Knock Retard processing speed Stock ECU vs JS box and keeping it alive

[CGASTON]

It can't prevent the knock from occurring in the first place


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I understand that!!!! If it didnt detect knock, then how is it expected to retard it....


Clint

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[John at J&S]

This is data from Ian Whiteside, calibration engineer at Ilmor Racing in the UK. It was from his personal formula three engine.

The engine is 2.0L, 14.0:1, NA. Engine management is a MoTeC.

Ian Whiteside

Special Projects
Mercedes-Ilmor Ltd.
Quarry Road, Brixworth
Northants, NN6 9UB
Tel: +44 (0) 1604 880100 ext XXXX
Fax: +44 (0) 1604 883066
E-mail: xxxxxxxxxxxxxxxxxx
John,
I ran my engine on the dyno last week and was very pleased with the way your
Safeguard system worked.



Firstly I ran the engine on 98 RON pump fuel and mapped the spark advance to 2deg clear of detonation (as determined by the dyno knock sensing equipment) and ran some baseline power tests.
To calibrate the Safeguard, I ran the engine at low speed at borderline det and adjusted the Sensitivity pot until the LED was just starting to glow.
Next I added 2 degrees of spark to the map ( to take it to BLD ) and ran some power curves with the Safeguard active, these were around 4% up at the lower speeds where the engine is very det limited and about 2% up at max power. I ran some more curves at +4 and +6 deg from map but did not get any noticeable improvement over +2. The Safeguard was in Individual Mode, so I
guess you can determine that the cylinder to cylinder variation in det limit is low. During all this running, the dyno knock system never indicated anything more than occasional trace detonation.
I then ran some 102 RON fuel (the control fuel for my series) at map +4 and got similar results to the 98 RON fuel at this timing. However at map +6 with the new fuel, the improvements at the lower speeds were over 8% compared to the baseline figures.
Overall, I'm delighted with the way the Safeguard performed. It was simplicity itself to set-up, gave excellent performance gains and all this at a very affordable price. It is a fantastic product and I will be recommending to my friends (although not the ones in my race series) - I want to retain some performance advantage !!! ).

The engine was run with the unit for a season with no damage, then he sold the car and bought one with a Pectel ECU with internal knock control.

I sold the car a few weeks ago, I however had no problems with the

controller. When I was on the dyno, the operator seemed quite impressed but I wouldn't tell him what make the system was - the dyno was also used by an engine builder who builds most of the engines in my race series, so didn't want to give away my secret weapon!

 

[norbs]

Not sure if this is a disadvantage or not but you won;'t be able to use your stock gn knock sensor with the newer JS boxes, you will have to adapt the bosch 2 wire sensor to work somehow? Also very loose motors with big piston to wall clearance might have false knock. I don;t think this is a concern to our v6's they are pretty tight. piston to wall.

 

[kidglok]

Would this be more sensitive to false knock?


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[norbs]

Would this be more sensitive to false knock?


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Not really , as it can only retard timing on the next spark event, where as the stock esc module can do it any time while the engine is running.

 

[John at J&S]

Norbs is right. Must have 0.006 (or tighter) piston to wall clearance.

I don't know his screen name, but he is running an MSD 10 with the Interceptor version and using the AEM data logger. I modified channel 1 of his unit so it would interface with the MSD. I haven't heard of any issues with false knock from him and he is using two of the donut style sensors. HW (Bill) Holder is the name.

 

[dr_frankenstein]

I have never had issues with any false knock and I run a loose gear drive for noise. This was exactly what Norbs had suggested to me on why the J&S was perfect for the situation and how I discovered the system. The sensitivity control allowed can really help with what engine noise is compare to true knock. And the sensitivity of the Bosch sensor is way better then the stock GN unit. All being said, if your concerned with piston slap then the J&S wouldn't do anything for you anyways because you probably can't tune if your allowing a motor to be that loose in the first place. While the unit may be easy enough for a amature to use... its definitely made for people searching for max performance.

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[Eric Stage I]

Eric:

The SafeGuard waits until the knocking cylinder is about to fire, then dials in the calculated amount of retard for THAT cylinder.

Yes, my only point is that knock usually starts with one cylinder, so as long as we can retard timing by the time that cylinder comes around again, we are good. At 6000rpm, that's 20ms later, so the stock ECM has no problem doing that.

The capabilities of John's cool device are a different matter entirely (individual cylinder retard).

Regards,
Eric

 

[CGASTON]

I have never had issues with any false knock and I run a loose gear drive for noise. This was exactly what Norbs had suggested to me on why the J&S was perfect for the situation and how I discovered the system. The sensitivity control allowed can really help with what engine noise is compare to true knock. And the sensitivity of the Bosch sensor is way better then the stock GN unit. All being said, if your concerned with piston slap then the J&S wouldn't do anything for you anyways because you probably can't tune if your allowing a motor to be that loose in the first place. While the unit may be easy enough for a amature to use... its definitely made for people searching for max performance.

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Have a question for you. Where did you install the bosch injector?


Clint

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[dr_frankenstein]

Have a question for you. Where did you install the bosch injector?


Clint

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Since i am a carb application i used the stock mounting location. But i do have an early block so the hole was not drilled and i just drilled the 5/16" hole and snugged it down there.

 

[John at J&S]

Bill Holder talks about his set up to determine which cylinder is knocking:
http://www.turbobuick.com/forums/threads/o2-sensor.398937/

He logs cam, crank, RPM, and the bargraph signal.

He has the Interceptor version, which was designed for waste spark or coil on plug. He's running a distributor, so he uses only channel 1 input. The output channels are 0-5v (MOSFET push-pull), so I had to modify channel 1 output to trigger his MSD 10.

The Interceptor has a "knock-finder" display on the front panel. For coil on plug, it shows which cylinders are being retarded.

For waste spark, it shows which pair of cylinders is knocking. Only the correct one from that pair will be retarded.

In single channel operation, the unit retards the correct cylinder, but only channel one of the knock-finder will light, so unless/until I bring back "Son of Knock-Finder" you will need to set up a data logger to determine the knocking cylinder. I don't think that will happen, as AEM's $400 AQ-1 data logger allows you to review and analyze the data, rather than get a fleeting glimpse from eight bargraphs.

This video show me testing the Interceptor:
https://picasaweb.google.com/JohnPizzuto/JSVampireInstallation#5389069501584814018

It's being triggered from a Digital Audio Tape recording I made in 1994 on Jim Bell's Mustang.

I recorded the knock signal on one channel, and the ignition trigger on the other channel. My ignition tester converts the distributor trigger signal into eight "coil on plug" signals to drive all eight channels of the Interceptor.

The top trace of the scope shows the bargraph signal, the bottom trace shows the knock signal.

The bargraph voltage is from a four bit D/A converter, limited to ten steps. The range is 0-1.3v, or 0.13v per step.

The unit listens for knock during the knock window, determines if there was knock and how much to retard this cylinder next time. It then outputs a voltage to the monitor jack that represents the amount of retard this cylinder will experience the next time it fires.

Note that if you sample the monitor signal at the ignition trigger point, you will get the data for the previous cylinder, so you must take that into account when data logging.

 

[QUIP'6']

Can you tap into stock knock sensor wire or do you have to drill and tap a 5/16 hole next to factory knock sensor and use a seperate one?

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[QUIP'6']

Can you tap into stock knock sensor wire or do you have to drill and tap a 5/16 hole next to factory knock sensor and use a seperate one?

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[John at J&S]

The unit can be set up to work with either type sensor. I normally set them up to work with a Bosch or similar two wire sensor.

There is a "sensor cal" pot just behind the monitor jack to control this. It can be accessed through the front panel, no disassembly required.

 

[CGASTON]

The bosch is a better knock sensor, correct....

 

[John at J&S]

The stock sensor is tuned to the knock frequency. The Bosch and other donut style sensors are not tuned and respond to all frequencies.

Which one is better? Can't really say, as my detection scheme seems to work with either one. Norbs' old unit is set up for the stock sensor. Dr. Frankenstein and HWHolder's units are set up for the donut style.

The untuned sensor will respond to the second and third harmonics of the knock frequency, while the stock sensor will not. Some literature reports the higher harmonics have an improved signal to noise ratio at higher RPM.

This is a pretty good student paper on engine knock. Too bad she didn't have one of my units to play with.

Graphs starting on page 33 show engine noise at various frequencies, with no knock and with knock:
http://dspace.mit.edu/bitstream/handle/1721.1/35635/76701513.pdf?sequence=1

 

[John at J&S]

Just reread post #14 from delcowizard:

this is quite interesting i turn knock control off after 4000rpm due to engine noise triggering it above that.my factory ecu (not a buick turbo ecu but still uses the maths above) cuts it off at 3600rpm stock.

What RPM does the Buick ECU ignore the sensor?

 

[John at J&S]

For those that don't have access to the code, this should be an easy test.

Have an assistant tap on the sensor at progressively higher RPM and check for retard.

 

[TurboBob]

.......

What RPM does the Buick ECU ignore the sensor?

there is no RPM cutoff in the LC2 code.

Bob

 

[John at J&S]

Yeah, that would be bad. The 300zx ignores the sensor above 3000 RPM.