How much knock is OK?

[Boostmeister]

I'm driving along the other day with the laptop plugged in and I give it a 'little' (not WOT) gas, the car downshifts and takes off like a rocket, BUT, when I check the screen the Knock Counter has gone from 1 to 6. Degrees retard shows 0. Is this potentially damaging to the engine and how do I correct it?

I'm running a thrasher 92, '237' reg, KN, TA-49. Thanks.

 

[Dan Thompson]

Of course it should be as low as possible but normally under 6 is acceptable, but then it depend on when it happens and how high the revs, etc, etc.

So try to get it lower since you where not at WOT. Might start with checking the DP to see if it is hitting the crossover or the frame rail, just hit the cat with the side of your fist.

 

[Orion231]

KR...

The only time you REALLY have to worry about KR that high is when you are in top or 3rd where you have alot of load on the engine. It is ok to get a little knock for a second or two so long as you let out! Keeping the pedal hammered will result in blown headgasket or busted crank. Sometimes you will get spikes of KR that happen out of the blue this is real knock but sometimes it is from tip in when you hammer it and the engine load and torque twists the chassis... Some people call it false knock because nothing detonated but the sensor picked up a vibration that set it off...My advice, 7 degrees and under u r ok. Just don't ever hold down the pedal when u see more than 5 or so, because if there is real audible detonation then it will spiral up till something lets go. So when u r cruising keep an eye on that KR...its hard to hear real detonation with an open exhaust too... Of course at lower boost levels things are as bad, but the few of us who run Alky or Water Injection get used to keeping an eye on the guage...

 

[Dan Thompson]

Yeah, that's what I said.

 

[Turbojorge]

I tune for < 4* AT ALL TIMES.

Don't worry to much about knock if your tranny kicks down and you pick up something on the Scanner. Thats usually transitional knock. Like Orion231 said, see what you get at the top of 3rd. Thats what really matters.

 

[ALBERTAN]

Originally posted by Boostmeister
Knock Counter has gone from 1 to 6. Degrees retard shows 0.

Based on that info you have no knock. You had knock at some point during logging as indicated by the knock counter reaching 6. But the retard being zero indicates no knock. I think of the counter as indicating an instance of knock while the retard indicates its severity and duration. Your case really doesn't sound too serious. Go back through the logs and record a few runs if using a slower datalogger (TLink or scanmaster) and see if you can get a indication of retard.

How much knock is OK is relative. On a stock car maybe 7* is survivable. Run the same stock setup on some race gas with healthy timing and say 24 pounds of boost and 7* could become a catastrophic event. While <4* may be acceptable, your goal should always be no knock. Just my 2 cents. Good luck.

 

[Turbojorge]

Re: Re: How much knock is OK?

Originally posted by ALBERTAN

How much knock is OK is relative. On a stock car maybe 7* is survivable. Run the same stock setup on some race gas with healthy timing and say 24 pounds of boost and 7* could become a catastrophic event. While <4* may be acceptable, your goal should always be no knock. Just my 2 cents. Good luck.

Very true. When I run 30* of timing and 23psi, I make sure I have 0 KR.

So far so good, and knock on wood.

 

[Boostmeister]

Thanks for all the replies. I have never seen anything but 0 in the Gegrees Retard data field, only the Knock Counter and I have never heard any knock. I have been hesitant to go WOT because of the Counter (new engine) and I don't want to take any chances. I guess I will steadly increase the throttle opening, working my way up to WOT while monitoring the Knock Retard since this seems to be the important parameter.