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

Low Boost?

Matronics Email Lists Forum Index -> Yak-List

View previous topic :: View next topic

Author Message

Yakbaas

Joined: 08 Oct 2008
Posts: 10
Location: FAMB

Posted: Mon Sep 06, 2010 11:25 pm Post subject: Low Boost?

Hi All

I only get 95-100 mm of boost pressure.I suppose it can only be a leak or is there something else I can check?

Any good ideas on finding a leak?



Riaan Prinsloo

- The Matronics Yak-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?Yak-List

viperdoc(at)mindspring.co
Guest

Posted: Tue Sep 07, 2010 4:59 am Post subject: Low Boost?

Check the lines to the sending unit and the manifold pressure gauge first

before assuming it is the super charger in the accessory case.

doc



--

- The Matronics Yak-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?Yak-List

dsavarese0812(at)bellsout
Guest

Posted: Tue Sep 07, 2010 10:05 am Post subject: Low Boost?

Please explain what to mean by 95-100 mm of boost. The normal manifold pressure for a 360 HP M14P at sea level (important) is around 880-890 mm. There is no sender for manifold pressure.  It is read direct from the supercharger. At sea level on a standard day, the manifold pressure instrument should read 760 mm.  Therefore the total boost AT SEA LEVEL is about 120 mm. Dennis



Sent from my iPhone



On Sep 7, 2010, at 2:25 AM, "Yakbaas" <riaan(at)golfcartpro.co.za> wrote:



 	  Quote: 	
		   

 

 Hi All

 I only get 95-100 mm of boost pressure.I suppose it can only be a leak or is there something else I can check?

 Any good ideas on finding a leak?

 

 Riaan Prinsloo

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=311640#311640

- The Matronics Yak-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?Yak-List

dsavarese0812(at)bellsout
Guest

Posted: Tue Sep 07, 2010 12:09 pm Post subject: Low Boost?

760 mm manifold pressure is with the engine off. 880-890 mm is at wide open throttle typically only seen on takeoff. Dennis

Sent from my iPhone

On Sep 7, 2010, at 1:03 PM, "A. Dennis Savarese" <dsavarese0812(at)bellsouth.net> wrote:

 	  Quote: 	

 Please explain what to mean by 95-100 mm of boost. The normal manifold pressure for a 360 HP M14P at sea level (important) is around 880-890 mm. There is no sender for manifold pressure.  It is read direct from the supercharger. At sea level on a standard day, the manifold pressure instrument should read 760 mm.  Therefore the total boost AT SEA LEVEL is about 120 mm. Dennis

 Sent from my iPhone

 On Sep 7, 2010, at 2:25 AM, "Yakbaas" <riaan(at)golfcartpro.co.za> wrote:

> 

> 

> Hi All

> I only get 95-100 mm of boost pressure.I suppose it can only be a leak or is there something else I can check?

> Any good ideas on finding a leak?

> 

> Riaan Prinsloo

> 

> 

> 

> 

> Read this topic online here:

> 

> http://forums.matronics.com/viewtopic.php?p=311640#311640

> 

> 

> 

> 

> 

> 

> 

> 

> 

>

- The Matronics Yak-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?Yak-List

Yakbaas

Joined: 08 Oct 2008
Posts: 10
Location: FAMB

Posted: Tue Sep 07, 2010 12:22 pm Post subject: Re: Low Boost?

I have 735mm  with engine off and only get 830mm on take-off roll.Still get 99% on rpm.

Had 2 take-offs in the last 20 hours where the rpm "hunt" between 99% and 89% (WOT),came back to 80% and still hunting 5% up and down.Only when I set 70% and 700mm it stabilized.Never done it again!

I don't think the 2 are related though.

- The Matronics Yak-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?Yak-List

dsavarese0812(at)bellsout
Guest

Posted: Wed Sep 08, 2010 4:53 am Post subject: Low Boost?

RPM hunting - just for the heck of it, have you recently  removed and cleaned the prop governor oil/finger screen on the right side of the  nose case?  Most likely not related to the manifold pressure  question/issue.

  

 I would like to know what your field elevation is.    As you know, the manifold pressure gauge reads atmospheric pressure with the  engine off.  Assuming your manifold pressure gauge is reasonably calibrated  (from what I have seen, many are not), 735 mm with the engine off would suggest  your field elevation is about 1000 feet or about 300 meters.  You can  easily check the calibration of your manifold pressure gauge by setting your  field elevation on your altimeter and reading the Kollsman window.  US  altimeters will need to be converted from inches to millimeters.  Compare  the MP gauge to the altimeter.  The MP gauge can be adjusted.  There  is a small covered hole in the rear of the MP gauge.  If I remember  correctly, it is a little stick-on cover.  Remove it and you will see the  adjustment screw inside.  You will need a special slotted tool to adjust  it.  But it can be done.  

  

 Have you tightened all of the intake tube gland nuts and the  intake tube collars?  If you have an intake drain kit, check to make sure  there are no leaks from the fittings on the intake drain kit.  Any leaks  around the intake tubes will cause a reduction in manifold pressure.    Check the flexible hose from the top of the supercharger to the manifold  pressure gauge.  The hose itself may be leaking.

  

 Dennis

 [quote]   ---

- The Matronics Yak-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?Yak-List

yakplt(at)yahoo.com
Guest

Posted: Thu Sep 09, 2010 2:25 pm Post subject: Low Boost?

Just to add to the already good advice... 

  

 I have had the primer hose rupture about 3 times now on my YAK-50.  If that line is leaking, you will also have low manifold pressure at Wide Open Throttle.    

  

 Yes, I need to put American braided hose in there.  I keep replacing it with the Russian hose... stupid I know. 

  

 Mark

 



--- On Wed, 9/8/10, A. Dennis Savarese <dsavarese0812(at)bellsouth.net> wrote:



 [quote]

From: A. Dennis Savarese <dsavarese0812(at)bellsouth.net>

Subject: Re: Re: Low Boost?

To: yak-list(at)matronics.com

Date: Wednesday, September 8, 2010, 8:50 AM



    RPM hunting - just for the heck of it, have you recently removed and cleaned the prop governor oil/finger screen on the right side of the nose case?  Most likely not related to the manifold pressure question/issue.

  

 I would like to know what your field elevation is.   As you know, the manifold pressure gauge reads atmospheric pressure with the engine off.  Assuming your manifold pressure gauge is reasonably calibrated (from what I have seen, many are not), 735 mm with the engine off would suggest your field elevation is about 1000 feet or about 300 meters.  You can easily check the calibration of your manifold pressure gauge by setting your field elevation on your altimeter and reading the Kollsman window.  US altimeters will need to be converted from inches to millimeters.  Compare the MP gauge to the altimeter.  The MP gauge can be adjusted.  There is a small covered hole in the rear of the MP gauge.  If I remember correctly, it is a little stick-on cover.  Remove it and you will see the adjustment screw inside.  You will need a special slotted tool to adjust it.  But it can be  done.  

  

 Have you tightened all of the intake tube gland nuts and the intake tube collars?  If you have an intake drain kit, check to make sure there are no leaks from the fittings on the intake drain kit.  Any leaks around the intake tubes will cause a reduction in manifold pressure.   Check the flexible hose from the top of the supercharger to the manifold pressure gauge.  The hose itself may be leaking.

  

 Dennis

 [quote] ---

- The Matronics Yak-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?Yak-List

dsavarese0812(at)bellsout
Guest

Posted: Thu Sep 09, 2010 2:49 pm Post subject: Low Boost?

Excellent Mark!  Didn't think about that  one!

 Dennis

 [quote]   ---

- The Matronics Yak-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?Yak-List

Display posts from previous:

	Matronics Email Lists Forum Index -> Yak-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