if you only want a tdc ref you could simply screw a bolt into the edge of aux pulley and use conjugation with a crank sensor
if you only want a tdc ref you could simply screw a bolt into the edge of aux pulley and use conjugation with a crank sensor
Hang on got to look up conjugation..........
Now there is an idea....small bolt wouldn't put the pulley too far out of balance.
1970 Mk1 Escort Tarmac Rally Car
MS (Megasquirt I assume) and Megajolt (which I have fitted to several engines) either don't have crip or have a limited crip function depending on what version of hardware and firmware you are running
The 90 degrees before TDC is for 4 cylinder engines and some measure of edjustmen could be built in to the sensor brack.
I bought trigger wheels of eBay for a lot less the buying from the likes of triggerwheels.com and made my own brackets, a little agricultural that they may appear
The trigger wheel is around 120mm diameter. The tip of the hall sensor is around 3mm but it is anybodies guess as to how much tooth needs to be over the tip to give a reading. 3mm around the diameter of the trigger wheel represents 2.87 degree of crank rotation so I can see it will be hard to get a spot on reading. I am using a Magneti Marelli WSS075 sensor but have been unable to find any info as to whether it is a rising edge or falling edge. The width of the trigger wheel tooth/gap doesn't matter and I don't think the rising/falling bit matters either TBH as I just need to pick either the rise or fall of the output signal and make that align to TDC at the point the tooth is recognised by the sensor.
The output of the pressure sensor shows a nice peak but I have no idea if there is any time delay shift in the signal.
1970 Mk1 Escort Tarmac Rally Car
QUESTION: Does the trigger wheel need to be moving in order to get a signal from the hall sensor or will a stationary trigger wheel (in teh correct place) also give a signal???????? I believe it has to be moving.
1970 Mk1 Escort Tarmac Rally Car
QUESTION: Does the trigger wheel need to be moving in order to get a signal from the hall sensor or will a stationary trigger wheel (in teh correct place) also give a signal???????? I believe it has to be moving.
1970 Mk1 Escort Tarmac Rally Car
Needs to be moving for a hall Sensor
Keep her lit
doesnt matter whether its a hall trigger or an inductive sensor, no movement = no signal
It can be stationary if u move the sensor no ? 😳
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indeed
I have been playing with the sensor today connected to the Picoscope. It is an inductive type and yes no movement = no signal. You also need a reasonable amount of movement (speed wise) to get much of a voltage.
I mounted the Webcon trigger wheel to a cordless drill so that I could see the output signal. It was hard to keep the wheel a constant (yet close) distance from the sensor so the signal was moving up and down a little however I did get a clear sin wave (the inductive sensor produces a sine wave whereas the hall effect produces a square wave). Thinking about what I need the signal for and given that the trigger wheel has a space to represent TDC I concluded it was not fit for my purpose. Graham was spot on above when he said to use a screw as the reluctor.
I then grabed an old jackshaft pulley and welded a blob onto one of the teeth. I then filed with into a nice little square block protruding from the tooth by around 4mm. Using the pulley in the drill I got a much better signal. Even though the sensor was around 6mm from the teeth (but only around 1mm from the block) I got 37 very small sine waves (one for each tooth) then a large short sine wave for the block. Nice. From this I think I will look at mounting the sensor against the jackshaft pulley, welding a small pin onto its edge as the reluctor then I can get 1 signal per rotation representing TDC #1.
One thing that I have not found a way to prove is just when/how the signal is produced. As the reluctor gets close to the sensor pin it starts to form a positive voltage which decays and then eventually becomes a negative voltage as the reluctor moves away from the sensor pin. I think I have to assume that the middle of the sine wave (point of zero voltage as it transitions from +ve to -ve) is the point where the reluctor is centred over the sensor pin. It is possible that due to manufacturing tolerances/design that the voltage is being produced offset to this position but given I cannot prove this I have to ignore it. As said above, the reluctor travels 2.87 crankshaft degrees across the sensor pin (assuming the reluctor is not larger than the sensor pin) which is the max error whereas the likely offset and error is likely to be a fraction of that.
1970 Mk1 Escort Tarmac Rally Car
im no expert here, but i would of thought a hall sensor would work better for you as that produces a digital off/on signal no gradual decay or rise of voltageOne thing that I have not found a way to prove is just when/how the signal is produced. As the reluctor gets close to the sensor pin it starts to form a positive voltage which decays and then eventually becomes a negative voltage as the reluctor moves away from the sensor pin. I think I have to assume that the middle of the sine wave (point of zero voltage as it transitions from +ve to -ve) is the point where the reluctor is centred over the sensor pin. It is possible that due to manufacturing tolerances/design that the voltage is being produced offset to this position but given I cannot prove this I have to ignore it. As said above, the reluctor travels 2.87 crankshaft degrees across the sensor pin (assuming the reluctor is not larger than the sensor pin) which is the max error whereas the likely offset and error is likely to be a fraction of that.
Several thoughts with using a hall sensor;
1. Is required power so is marginally more complex to wire and given the infrequency of use is not nice and simple like an unpowered 2 wire induction sensor
2. I would have even more trouble determining the point where the sensor switches on and therefore lining up TDC.
A digital signal is much cleaner to work with however.
1970 Mk1 Escort Tarmac Rally Car
I think your overcomplicating this and not taking into account the software.
Use middle of tooth to set triggerwheel to TDC, rotate engine 90 degrees set sensor to middle of tooth
Job done.
In fact it's even more simple than that, set engine to TDC, middle of dwell, fit sensor on bracket, rotate triggerwheel so missing tooth is 90 degrees after TDC
All the installation diagrams are on the Autosportslabs website or google Megajolt.
Has anyone used a Turbosport Billeted Front Crank pulley With 36-1 timing wheel?
If so, what sensor did you fit and have you got a picture of it mounted, please?
Not sure if the company is associated with this site or not!
Cheers Graham,
The reason I asked was due to the customer service I received. I purchased the pulley from them, but don't want to go back to him and ask about the sensor.
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