Project NSX: Part 19 – Designing a Crank Position Sensor and Knock Control

NSX Custom hall effect crank position sensor mountThe machining of this part is beautiful and perfectly matches the contours and mounting locations of the oil pump housing.

NSX Hall Effect Crank Position Sensor Mount and Tone WheelWe made a handful of these crank position sensor mounts and tone rings for our build and a few others.

NSX Hall Effect Crank Position Sensor and Tone WheelMounted in the car, the new crank position sensor looks great, is easily accessible, and gives us more clearance for our dry sump system.

NSX Crank Position Sensor and Tone WheelThe sensor mount gives us a ton of clearance to both the air conditioning and alternator belts.

NSX OEM knock sensorNext up we tackled upgrading our knock sensors.  The factory knock sensors are located in the valley of the V6 block, close to the middle cylinders of each bank.


  1. Back in my OEM engine calibration days, we referred to the time period where knock is likely to occur as the gate period. This can be determined by the crank angle and firing order. Knock should only typically occur during a small range of crank rotation for any given cylinder. We utilized 4 and 8 channel oscilloscopes to view and measure the raw knock sensor output signal, and then match it up against what we heard. A good microphone and a quality set of headphones go a long way. If a ‘knock’ waveform was detected for a particular cylinder, but was outside the gate period, it was largely ignored. We also calibrated the ECU to ignore these signals so it does not interfere with the knock control learning logic. Knock control system calibration on a modern Japanese V8 engine with 4 knock sensors could take 4-6 months. So basically, you’d run the engine at medium to high loads, advance the timing till a determined level of knock was achieved, and then analyze the data. After 4-6 months of knock testing, we’d do a HP check, confirm numbers, and then disassemble/inspect the engine. It was usually one of the last calibrations performed as any mechanical change or addition to the engine would change the harmonics, and require re-testing.

    FYI, most OEM engines are calibrated to run at a certain/safe level of knock. It’s perfectly fine in most situations. You’d be surprised at how durable most engines are… well the one’s I worked on anyway. 🙂

    1. I also have some past excursions in engine dev; we supplemented knock sensors with individual cylinder pressure sensors (also with an O-scope during dev). These were big engines though, and I think I remember the pressure sensors were a permanent part of the control system feedback in the same way as the knock sensors. Crank angle gating is definitely a normal part of knock strategy.

  2. These are the articles I hope to see anytime I click on MotoIQ, Thanks!!
    Hey one of the best project Supra articles has the wrong pictures in it- it’s an article about the cylinder head, but with all bodywork photos!!!

    Mike I also wanted your opinion on Bosch 4.9 wide band sensor placement in a turbocharged 4-500 horse flex fuel engine-
    Thanks guys sorry not fully on topic

Leave a Reply

Your email address will not be published. Required fields are marked *