MembersPage/GrmRacer/TriggerSetup

This page is to help with setting up the Primary Trigger option

Specifically for the VAG 60-2 wheel, but it will contain general information


VAG wheel & setup info

[primary] trigger setup image from Megatune

[Image] of transition trigger being used for a 60-2 setup. Its not 100%, but it does work.

With this setup I found ingition events occuring on (0 degree advance makes math easier)

Tooth 14 and tooth 46 thats 32 teeth apart I am going out on a limb here and we'd like this 30 teeth apart :-) otherwise there is a 12d difference between spark events and crankshaft rotation


Moment of Clarity

So to setup the primary trigger events..

Measure the angle of the crankshaft in reference to TDC that the missing teeth cross the VR sensor.

Then determine if that event is between 60degrees and Max desired ignition advance, or alternatively set it to 60 degrees

MembersPage/PeterNassy? question moved to the top.

But this also depends on what type of trigger wheel you use,right.I mean if i use a cam driven 5 window triggerwheel,time between valid trigger events cannot be the same if i would use a crank 60-2.Also want to know what is valid trigger event.

Lets talk about a 5 cyl.If camdriven 5 window hall,every window,right?If 60-2,every 60/5=12th teeth?Or every missing teeth?

\\NanssyPeter?

Peter, (assuming 4cycle engine)

These settings are for a crank trigger. That assumes a 720d rotation for one cycle. For a Camshaft triggered event (360d per complete cycle) the period length is generally multiplied by two. I will be making a set of pages that describe how to do all this for these types of configurations, but right now this is limited to crank trigger driven events.

The plan is to have a page that describes how to get the values for a crank trigger and a cam trigger, followed by several pages that specifically address the different types of engines 4clyn, 6clyn(even/odd/straight), V8, V10, V12.. My expertise lies with the 4clyn VW/Audi (VAG) products. But there will be lookup tables for both crank and cam trigger. This is mostly because I actually have both solutions that I have to do. the NA GRM car is a 4 window Hall sensor (cam) and the Turbo GRM car is a 60-2 VR crank sensor.

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MegaTune is an easy way to setup the trigger values, but you need to know what you are changing.

current decimal values

Primary Trigger GRM setup Mcel
Edge Rising Rising
Type Multitooth Multitooth
Filtering Disabled Disabled
Tooth Relation (Usually Disabled) Disabled Disabled
Trigger Settings
TDC after trigger (degrees) 60.0 60.0 VAG wheel on ABA block is 90d off TDC at the center of the missing teeth via calibrated eyeball
Number of teeth on wheel 58 58 actual nubs
Trigger Tooth 3 15 The third nub after the space actually the missing ones are counted, 3= the first after the space VAG ABA wheel appears to have the center of the missing teeth @ 90d off TDC, would this make this value 2
Next Trigger Tooth 15 (V8)/20 4clyn 15 Manual states NextTrigTooth?= imaginary teeth * 2 / cylinders (60 *2 / 4 = 30)
Crank minimum period (usec) 1280 1280
Tooth Width
Engine Phase, when reset240240 determines toothwidth unit; (equivalent to 720 crankdegrees = 2 crankrot= 120 teeth)
Angular width of tooth 2 2 120 teeth is 240, so 1 tooth width is 2
Angular width of missing tooth 6 63 times the above (2 missing teeth)
This part needs to be made either transparent to the end user or extremely well explained with a shortcut on howto do it.
Tooth Relation to Normal (usually 181) 181 181
Tooth Relation to Missing (usually 118) 118 118

These are all you settings, but these are not normally how motorheads describe thier motors or triggers.

Typical Descriptions

So using these values how do we get the other ones.


Suggestion

Do the number trunkation etc in the make mtt portion. Most NON - EE/CompEE/CS? engineers will not get the howto about converting decimals to an arbitrary (seemingly) number less than 255 ( 8-bit micro unsigned issue)...

So basically a good picture and straightforward equation, IF it is not automagically done for the config. If they don't care, they should copy a working example and not mess with the numbers they don't know.

Min Crank Period (review this statement)

This definately needs to be calculated somewhere else.. I thought it was for "cranking" aka starting the car. but it is directly related to Rev limiter.. you could call this the OVERREV point or something. I'm guessing its an early variable.

Angular width, etc.. This should all be auto-calculated.

since an 8bit number only can goto 255 (8-bit unsigned) so the whole point of this is scaling.

Example 60-2 wheel

  1. 1 its a ratio..
  1. 2 Given the number of teeth in a 720d rotation what is the new number in this ratio
  1. 3 Scaled Tooth angle is y
  2. 4 Scaled missing tooth angle is y * # of missing teeth

Proposed table

[Excelsheet]

Typical Meaning   Variable names 1-10 1-12 1-16 1-36 60-2  
Total Teeth Entered internal 10 12 16 36 60  
missing teeth Entered Number of teeth missing 1 1 1 1 2  
Teeth Present Calc Number of teeth on wheel 9 11 15 35 58  
Crank Rotations per complete clycle Entered internal 2 2 2 2 2 (2 for 4cycle 1 for 2 cycle)
Degrees per complete cycle* Calc internal 720 720 720 720 720  
720 / Total Teeth = Angle Per tooth (degrees) Calc   36.0 30.0 22.5 10.0 6.0  
Total Degrees scaled to 8 bit unsigned: 255/total teeth Calc   12.8 10.6 8.0 3.5 2.1  
Truncate for integer math Calc   12 10 7 3 2  
Scaled degrees per cycle Calc EnginePhase? when reset 240 240 224 216 240  
Scaled degrees per tooth Calc Angular width of tooth 12 10 7 3 2  
Scaled degree of missing spaces(teeth+1) Calc Angular width of missing tooth 24 20 14 6 6  
         

Now you have to Determine what the next trigger tooth is

Number of Clynders        
4clyn Entered 4 Good Good Good Good Good
Teeth until next clyn event Calc Next trigger tooth 5.00 6.00 8.00 18.00 30.00
  Calc Scaled deg/ cylinders 60.00 60.00 56.00 54.00 60.00
        
5clyn Entered 5 Good NotValid? NotValid? NotValid? Good
Teeth until next clyn event Calc Next trigger tooth 4.00 4.80 6.40 14.40 24.00
  Calc Scaled deg/ cylinders 48.00 48.00 44.80 43.20 48.00
        
6clyn Entered 6 NotValid? Good NotValid? Good Good
Teeth until next clyn event Calc Next trigger tooth 3.33 4.00 5.33 12.00 20.00
  Calc Scaled deg/ cylinders 40.00 40.00 37.33 36.00 40.00
        
8clyn Entered 8 NotValid? Good Good Good Good
Teeth until next clyn event Calc Next trigger tooth 2.50 3.00 4.00 9.00 15.00
  Calc Scaled deg/ cylinders 30.00 30.00 28.00 27.00 30.00
        
10clyn Entered 10 Good NotValid? NotValid? NotValid? Good
Teeth until next clyn event Calc Next trigger tooth 2.00 2.40 3.20 7.20 12.00
  Calc Scaled deg/ cylinders 24.00 24.00 22.40 21.60 24.00
        
12clyn Entered 12 NotValid? Good NotValid? Good Good
Teeth until next clyn event Calc Next trigger tooth 1.67 2.00 2.67 6.00 10.00
  Calc Scaled deg/ cylinders 20.00 20.00 18.67 18.00 20.00

The min_crank_per describes the minumum time between 'valid trigger events. If you use this table select your # of clynders and RPM limit. and then just plug in that number

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minmum period in microseconds(us) between trigger events
Assumes Crank Trigger # of clynders

RPM limit Safety Margin 2 or 4 cycle 4 5 6 8 10 12
1000 1000 4 15000 12000 10000 7500 6000 5000
1500 1000 4 12000 9600 8000 6000 4800 4000
2000 1000 4 10000 8000 6667 5000 4000 3333
2500 1000 4 8571 6857 5714 4286 3429 2857
3000 1000 4 7500 6000 5000 3750 3000 2500
3500 1000 4 6667 5333 4444 3333 2667 2222
4000 1000 4 6000 4800 4000 3000 2400 2000
4500 1000 4 5455 4364 3636 2727 2182 1818
5000 1000 4 5000 4000 3333 2500 2000 1667
5500 1000 4 4615 3692 3077 2308 1846 1538
6000 1000 4 4286 3429 2857 2143 1714 1429
6500 1000 4 4000 3200 2667 2000 1600 1333
7000 1000 4 3750 3000 2500 1875 1500 1250
7500 1000 4 3529 2824 2353 1765 1412 1176
8000 1000 4 3333 2667 2222 1667 1333 1111
8500 1000 4 3158 2526 2105 1579 1263 1053
9000 1000 4 3000 2400 2000 1500 1200 1000
9500 1000 4 2857 2286 1905 1429 1143 952
10000 1000 4 2727 2182 1818 1364 1091 909
10500 1000 4 2609 2087 1739 1304 1043 870
11000 1000 4 2500 2000 1667 1250 1000 833
11500 1000 4 2400 1920 1600 1200 960 800
12000 1000 4 2308 1846 1538 1154 923 769
12500 1000 4 2222 1778 1481 1111 889 741
13000 1000 4 2143 1714 1429 1071 857 714
13500 1000 4 2069 1655 1379 1034 828 690
14000 1000 4 2000 1600 1333 1000 800 667
14500 1000 4 1935 1548 1290 968 774 645
15000 1000 4 1875 1500 1250 938 750 625
15500 1000 4 1818 1455 1212 909 727 606
16000 1000 4 1765 1412 1176 882 706 588
16500 1000 4 1714 1371 1143 857 686 571
17000 1000 4 1667 1333 1111 833 667 556
17500 1000 4 1622 1297 1081 811 649 541
18000 1000 4 1579 1263 1053 789 632 526
18500 1000 4 1538 1231 1026 769 615 513
19000 1000 4 1500 1200 1000 750 600 500
19500 1000 4 1463 1171 976 732 585 488
20000 1000 4 1429 1143 952 714 571 476
20500 1000 4 1395 1116 930 698 558 465
21000 1000 4 1364 1091 909 682 545 455
21500 1000 4 1333 1067 889 667 533 444
22000 1000 4 1304 1043 870 652 522 435
22500 1000 4 1277 1021 851 638 511 426
23000 1000 4 1250 1000 833 625 500 417
23500 1000 4 1224 980 816 612 490 408
24000 1000 4 1200 960 800 600 480 400
24500 1000 4 1176 941 784 588 471 392
25000 1000 4 1154 923 769 577 462 385
25500 1000 4 1132 906 755 566 453 377