X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-bk0-f52.google.com ([209.85.214.52] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTPS id 5566882 for flyrotary@lancaironline.net; Tue, 29 May 2012 18:55:19 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.52; envelope-from=msteitle@gmail.com Received: by bkcjc3 with SMTP id jc3so3582783bkc.25 for ; Tue, 29 May 2012 15:54:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=9IhcGVVrMdK4wgd5d6NeXWn/cPRz0vgyt+imUot19ws=; b=wzMPKuWmzJqyc7eytywIKAq9PITgHhVYEwHsQT5pRoWOX634ZLoc/0bxRVOgBeg3SX v4qAYmifc/vXRpSsHrAS3te884lT+uiUDqlnPyBewhCLQYL0F8FbWPu2akyTxDbhCnxF 81v3HtookBdG2q/eoxhcRf0Rp07n/LohgxRifagVhKUQwrfUxe1cqTcsDR3BhmcwNye3 RONB49IJ78rj7bXZ404GDLuoi+4txXiyQaKkuNZ/lOMMP0OEfhsNuQ4voNNfgkS41GZp k/zBP0POYmkL6P6zcfdRR7+/gliUm2nN3PeRWj+otBaGbTu0g/yAh2rW92B/yxIhO6Zm 07Ng== MIME-Version: 1.0 Received: by 10.205.120.17 with SMTP id fw17mr7633414bkc.20.1338332083402; Tue, 29 May 2012 15:54:43 -0700 (PDT) Received: by 10.204.97.194 with HTTP; Tue, 29 May 2012 15:54:43 -0700 (PDT) In-Reply-To: References: Date: Tue, 29 May 2012 17:54:43 -0500 Message-ID: Subject: Re: [FlyRotary] Re: Injector balancing From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=000e0ce004806c398b04c134b806 --000e0ce004806c398b04c134b806 Content-Type: text/plain; charset=ISO-8859-1 Ernest, With my current setup, this p-port engine idles better than my side-port motor ever did. It will idle down to 750-800 rpm if asked, although I normally idle at 1500-1600. Still, it might be an interesting experiment to add temporary dividers in the airbox to see what effect it would have on tuning. If you take a close look at the picture I posted you can see the blue fuel rail. This is the primary fuel rail feeding the primary injectors. They're located downstream of the butterflies, very close to the intake ports and pointed directly at the rotor faces. I can't imagine how the fuel could find its way 18" back down the runner and back into the other runners. I've never found any residual fuel in the airbox either. I don't see how the fuel could be pooling so close to the ports, especially at 4500 rpm. But then I'm not an expert in fuel injection design either. Alleviating fuel pooling in the runners was one of the design goals with this latest intake. My previous slide throttle had both the primary and secondary injectors located upstream of the slide. This caused fuel pooling, especially at very low throttle settings. Needless to say, this made low throttle tuning almost impossible. So, the new intake has the primary injectors downstream of the butterflies, and it idles great. Mark On Tue, May 29, 2012 at 4:32 PM, Ernest Christley wrote: > Mark Steitle wrote: > > Ernest, > > > > I don't understand how that could happen if my injectors are after the > > airbox (see attached pic). > > > > Mark > > At idle, the intakes coming off the airbox can set up some serious > standing waves that will suspend fuel droplets and > let it stick to the walls. You're set-up is very similar to mine, in that > the fuel can run downhill and air has to pass > in front of one runner before reaching the others. Some of that suspended > fuel will coalesce on the wall and drivel > down the runner, and any coming out of the middle will get pushed back to > the rear (which will then be running over rich). > > It would also be interesting to watch individual MAPs across the runners. > Dollars to donuts that the first runner's > inlet is at a partial vacuum compared to the rear one. > > I may be wrong about the mechanism, but I know my fix fixed whatever was > wrong. I inserted a plate so that the runners > could not "see" the air intake. The air hits the plate and spreads out > before heading to the runners directly, instead > of flying past the first on the way to the second. > > Going off of what I think I know, I would use a handsaw to cut a slot > halfway through the plenum between the runners. > Then I would slide a partition between them. It would essentially create > three stalls that the runners originate from. > The point being that air would not be able to go past one runner on the > way to the second. > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > --000e0ce004806c398b04c134b806 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Ernest,=A0

With my current setup, this p-port engine idl= es better than my side-port motor ever did. =A0It will idle down to 750-800= rpm if asked, although I normally idle at 1500-1600. =A0Still, it might be= an interesting experiment to add temporary dividers in the airbox to see w= hat effect it would have on tuning. =A0

If you take a close look at the picture I posted you ca= n see the blue fuel rail. =A0This is the primary fuel rail feeding the prim= ary injectors. =A0They're located downstream of the butterflies, very c= lose to the intake ports and pointed directly at the rotor faces. =A0I can&= #39;t imagine how the fuel could find its way 18" back down the runner= and back into the other runners. =A0I've never found any residual fuel= in the airbox either. =A0I don't see how the fuel could be pooling so = close to the ports, especially at 4500 rpm. =A0But then I'm not an expe= rt in fuel injection design either.=A0

Alleviating fuel pooling in the runners was one of the = design goals with this latest intake. =A0My previous slide throttle had bot= h the primary and secondary injectors located upstream of the slide. =A0Thi= s caused fuel pooling, especially at very low throttle settings. =A0Needles= s to say, this made low throttle tuning almost impossible. =A0So, the new i= ntake has the primary injectors downstream of the butterflies, and it idles= great. =A0=A0

Mark



On Tue, May 29, 2012 at 4:32 PM, Ernest Christley <echristley@a= tt.net> wrote:
Mark Steitle wrote:
> Ernest,
>
> I don't understand how that could happen if my injectors are after= the
> airbox (see attached pic).
>
> Mark

At idle, the intakes coming off the airbox can set up some serious st= anding waves that will suspend fuel droplets and
let it stick to the walls. =A0You're set-up is very similar to mine, in= that the fuel can run downhill and air has to pass
in front of one runner before reaching the others. =A0Some of that suspende= d fuel will coalesce on the wall and drivel
down the runner, and any coming out of the middle will get pushed back to t= he rear (which will then be running over rich).

It would also be interesting to watch individual MAPs across the runners. = =A0Dollars to donuts that the first runner's
inlet is at a partial vacuum compared to the rear one.

I may be wrong about the mechanism, but I know my fix fixed whatever was wr= ong. =A0I inserted a plate so that the runners
could not "see" the air intake. =A0The air hits the plate and spr= eads out before heading to the runners directly, instead
of flying past the first on the way to the second.

Going off of what I think I know, I would use a handsaw to cut a slot halfw= ay through the plenum between the runners.
Then I would slide a partition between them. =A0It would essentially create= three stalls that the runners originate from.
=A0The point being that air would not be able to go past one runner on the = way to the second.

--
Homepage: =A0http:/= /www.flyrotary.com/
Archive and UnSub: =A0 http://mail.lancaironline.net:81/lists= /flyrotary/List.html

--000e0ce004806c398b04c134b806--