BMW Airhead questions

[R100RT]

New member here trying to narrow design choices on a project involving an air cooled BMW boxer (twin opposed cylinders). This is a 980 cc engine in a motorbike and if successful will become turbocharged and fuel injected. I have experience in turbocharging (successfully, & not just hot air), minimal however with EFI. I am comfortable with electronics though.

Forgive me if these questions have been asked/answered already. (been reading, but didn't see)

In point form then:
- When using Micro squirt, can the original Bosch Hall effect ignition canister be utilized for ignition control? (wasted spark, single sensor triggers off crank rotation once per rev). This engine fires its opposing cylinders evenly - they are 180 apart.
- If stock ignition mechanical advance is locked, does the M.S. have provision to provide advance curves?
- Assuming the stock BMW wasted spark when used on a turbocharged engine may lead to some backfiring through push through of fuel charge @ valve overlap that might coincide with scavenging cylinder plug firing (and any comments or knowledge of others here very much appreciated, especially if this is not generally a concern on a low boost application, max 12psi) does the M.S. allow for alternate spark provision to each separate cylinder only following its compression stroke?
- Does the M.S. have provision to input "knock" sensor signal? If so what might it control (timing, fuel mixture, boost control signal, etc. ?)
- Am I able to share 02 data between the M.S. and a separate fuel mixture gauge. (ignore this question - just noted comments regarding JAW)

Thanks in advance. I haven't noted a similar project on the forums, but if one of you have gone this route and don't mind sharing in some of the knowledge you've gained I'll do my best to reciprocate.[/i]

[Matt Cramer]

New member here trying to narrow design choices on a project involving an air cooled BMW boxer (twin opposed cylinders). This is a 980 cc engine in a motorbike and if successful will become turbocharged and fuel injected. I have experience in turbocharging (successfully, & not just hot air), minimal however with EFI. I am comfortable with electronics though.

Forgive me if these questions have been asked/answered already. (been reading, but didn't see)

In point form then:
- When using Micro squirt, can the original Bosch Hall effect ignition canister be utilized for ignition control? (wasted spark, single sensor triggers off crank rotation once per rev). This engine fires its opposing cylinders evenly - they are 180 apart.

Theoretically, it could do this - but in practice, this has a very low resolution that can make for timing errors. Something like a 36-1 wheel will make it more precise.

- If stock ignition mechanical advance is locked, does the M.S. have provision to provide advance curves?

Yes.

- Assuming the stock BMW wasted spark when used on a turbocharged engine may lead to some backfiring through push through of fuel charge @ valve overlap that might coincide with scavenging cylinder plug firing (and any comments or knowledge of others here very much appreciated, especially if this is not generally a concern on a low boost application, max 12psi) does the M.S. allow for alternate spark provision to each separate cylinder only following its compression stroke?

We haven't seen anything like that on our wasted spark Miata, which runs 14 psi of boost. The Microsquirt can run alternating spark on this engine but not with the stock trigger. You'd need some sort of cam trigger to provide cylinder identification.

- Does the M.S. have provision to input "knock" sensor signal? If so what might it control (timing, fuel mixture, boost control signal, etc. ?)

This feature is present on the full sized Megasquirt but not the Microsquirt. The MS2/Extra code may make it possible to do this.

- Am I able to share 02 data between the M.S. and a separate fuel mixture gauge. (ignore this question - just noted comments regarding JAW)

Yes.

[R100RT]

Thanks for the info Matt.
I'll have to digest movement towards the 36-1 wheel design, I know there is info on the site I can review for that.
A project like this always seems to be a balance of what will fit, work well, and look like it was meant to be (gotta look good).
Should the progression to a 36-1 wheel work out (lots of options at this point) and I look to M.S. for timing control, then could (and here's a laymans question) the Bosch Hall effect sender (which is cam driven) provide the positioning signal for alternating spark?
However should the backfire concern not be a concern the wasted spark works quite well.
Are you a distributor (of the Micro Squirt)?
I'll eventually be doing two of these (got a brother with the same air head who'd be less than happy if left out of the loop.

[Matt Cramer]

Should the progression to a 36-1 wheel work out (lots of options at this point) and I look to M.S. for timing control, then could (and here's a laymans question) the Bosch Hall effect sender (which is cam driven) provide the positioning signal for alternating spark?

Yes, it certainly can.

Are you a distributor (of the Micro Squirt)?

Yes, I work for one. Good luck with your project!