Knock levels

[goodwrenchdave]

I,m trying to continue tweaking my tune after a few mods. The tune I'm using is based on an original mail order tune made for my setup . Its a supercharged 2008 g8. runs great.
I'm terrified of detonation (knock) as its what blows apart such builds.
got plenty of injector and fuel and going up to a 2.55 pulley from stock. j
Noticed that the mail tunes knock settings have been modified from stock- likely due to the supercharger gear noise (dont know.....)
especially on the initial, min and multipliers. the transient values are not modified.
does anybody know or can suggest what these levels would be safe at or by what percentage of initial is a safe change. I,m just worried they may have been set too low in sensitivity. and there is minimal information as to what is normal.

[kingtal0n]

You can't depend on knock sensors for tuning high performance engines. I recommend focus more on tuning the engine correctly and inspections/maintenance which can assure reliability, and gain the knowledge to determine safe tuning practice.

Knocking has primary particular variables in tuning with relation to the mechanical setting up
1. IAT
2. Fuel quality, air fuel ratio & fuel behavior
3. Compression ratio , outside of boost and over time with boost added
4. Timing

Some variables cannot be easily interpreted or measured in an ideal way that have influence
A. Combustion chamber and piston heating per power throughput (power/time)
B. Heat retention vs rejection, e.g. insulation, piston oil squirts - oil cooling, heat transfer - plug heat range, initial temperature of components
C. Carbon cycling
D. Injection spray timing contribution to knock resistance


Never tune or depend on knocking to save the engine. In a factory engine it may work within some range of tolerable conditions but in a performance engine often by the time it starts to knock the damage is already done anyways.

[edcmat-l1]

OP, yes there is an acceptable level of KS sensitivity modification. Post up your file and I'll tell you if it's too much.

I will tell you that if you're not seeing any knock retard, that's scarier than seeing KR.

[kingtal0n]

I will tell you that if you're not seeing any knock retard, that's scarier than seeing KR.

Think about this, it is evidence that the knock sensors are not actually helping or giving useful information when it matters. Just noise. If it was real knock the engine is being damaged, head gasket would be damaged, compression into coolant, water in the oil, all the bad things would happen in a forced induction application. But no, the knock sensors report knock but there is no knock. Or the knock sensors fail to report knock and the engine falls apart, its been ruined. I've never seen a knock sensor actually reporting knock when there was real dangerous knock and if I would have it was already too late damage is done.

Go ahead and fix them so they light up and you get KR all the time and... and thats it. Its just a light on the dash that turns on with no real meaning. Like the gem in diablo 2 lobby.

[edcmat-l1]

Think about this, it is evidence that the knock sensors are not actually helping or giving useful information when it matters. Just noise. If it was real knock the engine is being damaged, head gasket would be damaged, compression into coolant, water in the oil, all the bad things would happen in a forced induction application. But no, the knock sensors report knock but there is no knock. Or the knock sensors fail to report knock and the engine falls apart, its been ruined. I've never seen a knock sensor actually reporting knock when there was real dangerous knock and if I would have it was already too late damage is done.

Go ahead and fix them so they light up and you get KR all the time and... and thats it. Its just a light on the dash that turns on with no real meaning. Like the gem in diablo 2 lobby.

Think about this, you don't really know what you're talking about. GEN4 knock sensor systems work pretty damn well. There isn't much you or anyone else is gonna "School" me on when it comes to these cars. Don't embarrass yourself.

Go try and school noobies or something. Your BS ain't workin here.

[kingtal0n]

Think about this, you don't really know what you're talking about. GEN4 knock sensor systems work pretty damn well. There isn't much you or anyone else is gonna "School" me on when it comes to these cars. Don't embarrass yourself.

Go try and school noobies or something. Your BS ain't workin here.

A good tuner does not use knock sensors or rely on knock sensors to tune a high performance engine. Tuning is done before you see the engine. I write my timing maps before I see the car and only minor adjustment afterwards. We might enable knock sensors after the fact and do some comparisons with various fuels but there is no way we can force an engine to knock under extreme load to generate the kind of acoustic recording necessary to dial in a knock sensor for wide open throttle successfully without risking the engine health. It would be blatant abuse of somebody else property.

Knock sensor may be used for part throttle knocking but that is not a concern for correct tuning as you've identified the type of engine config and have intuitive knowledge how the engine works and what to expect.

Only tunes I see actually pinging at part throttle working over a knock sensor are the OEM tunes and especially when people use the wrong fuel, bad gas, too much timing or fail to maintain their engines (carbon buildup) in which case knock sensor or no knock sensor the knocking comes and goes forever until the engine is cleaned, tuned properly, or repaired or replaced.

1,000 performance turbo engines and I've never heard knock or seen a knock sensor do anything really. You think you know but all I can tell is that you're using knock sensors for something which tells me you don't actually know what you are doing fully yet. I feel that you do not tune any stand-alone computers and have no read the instructions on how to setup an aftermarket knock sensor on a high performance forged configuration.

[Alvin]

I,m trying to continue tweaking my tune after a few mods. The tune I'm using is based on an original mail order tune made for my setup . Its a supercharged 2008 g8. runs great.
I'm terrified of detonation (knock) as its what blows apart such builds.
got plenty of injector and fuel and going up to a 2.55 pulley from stock. j
Noticed that the mail tunes knock settings have been modified from stock- likely due to the supercharger gear noise (dont know.....)
especially on the initial, min and multipliers. the transient values are not modified.
does anybody know or can suggest what these levels would be safe at or by what percentage of initial is a safe change. I,m just worried they may have been set too low in sensitivity. and there is minimal information as to what is normal.

I try to go as far as I can without modifying the knock sensor sensitivity. Most GEN 4's are OK with stock settings.

Do you know what knock sounds like? It could be a flat out knock, or it can sound like small rocks hitting the car, if its bad enough it can sound almost like static noise. If your not hearing it nor seeing it.. you are likely ok.

[kingtal0n]

I try to go as far as I can without modifying the knock sensor sensitivity. Most GEN 4's are OK with stock settings.

Do you know what knock sounds like? It could be a flat out knock, or it can sound like small rocks hitting the car, if its bad enough it can sound almost like static noise. If your not hearing it nor seeing it.. you are likely ok.

Knock sensors detect frequencies of knock as it begins... the distinctive ringing of engine parts think of a tuning fork touched with the correct tool vs your finger.

The frequency of knocking onset is inaudible to human ears.
In fact knock sensors typically cannot detect audible pinging from what I understand. If they do then it is because the knock persist in both (wide) frequency ranges.

And if the internals or engine parts have changed... anything including balancer or valvetrain, it can push sound frequency into new ranges where the knock sensor cannot detect.
In fact even the mounting of the sensor is critical, if the sensor is too tight or loosened up or the mounting is deteriorating, the sensor may detect too much amplitude or too weak and be completely useless.

They are unreliable in performance applications , generally. As somebody said "extremely sensitive" its true that

[edcmat-l1]

Knock sensors detect frequencies of knock as it begins... the distinctive ringing of engine parts think of a tuning fork touched with the correct tool vs your finger.

The frequency of knocking onset is inaudible to human ears.
In fact knock sensors typically cannot detect audible pinging from what I understand. If they do then it is because the knock persist in both (wide) frequency ranges.

And if the internals or engine parts have changed... anything including balancer or valvetrain, it can push sound frequency into new ranges where the knock sensor cannot detect.
In fact even the mounting of the sensor is critical, if the sensor is too tight or loosened up or the mounting is deteriorating, the sensor may detect too much amplitude or too weak and be completely useless.

They are unreliable in performance applications , generally. As somebody said "extremely sensitive" its true that

I'm well aware how a knock sensor works.

To say that they are ineffective in a GEN4 application is incompetence.

One more thread where you really don't know what you think you do. Glad you're posting it for everyone to see.

[kingtal0n]

I'm well aware how a knock sensor works.

To say that they are ineffective in a GEN4 application is incompetence.

One more thread where you really don't know what you think you do. Glad you're posting it for everyone to see.

Using knock sensor to tune an engine is a mistake. A careless, senseless, abusive mistake.

They are as effective as your ability to interpret the data like any other sensor.

I never said the knock sensor was ineffective. In my words Over-sensitive is not ineffective anymore than an oversensitive EGT gauge. I did infer that because of the way cause and effect works that it stands to reason by the time knock sensors become relevant in a high output application the damage is already done. Have to knock the engine to detect it, so how good is that going to be for your effort?

Better just to know what you are doing and not knock the engine in the first place. When you are that good, knock sensors won't be relevant anymore.

[edcmat-l1]

Using knock sensor to tune an engine is a mistake. A careless, senseless, abusive mistake.

Nobody said they were using "knock sensors to tune an engine". Those are your words.

[kingtal0n]

Nobody said they were using "knock sensors to tune an engine". Those are your words.

You need to make it clear that you are not using knock sensors to tune an engine , because that is not the message I think people are getting when they read your post about sensitivity.

Follow now,
Assemble an engine and transmission correctly, clean. Pressure tested. Timing tested. Compression is even. Correctly supporting hardware calibrated. Set the a/f and timing.

Then, after all of that, knock sensor should not be a thought or prayer and any attempt to adjust sensitivity is arbitrary because there is no reference value of noise. A stock setting is not a reference value for a performance engine. All you can do and the instruction manuals can suggest is to forcefully ping the engine to determine noise reference values. And I have never found that necessary or even practical because components typically change in performance applications before significant mileage accumulates. And the last thing you want is to force a knock condition at wide open throttle in a forced induction application and this goes double for high quality fuels which can cause pressure related damage despite not knocking and no knock detection.


editing because,
On second thought, useless might be applicable after all. In a hobby installation, anyways. Useful for spot checking but then you hand the vehicle to someone who has a scanner and its still useless to them after all.

[edcmat-l1]

You need to make it clear that you are not using knock sensors to tune an engine , because that is not the message I think people are getting when they read your post about sensitivity.

You need to shut the hell up and learn to read.

The OP asked:

does anybody know or can suggest what these levels would be safe at or by what percentage of initial is a safe change. I,m just worried they may have been set too low in sensitivity. and there is minimal information as to what is normal.

And I replied:

OP, yes there is an acceptable level of KS sensitivity modification. Post up your file and I'll tell you if it's too much.

I will tell you that if you're not seeing any knock retard, that's scarier than seeing KR.

You post to hear yourself talk. You're wrong more often than you're right.

You even posted in this thread they're over sensitive.

Jeez man just shut the hell up and go away.

[kingtal0n]

My turn to interpret:

Paraphrasing of course
The OP asked:
"I have a supercharged engine and I'm worried it might be knocking so is there anything I can do with the knock sensors to make them more sensitive so I can make sure the tuning is correct"

And you replied:
"Yes the knock sensors can be reliable when the sensitivity is correct to help you (do the thing you wanted to do, i.e. check the tuning of the engine)"


What you should have replied is something like,
"Yes the knock sensors can be increased in sensitivity however their sensitivity setting is arbitrary and they may be triggered for no reason without provocation or tuning related issues which is probably why they were disabled in the first place by a tuner who didn't want arbitrary (false) knock detection pulling timing which could rise the EGT and lead to other issues"

More harm than good having those knock sensors light up for no reason.
If the tune is shit and the knock sensors are going off its just as fucked as if there is no knock detection, knock detection wont save the engine. That is not what it is for. The op thinks they can be used to determine safe tuning and they cannot be used in this manner yet your reply leads him to believe that they can. That is why I have an issue, you are leading the op to believe some fantasy and it can ruin his engine.

[edcmat-l1]

My turn to interpret:

Paraphrasing of course
The OP asked:
"I have a supercharged engine and I'm worried it might be knocking so is there anything I can do with the knock sensors to make them more sensitive so I can make sure the tuning is correct"

And you replied:
"Yes the knock sensors can be reliable when the sensitivity is correct to help you (do the thing you wanted to do, i.e. check the tuning of the engine)"


What you should have replied is something like,
"Yes the knock sensors can be increased in sensitivity however their sensitivity setting is arbitrary and they may be triggered for no reason without provocation or tuning related issues which is probably why they were disabled in the first place by a tuner who didn't want arbitrary (false) knock detection pulling timing which could rise the EGT and lead to other issues"

More harm than good having those knock sensors light up for no reason.
If the tune is shit and the knock sensors are going off its just as fucked as if there is no knock detection, knock detection wont save the engine. That is not what it is for. The op thinks they can be used to determine safe tuning and they cannot be used in this manner yet your reply leads him to believe that they can. That is why I have an issue, you are leading the op to believe some fantasy and it can ruin his engine.

You're an idiot. No one ever said anything about increasing their sensitivity.

Please stop misinterpreting things and telling me how to post. I said exactly what I meant to say. It's not my fault you have a problem with reading comprehension.

What you should have replied is "Ed is right and I am wrong as I usually am". That would have been your most accurate post of the day.

Just go away. You don't know what you think you know.

[kingtal0n]

Please stop misinterpreting things and telling me how to post. I said exactly what I meant to say. It's not my fault you have a problem with reading comprehension.

What you should have replied is "Ed is right and I am wrong as I usually am". That would have been your most accurate post of the day.

Just go away. You don't know what you think you know.

If I am wrong, prove it. Tell me what you think increasing the sensitivity on the op's knock sensor is going to accomplish in relation to his concern about knocking with the supercharged engine tuning.

[edcmat-l1]

If I am wrong, prove it. Tell me what you think increasing the sensitivity on the op's knock sensor is going to accomplish in relation to his concern about knocking with the supercharged engine tuning.

I will say it again. No one said anything about increasing the sensitivity of the knock sensors. My GAWD you're an idiot sir. You have no read comprehension skillz what so EVA!!

The sensors are too sensitive in stock form. The idea is to DEsensitize them just a WEE bit. The OP wanted to know if there is an acceptable level. I replied yes there is, post your tune and I'll tell you if they're ok.

You have been off base, as you normally are, from the very beginning.

I'll say it again. STFU and go away you don't know WTF you're talking about.

[kingtal0n]

His sensors are already de-sensitized. You are going to increase their sensitivity because you claim they should be 'showing knock'. You are worried that they are not showing any knock.

The knocking levels are arbitrary. Low, High, a "wee bit". You make me laugh. If I told my pi I was going to increase the concentration of some chemical or reagent a 'wee bit' I would get a 3 hour lecture.

Non scientific, okay. I give you room because you are not a scientist. However there is the reality that your setting vs the current setting vs the stock setting is all arbitrary and none of the settings nor the use of knock sensors are going to help with his concerns of

I'm terrified of detonation (knock) as its what blows apart such builds.

I'll say it again,

Your 'wee bit' of adjustment is not going to cure or remedy the

I'm terrified of detonation (knock) as its what blows apart such builds.

problem.

You are offering a suggestion which is neither a solution nor has any quantifiable expression in relation to the proposed problem.

I just want you to use logic and stop relying on heuristics which leads to hubris which leads to somebodys EGT skyrocketing due to unknown variables, you don't know who installed those sensors or if they are even correct model or if something else has been done to his engine. You are only making random arbitrary changes without any evidence or logic flow. Not good practice. Luck, you rely on luck.

[edcmat-l1]

His sensors are already de-sensitized. You are going to increase their sensitivity because you claim they should be 'showing knock'. You are worried that they are not showing any knock.

You're clueless. I did not say I was going to increase them. I said I would let him know if they're ok. There is such a thing as desensitizing them too much.

The knocking levels are arbitrary. Low, High, a "wee bit". You make me laugh. If I told my pi I was going to increase the concentration of some chemical or reagent a 'wee bit' I would get a 3 hour lecture.

The knock sensor sensitivity is not arbitrary. My "wee bit" comment is my way of saying "I know how much but I'm not telling"

Non scientific, okay. I give you room because you are not a scientist. However there is the reality that your setting vs the current setting vs the stock setting is all arbitrary and none of the settings nor the use of knock sensors are going to help with his concerns of

You are no scientist either. The difference between me and you, you're trying to convince everyone you are.

I'll say it again,

Your 'wee bit' of adjustment is not going to cure or remedy the problem.

You are offering a suggestion which is neither a solution nor has any quantifiable expression in relation to the proposed problem.

I'll say it again. You don't know what you're talking about. It is in everyone's best interest on this board to completely ignore you.

First off, you don't know that there's a "problem". The guy asked for advice about something very specific. Something I have extensive knowledge in/of. That being, GEN4 knock sensor system's sensitivity.

I just want you to use logic and stop relying on heuristics which leads to hubris which leads to somebodys EGT skyrocketing due to unknown variables, you don't know who installed those sensors or if they are even correct model or if something else has been done to his engine. You are only making random arbitrary changes without any evidence or logic flow. Not good practice. Luck, you rely on luck.

My logic is, I've tuned well over 1000 GEN4 systems. I had them figured out a long time ago. I know what works and what doesn't. I know if you tune a GEN4 vehicle so there is NO knock retard, you've either deadened the sensors to the point they don't work or you've pulled so much timing you've detuned the engine.

Everyone is skeered of knock retard and that seems to include you. KR is not the end of the world. Bone stock vehicles have knock retard. The system is setup the way it is for a reason.

Now, you've already stated how these systems don't work and if you see knock retard it's already too late. You've shown your level of knowledge in this area.

You're clueless. Simple as that. Clueless.

[kingtal0n]

To the op and other would-be knock sensor users I propose this questions to consider,

As you increase the sensitivity or decrease the sensitivity of the knock sensors and begin to detect knock (or not)

A. How will you know whether any knock is 'real'
B. If the knock sensors do not detect any knock, how will you know that they can detect 'real' knock?
C. will you keep increasing the sensitivity until they do? And then A. again

And now,
D. If you find out the knock sensors are picking up false knock by adjusting fuel quality, what then? Do you
1. Reduce sensitivity and hope/pray that they will pick up true knock when it happens?
2. leave the false knocking and hope the tune file can compensate extra when real knock happens?

And the killer
3. If there is real knock and the response is to pull timing, how will you regulate the EGT rise due to significant timing reduction during a pull where the driver isn't looking at the laptop during knocking condition whether real or false?


Juggling these issues and considering all possible outcomes should lead you to the conclusion that the knock sensors are not to be used as a tuning tool and cannot be used to deal with this issue

I'm terrified of detonation (knock) as its what blows apart such builds.

The correct way to deal with this issue is to tune the engine correctly and make sure if the knock sensors do activate that the response of the ECU In terms of timing reduction or fuel addition does not cause (further) harm to the engine.
This has more to do with response than sensitivity, sensitivity is arbitrary but the response is precisely predetermined and can be made to work well in false and true knock situations both.


Again sensitivity cannot be properly adjusted by turning down or up the sensitivity 'a wee bit' and honestly it cannot be done at all in a high output configuration without forcefully pinging the engine under load enough to calibrate the knock sensors to the aftermarket condition assuming the engine was modified.

It is reasonable to ask these questions and I hope for everybodys sake they ask themselves.