[Diy_efi] injecting 5 port head

[Jean Belanger]

Think about it this way: the two paired cylinders are 180 degrees apart so
any fuel injected into the intake runner during 180 degrees is going to the
outside cylinder and all the fuel injected during the remaining 540 degrees
is going to the inner cylinder. This is actually not exact since the cam
opens the intake valve for more than 180 degrees but at best the real split
is worse than 1/3 and 2/3.

There are 2 ways I see to overcome this. The first one is what has been
discussed previously and is to time the injection pulses with the valve
opening. The second is to move the injectors up the intake tract such that
all injectors are seen by all cylinders so that any fuel injected can be
ingested by the cylinder on its intake cycle. This is basically throttle
body injection and is the other available Mini engine the SPi (single point
injection). A lot of the custom fuel injected A-series engines that claim to
have port injection actually have some variation of this second case but
that?s a different story.

If you see another method to make this work let us know because I'm sure
there are quite a few people interested in it. This type of engine is, to my
knowledge, the only one which requires sequential injection to make port
injection work and not just for emission or other reasons. On the other hand
port injection is probably not required and the engine will surely work very
well with some sort of throttle body injection.

By the way, I don't think anyone is planning to machine the head to put the
injectors there. The port injection discussed places the injectors in the
manifold as in other engine but as close to the head as possible for timing
precision reasons.

Jean

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
> Behalf Of Daniel Nicoson
> Sent: December 26, 2006 10:47 PM
> To: diy_efi at diy-efi.org
> Subject: RE: [Diy_efi] injecting 5 port head
> 
> Here's a stupid question, Does it actually have to be sequential?  We tend
> to focus on sequential since most autos use that but the OEM went to
> sequential primarily for emissions reasons at low RPM.
> 
> What if you thought more along batch-fire lines.  Put your injectors back
> up
> in the intake runner a few inches (no machining on the head itself this
> way)
> and then fire all the injectors every time an intake valve opens for 1/4
> the
> PW (on 4-cylinder).  Not claiming to have it all worked out but trying to
> keep minds open.  Batch fire systems have worked great for a long time,
> especially at other than idle RPM.
> 
> These engines probably won't know the difference between fuel injection or
> carburetion as long as they get the fuel they need.
> 
> KISS!
> 
> Good luck, interesting projects!  LOVE to hear more about the Spitfire
> engine project!
> 
> Dan Nicoson
> 
 

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