Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Thu, 24 Mar 2005 21:03:42 -0500 Message-ID: X-Original-Return-Path: Received: from [68.89.254.181] (HELO sdf1.mail.taturbo.com) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 819517 for lml@lancaironline.net; Thu, 24 Mar 2005 20:07:54 -0500 Received-SPF: none receiver=logan.com; client-ip=68.89.254.181; envelope-from=gwbraly@gami.com content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C530D6.FD381D98" X-MimeOLE: Produced By Microsoft Exchange V6.0.6487.1 Subject: RE: [LML] Re: superchargers X-Original-Date: Thu, 24 Mar 2005 19:07:17 -0600 X-Original-Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [LML] Re: superchargers Thread-Index: AcUwuYc/8L9XtbFnRW2rISkaCB8dQgAHX31w From: "George Braly" X-Original-To: "Lancair Mailing List" This is a multi-part message in MIME format. ------_=_NextPart_001_01C530D6.FD381D98 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable =20 >>In an airplane, you simply turn it on when you climb through a given = altitude and shut it off when you descend through the same level.<< =20 That is so impractical - - - and would so seriously increase pilot = workloads - - as to evidence a lack of appreciation for the real world = operating conditions involved in the operation of a high powered piston = engine across the typical range of operating conditions. =20 =20 >>Add to this list: 4) Increase engine speed; =20 5) Reduce major combustion chamber radius; =20 6) Reduce/Alter combustion chamber turbulence; =20 7) Alter combustion chamber wall angles to reduce infrared = and shockwave energy reflected into areas of instabillity. =20 8) Relocate spark plug(s)<< =20 Rob, I don=92t think any of those fall into the category of =93bolt = on=94 modifications that are feasible for any of the existing engines, = which is where this discussion started. =20 To increase engine speed, you have to figure out a way to let the prop = blades go super-sonic in a noise sensitive area - - or install a gear = box. =20 =20 >>Reductions in IAT from the intercooler will buy one LARGE = improvements in the detonation limited BMEP (ie, more horsepower = becomes usefully available). That sounds a lot like something I said earlier. Your'e starting to = agree with me.<< =20 Help me, but I don=92t recognize that as anything you said earlier. = I thought your point was that intercoolers made more power by increasing = the charge density - - but had little effect on detonation. =20 The only reliable way to measure detonation =93margins=94 is to = establish a detonation limited mean effective pressure - - and then to = make changes in those things that affect detonation and see how much in = excess of the previous detonation limited MEP you can go with whatever = it is one has changed. Running the boost pressure up doesn=92t get = you more power - - because the power is - - under those test conditions = - - already detonation limited. THAT is where I think we started. =20 =20 What one can do, is to insert a well designed intercooler - - and then- = - and ONLY then - - one can then run up the boost and obtain more power = before one once, again, runs into the detonation limited MEP. =20 Regards, George =20 --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.859 / Virus Database: 585 - Release Date: 2/14/2005 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.859 / Virus Database: 585 - Release Date: 2/14/2005 =20 ------_=_NextPart_001_01C530D6.FD381D98 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

 

>>In an airplane, you simply = turn it on when you climb through a given altitude and shut it off when you = descend through the same level.<<

 

That is so impractical - - - and = would so seriously increase pilot workloads - - as to evidence a lack of = appreciation for the real world operating conditions involved in the operation of a = high powered piston engine across the typical range of operating conditions.  

 

>>Add to this = list:

    =     4)    Increase engine speed;

 

    =     5)    Reduce major combustion chamber = radius;

 

    =     6)    Reduce/Alter combustion chamber = turbulence;

 

    =     7)    Alter combustion chamber wall angles to reduce infrared and shockwave energy reflected into areas of = instabillity.

 

8)        Relocate spark plug(s)<<

 

Rob,  I don’t think any = of those fall into the category of   “bolt on”  modifications that are feasible for any of the existing engines,  = which is where this discussion started.

 

To increase engine speed,  you = have to figure out a way to let the prop blades go super-sonic in a noise = sensitive area - -  or  install a gear box.  =

 

>>Reductions in IAT from the intercooler will buy one  LARGE improvements in the  = detonation limited BMEP (ie, more horsepower becomes usefully = available).

That sounds a lot like something I = said earlier. Your'e starting to agree with = me.<<

 

Help me,  but I =  don’t recognize that as anything you said earlier.    I thought = your point was that intercoolers made more power by increasing the charge = density  - - but had little effect on detonation.

 

The only reliable way to measure detonation “margins”  is to establish a detonation limited  mean effective pressure - -  and then to make changes = in those things that affect detonation and see how much in excess of the previous  detonation limited  MEP you can go with whatever it = is one has changed.    Running the boost pressure up = doesn’t get you more power - - because the power is - - under those test conditions = - - already detonation limited.   THAT is where I think we started.  

 

What one can do,  is to insert = a well designed intercooler - - and then- - and ONLY then - - one can then run = up the boost and obtain more power before one once, again,  runs into the detonation limited MEP.

 

Regards,  = George

 


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