel also.

I have noticed that the engine had minor knock at 1 bar and above (didnt go pat 1.3 bar) from 4000 RPM onwards even with a timing advance of 9 degrees.

Does any of you have experience with a stroker Audi I5 engine?

[gunni]

Knock can be caused by retarded ignition due to the fact that extremely hotter then normal exhaust gases heat up the exhaust valve that will then later work as a ignition source when fresh charge hits it under compression stroke.

So yes.

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http://en.wikipedia.org/wiki/Engine_knocking#Pre-ignition

[billman]

in that case shouldnt i see high EGT? I will try to raise it and see how it behaves also with proper fuel.