For anything you'd like to see added to Speeduino
User avatar
By ThomasColtart
#53017
I would like to suggest adding "batch" injection to the injection calculation options. Many older EFI vehicles especially V6's would have been wired batch from the factory and it would be nice to be able to support them(obviously ensuring the drive circuit can handle the loads). People are running speeduino right now with batch injection but they either have to use simultaneous injection or fudge the math to make it work with batch. Thank you for the consideration.
User avatar
By ThomasColtart
#53019
Batch and paired are the same for a 4 cylinder engine but for a 6 cylinder engine; paired implies 3 channels of 2 injectors per channel while batch would be 2 channels with 3 injectors each.
User avatar
By jonbill
#53020
Oh, thanks, whats the firing pattern for 2 channels of 3? don't you necessarily end up with some odd timing on a couple of cylinders?
User avatar
By ThomasColtart
#53240
Hmm, i was thinking about this more. I actually don't think it matters "batch" or "paired". Either way, the computer is calculating the required fuel for 6 injectors and weather its wired 2 channel or 3 channel it will fire all 6 injectors. There will just be an unused squirt event on injector channel 3 but all calculations and stuff should be correct. I was thinking that i would have to fudge some calculation for required fuel or something but now im thinking i dont. If anyone has any info let me know and when i get my car running on this ill let you guys know if it seems to work fine. Thank you,
User avatar
By jonbill
#53241
Yeah I agree. no need to fudge anything, you'll just have two cylinders' injectors firing on slightly odd timing, which you probably won't even notice.
only thing to be careful of is that you dont overload channels one and two.
User avatar
By PSIG
#53243
ThomasColtart wrote: Fri Sep 24, 2021 5:16 pm Hmm, i was thinking about this more. I actually don't think it matters "batch" or "paired".
It doesn't for fuel calculations, and you are correct that it is simply fired by the "wrong" channel. However, the fewer channels you use, the more cylinders will be different in fueling characteristics and some resulting performance.

On one channel (6inj x 1ch) with simultaneous and 2-squirts, there are 4 cylinders off-time. On two channels (3inj x 2ch) you have 2 cylinders off-time (120 & 240), with any timing or squirts combination. But, with 2inj x 3ch (paired) and 2-squirts/cyl, you have zero cylinders off-time and both quasi-sequential (double-shot sequential) and equally-timed fuel dwell for every cylinder. This carries the same cylinder pairing as wasted-spark ignition, which obviously must be correctly timed. These reasons are why the last option is preferred.

That said, yes it's better, but as shown by millions of 3x2 engines out there - yes you'll likely not know it unless tuned quite well. However, if you want to start at best advantage (or move to it later), paired is the easy option to get there with little effort and two wires. Your project, your decision. 8-)

TL;DR - when reasonably possible, wire injectors in paired "wasted-spark" configuration, or add a second sensor for full-sequential options.
User avatar
By Chris Wolfson
#53244
Most has been said, I may add something, that makes 2 channel x 3 batch injection even less desirable.

If you just throw the fuel into any intake channel, the fuel will have different times waiting for the valve to open. It may hit an open or closed valve and spent more or less time there.
The evaporating time has an influence on the burn rate of fuel and the temperature of the charge.

Why do all modern fuel injections go for sequential or at least semi? Why do many systems even change the injection timing with rpm? Just for fun? No, Simply because the emissions r and knock sensitivity per cylinder should to be as constant as possible.

If you want to tune an engine with an aftermarket ECU, you have to use a wide band lambda sensor. For auto tune, which most use, an exact signal is needed for best response and results. You want to know what happens inside the cylinder, not inside the exhaust. If some cylinder burns slower than another, your tune will not be the same as with an engine that has identical burn rate on all 6.
Even as the lambda sensor will measure the same AFR, a part of the fuel burns off in the exhaust instead of in the cylinder. So in cylinder combustion will be different. You loose power and/ or economy.

Second is the point where detonation takes place. You want to go as near to knock as possible. Different burn rates give different sensitivity to knock. So you end up with a less efficient ignition map, too.

So batch fueling will usually end up with a less than optimal tune. As it is hard to get a good tune anyway, batch or no batch may be the difference between a burned piston and a long lasting, reliable engine.

Even as you may not see a great power output difference, this should always be worth a few wires more connected.

So it is not a matter of taste how to fire your injectors, as many want to tell you. There are simply better and worse ways to do it.

The advantages of full sequential over semi sequential /paired are another thing and much less dramatic. This often gets mixed up.
User avatar
By ThomasColtart
#53270
Thank you guys for your thoughts. It has definitely helped me understand the calculations for my setup.

Agree with all of the above comments but to be honest I see very little advantage to 2 injectors per channel. The stock ECU fires all 6 injectors at the same time. That means 5 out of 6 events are not timed properly. Even with 2 injectors per channel, 1 event is not proper so honestly the only real ideal scenario is to have full sequential. Not to mention that for what im doing, im not going to be able to tune well enough to get any advantage even if I had full sequential(which is not really even supported on speeduino natively for 6 cylinders).

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