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Discussion Starter · #1 ·
After reading some of the recent tuning discussions on here recently I would like to fit an in-car real-time knock sensor display before starting any serious modifications such as ECU upgrade and mapping. Can anyone recommend a device, either using the standard knock sensor or an additional one?

Cheers,

Dave
 
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Discussion Starter · #2 ·
Dave,

I recall that Kevin (T27) has a knock sensor fitted to his VI which he seemed to be happy with. Possibly fitted by MA Developments, although not sure.

Steve.
 
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Discussion Starter · #3 ·
Steve is right I have a Knock Link fitted in my car, it has been calibrated using a det headset. I have modified the casing so as to fit the display lights in the instrument binacle. I can post a picture as soon as I buy a new camera :( broke the last one.

Kevin
 
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Discussion Starter · #5 ·
I bought all the components to make an AF meter years ago and they still gather dust.
I bought an autometer gauge for about $40 - 1 hour DIY fit - if that. Much more LED's to flash at you and for your passengers to ask - what's those flashy lights all about then - do you like knightrider or something - yes you can tell by my black satin shirt and bouffant hair-do.....KITT - turbo boost please.....yes Micheal....
 
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Discussion Starter · #6 ·
Thanks for the answers guys.

Kevin,

Be great to see a pic of how you have it installed. Just a few questions if you don't mind! How is the sensor connected to your car, is it in the manifold or the block? Overall, how effective and accurate have you found the Knock Link?

Lightspeed,

I'm not doing it for the Knightrider effect, I already have the flahing lights on the front of the car :D

Cheers,

Dave
 
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Discussion Starter · #8 ·
Knock Link alternatives

How to make one yourself

http://www.california.com/~eagle/knock.html


Also - ready made with lots of features

http://www.american-pi.com/safeguard.html
 
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Discussion Starter · #9 ·
Is it true that as lons as the AF mixture is kept within certain values no knock will happen?

No - it's engine timing/boost pressure/intake air temperature/combustion chamber cleanliness/compression ratio/combustion chamber design..... dependant as well as mixture dependant.
 
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Discussion Starter · #10 ·
Right, so a knock sensor would be a good idea on a car with more boost?
What types of knock sensors are available to fit the Evo 6?
 
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Discussion Starter · #12 ·
Claudius

As Lightspeed says the car already has one. The ECU will retard ignition if it senses detonation. Problem is I guess there is only so far it can retard. A gauge in the car will enable the driver to see if they have a knock problem or not. This is something I would have thought is as important as a boost gauge when modifying, but not many people seem to use one. I'm after one before I start some serious modifications just as a precaution.

I have also been looking for some gauge or display that works off the standard sensor, but haven't been able to find anything. Not sure if that would be a good way forward anyway as most people I have spoken claim the standard sensor isn't that good, but in most cases it is the sensor the ECU is reacting to.

Dave
 
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Discussion Starter · #13 ·
Apparently knock sensor is quite a science. The sensor works by detecting a particular variation in the sound wave the engine makes. Problem is this changes as the engine is altered. It is one of the reasons why Motec don't provide knock sensing - it can't be done reliably on widely varying engines.

The best way to protect from knock is to have the car properly set up using det cans and then monitor the things that cause knock to happen,like mixture, air temperature, boost, octane level etc.
 
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Discussion Starter · #16 ·
unfortunately, knock and A/F meters are of little use as it's difficult to watch them and the road at the same time, given that the critical time is when your foot is flat. May have some application for dyno or passenger tuning but not as good as logging.

a MUCH better way if you want to know what is happening is to log ie:

in this log i have just floored it at around 4500rpm TPS (throttle position 100%), KNK is the noise picked up by the knock sensor, MAP is the absolute manifold presure in KPa so 200 |EQU| 1 bar boost, 250 |EQU| 1.5 bar boost, etc

RPM MAP INJ TPS KNK ADV
4640 161 53 100 19 3
4710 221 87 100 27 3
4826 245 95 100 69 3

boost hits 1.45 bar, knock sensor noise rises as the boost comes in, ok so far

4941 254 99 100 159 2

boost now 1.55 bar, kerbang!!, look at the large increase in knock noise (159), this is probably detonation...note that timing is only 2 deg (|PLS|6 deg static |EQU| 8 total advance), injectors wide open... water injection any one?

5061 255 99 100 90 2
5181 254 99 100 40 2
5298 254 99 100 45 2
5413 247 99 100 43 3
5509 242 98 100 41 3

boost peaks at 1.55 bar (or a little more), knock noise droping again, all is well...

5634 240 98 100 37 3
5729 241 99 100 62 3

boost now holds at 1.4 bar till redline...

5845 241 99 100 119 3

kerbang! ouch, another one, easy to see 119 sticks out, could take a deg out of timing here (or link will if knock retard is activated)

5920 240 99 100 76 5
6015 240 98 100 53 5

it then settles down again and i am through the detonation danger zone (do have what appears to be 'phantom knock' at 7000 but that is another story)

-there is nothing wrong with the factory knock sensor
-knock is easy to see as background noise level increases with rpm when at full power and if there is a huge jump it is probably knock (may also be something else )
-data log only way to go!
-also link uses sophisticated algorithm to detect knock event (you can set threshold) and then will remove timing if knock retard on
-also logs o2 reading but haven't shown it here

andrew
 
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Discussion Starter · #17 ·
Andrew

This is exactly why I want to change my ECU :). However, I don't think I'll log and view every run in the car and I don't want to find out I have been suffering from bad detonation 5 days (or whatever) after the event. I want to able to see straight away if I have a detonation problem and do something right away about it, even if it's to just backing off. Keeping an eye on a knock gauge can't be any more difficult than a boost gauge provided it is mounted in the right place, easier perhaps if it uses lights.

Blade,

The feedback I am getting everywhere is that it is difficult to sense knock, but it can be achieved with good sensoring and calibration. After all it is a key part of most engine management systems on Evo's. Getting the car set up without detonation is one thing, but making sure it stays that way must be another. What if something changes like fuel or atmospheric conditions or a fault develops and detonation starts to occur? Your car must be running on the limit of detonation, but can you safely say if you are suffering from detonation whilst in the middle of a track day or be comfortable that none is occuring? For the cost of a detector and/or display it could be a wise modification providing at least an indication of a problem.

Dave
 
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Discussion Starter · #18 ·
i have to slightly disagree with andew on this one, if you have a knock display as the knock link you can see the noises on the led, so i they rise steadely they are just engine noises ( normal) however spikes in the display are porbably knock.

blade
what you need to do is calibrate the knock link to the det cans so they close. obviously they will not be as accurate as det cans but they will tell you when you knock. although motec maybe right , i would rather be safe than sorry.

probably the best way to mount it will be the steering column.
 
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Discussion Starter · #19 ·
dave, others,

ok i was assuming you were getting a link ecu, if you get a motec or other ecu that doesn't have knock protection then it may be better than no protection at all

because link works to detect and then prevent knock, you probably won't see anything much on the knocklink, because any time detonation occurs the timing will be retarded to prevent it (to a max of 6 degrees or static setting which ever occurs first)

you can check to see if the knock detect system has been activated at any time by looking on the hand controller (will save info until ignition turned off), you can also see how bad it was by how much timing it has pulled attempting to stop it, and where in the rpm range it occured (no need to wait 5 days, back straight will do)

the hand controller can also be set to display knock sensor reading in real time if you want, ala knocklink, although i prefer to let my ecu 'do the thinking for me' so i can concentrate on where i am going

andrew
 
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Discussion Starter · #20 ·
andrew
the link ecu will not try to figure out if the noise the engine produced is knock or not. it will tell you how many times did the engine noises go above a certain user defined threshold. so if you set the threshold (knock menu on the controller ) too low then you knock counter on the controller will register loads of knocks when it is in fact only hearing engine background noises. too high and you are only picking up big knocks only. data logging is the best way to tell if you are knocking or not but also a knck link is very useful when tuning as you can see the little spikes and when they happen so you can adjust your timing accordingly.
 
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