B6T

iTrader: (2)

I was just reading up on configuring the MS Version 3 to work with a rotary at: http://www.msextra.com/manuals/MS_Ex....htm#2rotormod

I was especially interested in learning how to set up the MS to fire the rotaries leading and trailing ignitions. From what I gather after reading the article, there seems to be some internal modification required to make this work. However, since that article also mentioned using the stock CAS, I'm a bit confused.

If I wanted to use a common 60-1 toothed wheel and the corresponding magnetic sensor, like those used on Electromotive EMS, will an unmodified MS 3 run both leading and trailing ignitions, after properly configuring the software to read the 60-1 wheel? Or does it require the internal modifications (addition of an LM1815 I think) regardless of the wheel type? Is the internal modification only necessary if you want to use the stock CAS?

Thanks a lot!

pmrobert

There are several options. You will need the second VR sensing circuit (the 1815 & other parts) if you use a totally stock CAS; you'd be using the 24 tooth lower wheel and the 2 tooth upper wheel in the CAS. An option that I personally use that works well is to remove 2 teeth, 180 degrees apart, from the lower wheel and use just the v3 VR circuit, no second decoder needed. It's then running in basically 12-1 mode; 24-2 running at half crank speed. Of course, the software needs to be properly configured, the CAS needs to be clocked to TDC,etc., no big deal. Your proposed 60-1 should work as well though that's a fair amount of fabrication and expense which may or may not be a problem depending on your access to machine tooling. The pros of the 60-1 crank mounted wheel would be very slightly improved timing accuracy as you've bypassed the small amount of play in the crank/CAS internal gear drive.

Edit: saw your sig just then. It appears that tooling access isn't a problem for you! Lucky guy....

B6T

iTrader: (2)

Thank you for clearing that up! Now I understand the purpose of the dual circuits! One circuit provides the engine rotation position, and the other circuit provides a TDC signal. Makes sense!

Prior to returning to school, I used to work at a shop that did Electromotive installations, and that also specialized in rotaries. That's how I knew about the 60-1 wheel. Performing the necessary machine work to install the 60-1 toothed wheel to the crank pulley shouldn't be a problem (I've already mounted one on my other car actually). In fact, I'll probably take that opportunity to have an oil return machined into the front cover for when I turbocharge the engine. This is good, the 60-1 wheel *should* be far more accurate then the OEM CAS.

Now what about the three coil outputs needed for the two trailing and single leading coils? Are they already in place on the MSv3 or is there modification required for those as well?

Thanks for your help!

renns

The three LED's on the end of the board can be re-assigned in software to be used as spark outputs. Details are shown in the FAQ, and also here:

https://www.rx7club.com/megasquirt-forum-153/v3-0-ms-build-pics-534544/