Return-Path: Received: from wb2-a.mail.utexas.edu ([128.83.126.136] verified) by logan.com (CommuniGate Pro SMTP 4.2b2) with ESMTP-TLS id 3185004 for flyrotary@lancaironline.net; Thu, 22 Apr 2004 15:33:21 -0400 Received: (qmail 28907 invoked from network); 22 Apr 2004 19:33:20 -0000 Received: from dhcp-191-101.per.utexas.edu (HELO benefits3.mail.utexas.edu) (146.6.191.101) by wb2.mail.utexas.edu with RC4-SHA encrypted SMTP; 22 Apr 2004 19:33:20 -0000 Message-Id: <5.1.1.5.2.20040422143006.029e19e8@localhost> X-Sender: msteitle@mail.utexas.edu@localhost X-Mailer: QUALCOMM Windows Eudora Version 5.1.1 Date: Thu, 22 Apr 2004 14:32:54 -0500 To: "Rotary motors in aircraft" From: Mark Steitle Subject: Re: [FlyRotary] Re: intake ideas? In-Reply-To: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="=====================_79504343==.ALT" --=====================_79504343==.ALT Content-Type: text/plain; charset="iso-8859-1"; format=flowed Content-Transfer-Encoding: quoted-printable At 03:01 PM 4/22/2004 -0400, you wrote: > > > >>One more comment on intake manifolds & race results. Do not ignore the= =20 >>benefits of a really clean air inlet with ram air recovery BEFORE the=20 >>manifold. At 1125 ft msl, 220 IAS, I saw manifold pressures around=20 >>31.8" Hg. Ignore this factor and you throw away about 6% "free"= horsepower. >> >> >> >> >>Al, I forgot to comment on your last note about your MAP tap in=20 >>manifold. I think it is highly possible you were seeing errors induced=20 >>by air stream eddies or some other unpredictable factors caused by that=20 >>location. It is a challenge to get MAP measurements when you have no=20 >>real plenum, only runners with high velocity air. >>Tracy >> >> >> >> >>I use the stock ports in the TWM throttle body. I assumed they would=20 >>know where to place the port to get a good measurement. >>Where do you measure MAP on your system? I can=C3=A2=80=99t believe that= you=20 >>could see that kind of pressessure at the engine end of a long intake=20 >>tube. But I remember once before when I was wrongJ. >>Al >>I measure it at the dynamic/plenum chamber, just under the throttle body. >>Tracy >>Hum-m-m. That=C3=A2=80=99s about equivalent to me measuriuring it in the= air=20 >>plenum before the TB. It would be very interesting to know what it is on= =20 >>yours about 4=C3=A2=80=C2=9D from the intakee port. Then there is the= whole=20 >>question of =C3=A2=80=98whihich=C3=A2=80=99 MAP pressure the EC-2 should= be interpreting=20 >>=E2g =E2=80=93 or maybe it doesn=C3=A2=80=99t matter. . . >>Al >> >> >> >> >>Before the TB? I don't follow you. Ideally, that would be true at WOT= =20 >>only, but it would be a fairly useless figure. And it would definitely=20 >>matter to the EC2 if you tried to measure MAP there (i.e., Would Not= Work ). >> >> >> >> >>At one time I did measure the MAP at the far end of the small (primary)=20 >>runners and found a .8" Hg drop at WOT compared to dynamic chamber=20 >>reading. I expected this drop. For reasons of not wanting to enter a=20 >>prolonged and fruitless discussion on rotary engine manifold design, I=20 >>will not explain why this drop is desirable : ) >> >> >> >> >>But my main point was that you can get about 2" of MAP increase from ram= =20 >>air recovery (at ~200 mph), REGARDLESS OF WHERE you measure it. >> >> >> >> >>Tracy >Tracy, >So, where's the correct location for the MAP port? > >Mark S. > >Go up 6 paragraphs and read it again : ) > >Tracy Sorry, I missed that... that's where I put mine. Mark --=====================_79504343==.ALT Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable At 03:01 PM 4/22/2004 -0400, you wrote:

One more comment on intake manifolds & race results.   Do not ignore the benefits of a really clean air inlet with ram air recovery BEFORE the manifold.   At 1125 ft msl, 220 IAS, I saw manifold pressures around 31.8" Hg. Ignore this factor and you throw away about 6% "free" horsepower.=20

=20
Al, I forgot to comment on your last note about your MAP tap in manifold. I think it is highly possible you were seeing errors induced by air stream eddies or some other unpredictable factors caused by that location.   It is a challenge to get MAP measurements when you have no real plenum, only runners with high velocity air.=20
Tracy

=20
I use the stock ports in the TWM throttle body. I assumed they would know where to place the port to get a good measurement.=20
Where do you measure MAP on your system? I can=C3=A2=80=99t believ= e that you could see that kind of pressessure at the engine end of a long intake tube. But I remember once before when I was wrongJ.=20
Al=20
I measure it at the dynamic/plenum chamber, just under the throttle body.=20
Tracy=20
Hum-m-m.   That=C3=A2=80=99s about equivalent to me= measuriuring it in the air plenum before the TB. It would be very interesting to know what it is on yours about 4=C3=A2=80=C2=9D from the intakee port. = Then there is the whole question of =C3=A2=80=98whihich=C3=A2=80=99 MAP pressure= the EC-2 should be interpreting =E2g =E2=80=93 or maybe it doesn=C3=A2=80=99t matter.= . .=20
Al

=20
Before the TB?   I don't follow you. Ideally, that would be true at WOT only, but it would be a fairly useless figure. And it would definitely matter to the EC2 if you tried to measure MAP there (i.e., Would Not Work ).

=20
At one time I did measure the MAP at the far end of the small (primary) runners and found a .8" Hg drop at WOT compared to dynamic chamber reading. I expected this drop. For reasons of not wanting to enter a prolonged and fruitless discussion on rotary engine manifold design, I will not explain why this drop is desirable : )

=20
But my main point was that you can get about 2" of MAP increase from ram air recovery (at ~200 mph), REGARDLESS OF WHERE you measure it.

=20
Tracy

Tracy,
So, where's the correct location for the MAP port?

Mark S.

Go up 6 paragraphs and read it again : )

Tracy
Sorry, I missed that... that's where I put mine.

Mark
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