What causes KNOCK???

[Corman12345]

What is the cause of knock, i use 92+ fuel and have even tried additives and my timing keeps retarding at high boosts

 

[98TsiAWD]

Detonation, carbon buildup on the pistons, running lean etx.

 

[Corman12345]

Originally posted by 98TsiAWD
Detonation, carbon buildup on the pistons, running lean etx.

I know its not carbon buildup because i just rebuilt the motor and its not running lean. I have an A/F meter

 

[doug]

Originally posted by Corman12345
I have an A/F meter

That doesn't really help much. Try to datalog if you can so you can see your timing curve.

 

[steve]

If by additives you mean some sort of octane booster solt in autoparts stores you need to keep in mind that it actually takes a lot more than one bottle of that stuff to go from 93 to 94 octane.

Try searching here for toluene or read http://noclownz.dnsalias.net/racegas.htm to get an idea how much "additive" you need to make any difference.

Steve

 

[1fast97gsx]

you're prolly running lean ...

 

[DSMJim]

Originally posted by Corman12345
What is the cause of knock, i use 92+ fuel and have even tried additives and my timing keeps retarding at high boosts

Stuff like 107+ Octance booster gives you 7 points of octane. That means if you have 92 octane in your tank you now have 92.7, whoptie do.

Your running too much boost, too small an injector, or too little octane.

Oh BTW your blinky light-show A/F meter is junk, pull it out of your car and throw it in the garbage it's absolutly the most useless gauge that has ever been produced to date by any gauge company. If you don't know why look it up. I'll sell you a disco ball if you want flashing lights for $10 you can hang from your rear-view mirror, it's acctually proven to be more accurate to one that's hooked upto your O2 sensor.