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In regards to knock control/monitoring on any motor, have you ever heard of using a knock sensor to determine what the "normal" operating noise of an engine would be and tightly link the knock threshold around those values?
I have a 13b turbo with an elite ecu, and a few notable rotary tuners/builders in America have used that theory to monitor and create about as safe of a knock prevention strategy for rotaries as can be, and discussed alot in some forums.
Especially with the development of "unbreakable" style apex seals in the last 10 or so years there is a very small amount of knock that can be got away with before serious damage occurs, usually just with a flattened spring or two, or a small dent in the rotor face.
I know this is usually a teardown and rebuild situation anyway, but I'd imagine it would help to know exactly the cause that created the knock event and prevent further incidents.
I would love to hear your thoughts and anyone else's on this, regardless of the motor, and if the closer to mbt the "noisier" the motor gets, as rotary are typically tuned with a bit left on the table in terms of timing
Hello Matt this is pretty much how i have tuned for years, i use the add of knock muffs as well as logging
So am I correct in thinking that as you get closer to mbt that the noise increases in the motor?
"In regards to knock control/monitoring on any motor, have you ever heard of using a knock sensor to determine what the "normal" operating noise of an engine would be and tightly link the knock threshold around those values?"
Many professional-level ecus do this, often called "Adaptive knock control" or similar, this is where instead of comparing combustion noise to some pre-determined noise threshold table you instead compare the noise of the current combustion event against previous averaged combustion events. This means changes in boost, timing, temperature, clearances, engine wear etc don't have any influence on the relative knock level measurement. However - it is not quite as simple as it sounds - the noise level from cycle to cycle changes dramatically during transients so the strategy needs to use different comparisons under different conditions. Cosworth/Bosch/Life Racing have offered this for some time in some of their ECU's (some are pay-extra options) and Link G4X is the only one I know of offering it in a more consumer-level ecu.
Thanks Adam, that's exactly what I was thinking,
I'm not terribly concerned with transient conditions but when on boost and over a particular boost level is my main point of concern.
My 13b will be on pump fuel for the racing category restrictions, and water injection to cool and slow the combustion process. I know I can run 16ish psi with no knock, as have done for 2 years now, but to be competitive we need another 50 to 75hp or a target about 20 to 22 psi, which for a rotary on 98 is definatelly playing with fire.
Thanks for the help Ross and Adam