Ignition stupid question of the day (328)

There are nine fixed ignition maps (software). The correct map is chosen by load (vacuum) and rpm. I suppose anything could be changed but I've never heard of it on these cars. Dizzys cannot be rotated. Why do you want to change timing? If you want adjustability (and to get rid of dizzys/rotors) then you should consider the Electromotive XDI or XDI-2. Kind of a big project and I'm not sure there is any performance gain. You do gain adjustability of redline, increased realiability, reduced parts cost, maybe reduced oil leaks once the dizzys are gone and the area is well sealed.

By the way, you wrote: "My 911SC with CIS ignition"...... CIS is only mechanical fuel injection. Nothing to do with ignition.

 

Referring to the U.S. 308 2Vi . . the advance curves are crap and I will be replacing the digiplex boxes in car #2 with a Haltech ECU that will control both dizzy's and reads the stock triggers . .. I'm not sure if the 328 curves are as "weak" as the 2V curves. My experimentation with car #1 which has a Haltech ECU controlling the timing and EFI has left no doubt in my mind that there is a lot of low end torque and throttle response to be gained by optimizing the advance curve (especially for such low compression engines) . . I've not seen peak hp change much but when you pull hard all the way from 2000 rpm peak hp becomes less important . . old saying "hp sells cars, torque wins races".

Sean

 

I was also trying to think of a simple way to mechanically advance the timing and leave the digiplex boxes in place . . .i.e. just increase base/static timing.

There's a few ways you could do this but at the end of the day I like the idea of not using the digiplex anymore. If you really want to stick with them, you could alter base timing by moving the pickups a few degress that are mounted in the plate between the bellhousing and block (or move the pins on the flywheel . . .not easily adjustable though ) . .. . not simple to do because they fit pretty snug in there relative positions/hole. Other thing I thought about is there might be a "black box" that could be plugged in between the triggers and digiplex's that might somehow alter the relative timing of the trigger to TDC. Getting a little deep here but if someone wants more info about my thought process on this let me know . . you'd have to swap which trigger controls which bank to get enough advance which is what I did with the Haltech also.

 

I think you misunderstood him - The car is a 911SC with CIS, it has an ignition system that he is talking about. I think the CIS reference is there just to show that the engine management systems might be very similar.

 

lets see on the dyno yesterday I advanced the timing at 2800rpm from 28* to 33* and picked up a whopping 20ft/lbs of torque at just that one point. was able to get an average of 14hp more from fine tuning the timing. I'd say the programmable ignition is well worth the cost. and it's not hard to install and tune. it does help if you can spend a few days on the dyno though

 

The Multiplex also had three "ID" pins, which are grounded (or not) by the 328's connector harness.

Anyone know any of the other vehicles that uses this computer, and if their ignition maps are different?

Here's the one for the 328, according to the Technical Specifications book:
(Don't ask me how they can pull that off with a 144 tooth flywheel (2.5 degree RPM sensor).)
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