Knock Knock....... Knock controller???

[Boostmax]

Has anyone ever successfully added a knock sensor to their bike?

I just picked up a very nice supercharged VMAX, ground up restoration and refit of EVERYTHING....complete bike rebuild has 50 miles on it. Should be running around 14 pounds of boost in the 170-180HP range. I'd hate to blow it up due to running lean and/or detonation/pre-ignition/knocking/pinging.

I just got a dynojet wideband commander setup for real time monitoring/logging air fuel ratios. That takes care of the running lean scare.

Now I need to safeguard against detonation/preignition.
What I see thus far, my options are....

1)
Knocklite...varying reviews...decent price $200

http://tunertools.com/articles/KnockLite.asp

2)
Phormula Knock analyzer...bit pricier $400, has some videos to see how it works...no reviews that I've found... video uses a soundtrack to demonstrate the effectiveness of the analyzer, but knock is so painfully obvious in that soundtrack, its ridiculous.....DOnt need an analyzer for knock that obvious!!

http://www.phormula.co.uk/

3)
J&S Safeguard knock controllers $500

Integrated knock detection with adjustable individual cylinder retard and allows retard for boosted engines at varying rpms and boost levels... Lots of adjustability and can actually aid in tuning the engine better as opposed to one way signal like the others... Closed loop knock detection and ignition control.

http://www.jandssafeguard.com/safeguard.html

 

[RaWarrior]

Whether or not ping will be a problem is directly related to the skill of the engine builder.

OE systems with knock sensors are in essence a glorified pinball machine "tilt" sensor that responds to accelerations greater than a designed-in threshold. The vibration/shock of detonation triggers the sensor, which tells the ECU to retard the timing until the sensor stops activating. This of course cuts power but prevents engine damage.

Knock sensors are also tuned to the particular engine they're installed in. It's a piezoelectric sensor that "looks" for vibrations in a certain range. In in kHz, but can vary fairly widely depending on the engine. I'm sure that one you mentioned technically works....but due to the varying frequencies of "knock" in different applications, it might not work 100% on every engine, hence mixed reviews.

I'd tune it to run on 91 (since 93/94 isn't always available), if you intend it to be a daily driver or road-tripper.

There are some rather complex formulas to figure it all out based on boost pressure, compression ratio, elevation, fuel characteristics, ect.

 

[Boostmax]

Whether or not ping will be a problem is directly related to the skill of the engine builder.

OE systems with knock sensors are in essence a glorified pinball machine "tilt" sensor that responds to accelerations greater than a designed-in threshold. The vibration/shock of detonation triggers the sensor, which tells the ECU to retard the timing until the sensor stops activating. This of course cuts power but prevents engine damage.

Knock sensors are also tuned to the particular engine they're installed in. It's a piezoelectric sensor that "looks" for vibrations in a certain range. In in kHz, but can vary fairly widely depending on the engine. I'm sure that one you mentioned technically works....but due to the varying frequencies of "knock" in different applications, it might not work 100% on every engine, hence mixed reviews.

I'd tune it to run on 91 (since 93/94 isn't always available), if you intend it to be a daily driver or road-tripper.

There are some rather complex formulas to figure it all out based on boost pressure, compression ratio, elevation, fuel characteristics, ect.

The sensor actually has no filter nor sensitivity to a certain frequency. The raw signal is sent to a processor that analyzes the raw signal and filters out what is "normal" compared to the spikes that are actually detonation. The processors have settings and logic that are unique to each manufacturer. These settings tell the processor a certain range of frequencies to pay attention to and help it learn what is normal background noise and what is not..

The knocklite is neat that it has rpm sensing and you actually set it to understand what typical engine noise is at at 3 different rpms. low, mid, and high rpms. I heard that if you set it on a dyno at wot with conservative boost settings, it will understand what your typical engine noise is and then be able to pick up the pinging when your settings become too aggressive.

The phormula just uses acoustics at a specified frequency. I'm not too excited after viewing their videos online.

The safeguard is a different beast altogether. It is actually an Ionization current sensing knock detection device. This actually uses the spark plugs to determine knock. Theory is that there is a current that can travel through a flame when it is present. The sensor constantly analyzes this current and can understand the timing of when the current exists vs. the the actual timing of the engine's spark. If the sensor picks up that a flame exists before the spark, it is knocking. Wire and plug type are critical in this setup. I like this best, plus all the closed loop timing adjustments that can automatically be made.

 

[Boostmax]

Whether or not ping will be a problem is directly related to the skill of the engine builder.

SO very not true. Any time you are dealing with high HP engines and have them tweaked for max HP, you are basically getting as close to your knock limit as possible without crossing over that line. Basic engine tuning 101. If you tune your bike perfectly on a cold day with 93 octane, your bike will most likely knock after sitting in traffic on a hot summer day. If you get a bad tank of gas with lower octane fuel, you're engine will knock. If your boost pressure becomes elevated for whatever reason, youre engine will knock. Some engines will knock at WOT at lower rpms vs. higher. Others vice versa depending on the fuel system and their ability to adjust fuel settings vs rpm.

All of this has absolutely nothing to do with the "skill" of the engine builder. If you were referring to the engine tuner, you are correct. You can have a million dollar engine built by the world's most talented creator, but it will knock like hell and destroy itself if the tuning is improperly done OR if it is calibrated properly and then any of the above circumstances arise.

I want to tweak my motor right up to that knock limit to maximize the power and performance and brute force/strength/amazingness of my engine setup :worthy:. To do so, I need to know where that knock limit is. I also want to be notified if my engine begins knocking....aka..self destructing...for whatever reason so that I know to take it easy until I figure out what the cause is. I can hear obvious knock, but it and damage begins to happen so much sooner than the human ear can detect. If no one chimes in, guess I'm on my own on this project and I'll keep everyone updated on my triumphs and failures of getting a good knock detection/controlling system together..

 

[RaWarrior]

You're right, it is the tuner. I assumed since you bought your bike "as is", that it had been previously tuned for the blower. I assume that person was Jon Cornell. I have no experience and have heard little about his engine builds so I can't comment about his abilities. However, stock engines not designed for forced induction are inherently less suited than ones that were, or ones that are set up incorrectly with too-high compression, less than optimal valving, ect, will be more "prone" to knocking, so saying the builder is irrelevant is also not true.

You're right, max performance is at the knife-edge of knock (this is why a stock engine makes the most power on 87 octane, or the lowest octane possible w/o knock).

I had not heard about "current sensing" setups before, that's news to me. All motors I've worked on with sensors have simple bolt on "tilt" sensors, since they were all put there by the OEMs.

If you want your setup to last and be reliable, a "daily driver", then I would advise against pushing it to the absolute limit. Boost conservatively for daily street riding, if you get to a strip or something then adjust it to the max. A few years ago on our turbo-ethanol snowmobile, this was the mindset "MAXIMUM POWER ALL THE TIME". It was tuned right to the edge, and ran like a raped ape for a few hundred miles, then nuked on a long WOT pull. When it got rebuilt, a provision was added for "on the fly" tuning, there was a switch on the dash essentially for "normal" and "max" tuning. Max gave full 16lbs of boost and the knife edge mapping and required 94 octane. "Normal" dropped it to around 10 and changed maps to suit. It still had plenty of power for everyday riding, but was easier on fuel and the motor is still going strong a few years later. It was almost like a "push to pass" button, an instant power boost when needed, but we all knew better than to leave it there for too long.

NASCAR and F1 teams run their motors to the absolute edge, and they also have deep pockets to rebuild them after each race.

 

[Boostmax]

You're right, it is the tuner. I assumed since you bought your bike "as is", that it had been previously tuned for the blower. I assume that person was Jon Cornell. I have no experience and have heard little about his engine builds so I can't comment about his abilities. However, stock engines not designed for forced induction are inherently less suited than ones that were, or ones that are set up incorrectly with too-high compression, less than optimal valving, ect, will be more "prone" to knocking, so saying the builder is irrelevant is also not true.

You're right, max performance is at the knife-edge of knock (this is why a stock engine makes the most power on 87 octane, or the lowest octane possible w/o knock).

I had not heard about "current sensing" setups before, that's news to me. All motors I've worked on with sensors have simple bolt on "tilt" sensors, since they were all put there by the OEMs.

If you want your setup to last and be reliable, a "daily driver", then I would advise against pushing it to the absolute limit. Boost conservatively for daily street riding, if you get to a strip or something then adjust it to the max. A few years ago on our turbo-ethanol snowmobile, this was the mindset "MAXIMUM POWER ALL THE TIME". It was tuned right to the edge, and ran like a raped ape for a few hundred miles, then nuked on a long WOT pull. When it got rebuilt, a provision was added for "on the fly" tuning, there was a switch on the dash essentially for "normal" and "max" tuning. Max gave full 16lbs of boost and the knife edge mapping and required 94 octane. "Normal" dropped it to around 10 and changed maps to suit. It still had plenty of power for everyday riding, but was easier on fuel and the motor is still going strong a few years later. It was almost like a "push to pass" button, an instant power boost when needed, but we all knew better than to leave it there for too long.

NASCAR and F1 teams run their motors to the absolute edge, and they also have deep pockets to rebuild them after each race.

I agree, my engine tuning will need to provide a small margin of safety to the "knife edge" for normal changes in combustion variables, however you need to know A/F ratio AND knock feedback to even define where that knife edge is. You can tune your setup so conservatively that you are in a safe zone, but you leave so much power on the table.....Being the perfectionist that I am, I cant do that.....literally cant.... :biglaugh:

The blower is a bolt on kit. Very rough and crude with an off the shelf Holley 390 4 barrel carb compared to todays modern 3D fuel mapped fuel injected engines. The engine has low compression pistons and upgraded rods which is great, however simply bolting all this together and tuning the carb well enough to seem to run properly is not enough IMO....cant help being a perfectionist...... There has been no dyno tuning, there has been no carb modifications to run in a drawn thru FI setup. I can guarantee that there will be lean spots in the transition area from 2 barrel to 4 barrel using the vacuum operated secondaries, and I would assume that there will be some pinging using 93 octane and 14psi with the stock ignition system. I also dont have deep enough pockets to be rebuilding this motor any time soon which is why I want to protect it by installing the A/F ratio gauge and knock indicator/controller. If I can detect if the engine is running lean or knocking, I can prevent certain engine death no matter how aggressive I set my fuel/spark tuning. Thats what I am trying to accomplish here. Even if I do set everything slightly conservatively, I could get a bad tank of gas and unknowingly roast my engine...or a different uncontrollable circumstance could yield the same results. I've blown up a couple FI engines in the past, one due to my own fault....got a bit boost greedy at the drag strip, the other well, is still unknown what the initial failure was in the pile of shrapnel that was left over. Regardless, I dont want that to happen again.

I have a wideband A/F sensor setup on the way.

I'll probably get the J&S Safeguard knock controller setup and adapt it to the vmax. Put a Dyna 3000 on setting 5 on there which would knock like mad with high boost levels and use the boost retard setting to pull ignition timing at higher boost levels to prevent knocking. The safeguard automatically retards upon knock detection and gives a visual display of detection....that will protect against engine damage in case of a bad tank of gas or whatever or will notify me of when I need to pull more timing from the boost/timing setting. All this can be done on the fly in actual driving conditions.

Should be able to dial in a very precise ignition map using this setup and have automated safety in case of any failure/variable which causes knocking....

I'll start a new thread on it when I get the time to tackle the job.......so many projects.....ugh....

Turbo ethanol sled.....:drool:

 

[RaWarrior]

Well it definitely sounds like you'll get this sorted out. We've been using Dynojet wideband-2 sensors for a few years and have had good luck with them.

Turbo ethanol snowmobile....not as cool as it sounds. Mostly because it says Polaris on the hood, and is thus, garbage. The ECU crapped out on it this year, so it's sitting in the corner collecting dust once again. It absolutely inhaled E85 and wasn't even all that fast. We're talking 5mpg or so if you were getting on it a lot, which is lousy even by muscle sled standards. My N/A 4 stroke Yamaha sled would eat it for breakfast and use less than half the fuel(pump gas).

But, it was very eco-friendly, since what it shot out the tailpipe was very, very, little more than CO2 and water.