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Old 12-07-2009, 05:06 PM   #1
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Default Crank Triggers from BE (Split from Full Lightweight Timing thread)

Integrating a VR or hall wheel in the crank and cam would be awesome...
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Old 12-07-2009, 06:34 PM   #2
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Quote:
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Integrating a VR or hall wheel in the crank and cam would be awesome...
Yes...yes it would.

And just to reiterate

Yes...yes it would.
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Old 12-08-2009, 04:41 PM   #3
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While we're at it, if you pursued this, don't put 74 million teeth on it. 4 might be too few, but it's closer to right than 60, in my humble opinion. :-) 20 would probably be great.
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Old 12-08-2009, 05:11 PM   #4
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Quote:
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While we're at it, if you pursued this, don't put 74 million teeth on it. 4 might be too few, but it's closer to right than 60, in my humble opinion. :-) 20 would probably be great.
you're thinking crank wheel.

cam only needs one or two or 3 for sync.

crank needs more for timing accuracy... and why not stick with a current standard setup like 60-2 or 36-1 or whatever?
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Old 12-08-2009, 05:19 PM   #5
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(mod note: edited out the stuff from the lightweight timing kit thread)

Right now we have 3 indicators as stock for synch. I don't think you'd want to do much with the cam as far as timing because its connected to the crank by a bungee cord.

Last edited by y8s; 12-12-2009 at 12:17 PM.
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Old 12-11-2009, 02:38 PM   #6
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You do get a cam signal off of there - something that tells you which half of the cycle you're on. You're right, a cas-like signal would be a joke off the cam, but if there's a good crank signal...
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Old 12-11-2009, 03:19 PM   #7
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I care more about the crank. I think modding the stock CAS is fine for cam. I've been trying to find someone who will build me a crank sensor.
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Old 12-11-2009, 07:39 PM   #8
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For those running 99+ motors, they will likely want both cam and crank triggers. If you're making it yourself, it's easy to add it in - a shame to have someone jerry rig something after putting on a flawless kit like that.
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Old 12-11-2009, 08:36 PM   #9
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Just out of random curiosity, and because this thread has drifted off topic anyways, what happens with a car that's running on a crank wheel/sensor setup and has a timing belt that's off a tooth or two on one of the cams? Wouldn't it be slightly different? Or would it just be the cams taking the place of the pistons being in the wrong position, and it would still run crappy.
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Old 12-11-2009, 09:08 PM   #10
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If the crank has a decent wheel - with a missing tooth or some other way to have a clearly defined TDC, there's no issue - the cam is just there or not - within half a cam rotation should be fine.
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Old 12-15-2009, 07:38 PM   #11
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Quote:
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Right now we have 3 indicators as stock for synch.
Totally missed that. That's awesome. The only possible drawback is if someone wanted a single tooth in case they didn't want to decode the ridiculous miata timing signals.

Additional crank teeth are basically never used, except in misfire detection. Especially on the slower processors (MS-I and the like) you're wasting quite a bit of time dealing with interrupts from crank teeth events. 36-1 is the MOST I would do. I made some assumptions, but at redline you were dealing with basically nothing but crank triggers on MS-I and a 60 tooth wheel. That leaves little time for other calculations.

The question is - are you USING that extra information? Sure you can say it's not a big deal, but if it only hurts you a little, but for no gain, is it worth it? No. There's information available there, but no system I've seen (aftermarket) uses it! So, stick with ~20 teeth ideally. Maybe 18? The 4 teeth on the OEM mazda crank works pretty damned well for timing accuracy (certainly well within 1* of jitter most any time you're over 1800 rpm)...

That's what I'm getting at - a step up from OEM without being overkill.
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Old 12-15-2009, 09:45 PM   #12
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The AEM will work better with 8 to 12 teeth on the crank than the 4-which-theAEM-treats-as-2 that the 99 has.

With just 2 teeth on the crank, the AEM will be blind to rapid crank acceleration (like in neutral).

I would buy an 8-toothed one one which replaced the factory crank sensor. However, it MUST be positioned so that the VVT cam signal doesn't "cross over" a tooth when going from retard to advance. i.e. 8 teeth = 45* between teeth, and the cam phase range is 36* IIRC...

Last edited by JasonC SBB; 12-16-2009 at 02:17 AM.
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Old 12-17-2009, 03:33 AM   #13
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I guess in theory you could use the uneven spacing of the crank teeth to know where you are, or any 'missing tooth' to do the same. That's the point, it takes more intelligence to use more teeth otherwise you're just wasting time.
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Old 12-28-2009, 06:12 PM   #14
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I suppose I could grind off the 2 teeth from the '00 cam gear (leaving just 1) so i could then use any 8 or 12 tooth crank wheel with my AEM.
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Old 12-28-2009, 06:20 PM   #15
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Or tap a bolt into an adjustable gear, on the forward face but near the outer edge. Which is what I have from M2CupCar's Cup Car.
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Old 12-28-2009, 06:50 PM   #16
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That bolt has to cause some serious balance issues. Did you weight the other side as well to offset it?

I'm trying to find a crank wheel as well. I'm wondering if the 96+ crank pulley boss and one of the trigger wheels will work on a 1.6L. I'm not sure if the newer pulley is needed or not.
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Old 12-28-2009, 07:26 PM   #17
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It's a little tiny bolt and actually there is a little material ground off the gear around it. Everything survived racing at super high rpm on a motor that spun in excess of 8k. If it holds up for a race season on a Cup car, it will be fine on the street too. I'm not in the least bit concerned. I guess it could be spin balanced at a machine shop.
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Old 12-31-2009, 02:21 PM   #18
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Quote:
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Or tap a bolt into an adjustable gear, on the forward face but near the outer edge. Which is what I have from M2CupCar's Cup Car.
That's brilliant.

As to balance, perfectly balanced is always the goal, but I doubt that a small bolt head spinning only half the engine RPM at such a small radius could cause problematic vibration.

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Old 12-31-2009, 04:08 PM   #19
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Excuse the pics. This is a dirty, used part. This works with the stock BP4W/MSM sensor, though of course with aftermarket management.
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Crank Triggers from BE (Split from Full Lightweight Timing thread)-camgear.jpg   Crank Triggers from BE (Split from Full Lightweight Timing thread)-camgear1.jpg  
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Old 01-01-2010, 05:21 PM   #20
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Thanks for the pics. Very nice and even smaller than I imagined.

Unfortunately, I'm dense. You're using the stock sensor (from a NA?) and mounting the sensor over your aftermarket cam gears how?

M.
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