Nissan CAS wheel

[max@zl2max.gen.nz]

Looking through the MS1Extra stuff found this pic of the nissan CAS, this is an aftermarket wheel

Since we where typing about it ....

Max

[rb26dett]

i'm not 100% certain, but that looks like the mitsi unit that comes in DSMs and evos and mazda 4 cyls. thats nothing like my skyline one. either way good info to have.

fred.

[Matt Cramer]

We've got a picture of a stock 240 Nissan wheel too, and while the pattern is different, it appears to have a bit in common with the Mitsu CAS. If you look closely you can see the three Mitsubishi diamonds on the optical sensor.

[newtyres1]

Max,

That looks identical to the one I have that came from an SR20 engine, which has P/N RSB-14 cast into it under the wheel. It originally had 4 windows on the inner ring and 360 on the outer. Note the aftermarket wheel's second trigger doesn't appear to be centred between the outer holes, it is offset slightly the same as the optical sensors within the assembly. If the rotation direction is CCW it would be centered according to the output signals.

Ian.

[KaPower]

Thats an Autoronics Cas disc. I think its a Newzeland, or Australian company. They offer atleast 4 different discs to make Nissan's compatable with there standalone ECU.

I have seen someone use a disc like that for a wasted spark Haltech setup on a ka24de.

[rb26dett]

i dont see it here, but thanks for that, that ought to make msing an rb quite easy!

http://www.autronic.com/image_files/tri ... andisk.jpg

fred.

[KaPower]

I bet one of those triggers will work for you, E-mail them and find out. Be shure to let us know what you find out.

[510rob]

Gordon,

I've been drawing up a new CAS plate to run slightly different config than what you've got shown, but I'm curious what timing angles you'd run with the plates you provided pictures of. From my measurements, the inner optical sensor is advanced about 30° wheel (60° crank) from the outer sensor...

[510rob]

* The outer 1° sensor(s), with three aperture slots, must contain multiple (perhaps three?) opto pickups, and must be connected to some type of sequential detector block; the opto behavior is not at all what I'd expect to see from a simple opto-sensor being interrupted with a piece of paper; it seems to require a properly sequential change on each consecutive aperture slot in order to register a valid edge-trigger signal. The sensor works as an "opto" only when the wheel is turning as it would in normal operation. Mitsubishi may have done this to eliminate false timing signals at low speeds/cranking ???

* The inner "120°" sensor is a typical binary sensor.

* Both outputs need pull-up resistors.




I stumbled across an interesting description of the CAS timing scheme...

If you have a look at the pic of the Rb25 CAS you will see the slots on the outside of the disk are at 1 deg spacing and the inside of the disk the 6 slots are of vairing size starting at TDC for each piston. There are 4deg difference in each slot with the first slot 4 deg wide and the last 24deg wide. The divider simply counts the number of degrees using the 1deg signal while the 60deg signal is low (while there is metal between the sensor, not slot). The results are in binary

36 = 100100, 40 = 101000, 44 = 101100, 48 = 110000, 52 = 110100, 56 = 111000

If you only read the middle digits, take the 1 off the front and the 00 off the end your left with

001 = 1, 010 = 2, 011 = 3, 100 = 4, 101 = 5, 110 = 6

These 3 digits are latched and feed through a binary to 1-of-6 decoder. The outputs from the decoder are on for 120deg of each cycs compression stroke up to TDC and is conected to the base of 6 NPN transistors. The colectors of the transistors are conected the the ignition signal from the ECU and the emitters conected to the RB25 coil driver pack, 1 for each coil. The ign sig from the ECU only gets to the coil to be fired and is blocked to all the others by the transistors.
I also convert the 60deg signal from wide slots to narrow slots so the RB30E ECU thinks its got a RB30 CAS.

http://www.calaisturbo.com.au/printthre ... ge=2&pp=40