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Old 11-12-2009, 06:37 PM   #1
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Default Why not a Hall Effect ring?

Ok, so I'm going to preface this with I AM NOT HYPER, so if this is a stupid idea please feel free to e-bitchslap my ignorance out of my head and I'll drop it.

I started looking around and found this page, which I thought was a pretty clever idea. My question is, with slight alteration to the megasquirt, would it be theoretically possible to produce a clean enough signal with small rare earth magnets to provide an improvement over the stock cas? Specifically if I were to use several magnets 36-1 style? If so, it could prove quite a bit easier than having a toothed gear welded/pressed onto the stock pully with no need to be concerned about balancing.

If you guys think its plausable, I'd be willing to buy the parts and play guinea pig/do a write up.
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Old 11-12-2009, 06:52 PM   #2
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The only real problem with the CAS stems not from the way it works internally, but from the fact that it's driven off of the timing belt. To improve spark stability, you need to take your primary trigger directly from the crankshaft as the NBs do, though it matters not whether you use a VR sensor or a hall effect sensor to do so.

Further, with the MS1 it does not matter how many trigger points you have on the wheel. Even if you are running 60-2 or 36-1 (like I am), the MS "pays attention" to only two of the teeth, namely those specified as Trig Pos A and Trig Pos B in the wheel decoder. (In theory, higher toothcounts can actually have a slightly negative effect on MS1 performance, since the processor spends more of its time in the interrupt routine. Whether or not this phenomenon could actually be measured and proven is debatable.) The MS2 is capable of utilizing higher count wheels to improve the dwell countdown accuracy just a tad, but this is miniscule compared to the improvement in switching from a cam-driven trigger to a crank-driven trigger.

Neat find, though. You should show this to all the guys who want to tear out their EFI and install sidedraft carbs.
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