FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: BigBlueIron on January 29, 2019, 12:47:39 PM
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Anybody have any experiences good or bad with this product http://www.jandssafeguard.com/safeguard.html (http://www.jandssafeguard.com/safeguard.html) Or anything for knock detection? Or am I overthinking it.
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I tried one, couldn't get it to work right on any dyno engine. I was pretty disappointed with it.
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I have not tried that particular product. But I have done a few swaps of OEM injected engines that have knock sensors. Most "performance" engines has configurations that cause harmonics that the knock sensor sees as a combustion event and gets confused. If it's a mild case you can sometimes tune around it, but in most cases I've just tuned the knock sensors out all together.
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+1 on the above comment. At Ford, we had to tune the knock sensor for each engine. Even if you moved the sensor on the engine more than a little bit, no more workie! Sometimes we had to search hard to find a spot on the engine with a clean signal.
A knock sensor is basically a tuned resonator with a coil attached. Electronics guys would call it a "band pass filter". You're looking for a particular telltale frequency in a sea of noise.
I'd be very skeptical of a one-size-fits-all product.
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It's amazing what the signal looks like just moving the sensor a few inches one way or the other! It was on one of those other engines (SBC) that I was using a lot of OEM EFI stuff on but it was a solid roller engine and just changing valve lash tighter or looser would make a difference. I think making a knock sensor work on a typical street/strip build is possible, but I don't think the reliability and the gains are worth the hassle. You could spend the afternoon on a chassis dyno or at the track with a laptop and get better results for preventing "unwanted combustion events" I think.