Is 12-1 wheel a good wheel to use for Megasquirt on a I6?

[ShaggyZ]

(unwisely posted this in Toyota L6 and waited several weeks with no response)

 

A guy on SupraForums.com is sticking a 2JZ-GTE in his 4Runner and will also be using Megasquirt. Actually he's already got video of it up and running, though not driving.

 

He's using LS2/truck coils and he has modified his stock crank sensor wheel so it's a 12-1 wheel for the stock 2JZ crank sensor to read - he just cut off one of the 12 teeth. I was planning on using the stock crank sensor and the rear cam sensor for TDC per Speeder's note in another thread. Apparently the 12-1 is accurate enough for this guy and I think he's shooting for ~500HP, though I don't recall.

 

I haven't gone headfirst into Megasquirt or standalones in general yet, but I do seem to recall a 12-1 not providing very good "resolution" in lower RPM while the higher tooth wheels (eg 60-2) provide too much feedback at higher RPM. My intention for the near future is to only have an engine that spins to ~6500RPM but may push it to ~7200 or so one day.

 

My post here has a two-fold purpose: 1.) to show others this can be done and 2.) to get some thoughts from the HybridZ perspective. I'll probably go the same route as this guy because it's simple, it works, and I can hit him up for some fuel/ignition maps. I was planning to use the LS2/Truck coils, as well.

 

 

http://supraforums.com/forum/showpost.php?p=6660578&postcount=103

 

[randy 77zt]

it will work-you just have to set up for time based cranking instead of trigger return.how many teeth are on oem toyota wheel?i just made a 30 tooth wheel out of old 81zxt 90 tooth wheel and tested it with running engine-timing was correct per the map.the thing with ms is read-read-read.i spend more time doing research than i do working on the car.

[ShaggyZ]

it will work-you just have to set up for time based cranking instead of trigger return.how many teeth are on oem toyota wheel?i just made a 30 tooth wheel out of old 81zxt 90 tooth wheel and tested it with running engine-timing was correct per the map.the thing with ms is read-read-read.i spend more time doing research than i do working on the car.

Thanks. I realize it will work because I've seen a running example, but I'd like to know how well and what I'm possibly missing versus a 36-1, for example.

 

Stock tooth-count is 12 on the Toyota crank sprocket. The 2JZGTE uses two cam angle sensors in addition to the crank sensor.

[Careless]

can you use 3 of those plates and stagger them, and then cut the tooth off one?

12-1

24-1

36-1

if you want.

[ShaggyZ]

can you use 3 of those plates and stagger them, and then cut the tooth off one?

12-1

24-1

36-1

if you want.

 

The plate I believe you're referring to is part of the crank sprocket, which needs to be aligned for the timing belt. Not a bad idea, but I'd have to do a lot more work than I'm willing to do what I think you're suggesting.

[Careless]

right on. it looked epoxied to that sprocket, which i based my question on. indeed it would be too much work to make it align properly and stay there.

[Brad-ManQ45]

I will be using 12-1 with the magnets drilled into the back of my crank dampner

[Matt Cramer]

I've seen Megasquirt used with 12-1 wheels before without issue. Cranking timing will not be quite as precise, but there's very little practical difference compared to a 36-1 or 60-2 at those engine speeds. If you had a motorcycle with three times that redline, I'd definitely go with a 12-1.