In researching a bit about ECU to run my 20b, I think I'm sold an on Autronic. It seems like the SM4 with the optional multiplexor (or whatever it is) for the igniton will do the trick properly. I do have a few questions though which will dictate how the engine is built, and some regarding tunning.

First, can the SM4 handle running a negative split, in vacuum, on the rotary? Yes I do understand that negative split has previously been considered a huge no no.

Is there a specific benefit to selecting the FC style front cover with CAS over the FD style pickups. I'm strickly speaking from an accuracy/tunning standpoint. I was told that the FD style is more accurate in regard to determining crank position, but that doesn't matter if the increased accuracy of the FD is beyond the reading/controlling accuracy of the ECU.

I seem to hear people running identical sized injectors in both primary and secondary ports. With my only standalone expereince being Haltech, I'm not clear if the Autronic CAN'T run different sized injectors, or if for some reason same size injectors is prefered by the people I've spoken with. I realize that the driver controller is capable of running a 1000cc (for example) injector at idle, but I can't believe that is as efficient as running a 550cc (for example) injector for idle.

Thanks
Chris

 

sorry double post...

 

The sm4 can run negetive split no problem as they are simply controlled by the ignition offset wich can be set up a number of ways.

As for the front cover, I would use the fd style one but build my own trigger disk and convert it to hall effect sensors due to the better accuracy and ease of software setup.

For injectors I would run the largest ones you can in all holes... You will not have a problem with idle quality. But if you want to run smaller primaries it can control them but the you will have to play with the injector trims and how they come online... The availible base cal files work well with same sized injectors but Im not to sure about different sized ones...


Regards
Justin
www.alienauto.com

 

That's the info I was looking for. Thanks. Are you running a modified FD cover/setup? Got any pics of what you did?

-C

 

Yes you can run different sized injectors for idle and secondaries. There's no problem there.. Only thing is you have to map the injector trim tables accordingly so you have smooth transition between primary and secondary. It's easier to map this with the same size injector and this is the reason most of us do it this way. I have also done a car with 550/1600 and it worked fine. so either way you have nothing to worry about.

As for trigger accuracy you'll be fine with either fc or fd. For the ultimate a hall effect as justin stated would be the best way to go. I would build my own trigger wheel off the e shaft with hall sensors. Is this really necessary for most NO but for the all out drag car yes...

 

Justin/Enzo, can the primary and secondary injector angles be adjusted independently of each other? I have been told this is important because the secondary injectors are further away from the intake ports than the primaries. I know there is a single injector angle map, but I'm not sure if it is possible to dial in split between the two sets.

Justin, thanks for sending me the info on the multiplexer, that was a big help.

 

yes... We can adjust both groups of injectors. So your primaries would be group 1 and the secondaries group 2. Although i have found placing the injector as close as possible to the port will yield better results, SO if possible customize your injector placement so all your injectors are mounted as close as possible to the ports..

 

Sorry. I don't know what injector angle is? Sounds like phasing of some sort maybe?