EFI w/ Knock Control on old mag case motor
 

Who's done it? The 964+ had a bridge on each bank of cylinders with knock control... possibly could be retro-fitted to the early style cylinders?

The engine we're doing is going to be full ITB EFI, Motec controlled with dual lambda, crankfire, etc... all the goodies.

I'm curious if anyone has integrated knock control on one of these.

Thx.

I haven't done it in that configuration but I wouldn't bother. A competent Dyno operator/tuner should be skilled enough to safely tune and set up the engine without knock control. Add timing until no more power comes in the curve. Take a little peak timing out to add longevity/safety buffer. Enable IAT timing trim for heat soak such as stuck in hot traffic or extended pit stop. The consistency of fuel grade then becomes most important. Tune for an octane/fuel supplier you trust. Street car or race car?

I would recommend adding EGT feeds; more the merrier. With lambda / egt per exhaust port you can tune at the individual cylinder level rather than in the aggregate; each cylinder in full sequential mode has it's own unique ignition and fueling trim map. It's one way of spending a little more up front to delay your next overhaul.

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This keeps coming up.

Application notes for knock control (Megasquirt, I think) I read once - they advised against mounting the sensor high on the cylinders.

So, yeh, no idea why the factory used a cylinder bridge on the 964's onwards - and it really doesn't seem to be necessary. Lot of guys running knock control without that.

Mine is mounted on an M8 stud under the shroud; others have mounted on the case in a convenient location (like the unused factory tapping by the oil chimney) and report that it works fine there too. Jake Raby uses the bell housing on Type IVs. http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1018043-placement-knock-sensor.html

Just need to mount to the case, and the Bosch app note says that ONLY the sleeve in the sensor should contact the case.

I have used a J & S Safeguard for 10's of 1000's of miles on a 930; both the traditional model for CIS/distributor and more recently the Interceptor direct "smart coil" version with MoTeC. Works great. The only false knock indications I've ever seen is from valve train noise when shifting from WOT (it "hears" all the slack when you lift, but clears instantly when power re-applied) or transmission clanking.

When my distributor abruptly froze fully advanced, the only indication I had was the Safeguard lighting up and protecting the motor: http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/611409-my-j-s-safeguard-paid-itself-last-week.html

When we went motec, my wrench (motec reseller and trained/licensed to sell the knock feature) said "go with another Safeguard; it's so much simpler to setup and use".

The Safeguard model I use now with COP (Interceptor) J&S Eight Channel Interceptor has per-cylinder knock indication, monitor/headphone output and the ability to feed knock indication back to the Motec.

But since twin-plugged and EFI, the only time it triggered was when I got 3rd at low speed thinking it was 1st and the transmission made clanking noises...

This is helpful and useful thanks.

Agree that knock is not an issue, assuming you have full control over fuel, and proper tune. But that's not the situation in real world, hence the desire for one additional input.

The car will be street, mostly, but, aggressively driven from sea level to 7k ft elevations, in 60-100 degree weather. I live in SoCal and that's the hills, canyons, and deserts I drive my cars in. And, our fuel here, is kinda crappy, 91 is the best, E85 is available but only in urban areas mostly.
So I'd like the engine to be able to adapt in modern ways given very diverse driving conditions.

The current engine right now has carbs, and, frankly they suck. Good at sea level, don't like going up to the peak of angeles crest.

Yeh - even if everything is setup perfectly and working great with the initial tune, how do you detect/guard against issues that develop over time? Or a failure like a clogged injector? A tank of bad fuel?

Various methods - check spark plugs often, read them. I usually pull plugs for inspection while changing my oil... good task while waiting for everything to drain.

Watch AFR and EGT. There are open-tip EGT probes that will give you faster swings than the old closed tip found on VDO systems of yester-year.

Listen to the engine, pay attention to the feedback it gives you in sounds, smells, and most importantly the seat of your pants. If the operator is familiar with the machine then detection of issues is easier than you might expect. The more time in the seat, the more you'll learn the sound of it's voice and be highly sensitive to any changes with or without a knock light/timing pull.

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Yes, Motec M130 with two knock sensors and two o2 sensors providing enough information to allow individual fuel and ignition trimming. The M130 is clever enough to see through the valvetrain and other background noise.


https://i.imgur.com/vGQGl8N.jpg



https://i.imgur.com/uxIqnbt.jpg

^^^ Thanks Appreciate that.


If I wanted to do this much work I'd keep carbs :-)

I'm so with you in my hatred of carbs... I've tuned and cleaned so many... I'm done. Like a retired butcher. I never want to see the inside of one again.

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If your ECU has the ability to control the timing against engine "det", why not use it. It always comes down to what you programs as an acceptable level of engine noise.

The ECU has no clue what detonation is, it only knows noise and pressure if a pressure sensor is included. You can always turn it off.

I agree that reading the plugs or measuring the combustion pressures against what the ECU records as knock is a must. But many today have never been schooled on how to read a spark plug. But reading a plug is a factor of two. First you have to know what you are looking for and second you have to submit the plug to a running condition and look only at the plug under those conditions.

Looking at the plugs while changing the oil will probably give you a false reading as I cannot comprehend changing the oil immediately after doing a hard cut a WOT at max torque RPM.

Also, the most dangerous detonation is so high a frequency, the human ear cannot hear it without some sort of measuring device.

I wouldn't trust aftermarket knock control to save my engine. Don't put too much faith in that!
A proper tune, barometric and IAT compensation. CHT sensor and compensate for that too.
You tune for the fuel you can get. If possible use dual maps for different kind of fuels. If an injector should clog, unlikely to me, you notice that on idle and light throttle cruise when you are leaner near stoichiometric, when you hammer it you are a lot richer and safer.

I find that an odd comment and logic hard to apply??

Why do you think after market knock systems are unfaithful??

If you think you are trustworthy to map the fuel and read a lambda sensor, spark plugs or whatever, why should the same not apply for setting up the knock strategies?

There is a sensitivity setting for aftermarket knock systems. The oem tests for thousands upon thousands of hours to fine tune their knock systems with respect to gain on the signal and to tune out phantom noise. Even with all those engineers and hours, you still hear new oem vehicles knocking in traffic, going up hills, you name it. This because they're tuning for strict emissions. In the aftermarket tuning world, you're usually going for performance first not emissions so you have more flexibility to tune away from the knock limit and focus on power output.

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Reactionary attitudes and xenophobia around knock detection on 911s is wide-spread and commonplace- decades after the first guys here fitted one and found they worked. I bought mine in 2010 after reading a 2002 post here from a guy who'd fitted one 10 years and many 1000's of miles prior.

Some say "aircooled motors are too noisy". But the factory not only considered the technology functional, but worth fitting to the 964s onwards. They're not magically any quieter.

At least one of the aftermarket ones is well designed, documented, supported and far easier to set up than ECU-based knock control.

I won't comment on systems I've never used.

Tuning "away from the knock" limit robs power. Remember, when you tune for "no knock" you are tuning to silence the cylinder that knocks the easiest, robbing power from the others.

Yes, knock detection can be difficult, as you are trying to ignore engine noise that you CAN hear, while detecting knock that you CAN'T hear (inaudible knock). But, there are ways to do it without spending thousands and thousands of hours, if you put on your thinking cap.

Ian Whiteside, a former calibration engineer at Ilmor Engineering, sent me this data, from his personal formula 3 engine. It was running a Motec, mapped on a dyno with knock sensing headphones within 2° of the knock limit. The SafeGuard was then installed, and timing bumped in steps. He ran the unit for a season at "Base Map +2" with no engine damage, then sold the car.

Scroll down to the bottom on my testimonial page for his comments:
SafeGuard Testimonials

I've been working with a company providing engines and engineering services to the vintage F3 community. They are very close lipped about results. About the only thing they will say is they found a few horsepower. They also said they proved it worked when they used it to map their MBE ignition system. They thought their map was close enough, so they bypassed it, using the J&S as a detector instead of a controller, and blew the engine. The owner said the knock/retard bargraph gauge got into the Red near the end of a run, but he decided to push though the last 1000 RPM, and they damaged the engine, lifting the head, and pinching a ring.

http://jandssafeguard.com/Ian/Ian'sData.gif

Here's a video showing the J&S detecting (and controlling) knock that was missed by the Siemens ECU on a Mini-Cooper:

https://www.youtube.com/watch?v=tjA8xiPd3SU

This screen shot shows the J&S detecting knock with the water-methonal injection turned off. Note in the video when the water-meth is turned on, there are no detections, demonstrating the J&S was previously responding to real knock.

http://forums.pelicanparts.com/uploa...1584998996.png


As far as I know, this was the first time a J&S was used on a Mini-Cooper. I sent them a unit, they installed it, and it worked better than the factory system with their thousands of hours tuning out knock phantoms.

Thinking is hard work.

I've been running a J&S for 7 or 8 years now, lots of track and street. Totally transparent once installed. I got it when I added a chip to the Motronic, just in case. It works great, and it does come on occasionally. Knock sensor is bolted to the oil breather cover.

Probably overkill for what I am doing, but engine parts are really expensive ...

J&S are the very best

Can the J&S system be used with a waste spark system?

Twin plug waste spark? Like Electromotive.

Walt:

For twin plug with two HPV-1's, you will need the "dual three channel" Vampire version.

The negative terminal of each coil connects to a Vampire "control wire".

http://forums.pelicanparts.com/uploa...1409225650.gif

For access to the negative terminals of the coils, you will also need coil interface modules from MSD. These are "break out" boxes that fit between the HPV-1 and the coils. They were designed to allow MSD to inject high voltage to the coils, but we use them to connect the Vampire to the negative terminal of the coil.


http://forums.pelicanparts.com/uploa...1409226227.jpg

I did one for Robert Poirier a few years ago. I don't know if he is on the forum, but he did reply by email at the time that it was working well.

I created the above drawings for his installation.

During the install, he found the Electromotive designer reversed the terminals on "Coil A", probably to simplify the PCB layout, so you must verify which terminal is Coil Negative for each coil.

The newer XDI DFU's do not require the MSD coil interface adapters.

Connect the Vampire control wires to wires A, B, and C of the four pin cables connecting each DFU to the XDI ECU's.

Again, the dual three channel Vampire is required.

Just another interesting datapoint - the J&S seems to have detected early failure of the mechanical AFM on my car.

Recently my J&S became rather active, especially at part throttle. Shortly after, *really* active, as in active anytime the car was not at steady cruise. The car ran fine, sounded fine, RPM blipped fine, no change in power - no sign of anything amiss whatsoever. I first replaced the knock sensor, thinking it somehow went south for the winter, and then checked all of the wiring to the J&S, but got the same knock activity level.

After more diagnosis, turns out the flapper AFM had worn away enough of its potentiometer track to muck up the engine management. Voltage was jumpy with flap travel. Apparently not enough to be noticeable to me as a driver, but definitely noticeable to the J&S. I did the "shift the contact points" trick mentioned elsewhere on this forum, and the knock activity is back where it used to be (very little).
Of course, different weather, different results - but driving season is over in MI, so further testing will need to wait for next year.

In retrospect, there was some other early warning before the knock issue. The engine (per J&S AFR readout) seemed to run lean. It was a very gradual change, and was mostly at WOT - I was under the assumption the AFM is ignored at WOT in favor of RPM, is this incorrect? Anyhow, I figured maybe the O2 sensor, installed for at least 5 track seasons and 30+K miles, was past its prime. Replacing it did produce 'richer' readings, so I thought 'problem solved' - apparently not!

So, thanks for the early warning John!

Thanks for the attaboy.

I'm flapper-gasted.

:)

I think I have stated this before at some point: the 964 style bridge is used to control knock in each INDIVIDUAL cylinder. It is not required if you are controlling all of the cylinders the same as a batch.
It is also generally true that OEM’s do not advance the timing beyond MBT, only retard away from MBT when knock is detected.
OEM systems have an adaptive behavior that continually learns the propensity for knock in each cylinder.
There is quite a bit of effort that goes into filtering and windowing the signal from the knock sensor. The sensor is essentially an accelerometer that measure vibration amplitude and frequency. Modern knock sensors actually have this active filtering built into the sensor.
The worst knock in our engines is pre-ignition, not combustion, and is not easily predicted from the knock sensor.

The knock bridge is not required for individual cylinder knock control, given an intelligently designed knock controller.

Knock detection actually occurs in the electronics connected to the sensor.

The knock frequency is proportional to the cylinder bore diameter.

All modern knock sensors are non-resonant, flat response, out to 20kHz. Bosch has been producing them since the mid '80's. These are the so called "donut style" two wire sensors. They produce a low level output signal and require a shielded cable.

Resonant knock sensors are an earlier technology. These are mechanically tuned to a certain frequency. They are larger diameter, stud mounted, most commonly with a single wire, unshielded output cable.

The earliest are called "spike tuned", and have the highest response over a very narrow frequency band. This would seem to be ideal, but the knock frequency shifts with combustion temperature and could go out of band, losing the knock signal.

"Broadband resonant" knock sensors produce an output over a wider bandwidth, allowing one sensor to fit a wider range of engines, and allowing for the frequency shift with combustion temperature. In the '80's and '90's, GM produced broadband resonant sensors in three frequency bands, to cover all cylinder bore diameters.

Given modern electronics with intelligent knock control, non resonant sensors are now preferred, as one sensor can fit all engines.

How does one adjust your system the bore diameter. I would love to use the Universal unit on my 930 with 97mm bore size.
Thanks
David

There is no adjustment for bore diameter. The system uses adaptive signal processing to ignore engine noise while maintaining high sensitivity. It's been demonstrated to work on many engine types.

For example, I was searching just last night and ran across this old thread on a Ford Mustang forum, about our Vampire version. It uses the same detection strategy as the Universal version:
https://www.moddedmustangs.com/threads/whoa-975-hp-from-a-terminator-and-2-9-whipple.578170/page-2

This is where we ended up
7r case
Custom 2.8 nickies with 993 style knock boss cp custom pistons
Heads got the full and complete xtreme treatment

Here’s a head with provision for cht

Long block is done.

Induction and electronics assembly next week.

Controls is motec m130

http://forums.pelicanparts.com/uploa...1610677280.jpg
http://forums.pelicanparts.com/uploa...1610677280.jpg
http://forums.pelicanparts.com/uploa...1610677280.jpg