Return-Path: <13brv3@bellsouth.net> Received: from imf17aec.mail.bellsouth.net ([205.152.59.65] verified) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2575583 for flyrotary@lancaironline.net; Wed, 10 Sep 2003 23:51:12 -0400 Received: from rad ([68.212.14.21]) by imf17aec.mail.bellsouth.net (InterMail vM.5.01.05.27 201-253-122-126-127-20021220) with ESMTP id <20030911035110.NRTK17943.imf17aec.mail.bellsouth.net@rad> for ; Wed, 10 Sep 2003 23:51:10 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: turbo wastegate requirements Date: Wed, 10 Sep 2003 22:51:10 -0500 Message-ID: <006801c37817$f043ec30$0201a8c0@rad> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0069_01C377EE.076DE430" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_0069_01C377EE.076DE430 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable I am totally new to all of this, but have to learn. I don't want much = boost (maybe 35" or so MAP) for takeoff, but want to turbo normalize to around 15k'. I know detonation is a problem with high boost and I will have limited intercooler resources. With that in mind, how does this sound = .... =20 Sounds like we're after the same thing. BTW, I have no intercooler at = all, which is another reason that I'm afraid to run too much boost for too = long at Summer sea level temps in Florida. I can definitely tell the = difference in mixture between the A and B controllers on the EC-2. The A = controller uses the temp sensor, and the B controller does not. The temp must be elevated quite a bit, but until I get the EM-2 to read it, I won't know = how much. =20 I would have a manual internal waste gate. The waste gate would be = normally open (dumping all exhaust past the turbo). On takeoff, I would run WOT = (say 29"), no boost. I could close the waste gate a little and get 33" for example for a hot day or short field. As I climb out at WOT, I = gradually close the waste gate to maintain 30" MAP. Since I'm running essentially = NA at low altitude (where the atmosphere is warmer) I don't need much in = the way of an intercooler. As I climb and progressively close the waste = gate to maintain 30", I need more intercooling, but this need is reduced by the cooler atmospheric temps. At altitude, say 15k' - 17k', 30" has me = going like a bat out of hell, and the cooler air going into the system = requires less intercooling.=20 The only problem I see with this plan is your assumption that opening = the wastegate will eliminate all the boost. In reality, stock wastegates = aren't able to do this for us. If you look at how an internal wastegate = works, you'll see that it isn't a valve that diverts exhaust from the turbine = to the open exhaust pipe. It's really just a door that opens to give the exhaust an easier path to the tailpipe. This doesn't stop some of the exhaust from turning the turbine and creating some boost. =20 In a car, where you have catalytic converters, mufflers, and restrictive = air filters, there's enough restriction in the system to limit the amount of = air that can move through the engine. In the case of a stock engine with = these restrictions, the stock wastegate is as effective as it needs to be. = When you remove these restrictions, even in the car, boost can't be = completely controlled by the wastegate anymore. Some wastegates are more effective than others. In RX-7's for example, the series 5, 89-91 turbo wastegate = is quite a bit bigger than the one on the series 4, 87-88 turbo. My = series 5 wastegate has been wide open, and the turbo still wants to make more = than 3 psi of boost. Until I set the pop-off valve for a higher number, and go = to a safe altitude to test it, I won't know how much it will really make. Ideally, I'd like to be able to open up the flow of the wastegate until = I could only produce 3 psi of boost with the wastegate open. At that = point, I would only have to insure than the wastegate is open at low altitudes, = then I couldn't overboost the engine. I can't wait to get my temps in order, = so I can see what the turbo will really do. =20 Cheers,=20 Rusty ------=_NextPart_000_0069_01C377EE.076DE430 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Message
I am totally new to all of this, but have to learn.  I don't = want much=20 boost (maybe 35" or so MAP) for takeoff, but want to turbo normalize to = around=20 15k'.  I know detonation is a problem with high boost and I will = have=20 limited intercooler resources.  With that in mind, how does this = sound=20 ....  
 
Sounds like=20 we're after the same thing.  BTW, I have no intercooler at all, = which is=20 another reason that I'm afraid to run too much boost for too long at = Summer sea=20 level temps in Florida.   I can=20 definitely tell the difference in mixture between the A and B = controllers on the=20 EC-2.  The A controller uses the temp sensor, and the B controller = does=20 not.  The temp must be elevated quite a bit, but until I get the = EM-2 to=20 read it, I won't know how much. 

I would have a manual internal waste gate.  The waste gate would = be=20 normally open (dumping all exhaust past the turbo).  On takeoff, I = would=20 run WOT (say 29"), no boost.  I could close the waste gate a little = and get=20 33" for example for a hot day or short field.  As I climb out at = WOT, I=20 gradually close the waste gate to maintain 30" MAP.  Since I'm = running=20 essentially NA at low altitude (where the atmosphere is warmer) I don't = need=20 much in the way of an intercooler.  As I climb and progressively = close the=20 waste gate to maintain 30", I need more intercooling, but this need is = reduced=20 by the cooler atmospheric temps.  At altitude, say 15k' - 17k', 30" = has me=20 going like a bat out of hell, and the cooler air going into the system = requires=20 less intercooling.=20

The only=20 problem I see with this plan is your assumption that opening the = wastegate will=20 eliminate all the boost.  In reality, stock wastegates aren't able = to do=20 this for us.   If you look at how an internal wastegate works, = you'll=20 see that it isn't a valve that diverts exhaust from the turbine to the = open=20 exhaust pipe.  It's really just a door that opens to give the = exhaust an=20 easier path to the tailpipe.  This doesn't stop some of the exhaust = from=20 turning the turbine and creating some boost. 

In a car, where=20 you have catalytic converters, mufflers, and restrictive air filters, = there's=20 enough restriction in the system to limit the amount of air that can = move=20 through the engine.  In the case of a stock engine with these = restrictions,=20 the stock wastegate is as effective as it needs to = be.  When you=20 remove these restrictions, even in the car, boost can't be completely = controlled=20 by the wastegate anymore.  Some wastegates are more effective than=20 others.  In RX-7's for example, the series 5, 89-91 turbo wastegate = is=20 quite a bit bigger than the one on the series 4, 87-88=20 turbo.   My series 5 wastegate has been wide open, = and=20 the turbo still wants to make more than 3 psi of boost.  Until = I set=20 the pop-off valve for a higher number, and go to a safe altitude to = test=20 it, I won't know how much it will really make.  Ideally, I'd like = to be=20 able to open up the flow of the wastegate until I could only produce 3 = psi of=20 boost with the wastegate open.  At that point, I would only = have to=20 insure than the wastegate is open at low altitudes, then I couldn't = overboost=20 the engine.  I can't wait to get my temps in order, so I can see = what the=20 turbo will really do. 

Cheers,

Rusty
------=_NextPart_000_0069_01C377EE.076DE430--