[Diy_efi] sequential injection timing

[Bruce]

----- Original Message -----
From: "Brian Dessent" <brian at dessent.net>
Subject: Re: [Diy_efi] sequential injection timing
> Kent Martin wrote:
> > Does any one know at what angle you should start fuel injection
> > in a sequential injection arrangement. I would have assumed

> It might be that injecting onto the back of the hot intake valve helps
> vaporization.

Yes, but the primary action to get the fuel *burnable* is the exhaust, at
overlap that atomizes the fuel.

>I think that the injection timing really only matters for
> idle and part throttle,

Yes.

>since under moderate to heavy load the injector
> would be open more than closed -- to the limit that under WOT it would
> be mostly open all the time anyway (say 70-90% duty cycle) so it
> wouldn't really matter much.

True.

>That said, I'm no expert by any means so I
> could be off base there.  I seem to remember reading/hearing that under
> heavy load you don't really gain anything from sequential vs. batch so
> that implies that the timing doesn't matter much for these conditions.

With really large injectors, there is at times much to be gained with a
single batch fire system.  Firing the injectors twice as often helps with
atomization.  My little 3.8L with 55#/hr injectors is much sweeter in batch
mode then SEFI.
Bruce

> Brian


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