Quote:
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.
