Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Manifold Pressure

Matronics Email Lists Forum Index -> M14PEngines-List

View previous topic :: View next topic

Author Message

ScottA

Joined: 05 Jan 2006
Posts: 100
Location: Park City, UT

Posted: Sun Apr 09, 2006 11:28 pm Post subject: Manifold Pressure

Wonder what to expect (roughly) for a take off Manifold Pressure on a standard day at a 5000’ MSL airport with the standard M14P?  

   

Thanks,  

Scott

- The Matronics M14PEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?M14PEngines-List

dsavarese(at)elmore.rr.co
Guest

Posted: Mon Apr 10, 2006 7:38 am Post subject: Manifold Pressure

Scott,

 On a standard day at sea level, barometric pressure in inches  is 29.92" which equals 760 mm.  At 100% the supercharger boosts the  pressure (at sea level) to approximately 885 mm or 34.85", a factor of 1.165.    At 5000' on a standard day the barometric pressure should be about  24.9 inches, or 632 mm.  Given the supercharger boost factor,  at 5000' with 100% rpm the manifold pressure should come up to about 736  mm.   I'm sure if my numbers are wrong someone will definitely correct  me. -)

 Dennis

  

 [quote]   ---

- The Matronics M14PEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?M14PEngines-List

tedwaltman(at)i1ci.com
Guest

Posted: Mon Apr 10, 2006 7:50 am Post subject: Manifold Pressure

Dennis,

  

 This whole debate started with a couple of us comparing MP  on our M-14 engines.  Yesterday, at roughly std temp--or maybe a few  degrees warmer--I saw 26.1" at takeoff at 4,965'.  A standard engine on a  Swift was showing about 22" at takeoff (at 1,921 prop rpm or 2,919 engine  rpm).  We were both at roughly 25" before engine start.

  

 So, I'm not seeing the 736mm, or 28.97", you indicate  below.  Perhaps my gauge is a bit off?

  

 Ted



   From:  owner-m14pengines-list-server(at)matronics.com  [mailto:owner-m14pengines-list-server(at)matronics.com] On Behalf Of A.  Dennis Savarese

Sent: Monday, April 10, 2006 9:38 AM

To:  m14pengines-list(at)matronics.com

Subject: Re: Manifold  Pressure

 

 Scott,

 On a standard day at sea level, barometric pressure in inches  is 29.92" which equals 760 mm.  At 100% the supercharger boosts the  pressure (at sea level) to approximately 885 mm or 34.85", a factor of 1.165.    At 5000' on a standard day the barometric pressure should be about  24.9 inches, or 632 mm.  Given the supercharger boost factor,  at 5000' with 100% rpm the manifold pressure should come up to about 736  mm.   I'm sure if my numbers are wrong someone will definitely correct  me. -)

 Dennis

  

 [quote]   ---

- The Matronics M14PEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?M14PEngines-List

ScottA

Joined: 05 Jan 2006
Posts: 100
Location: Park City, UT

Posted: Mon Apr 10, 2006 7:53 am Post subject: Manifold Pressure

That is about what I was thinking we should see roughly 29 inches.  With no real charts (that I know of or can understand) I am wondering when the supercharger starts to loss it effectiveness in giving the approx. 5 inch.  

   

Scott  

         

  

From: owner-m14pengines-list-server(at)matronics.com [mailto:owner-m14pengines-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese

 Sent: Monday, April 10, 2006 9:38 AM

 To: m14pengines-list(at)matronics.com

 Subject: Re: M14PEngines-List: Manifold Pressure  

  

     

Scott,  

    

On a standard day at sea level, barometric pressure in inches is 29.92" which equals 760 mm.  At 100% the supercharger boosts the pressure (at sea level) to approximately 885 mm or 34.85", a factor of 1.165.   At 5000' on a standard day the barometric pressure should be about 24.9 inches, or 632 mm.  Given the supercharger boost factor, at 5000' with 100% rpm the manifold pressure should come up to about 736 mm.   I'm sure if my numbers are wrong someone will definitely correct me. -)  

    

Dennis  

    

   

  [quote]    

---

- The Matronics M14PEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?M14PEngines-List

dsavarese(at)elmore.rr.co
Guest

Posted: Mon Apr 10, 2006 7:58 am Post subject: Manifold Pressure

Most likely the gauge is off, just like I know mine is.   We're at 200' MSL here at our airport.  So our MP gauges should read pretty  close to 760 mm on a standard day.  I can tell you this.  Mine  surely does not.  It reads low by about 30-40 mm compared to the other 4  Yaks in our hangar.   The numbers should be just about right I  think.  I used this site, http://www.digitaldutch.com/atmoscalc/,  to get the standard atmospheric pressure at 5000'.  The rest of the data  came from the engine manual and basic calculations.

 Dennis

  

 [quote]   ---

- The Matronics M14PEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?M14PEngines-List

dsavarese(at)elmore.rr.co
Guest

Posted: Mon Apr 10, 2006 8:02 am Post subject: Manifold Pressure

The super charger drop is basically linear, assuming 100%  power.  It never really loses its "effectiveness".  It will always  boost above atmospheric pressure, as long as it's turning.  -)   It just starts off higher (+5" approximately).

 Dennis

 [quote]   ---

- The Matronics M14PEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?M14PEngines-List

ScottA

Joined: 05 Jan 2006
Posts: 100
Location: Park City, UT

Posted: Mon Apr 10, 2006 8:27 am Post subject: Manifold Pressure

That brings up the question (at least for me) if you had a small leak in the MP line on a supercharged engine would that cause low indication due to pressure loss?  Whereas on none turbo or supercharged a leak may cause higher indication due to less vacuum (because it is really vacuum and not “pressure” on a standard engine, i.e. MP usually drops slightly when takeoff power is applied).  Too much thinking…  

   

Scott  

         

  

From: owner-m14pengines-list-server(at)matronics.com [mailto:owner-m14pengines-list-server(at)matronics.com] On Behalf Of A. Dennis Savarese

 Sent: Monday, April 10, 2006 9:58 AM

 To: m14pengines-list(at)matronics.com

 Subject: Re: M14PEngines-List: Manifold Pressure  

  

     

Most likely the gauge is off, just like I know mine is.  We're at 200' MSL here at our airport.  So our MP gauges should read pretty close to 760 mm on a standard day.  I can tell you this.  Mine surely does not.  It reads low by about 30-40 mm compared to the other 4 Yaks in our hangar.   The numbers should be just about right I think.  I used this site, http://www.digitaldutch.com/atmoscalc/, to get the standard atmospheric pressure at 5000'.  The rest of the data came from the engine manual and basic calculations.  

    

Dennis  

    

   

  [quote]    

---

- The Matronics M14PEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?M14PEngines-List

dsavarese(at)elmore.rr.co
Guest

Posted: Mon Apr 10, 2006 9:31 am Post subject: Manifold Pressure

Yes, too much thinking for sure! -)  Sounds about right  to me.

 Dennis

  

 [quote]   ---

- The Matronics M14PEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?M14PEngines-List

Display posts from previous:

	Matronics Email Lists Forum Index -> M14PEngines-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum