V8/10/12 Sequencial Injection

[jharvey]

My understanding is that Fred has a 6 banger, so it worked well for him as a test platform. There is certainly enough hardware and software room for 8, but the focus is to work with what he has. It's a KISS approach.

I've been working on the schematic and PCB with the intention of adding injectors, ignition, other at a later date. I'm taking a modular approach, so you can add or delete certain features as you wish.

[Fred]

I don't own a 6 pot. I just intend to get one in the future. I may even get a V8 in future, but I wouldn't be all that concerned about sequential on it if I do. The more cylinders you have the less it matters.

If you had 1000 cylinders you could dump in fuel however you wanted and it would run smooth enough. Additionaly if you did "semi" on the 1000 cylinder engine the throttle response would be fantastic. In that respect semi on a v8 gives nearly the same response as full sequential on a 4 cylinder. Large cylinder count engines are much less sensitive to the differences that sequential brings. Lastly, it's also less important because typically you make "enough" power with less specific power on a V8 and therefore don't have huge injectors and the associated problems that sequential helps avoid. If you were building a 6 litre 1200hp v8 I would say sequential would be beneficial, but not at 600hp, there it doesn't matter much.

Hardware limitation is the reason anyway, there are only 8 timer channels and 2 are needed for accurate RPM acquisition. That leaves 6 for general use. There is nothing stopping us from putting out a software variant that controls 8 channels sequentially and less accurately in the future, but it's not a high priority at the moment.

I hope that helps.

Fred.

[johu]

Thanks Fred. Your answer and earlier discussions on this thread are very informative.

[Fred]

No worries :-)

I think Sean mentioned the only real disadvantage earlier which is that if you need to trim cylinders you can't without sequential. If your manifolds and heads are reasonable though you shouldn't need to do that at all really. I'm not familiar with your engine setup (even though you told me about it) but none of the little jap engines need any sort of cylinder trim unless you are trying for the equivalent of 1800hp from your engine :-)

What sort of output are you looking for on her anyway? Boost or NA?

Fred.

[SleepyKeys]

Even my old pushrod V8 dinosaur has very little offset and thats only specified for idle conditions. I'll post up the tables tonight.

[johu]

What sort of output are you looking for on her anyway? Boost or NA?

Setup is close to what it's from factory. I don't think this setup has that high requirements from ECU. Only changes are intake manifold with throttle body, headers, camshaft and valve covers. Since new valve covers don't have provisions for stock COP ignition and I prefer bit more traditional look I'm using ACDelco D585 coil packs from GM for ignition. Still need to decide if I dare to sandwich them between intake manifold and block or hide somewhere else to keep them cool.

BTW. Any opinions on firing both plugs (in one cylinder) at exactly same moment or should there be slight delay between to create longer duration for spark?

[Fred]

BTW. Any opinions on firing both plugs (in one cylinder) at exactly same moment or should there be slight delay between to create longer duration for spark?

Start a thread in general EMS and you might find a few more people commenting. This isn't the place for that and I'd only be guessing anyway, I suspect both at the same time, but it would be interesting to have a discussion on it :-)

[L98TPI]

I would like to put in a vote for covering V8s. In my hot rod crowd any box that could not do 8 sequential and 8 spark is not all that attractive. I hear ya about the "not a big deal with more cylinders" its a lot about the perceived limitation. Oh and I need stepper motor IAC too Maybe there is a clever way to read rpm without using timers?

[SleepyKeys]

Those kinds of crowds are the most fun to beat up on with "inferior" home brew "junk".


or the other way around haha

[Delta]

I would like to put in a vote for covering V8s. In my hot rod crowd any box that could not do 8 sequential and 8 spark is not all that attractive. I hear ya about the "not a big deal with more cylinders" its a lot about the perceived limitation. Oh and I need stepper motor IAC too Maybe there is a clever way to read rpm without using timers?

Plenty of easy ways to read rpm - lots of IC's that do frequency to voltage conversion - its not RPM thats the problem - its engine angle. You not only want to know how fast its turning - but also where in the 720deg it is. You can get away with knowing where in the 360deg it is if you use wasted spark and semi sequential (two fire at once) injection. Some engine control systems make do with very archaic angle control - ie use some algorithm that takes one pulse per rev at a fixed angle plus the current rpm plus the expected rpm accel +- based on say tps, map etc. This is fine if you know a lot about the engine and are not concerned with very accurate timing of spark and injector.

It IS possible with enough cpu grunt to input to an interupt line rather than a hardware timer but I wouldn't want to do it if you plan on high rpm - which an EMS must cater for.