Jerry Hey wrote:

On Monday, June 20, 2005, at 08:07 AM, David Staten wrote:

    The injection controller will be the Real World Solutions EC2. It
    does stage. No, you aren't wrong. That is what I want. It's not
    overly complicated when you dont have to build it from scratch..
    thats why Im using the stock TB. The only thing I am having to fab
    is the runners and two injector bosses.
         I am using stock fuel injector ports on the primaries (which are
    in the block). Those are less than 2 inches away from the primary
    intake ports. I will not be moving them.
         As for secondary positioning, how far back can I go before I have
    to start worrying about the fuel charge not being inducted all the
    way into the secondary ports? As in... the fuel charge shot into
    the secondary runner (when secondaries are active) gets sucked all
    the way in on THAT intake stroke, and not, lets say.. the next
    one...Or are you saying that doesnt even matter? If injectors do
    better farther away from the port/way upstream, why are they not
    like that in the stock config? Several other EFI engines I've seen
    appear to inject RIGHT before the intake port (Noticed while
    shopping for intake parts), not way upstream...
         It seems that the folks who have difficulty idling at low power
    smoothly are the ones who 1) dont sequence their airflow into
    primaries first, secondaries only at higher power... and who have
    their injectors 20 something inches away from the ports. Thats
    just an observation I've picked up over the past year... and maybe
    its mistaken.
         Dave


Dave, based on Paul Lamar's current p port testing there is no problem with placing the injectors at the far end of the runners. This is also backed up by an article on the internet (How to Fabricate an Intake Manifold) The idle issue is not with injector location but rather with butterfly location. The further the butterflies are from the port, the worse the throttle response and idle. At least that is the current theory and is born out by Ed's experience when he place the butterflies at the far end of his intake runners. Jerry

Hopefully Ed will be back soon to confirm or refute this, but all of Ed's intakes that I've seen have had the throttle body on the plenum at the other end of the intake tubes. That's what he's using now, or was when he left here Memorial Day weekend. The manifold he had problems with had the *injectors* mounted over there with the throttle body. (See Rusty's post also.) Ed has no problems with throttle response using close mounted injectors & plenum mounted throttle body.

Tracy has confirmed that the only way to adjust injector timing is with the mechanical timing of the pickup on the engine. Moving the injector 15-30" away from the rotor housing just seems like it would have a radical effect on injector timing at low power settings when the injector has a short 'on time' & there's a relatively long slug of unfueled air. It seems to me that if the slug of 'fueled' air isn't timed properly to enter the rotor chamber & get trapped there, part of it will bounce around in the (cold) intake tubing & condense out on the walls, especially at low power settings.  IIRC, one of the reasons auto makers went from throttle body injection to direct port injection was because fuel condensation on the tubing walls was causing inconsistent & unpredictable mixtures.

I visited Paul Conner back in November, before he had flown. At that time he was using a throttle body with the injectors mounted on the throttle body, away from the intake ports. The throttle body was mounted more or less in an 'updraft' configuration, similar to a typical a/c carb on a Lyc or Continental. With the engine idling fairly smoothly, fuel was dripping out of the throttle body in almost a steady stream. Now, if everything is working normally & the engine is idling smoothly, where was the fuel coming from? This is not a normal symptom of updraft a/c carbs or injector throttle bodies.

Charlie

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