Knock after block and head skimmed twice

[Giiioo]

i build engine last year, block was bored to 87mm and skimmed, head was also skimmed, after 7000km head was lifted duo to standard arp studs, split motor again, skimmed both block and head, in total skimmed 0.6mm. now installed 625+ studs and still stock head gasket, on dyno day connect knock gauge on stock knock sensor it shows knock on 6000+rpm on any timing even on 0 degree, if knock control is on timing retarding even on idling, car is running on spring mode 0.5 bar boost, pistons is 8.5.1 compression, 93 octane, is it possible stock knock sensors is to sensitive for aem v2 or my problem is compression ratio? tuner said need oversize head gasket, i ask other tuners they said with 0.6mm skimming my ratio will be somewhere 9.0.1 and that can not be reason for detonation, i want make sure my problem is head gasket size before i split my motor again

[Tricky-Ricky]

Knock sensors are piezo electric and do suffer a form of wear, in the form of a frequency shift, also bore size determines resonant knock frequency,

also a much modified engine can often cause false positives due to high frequency vibration/resonance, its worth fitting whats known as a wide-band sensor, if the V2 is capable of responding a wider range of signal.

 

I would also say that IMO a compression change from 8.5 to 9 to1 on 93 octane fuel is enough to cause knock if the map has not been tweaked.

[Giiioo]

Knock sensors are piezo electric and do suffer a form of wear, in the form of a frequency shift, also bore size determines resonant knock frequency,

also a much modified engine can often cause false positives due to high frequency vibration/resonance, its worth fitting whats known as a wide-band sensor, if the V2 is capable of responding a wider range of signal.

 

I would also say that IMO a compression change from 8.5 to 9 to1 on 93 octane fuel is enough to cause knock if the map has not been tweaked.

thanks for reply. problem is boost is only 0.5 bar, tuner retard timing up to 0 but still showing knock on the gauge,

[Tricky-Ricky]

As I said, try changing the sensor.

[chrispot]

i build engine last year, block was bored to 87mm and skimmed, head was also skimmed, after 7000km head was lifted duo to standard arp studs, split motor again, skimmed both block and head, in total skimmed 0.6mm. now installed 625+ studs and still stock head gasket, on dyno day connect knock gauge on stock knock sensor it shows knock on 6000+rpm on any timing even on 0 degree, if knock control is on timing retarding even on idling, car is running on spring mode 0.5 bar boost, pistons is 8.5.1 compression, 93 octane, is it possible stock knock sensors is to sensitive for aem v2 or my problem is compression ratio? tuner said need oversize head gasket, i ask other tuners they said with 0.6mm skimming my ratio will be somewhere 9.0.1 and that can not be reason for detonation, i want make sure my problem is head gasket size before i split my motor again

 

 

i am no tuner but i thought it was best to listen to knock with headphones from the knock sensor, rather than an electronic knock detector due to other noises that are hard for a electronic device to filter out?

 

maybe try the above method?

 

or can you hear the engine knocking with your own ears?

 

regards chris

[Giiioo]

i am no tuner but i thought it was best to listen to knock with headphones from the knock sensor, rather than an electronic knock detector due to other noises that are hard for a electronic device to filter out?

 

maybe try the above method?

 

or can you hear the engine knocking with your own ears?

 

regards chris

I have to fit opel knock sensor and listen with headphones. I post result soon as i have news. Thanks for your reply

[chrispot]

i did have one thought on listening to engine knock, rather than listen to knock through headphones listen to knock through car stereo as most have a aux input, but more for road based tuning. or could be set up to check once now and again after mapping on rolling road? not sure if it's necessary to checked once mapped but can't hurt for piece of mind?

[Giiioo]

i did have one thought on listening to engine knock, rather than listen to knock through headphones listen to knock through car stereo as most have a aux input, but more for road based tuning. or could be set up to check once now and again after mapping on rolling road? not sure if it's necessary to checked once mapped but can't hurt for piece of mind?

car was on dyno but we can't continue tuning duo to knock shows on the gauge.

[chrispot]

i was not refer to your problem you have now. just something that could / might be useful in the future? hope you get it sorted. let us know what the problem was.

[Giiioo]

I will post it soon

[Tricky-Ricky]

I have to fit Opel knock sensor and listen with headphones. I post result soon as i have news. Thanks for your reply

 

Knock frequency for 87mm bore size is 6.6 kHz so are you sure the Opel knock sensor can respond to that frequency? if its intended for a different engine/bore size it will not respond correctly.

How was the knock registered before? via the std Toyota sensor via the AEM? or by some other means?

Normally if knock is detected the ECU should be setup to retard the ignition, was this the case on the dyno?

 

And as chrispot says, even if you have electronic knock detection its always better to have a physical means of listening, you cant beat det cans! I am surprised that your tuners would map without, I always used det cans even though I had a Phormula KS4 fitted as well as std knock sensor.

[Giiioo]

Knock frequency for 87mm bore size is 6.6 kHz so are you sure the Opel knock sensor can respond to that frequency? if its intended for a different engine/bore size it will not respond correctly.

How was the knock registered before? via the std Toyota sensor via the AEM? or by some other means?

Normally if knock is detected the ECU should be setup to retard the ignition, was this the case on the dyno?

 

And as chrispot says, even if you have electronic knock detection its always better to have a physical means of listening, you cant beat det cans! I am surprised that your tuners would map without, I always used det cans even though I had a Phormula KS4 fitted as well as std knock sensor.

when knock control was on on aem v2 timing was retarding by 6 degree on idling about 3500rpm, after that we try knock gauge, connected to stock sensor n2, at pick torque there was no knock but after 6000-6500rpm gauge shows red, it was a same on 15degree and 0 degree of timing, i can post my map if someone is good here for aem v2, maybe i need knock setting

[Tricky-Ricky]

when knock control was on on aem v2 timing was retarding by 6 degree on idling about 3500rpm, after that we try knock gauge, connected to stock sensor n2, at pick torque there was no knock but after 6000-6500rpm gauge shows red, it was a same on 15degree and 0 degree of timing, i can post my map if someone is good here for aem v2, maybe i need knock setting

 

I presume you mean that knock control was retarding ignition by 6 degrees from idle to 3,500rpm,

and if there is no knock at peak load, but registering knock after 6,000rpm at low boost pressures, says to me that there is definitely something amiss.

Was the base ignition timing and valve timing set correctly after the rebuild?

Are you using the same map that was used before the engine rebuild?

What are the AFRs during peak load and after 6,000rpm?

Who is doing the remapping?

[Giiioo]

I presume you mean that knock control was retarding ignition by 6 degrees from idle to 3,500rpm,

and if there is no knock at peak load, but registering knock after 6,000rpm at low boost pressures, says to me that there is definitely something amiss.

Was the base ignition timing and valve timing set correctly after the rebuild?

Are you using the same map that was used before the engine rebuild?

What are the AFRs during peak load and after 6,000rpm?

Who is doing the remapping?

yes you're rite, sorry for my bad english, my friend is tuner, car was running perfect 7000km, she made 673whp on dynodinamics on 27psi 93+water methanol, all was good until head lifted, when i split motor block and head needed skimming again, my tuner recommend me to go for over sized hg but i was think car will be more fan with little bit high compression and it is, i have full boost on spring mode at 3900rpm and its very responsive,i'm using boostlab s366 billet turbo, spa ported cast manifold, we setup base timing also try to play with cam gears and mix some millers octane booster but knock was still there all the time, when we change intake valve timing he change it in ecu to. afr was 11.2-11.4 on previous tune he listen with headphones, now we try with gauge, we will try listen again and see is it detonation or something else Edited April 27, 2015 by Giiioo (see edit history)

[Morpheus]

You could always Diamondyze the pistons and coat the valves and chambers.

 

They claim to be unable to get their test engine to knock under any circumstances after treatment.

 

http://camcoat.com/main/

 

http://diamondyze.co.uk/test-results/

Edited April 27, 2015 by Morpheus (see edit history)

[Giiioo]

found one problem, i don't know how that happened, plug for n4 injector was connected on n5 and n5 was connected on n4, i hope that was my issue, car will be back on dyno soon and i will post result. thanks guys for your help.