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Discussion Starter · #1 ·
When engines have failed on the VR38 which cylinders normally go and when rods have bent which cylinders are these common to happen on.
Reason i ask is i have been doing some calibrating on the VR38 for a whole new breed of engine control on the GTR and found some interesting results last night when setting up the Closed loop individual cylinder knock control.

Below is a log showing the knock traces from each cylinder


Red is Cyl4 and Dark Blue is Cyl3 you can see the difference compared to rest. The centre cylinders are always louder so gain has been adjusted to suit already which is due to the knock sensor placements but even so the centres are always first to knock and its not just because sensors are placed in centre of block as it knows which cylinder its firing based on listening to the correct Freq in a set window after each event has occured so shows that maybe the centre feed intake design favours the centre cylinders or its just purely down to that the centres run hotter due to cooling designs.
Will back up when I get all 6 egts in the manifolds.
Just to note the stock ecu regarded none of the above as enough to pull timing as i have left the stock in to keep the canbus happy and monitor knock as a extra sanity check (will be removed next week when canbus patch is applied
)

But interesting enough now the standalone ecu is running the engine and injection has been set to match the larger injectors properly it enabled the engine to take more timing and produce the below.


Ryan

BTW before anyway asks why its lost power below 2400rpm its due to how much time the load it kept against the engine at the beginning of the run. The longer its held the more boost its creates.
 

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There are a few impressive looking spikes on the #4 trace (esp just before 10s), but I think your gain is still a bit high considering the overall noise from that cylinder. How do the gains you've set for your graph/display/logging relate to the noise thresholds the OEM ECM uses for knock control?

From previous testing I also found that even an apparently high impedance op amp (10Mohm claimed) input can drag down a knock sensor signal, so were you using the OEM knock sensors for your logging at the same time as the OEM ECM was using them for knock control?

The OEM ECM knock control doesn't appear to have any dynamic adaptations like say the 4G63 has, but I believe it is still gated and filtered. With a lot of internals the centre cylinders just saturate the OEM settings and you end up at 65535 which disables the knock control on that cylinder. Perhaps aftermarket you can get more dynamic range through gain control.
 

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There are a few impressive looking spikes on the #4 trace (esp just before 10s), but I think your gain is still a bit high considering the overall noise from that cylinder. How do the gains you've set for your graph/display/logging relate to the noise thresholds the OEM ECM uses for knock control?

From previous testing I also found that even an apparently high impedance op amp (10Mohm claimed) input can drag down a knock sensor signal, so were you using the OEM knock sensors for your logging at the same time as the OEM ECM was using them for knock control?

The OEM ECM knock control doesn't appear to have any dynamic adaptations like say the 4G63 has, but I believe it is still gated and filtered. With a lot of internals the centre cylinders just saturate the OEM settings and you end up at 65535 which disables the knock control on that cylinder. Perhaps aftermarket you can get more dynamic range through gain control.
Certainly is and it resulted in the first knock event step calibration to be more aggresive in the base map to remove the spikes but stock ecu didn't care even with the Standalone removed from the knock signal but tbh there was no need to as it has no effect on the signal after checking with a scope. See i believe its not gated as i watch the stock ecu correction constantly via the check light for any correction and i every so often see it correcting in transient vacuum situations on gear changes where background noise is resulting in similar freqs

The gains on 4 are maybe abit high but when an engine costs over 10,000 i would rather be sure for intial setup it reacts quickly on the event even if it is background noise.

I have found this alot with the stock ecu control of knock after checking with det cans, grab some cans and load up engine at say 2500rpm your be surprised what you hear and what the stock ecu does. Still surprises me to this day that the e-mail tunes and even custom tunes result in no tuners monitoring knock apart from on the stock ecu. I certainly wouldn't relie on this with a customers car.

So which cylinders have been known to bend rods guys?
 

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my first engine was number 4 OEM ENGINE stock, my second Engine we shipped it back to JAPAN for them to check.(it was due to hydrolock due to liners)..

so what your saying is the COBB/OEM cant check for knock on each cylinder ?

will the S8 Ecu be able to do this ?

can the S8 offer a engine cut say if there was an issue with the fuel etc ? ie pressure or something

SUBSCRIBED
 

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Certainly is and it resulted in the first knock event step calibration to be more aggresive in the base map to remove the spikes but stock ecu didn't care even with the Standalone removed from the knock signal but tbh there was no need to as it has no effect on the signal after checking with a scope. See i believe its not gated as i watch the stock ecu correction constantly via the check light for any correction and i every so often see it correcting in transient vacuum situations on gear changes where background noise is resulting in similar freqs

The gains on 4 are maybe abit high but when an engine costs over 10,000 i would rather be sure for intial setup it reacts quickly on the event even if it is background noise.

I have found this alot with the stock ecu control of knock after checking with det cans, grab some cans and load up engine at say 2500rpm your be surprised what you hear and what the stock ecu does. Still surprises me to this day that the e-mail tunes and even custom tunes result in no tuners monitoring knock apart from on the stock ecu. I certainly wouldn't relie on this with a customers car.

So which cylinders have been known to bend rods guys?
This from my email to you 30 Aug:

"I am always recommending det cans to allow tuners to calibrate the knock control especially with cams, forged pistons etc. Few seem to make it work, and some have strange approaches such as pulling plugs and looking for drops in torque on the dyno. Personally I prefer to listen with det cans, but I don't on my own GTR as I'm quite happy with the OEM knock control as I have a completely stock car except for a tune and I really like its refinement, smoothness and reliability in this spec. I used to use them heavily on my Subarus as the OEM knock control was not so good and the car was much more modified, plus it was easier to hook them up and listen whilst the car was driving. I didn't persist in looking for a place on the GTR block to hook them up because of the low mod state of my car, but if I personally were to calibrate high power GTRs it would be the first thing I'd do. I can usually hear knock without det cans as I'm quite attuned to it from previous calibration, certainly I could always hear Subarus knock by the time they hit a red on the old knock links. I've never heard a lightly modified GTR knock, but a lot of people mistake noisy bell housing bearings/propshafts/transmission noises for knock on GTRs."

I couldn't find a way to use my old mechanical det cans because I couldn't easily route a hose through a door or grommet in the firewall as easily as I could on Impreza/Evo and without a dyno personally I had to get the bonnet/hood closed to load up the engine. I tried a Knocklink and the signal was quite low on the top of the inlet manifold. If there is a way to piggyback from the stock knock sensors without affecting their readings by using a high impedance op amp, it could be an interesting product, with options from then to simply use headphones, record the audio, and various live or post processing options, or indeed a full Syvecs.

I'm probably stating the obvious pointing this out to you Ryan, but some think the ECU is registering knock when it is merely crossing the load threshold for knock control and the previous knock value used in the knock control area is reused, not signifying a new knock event. It depends how the knock is reported in the OEM ECM logging software, not sure how the software you're using does it, but if the report of knock is only in degrees you'll be missing a lot of detail.

You have an interest here is promoting a new standalone, and good luck to you as it will be genuinely interesting, but if we are going to say that the OEM ECM is having a substantial number of false positive and false negative knock events that result in significant loss of performance vs safety, and infer that email tunes are damaging engines, then better evidence will be convincing. I'm not saying the ECM is always appropriate in its knock control, but that I'm happy with what I've personally seen of it, and a few ticks heard in det cans when you think the OEM ECM should have done something, and a few knock events when you think it shouldn't, and comparing that with a rate of damaged internals from a forum straw poll is of interest value but not conclusive, but I'll be the first to change my opinion based on a more cohesive argument. Perhaps at this stage you're trying to ask the interesting questions or are you stating a marketing or technical position that OEM knock control is damaging engines?
 

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Discussion Starter · #11 ·
my first engine was number 4 OEM ENGINE stock, my second Engine we shipped it back to JAPAN for them to check.(it was due to hydrolock due to liners)..

so what your saying is the COBB/OEM cant check for knock on each cylinder ?

will the S8 Ecu be able to do this ?

can the S8 offer a engine cut say if there was an issue with the fuel etc ? ie pressure or something

SUBSCRIBED
I can't comment on how the stock ecu (cobb/ecutek) determines what is knock but im sure it's not gated after my findings. If it did trim based on cylinders Cobb/EcuTek would have found the cylinder trim parameters. On the S8 you can log each cylinder at up to 1000hz which is filtered, gated and fully adjustable to suit differences in the combustion chamber which I imagine alot of the High hp VR38 have had done. If the high hp engine builds in the GTR world are changing the Combustion chamber then I would not be relie on the stock knock control any longer and ensure det cans are used. To be honest if you are tuning the vr38 right on the limit of the fuel I would ensure the tuner has det cans on.
Considering that the stock ecu did nothing even though we were picking up knock on 4th is worrying…. I did bring the engine to the point where the stock ecu saw knock in lower boost areas and it was then picked up on a lot of the cylinders on the S8 and produced a serious spike!.

BTW the gains in power we found were purely down to being able to add more timing so that says to me a few things are not right with stock ecu with bits that are not stock but don't want to give to much away ;)

S8 of course has individual knock control as you can see it working in the log when it pulls timing just on 4th, be it the first event step needed to be larger to remove the tiny knock events on 4[sup]th[/sup]. But this standalone is what keeps 800+hp engines running constantly at full wack for over 24 hours in leman so it has a lot of strategy additions to the knock control.

Yes Engine trips are one of the big things that it will bring to the VR38. Will monitor fuel pressure relative to manifold pressure and trip/trim fuel to fix issue instantly. Same with oil pressure say oil pump fails or big leak and pressure drop it trips engine. Plus actually have proper wideband lambdas fitted and running in closed loops.

List is endless with ability to have over 30 inputs of extra sensors to trim say egt on each cylinder etc but will all be released soon. Please note this is not a system like the Proefi or haltech which requires stock ecu still and a complete replacement which joins the canbus system and actually applies torque reduction on gear changes unlike the haltech/proefi which has resulted in a few broke boxes.
 

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S8 of course has individual knock control as you can see it working in the log when it pulls timing just on 4th, be it the first event step needed to be larger to remove the tiny knock events on 4[sup]th[/sup]. But this standalone is what keeps 800+hp engines running constantly at full wack for over 24 hours in leman so it has a lot of strategy additions to the knock control.

Yes Engine trips are one of the big things that it will bring to the VR38. Will monitor fuel pressure relative to manifold pressure and trip/trim fuel to fix issue instantly. Same with oil pressure say oil pump fails or big leak and pressure drop it trips engine. Plus actually have proper wideband lambdas fitted and running in closed loops.

List is endless with ability to have over 30 inputs of extra sensors to trim say egt on each cylinder etc but will all be released soon. Please note this is not a system like the Proefi or haltech which requires stock ecu still and a complete replacement which joins the canbus system and actually applies torque reduction on gear changes unlike the haltech/proefi which has resulted in a few broke boxes.
the above is very appealing am sure for many - am certainly keeping my eye on this S8 ecu.
 

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Discussion Starter · #13 ·
This from my email to you 30 Aug:

"I am always recommending det cans to allow tuners to calibrate the knock control especially with cams, forged pistons etc. Few seem to make it work, and some have strange approaches such as pulling plugs and looking for drops in torque on the dyno. Personally I prefer to listen with det cans, but I don't on my own GTR as I'm quite happy with the OEM knock control as I have a completely stock car except for a tune and I really like its refinement, smoothness and reliability in this spec. I used to use them heavily on my Subarus as the OEM knock control was not so good and the car was much more modified, plus it was easier to hook them up and listen whilst the car was driving. I didn't persist in looking for a place on the GTR block to hook them up because of the low mod state of my car, but if I personally were to calibrate high power GTRs it would be the first thing I'd do. I can usually hear knock without det cans as I'm quite attuned to it from previous calibration, certainly I could always hear Subarus knock by the time they hit a red on the old knock links. I've never heard a lightly modified GTR knock, but a lot of people mistake noisy bell housing bearings/propshafts/transmission noises for knock on GTRs."

I couldn't find a way to use my old mechanical det cans because I couldn't easily route a hose through a door or grommet in the firewall as easily as I could on Impreza/Evo and without a dyno personally I had to get the bonnet/hood closed to load up the engine. I tried a Knocklink and the signal was quite low on the top of the inlet manifold. If there is a way to piggyback from the stock knock sensors without affecting their readings by using a high impedance op amp, it could be an interesting product, with options from then to simply use headphones, record the audio, and various live or post processing options, or indeed a full Syvecs.

I'm probably stating the obvious pointing this out to you Ryan, but some think the ECU is registering knock when it is merely crossing the load threshold for knock control and the previous knock value used in the knock control area is reused, not signifying a new knock event. It depends how the knock is reported in the OEM ECM logging software, not sure how the software you're using does it, but if the report of knock is only in degrees you'll be missing a lot of detail.

You have an interest here is promoting a new standalone, and good luck to you as it will be genuinely interesting, but if we are going to say that the OEM ECM is having a substantial number of false positive and false negative knock events that result in significant loss of performance vs safety, and infer that email tunes are damaging engines, then better evidence will be convincing. I'm not saying the ECM is always appropriate in its knock control, but that I'm happy with what I've personally seen of it, and a few ticks heard in det cans when you think the OEM ECM should have done something, and a few knock events when you think it shouldn't, and comparing that with a rate of damaged internals from a forum straw poll is of interest value but not conclusive, but I'll be the first to change my opinion based on a more cohesive argument. Perhaps at this stage you're trying to ask the interesting questions or are you stating a marketing or technical position that OEM knock control is damaging engines?
I remember your e-mail John and i know that you know what your doing when it comes to calibrating mate as if Pat/Merv say you are good i listen. Look there are lots of cars out there on e-mail tunes etc so i havn't really got a leg to stand on saying it wrong at present but if these e-mail tunes etc are finding peak torque based on the fact that the vr38 is knock limited and taking it to the point of knock i bet and then back off. If that the case then i just saying that the ecu saw nothing when we saw stuff on 4th and might explain why thats the cylinder which goes first...

Im just interested John as like your self get a kick out of this stuff, Look jump on a plane in jan and come do some testing with us if you wish with the S8 plugged in our testing piggyback loom and a Cobb on it. You can help us find the last CanBus bytes also for a few items


Ryan
 

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I don't think the serious engine builders are relying on unadjusted knock calibcation tables Ryan, simply because in many cases this produces a wall of false knock and you can't run appropriate timing. The most common situation I've heard is that they reach saturation on the knock thresholds on the noisiest cylinders so they are effectively tuning without knock control at some engine speeds on some cylinders, but those who do this are happy to do so, and not phased by tuning without knock control or adjusting it.

I haven't found the gating in the code, but based on how OEM knock control has been done and how old the Nissan patents are that include gating, I'd be astonished if it wasn't gated, but observations of its responses won't tell you whether it is or isn't gated unless you produce a simulated signal and watch it, or go through all the circuits on the ECM. However, the noise threshold system's operation (even though the code is sprawling) is simpler than I expected.

Have you access to the OEM ECM per cylinder knock noise adjustment thresholds? Knock on any cylinder drops the knock value by 307 and affects all other cylinders, this is why we only report one knock value because it affects all cylinders. I'm sure you could get a little more performance by waiting to retard each cylinder when it knocks but if you had high cylinder pressures you might prefer the cautious method of retarding all? Nissan state that the VR38 is not designed to knock in normal conditions running its rated fuel, so their knock control is a backup, perhaps this is why they retard all cylinders when only one knocks?
 

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I I can usually hear knock without det cans as I'm quite attuned to it from previous calibration, certainly I could always hear Subarus knock by the time they hit a red on the old knock links. I've never heard a lightly modified GTR knock, but a lot of people mistake noisy bell housing bearings/propshafts/transmission noises for knock on GTRs."
I've got a few years of hearing knock under my belt. I have heard a 100% stock, brand new GT-R knock on a 1-2 shift. I was picking the car up in Arizona, it was hot, but not as hot as it gets. Cruising around the block on the pre-delivery, and I heard it rattle when I got on it hard. July/2008 or so.
 

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If we get more det can use from this thread that will be a successful achievement. Maybe some could share how they mount their extra sensors/couplings or what they use to tap the OEM knock sensor wiring? There is a definite split in practice across the Atlantic on this issue on a number of platforms, with exceptions on both sides. Same with approach to temperature monitoring and boost levels on a given octane and compression ratio. On the 4G63, the Americans used to use quite large turbos on standard internals, but keep the boost down and use race fuel. Brits couldn't believe why the engines didn't blow up. Americans on the other hand, couldn't understand why eg 37 PSI on 93 octane with 9:1 compression didn't blow up and actually produced massive torque reliably.
 

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Have you access to the OEM ECM per cylinder knock noise adjustment thresholds? Knock on any cylinder drops the knock value by 307 and affects all other cylinders, this is why we only report one knock value because it affects all cylinders. I'm sure you could get a little more performance by waiting to retard each cylinder when it knocks but if you had high cylinder pressures you might prefer the cautious method of retarding all? Nissan state that the VR38 is not designed to knock in normal conditions running its rated fuel, so their knock control is a backup, perhaps this is why they retard all cylinders when only one knocks?
I have not looked at the stock threshold as it not viewable in the Ecutek software

Can you see what frequency it is listening for or change it to suit different engine configs, if it even does this?

Also i imagine it does not listen in a set window like the S8 to remove background noise if its becoming saturated as standard?

BTW John the extra power did not come from allow more timing in cylinders which were not knocking but down to a calibration which greatly improved the combustion stability and aloud even more timing over Stock but increased the torque just without touching the timing. More will be release when its out to the market but there is something you are missing on the stock ecu controls at present.

Ryan
 

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a calibration which greatly improved the combustion stability
blablabla
there is something you are missing on the stock ecu controls at present.
Improved combustion stability!? What is that?? Is it measurable? You mean you have somehow increased the threshold for knock?
Anyway, what John does not know, is not worth knowing
 

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Discussion Starter · #19 ·
+3

Improved combustion stability!? What is that?? Is it measurable? You mean you have somehow increased the threshold for knock?
Anyway, what John does not know, is not worth knowing
On a Stock car it wouldn't make a difference as nisan would have got it right but on a modified engine which has changes to allow for over 600hp then it definatly wont be right any longer on the stock ecu with a cobb or ecutek i can assure you.

Ryan
 

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Discussion Starter · #20 ·
John is a very knowledgeable gent who i will listen to anytime but he is not a full time calibrator who works alongside with a leading world engine research (http://www.aerltd.com/) company setting up different engines daily on engine dynos/chassis dyno. In fact he does not believe in Dyno tuning

Making changes to a Rom file is not exactly calibrating an engine like a standalone espically when the stock strategies do most of the work.

Ryan
 
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