EFI w/ Knock Control on old mag case motor

[spyerx]

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.

[Lapkritis]

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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[spuggy]

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. Placement of knock sensor

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: My J&S Safeguard paid for itself last week...

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...

[spyerx]

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.

[spuggy]

Originally Posted by spyerx

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.

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?

[Lapkritis]

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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[Peter M]

Originally Posted by spyerx

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.

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.

[spyerx]

^^^ Thanks Appreciate that.

Originally Posted by Lapkritis

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.

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

[Lapkritis]

Originally Posted by spyerx

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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[Neil Harvey]

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.

[Neil Harvey]

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

[safe]

Originally Posted by spyerx

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.

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.

[Neil Harvey]

Originally Posted by safe

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?

[Lapkritis]

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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[spuggy]

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.

[John at J&S]

Originally Posted by Lapkritis

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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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.

[John at J&S]

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.




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.

[burgermeister]

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 ...

[racing97]

J&S are the very best

[Walt Fricke]

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

Twin plug waste spark? Like Electromotive.