5810ap1

Hi. What is safe knock count,,,I have been getting 10 counts of knock every gear 3rd gear and up...running 10psi/kpro/8.88-1 comp....should I try to aim for 0 knock...I searched many threads but could not get answers.........when is it considered unsafe in F20c. Thanks.:

s2kseven

Truth is, you will only hear the severe engine knock. Human ears will never hear 80% of the combustion knocks. tHERE are knocks that human ear cannot interpret. That is why knock sensor buried in the heart of the engine.
There are threshold values that the ECU relying with (through electronics). You can't rely on what you hear. If there are issues in the fueling system -
say in...(octane grade-air fuel mixture & advance timing), best to rely in the ECU threshold value (most ECU's default threshold is 50 knocks) before the ECU will react to the change. Example ... if the ecu hear say 50 knocks (this is by mili-seconds), the ECU will decrease say the advance timing to 2, 3, 4 degrees. You have a decision to make changing the threshold value. That's why there are tools for you ---> you need to learn how to interpret datalogs & not rely on what you hear or it'll result to a catastrophic engine failure.

5810ap1

HI, thanks for the reply.......I am using logs to monitor knock/timing/etc..

camuman

Can it show knock voltage?

s2kseven

Knock sensor uses piezoelectric voltage signal -- converting it to electrical charge.

camuman

I meant can the program display the knock voltage instead of knock count. What does knock count even mean?

s2kseven

Yes...in AEM you will see voltage when there is a knock. A knock sensor is 0-5 volts. Stay away from a higher voltage but every engine behaves differently.

"What does knock count even mean?"

Well, self explanantory...it's a measuring stick if your engine functioning well. As I mentioned, the grade of fuel -
too much boost - too much advance timing & wrong air fuel mixtures absolutely will destruct the engine. Counting knocks over the threshold need immediate attention.
But, rule of thumb is, if you see higher spikes, take timing out there and check if it goes down. If so it was knock, if not, its engine noise.

Ben @ Carolina Dyno

There is a lot of misinformation out there about how a knock detection system works. Most software doesn't have the ability to properly detect knock once aftermarket parts are installed. s2kseven is right about the sensor being a piezoelectric transducer, which is basically nothing more than a microphone. The stock ecu amplifies this signal and looks for noise AT CERTAIN FREQUENCIES this is key in differentiating real knock from engine noise. By looking for noise in certain frequency ranges Honda is basically putting a filter on the channel to block engine noise from creating a false knock reading. If you look into other aftermarket knock systems (MoTeC SKM manual can explain all this in more detail) you will see they operate in the same fashion.

Now think about how this relates to your application. You have an ecu out of a different car that has an entirely different block, head, exhaust, valve train, etc. It's not tuned to the same knock frequency that yours is. If you log knock voltage you will see it rise rather high sometimes almost to 5v (it's max reading) in direct proportion to RPM. Obviously your engine is not knocking more and more as the rpm's climb it's just getting louder and louder. The problem with looking at voltage is you are looking at overall noise. To determine if it's knocking you need to look for spikes at certain frequency levels which you can't do.

That said you can't really use knock counts to determine if your engine is really knocking. If your knock counts are high and taking away timing lowers them it is likely real knock. If you're timing is already below a reasonable level and you still have knock counts you are most likely looking at noise. The filtering in the K-Pro software can help with this somewhat but the truth is it's never going to be any better than using some common sense and having it properly dyno tuned.

mase1

I agree with most of what you said except for this. IF the tables arent setup correctly then your statement doesnt hold true.


To the OP, in regards for the sake of argument, the BEST course of action is to have the engine dyno tuned correctly and setup for the knock tables, after all if its been properly tuned you shouldnt be having to guess if its knocking or not. Its impossible to say without looking at the calibration or any datalogs if your engine's knock count is too high.