Syvecs Forums

I am trying to get this right first time around.
My sensor is roughly fitted 135 degrees before TDC
Does the gap have to go 90 degrees after the sensor when the engine is at TDC?
I have a 4 cylinder engine, and I thought the gap should be away from any timing events, I will have a cylinder firing every 180 degrees of crank rotation so as long as I have say 5 teeth either side of the sensor at TDC that's 100 degrees leaving 80 degrees of space the gap can be in or does it have to be accurately 90 degrees?
And in scal, you set the reference tooth to the 2nd tooth from the gap?
Or am I getting this totally wrong? Haha
Thanks
Graeme

The last part of your question, it only has to be that way if you have set the gap validation (IE: third tooth after gap), if not then its the second tooth after the gap.

Rest inc this is all explained if you hit 'F1' help in SCAL.
I attached a PDF on it.

Trickster wrote: ↑Wed Aug 28, 2019 12:44 pm I am trying to get this right first time around.
My sensor is roughly fitted 135 degrees before TDC
Does the gap have to go 90 degrees after the sensor when the engine is at TDC?
I have a 4 cylinder engine, and I thought the gap should be away from any timing events, I will have a cylinder firing every 180 degrees of crank rotation so as long as I have say 5 teeth either side of the sensor at TDC that's 100 degrees leaving 80 degrees of space the gap can be in or does it have to be accurately 90 degrees?
And in scal, you set the reference tooth to the 2nd tooth from the gap?
Or am I getting this totally wrong? Haha
Thanks
Graeme

Timing references are setup after TDC in Scal, so factor that in. Some ecu's do seem fussy about where the gap is etc, but have never heard any Syvecs info to say it's a concern.

36-2 is becoming more popular where the gap becomes more defined though.

This is mine for a visual reference, 36-1, with the DTA this had a tooth ref of 67 deg BTDC for the first full tooth after the gap.
Same setup on my Syvecs I have it around 301.5degATDC, using the second tooth after the gap as the reference.

As graph shows, cyl1 compression is on the bottom graph to show you where TDC occurs, relative to tooth count. If we could overlay a 720 graph on View...would could examine the various events much easier. But we cant lol ( and I've asked )

edit, notations on my first pic pic probably didnt make so much sense, so have amended it here

Thanks for the replies! Good info as always!
I am going to use the stock dizzy for cam phase, which is already setup, so hopefully changing to the 36-1 should be straight forward.
Steve what engine do you have, and is that cylinder pressure under cranking in your log? What kind of sensor detects that?
Graeme

Just a cheap chinese pressure sensor, adapted onto a fitting from a compression tester. Obviously cyl1 plug isnt in place, but it will let you do a running compression test.

I think it was either a 300psi pressure sensor, absolute. So it can read vac too. Resolution was only listed at around 2ms, so not the fastest by any means
Any lag would be negligible at cranking speeds, but relative to cam trigger it is apparent if you rev it up a bit. Whether that's expected, the sensor..or other, I don't know.
I've never tried a faster sensor. The likes of Pico's WPS is supposed to be very fast...but then it's near a grand, so it'd bloody need to be lol.

That's pretty cool! I wonder if any engines have actually running pressure sensors, mega high pressure and heat but would be interesting to see!

Graeme

Proper in cylinder transducers seem to be very expensive and fragile, but they are out there.

Many modern diesels have pressure transducers built into the glow plugs. As to how accurate or good they are, no idea.

it's long overdue that there would be good options for regular petrol engines though, and especially in the tuning world.

Definitely would be useful in tuning!

In the engine configuration where the option - ignore cam after 720 sync (or however it is worded) it says it is advised against on keyed by single cam, why is this?

Thanks
Graeme