X-Virus-Scanned: clean according to Sophos on Logan.com X-PolluStop: No license found, only first 5 messages were scanned Return-Path: Received: from zproxy.gmail.com ([64.233.162.200] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with ESMTP id 993599 for flyrotary@lancaironline.net; Mon, 13 Jun 2005 01:13:22 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.233.162.200; envelope-from=wdleonard@gmail.com Received: by zproxy.gmail.com with SMTP id 34so877173nzf for ; Sun, 12 Jun 2005 22:12:37 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:in-reply-to:mime-version:content-type:references; b=ZE74mPzOmsWTme+UzPGYVX5X09YQ9nEgPKThjgYUXG4z34vTgoc3vm8Vhg/BMpsPVbd/sOrYMWTDOL4hHwhbktAdDtilsGseTwml8SgYt8Ae8FOJwdrGL9ErzZ/aJzx9vxrAGmJ2dBOBZ6HpiHykVq17SoUD0frYQwDuMWv0zbw= Received: by 10.36.74.17 with SMTP id w17mr2639469nza; Sun, 12 Jun 2005 22:12:37 -0700 (PDT) Received: by 10.36.9.4 with HTTP; Sun, 12 Jun 2005 22:12:37 -0700 (PDT) Message-ID: <1c23473f050612221213f9c314@mail.gmail.com> Date: Sun, 12 Jun 2005 22:12:37 -0700 From: David Leonard Reply-To: David Leonard To: Rotary motors in aircraft Subject: Re: [FlyRotary] T3-60 compressor map for Dave. In-Reply-To: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_10950_30570691.1118639557942" References: ------=_Part_10950_30570691.1118639557942 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On 6/12/05, Ian Dewhirst wrote: > Hi Dave, I have attached a T3 60 series compressor map. Based on your=20 > spreadsheet it should be a good match. A new wheel and housing is not too= =20 > expensive, install and balance was around $100 last I had it done. If you= =20 > would like another compressor map I could look through my collection, I h= ave=20 > about 60 or so, though some are not the best because they were faxed to m= e=20 > back in the days of thermal fax machines. > The red line on the image is 30" map, blue is 35", green is 40"=20 >=20 Ian, You apparently know your turbochargers. The problem with the T4 60 trim is that it is basically the same as the=20 stock compressor, which tended to allow the turbine to overspeed and that i= s=20 why I am trying something bigger. I am starting to wonder if this is really surge. I went flying again today= =20 with the wastgate fully open and the pop-off set to full loose. I climbed= =20 out at 32" which was a real treat, letting the MAP fall with altitude. I go= t=20 to the test area and let the boost creep up a little. At 9500', 27"MAP 5800= =20 rpm (170 KTAS) it happened again. That is just not asking a lot of boost=20 from this turbo. I am still keeping my mind open to other possibilities but= =20 just cant come up with anything that makes sense.=20 The problem with the turbo maps is that there are too many variables (like= =20 VE and throttle body losses and compressor efficiency) which can all have= =20 such a huge effect. In your spreadsheet I think your pressure drop across the intercooler is= =20 > too high, 2 psi for the intercooler and 0.5 psi for the throttle body=20 > might be closer, I took my laptop for a ride in my car and went for a dri= ve=20 > to confirm this, I lose 1.2 psi across a Spearco intercooler, and 0.3acro= ss the TB, I tried to aproximate the flow you are planning. Compressor=20 > efficiency is a bit low at 60%. VE might be a bit high. Adjusting these= =20 > figures will move the lines I drew on the image to the right and down. If= =20 > you decide on a stree port the map will look better still. > -- Ian >=20 Don't forget that the throttle valve is half closed. On the ground a half= =20 closed throttle (n.a) would give about 24 MAP (all guessing here), or about= =20 a 3 psi drop. In other words, keeping that throttle closed is hurting my=20 boost. VE for a stock rotary is reported to be quite high, >100% at some rpm, >80= %=20 for most RPM. However, that is mostly due to tuning effects of the intake= =20 and mine probably could not possibly get any worse. You are right, I may=20 have a 60%VE until I install the ported engine. --=20 Dave Leonard Turbo Rotary RV-6 N4VY http://members.aol.com/_ht_a/rotaryroster/index.html http://members.aol.com/vp4skydoc/index.html ------=_Part_10950_30570691.1118639557942 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
On 6/12/05, = Ian Dewhirst <ianddsl@magma.ca> wrote:
Hi Dave, I hav= e attached a T3 60 series compressor map.  Based on your spreadsh= eet it should be a good match. A new wheel and housing is not too expe= nsive, install and balance was around $100 last I had it done.&nb= sp; If you would like another compressor map I could look through my collec= tion, I have about 60 or so, though some are not the best because they were= faxed to me back in the days of thermal fax machines.
=  
The red line o= n the image is 30" map, blue is 35", green is 40" 
 
Ian, You apparently know your turbochargers.
 
The problem with the T4 60 trim is that it is basically the same = as the stock compressor, which tended to allow the turbine to overspee= d and that is why I am trying something bigger.
 
I am starting to wonder if this is really surge.  I went flying a= gain today with the wastgate fully open and the pop-off set to full loose.&= nbsp; I climbed out at 32" which was a real treat, letting the MAP fal= l with altitude.  I got to the test area and let the boost creep up a = little.  At 9500',  27"MAP 5800 rpm (170 KTAS)  it happ= ened again.  That is just not asking a lot of boost from this turbo.&n= bsp; I am still keeping my mind open to other possibilities but just cant c= ome up with anything that makes sense. =20
 
The problem with the turbo maps is that there are too many variables (= like VE and throttle body losses and compressor efficiency) which can all h= ave such a huge effect.

 
 
In your spread= sheet I think your pressure drop across the intercooler is too high, 2 psi = for the intercooler and 0.5 psi for the throttle body might be closer,= I took my laptop for a ride in my car and went for a drive to confirm= this, I lose=20 1.2 psi across a Spearco intercooler, and 0.3 across the TB, I tr= ied to aproximate the flow you are planning.  Compressor efficien= cy is a bit low at 60%.  VE might be a bit high.  Adjusting these= figures will move the lines I drew on the image to the right and down.&nbs= p; If you decide on a stree port the map will look better still.
=  
-- Ian<= /span>
 
Don't forget that the throttle valve is half closed.   On th= e ground a half closed throttle (n.a) would give about 24 MAP (all gue= ssing here), or about a 3 psi drop.  In other words, keeping that= throttle closed is hurting my boost.
 
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