jbelanger wrote:Limiting the injection timing to anything but the full 720 degrees does not make any sense.
Who is limiting it? :-p
With the same trigger pattern, and therefore I assume the same reference angle, you can have vastly different engine configurations (intake manifold geometry, injector placement,...) that will require completely different timing.
You assume FAR too much, that's not like you, I must have pissed you off recently, sorry if so.
Here is how it works:
- A decoder has it's own zero angle, and total angle range (unique crank wheels are 360, unique cam are 720, dizzy style are 720/cyls, etc)
- There is a full cycle decoder to engine offset angle to align the decoder with the engine (to bring number 1 TDC to zero degrees for a typical piston engine)
- Each channel (and in future virtual channel) has its own full cycle centre angle (to find each cylinder's TDC for ignition use, or some arbitrary centre/base for fuel use)
- Timing input from various sources is compounded upon this base, the main one being table tuned angle, which is what I was asking about, whether it was clear or not.
Even on the same engine, you may need significantly different timing depending on the RPM and load since you may not want to inject at the same timing depending if you want to maximize economy or power. And if you have staged injection with low and high injectors, the propagation time will mean significant timing change.
Now we're getting to it, talk ball-park numbers, I'm interested! Hmm, I just realised who else I should link here!
So having only a partial cycle range for injection timing is an unacceptable limitation in my view that will come and bite you in the ass at one point or another.
We're only talking about timing relative to an arbitrarily per channel centre timing which is full cycle (720, 460, 180, 90, etc), for a given decoder. And by that I mean, it's configurable independent of the decoder, but must not exceed the full angle of the decoder that is in use.
Even limiting the ignition range to 50 degrees doesn't make sense if you want to do some form of anti-lag at some point.
Again, see above, this is not the total range, just the NORMAL case tunable range, maybe a little ATDC timing is desirable at low rpm and high load, perhaps it should be the 63.75 option with 5 or 10 ATDC and the balance BTDC? Things like antilag, spark retard limiters, etc can and will use their own separate offsets to achieve this and do not need to care about the limited range of the tunable dynamic adjustment tables.
You're better off planning to be able to cover the whole cycle range for any timing value right now rather than dealing with a completely arbitrary and potentially crippling limitation later.
It can, but last time I checked, if you fire a plug on the intake cycle it blows your intake manifold off ;-) The timing range questions are mainly about fuel injection timing, which I'm not an expert on, esp not siamese, which you ARE an expert on.
So with that in mind, the siamese port injection timing range becomes irrelevant since you should be able to cover the entire cycle.
Nothing is irrelevant, please please, give me some info on this, even if it is an RTFM and link! :-) Before designing something you should fully understand it, and that is what this thread is about. There is working code, but it is inadequate in various ways, and before I change it further I want to know as accurately as possible which direction I should be heading in. Your stuff is the weirdest stuff, so please, educate me on centres, timing range, etc, anything and everything. You started below, I'll try to get you to clarify that now.
One thing that will be necessary is to have different timing on the inner and outer cylinders.
Can you do a detailed post on the different possible configurations? It's been a long time since we discussed this, but if you want it doable with FreeEMS, now is the time to speak up and lay down detailed requirements. We're talking 2 injectors or 4? If 2 I would assume their timing would be different, but the same relative to the valve movements. So we must be talking 4, at which point I would assume that each of the four channels would be centred independently and tunable around that centre in two pairs?
It might even be good to be able to have different timing references for the two, for example middle-of-pulse for one and end-of-pulse for the other
Sure, that would be on a per channel/virtual channel basis anyway, consider it done.
What else? How much range??? :-)
Another thing that doesn't make sense is this:
Fred wrote:
- Dwell is based on battery voltage and can be exceeded to aid scheduling, dwell will always be as requested or more
- Some sort of minimum spark duration window such that a maximally long spark can complete before dwell resumes
The 2 statements contradict each other at some point. You can't have dwell always as requested or more and have a minimum spark duration always respected. And if the list shows the order of priority then it doesn't make sense since you can't always respect dwell duration and continue to have a running engine under certain situations. At some point you will need to reduce dwell to even be able to have spark. And saying that this is a badly designed engine is not an excuse for not reducing the dwell and the minimum spark duration when you run into a spark event collision. Or at least mention what will need to be done in that case such as spark cut. But that would be a poor option in my view; it would be much better to share the available time between the spark duration and dwell rather than introduce an artificial and unexpected spark cut.
I've added an "unless otherwise configured" clause to remove the contradiction, thanks! :-) Yes, I'm well aware of shitty distributor car limitations, I'm driving one on FreeEMS every day ;-)
Mild launch and 1st/2nd gear pulls to a low end-of-torque at 5500 (redline is 6k but there was never any point revving it there...) :
Excuse the noise, it's for a known and intentional reason :-)
Thanks for your input so far, I hope we can get some better info and clarifications on the siamese situation in the next post!
Fred.