Siamesed Injection
Turbo Mini Forums

Okay, hopefully not a stupid question/comment, but here goes.

With the siamesed code, I've noticed reading some of the threads that people are having an issue with the cylinders 2 and 3 running a little rich. Could this be alleviated by only machining those combustion chambers out? They're getting too much fuel for the air charge, generally 2:1 too much, right?(Meaning double the fuel, to air) If you were to enlarge the center chambers the fuel would be more dispersed when the air came in, creating a proper stoichiometric ratio. This would lower compression in the center two cylinders, but I don't imagine you would need to rechamber them by much, maybe a few cc's? Hope this makes sense to someone.

-James

Yes, it's me again. The more I think on it the more ideas pop into my head, hopefully something I say is actually right. If the injectors used on a twin rail system were set up so that injector on 1 would fire, and when that valve starts to close, injector on the next open valve(2?) were to fire then, would it not be timed correctly so that when one injector closed, then the next port would be open and set up in sequence to fire?

Why don't you start from page one of the injection posts, before typing any more.

That will help you out a lot.

Making the combustion chambers bigger won't get more air in. You'd need to make the cylinders bigger. and since the fueling difference is not static, you wouldn't be able to correct the AFR difference for the whole rpm/load range (not to mention that you'd bring a whole lot of other issues compared to simply injecting the correct amount of fuel).

And you wouldn't need to have a twin rail system but you'd need to have 2 injectors per port with each one being able to use around 20% duty cycle.

I don't want to be rude but the latest Megasquirt code that Paul S and Rod S are using is the result of a lot of investigation, discussions, experimentation from quite a few people and I'd be really surprised that someone could come up with a configuration that is either not covered by the code or hasn't been tossed aside due to being inadequate for one reason or another. And most of those configurations (like the second one you suggest) have been discussed on this forum and the reasons why they were deemed suitable or not is also explained in one or more posts.

So, while it is always good to challenge what is established you need to do your homework if you do. Also, if you want to contribute on the subject and are ready to actually try something on your Mini, I think it would be more valuable to try and join Paul and Rod and push on the development of the siamese code with your own setup (but that's my own biased opinion).

Jean

http://www.jbperf.com/