36-1 Trigger wheel fitting

stevieturbo
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Re: 36-1 Trigger wheel fitting

Post by stevieturbo »

pretty sure keyed by single cam is for crank trigger patterns where there are no identifying teeth. ie, 24 teeth, 36 teeth...

Not for 24-1, 36-1, or similar.

So if you were to ignore the indexing which would be the camshaft....any small errors with the main trigger could not be recognised which could lead to problems.

With say a 36-1, even with no phase ID once running.....it's still repeatedly counting each TDC event accurately anyway. With no ID teeth this is impossible.
Trickster
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Joined: Mon Nov 28, 2016 6:09 pm

Re: 36-1 Trigger wheel fitting

Post by Trickster »

That what I was thinking, I never noticed before as I have never really looked into engine configuration too much, but mine is set to ignore cam after 720, on stock dizzy pickup 24teeth and single cam tooth. Its always been OK, just got me curious.

I did assume the engine would only need to know its phase position once.

How does the ecu calculate precise ignition when it only has say 35 teeth, it can physically see every 10 degrees, is it simply a calculation of the speed the teeth pass by with the amount teeth/degrees per cycle and the more teeth the more accurate it can be? If an engine is accelerating it must always be playing catch up to an extent?

Not that any of that matters, just find it interesting haha

Graeme
MR2 Turbo 5sgte 750hp 527ft/lb Syvecs S6
stevieturbo
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Re: 36-1 Trigger wheel fitting

Post by stevieturbo »

As the instructions suggest.....ignoring cam with such a setup seems a very bad idea.

If the engine only read and accepted phase/TDC ID once.....that might be after one or two revolutions at startup.

How many hundreds of thousands of revolutions might it run for thereafter....and how much chance is there of some small errors creeping in ?

If you've ignored any means of identifying errors, or re-indexing as it runs.....that is a bad idea.

Catch up....maybe, but not really.

Your ecu could be going and watching a movie in between it detecting each of the 35/36 teeth. You might think an engine turns fast...and it does. But when a processor is doing a few million things per second, a trigger passing a wheel at a few thousand turns a minute really isnt fast at all.
Trickster
Posts: 63
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Re: 36-1 Trigger wheel fitting

Post by Trickster »

Yeh I understand the processing power, 100mhz as an example does make the trigger pickup seem walk in the park material!

I am setting up my crank pickup sensor today, fabricating a bracket should be fun, but looking forward to escaping that stock pickup!

Graeme
MR2 Turbo 5sgte 750hp 527ft/lb Syvecs S6
RICE RACING
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Re: 36-1 Trigger wheel fitting

Post by RICE RACING »

stevieturbo wrote: Wed Aug 28, 2019 9:23 pm edit, notations on my first pic pic probably didnt make so much sense, so have amended it here

crank ref syvecs2.jpg
Stevie did a good job above.

Here I same idea of logging the crank wheel I made up and a Syvecs pressure sensor (of appropriate range) to do a non running or roughly cranking speed engine TDC indirect measure, as its on a total shit box of an engine (Wanker or Wankel) :) there are a few caveats but once you do some testing its repeatable and an alternate method where direct measurement is not possible ;)

Also debunked a rubbish technique someone high lighted to me about using Mr Bubbles to do a similar thing....... that is not so nice :lol:

VIDEO > https://www.youtube.com/watch?v=wtOWk260sPc

And a few [pics] below....
TDC3.jpg
TDC3.jpg (302.32 KiB) Viewed 3368 times
don tooth VR.jpg
don tooth VR.jpg (396.82 KiB) Viewed 3368 times
Mr Bubbles1.jpg
Mr Bubbles1.jpg (551.27 KiB) Viewed 3368 times
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stevieturbo
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Re: 36-1 Trigger wheel fitting

Post by stevieturbo »

Would be interesting to see with 2 sensors what pressure in the chamber is like there ? Or do you think they'd pretty much mirror each other ?
RICE RACING
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Re: 36-1 Trigger wheel fitting

Post by RICE RACING »

stevieturbo wrote: Fri May 29, 2020 1:35 pm Would be interesting to see with 2 sensors what pressure in the chamber is like there ? Or do you think they'd pretty much mirror each other ?
You mean the T & L plug locations? if so those are basically the same despite having the T hole (very small opening to chamber) and L hole being full sized of spark plug diameter opening.

I did not want to make a career out of it so once I gathered the data I called it :lol:
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Trickster
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Re: 36-1 Trigger wheel fitting

Post by Trickster »

Never followed up on this but I got the crank sensor working perfectly, I tested the timing with a light on the old setup (stock Toyota) and for some reason it was bouncing all over up to 5 degrees + - of the 10 degrees btdc its supposed to be at.

I swapped to the new pickup and it fired right up, my initial sensor position which I measured with a wheel was off by 1 or 2 degrees, adjusted that and it sits on 10 degrees btdc perfectly.

Makes me wonder if the original pickup had been causing ignition scatter which killed my cylinder head as the knock level was through the roof.

Tuning this time made much more power and didn't even get to knock limit, I asked my tuner to stop at the power level we made as I thought it was enough for the motor mechanically.

As a follow up I'd say anyone changing to Syvecs should ditch a cam pickup like my Toyota had and go with a crank pickup, I bought a cheapish trigger wheel and a ntk Ford zetec sensor, made a bracket from aluminium, took a bit of fiddling but was worth it.

Graeme
MR2 Turbo 5sgte 750hp 527ft/lb Syvecs S6
RICE RACING
Posts: 277
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Re: 36-1 Trigger wheel fitting

Post by RICE RACING »

Trickster wrote: Tue Jun 02, 2020 10:42 am Makes me wonder if the original pickup had been causing ignition scatter which killed my cylinder head as the knock level was through the roof.

Graeme
See it a few times on timing belt equipped engines, and yes it causes higher knock due to inaccurate timing events.
Best thing is to throw them in the rubbish and put on a proper crank trigger ;)
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stevieturbo
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Re: 36-1 Trigger wheel fitting

Post by stevieturbo »

Trickster wrote: Tue Jun 02, 2020 10:42 am
As a follow up I'd say anyone changing to Syvecs should ditch a cam pickup like my Toyota had and go with a crank pickup, I bought a cheapish trigger wheel and a ntk Ford zetec sensor, made a bracket from aluminium, took a bit of fiddling but was worth it.

Graeme
A crank trigger for crank position is a no brainer regardless of what ecu. It's actually bizarre some manufacturers do rely on camshaft for such a reference.
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