Engine Knock Detecters
Discussion
The first question i would ask is "why?"
Running an engine close to its knock threshold makes sense if:
1) you want to make the absolute highest BMEP possible
2) You want to reduce the specific fuel consumption to the absolute lowest level
3) You are constrained by other rules, regulations or requirements to require the maximum thermal efficiency of your engine
For a typical "hobby" car, with the assumption you're not racing to win anything, you'd be far better spending the money of a decent, safe base map. If you start with conservative settings, and ensure you have the correct parameter trimming to account for the expected range of boundary condition changes then you don't need knock sensing or detection. Running less spark, and using a little more boost to make your power target is a much safer way of doing it, and moves a significant proportion of the peak thermal/mechanical loads away from the combustion system, giving your base engine an easier time of things.
Also, IME, i can count the number of correctly calibrated and effective knock control strategies i've seen, on the fingers of one foot....... ;-)
Running an engine close to its knock threshold makes sense if:
1) you want to make the absolute highest BMEP possible
2) You want to reduce the specific fuel consumption to the absolute lowest level
3) You are constrained by other rules, regulations or requirements to require the maximum thermal efficiency of your engine
For a typical "hobby" car, with the assumption you're not racing to win anything, you'd be far better spending the money of a decent, safe base map. If you start with conservative settings, and ensure you have the correct parameter trimming to account for the expected range of boundary condition changes then you don't need knock sensing or detection. Running less spark, and using a little more boost to make your power target is a much safer way of doing it, and moves a significant proportion of the peak thermal/mechanical loads away from the combustion system, giving your base engine an easier time of things.
Also, IME, i can count the number of correctly calibrated and effective knock control strategies i've seen, on the fingers of one foot....... ;-)
Max_Torque said:
The first question i would ask is "why?"
Running an engine close to its knock threshold makes sense if:
1) you want to make the absolute highest BMEP possible
2) You want to reduce the specific fuel consumption to the absolute lowest level
3) You are constrained by other rules, regulations or requirements to require the maximum thermal efficiency of your engine
For a typical "hobby" car, with the assumption you're not racing to win anything, you'd be far better spending the money of a decent, safe base map. If you start with conservative settings, and ensure you have the correct parameter trimming to account for the expected range of boundary condition changes then you don't need knock sensing or detection. Running less spark, and using a little more boost to make your power target is a much safer way of doing it, and moves a significant proportion of the peak thermal/mechanical loads away from the combustion system, giving your base engine an easier time of things.
Also, IME, i can count the number of correctly calibrated and effective knock control strategies i've seen, on the fingers of one foot....... ;-)
Yep, wouldn't disagree that knock " control " of any kind is a game of chance, however there is an argument to be had that something is better than nothing, more so on a modified car.......the map on my car is regarded as "safe", in as much as the power output and more specifically the torque are deliberately limited to safeguard the weakest links in the chain ( conrods and 4th gear on an Evo ) but you can't legislate for things like a bad batch of fuel such as the one I filled up with in Crete. Running an engine close to its knock threshold makes sense if:
1) you want to make the absolute highest BMEP possible
2) You want to reduce the specific fuel consumption to the absolute lowest level
3) You are constrained by other rules, regulations or requirements to require the maximum thermal efficiency of your engine
For a typical "hobby" car, with the assumption you're not racing to win anything, you'd be far better spending the money of a decent, safe base map. If you start with conservative settings, and ensure you have the correct parameter trimming to account for the expected range of boundary condition changes then you don't need knock sensing or detection. Running less spark, and using a little more boost to make your power target is a much safer way of doing it, and moves a significant proportion of the peak thermal/mechanical loads away from the combustion system, giving your base engine an easier time of things.
Also, IME, i can count the number of correctly calibrated and effective knock control strategies i've seen, on the fingers of one foot....... ;-)
As you'll know, a knocklink is an extremely old fashioned and rudimentary form of information update, and requires a baseline setting from using det cans for accuracy, but if I hadn't had it at the time, I might have had an engine rebuild to finance. Having never seen a red light on the knocklink for 4 years, the fact it did nothing but light up red every time I attempted to drive it on boost with that tank of fuel meant I knew not to try. Therefore, worth having.
I'd agree that having a map a good step away from the edge is sensible, but I'd still argue that for the cost, some form of knock monitor isn't an extravagance.
Edited by Heaveho on Sunday 23 April 22:43
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