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Manifold pressure

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GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Sun Oct 29, 2006 12:22 am Post subject: Manifold pressure

Did an interesting test today.



2004 Tiger with a JPI 800.  With Manifold Pressure.



My TIger, 1987 Tiger with a JPI 800.



Engine not running:  both indicate the same manifold pressure



During a climb at WOT (wide open throttle) from 4000 ft to 6500 feet, 

manifold pressure in the 2004 was 1/2 inch less.



Straight and level, WOT, MAP in the '04 Tiger was 7/10 inches less.

I've thought for a long time that the design of the carb air inlet on 

the AG5B was stupid.  Now I'm convinced.

________________________________________________________________________

across the web, free AOL Mail and more.

_________________
Gary
AuCountry Aviation
Home of Team Grumman

FLYaDIVE(at)AOL.COM
Guest

Posted: Sun Oct 29, 2006 3:44 am Post subject: Manifold pressure

In a message dated 10/29/2006 3:24:02 AM Eastern Standard Time, teamgrumman(at)aol.com writes:

  	  Quote: 	
		  --> TeamGrumman-List message posted by: teamgrumman(at)aol.com



Did an interesting test today.



2004 Tiger with a JPI 800.  With Manifold Pressure.



My TIger, 1987 Tiger with a JPI 800.



Engine not running:  both indicate the same manifold pressure



During a climb at WOT (wide open throttle) from 4000 ft to 6500 feet, 

manifold pressure in the 2004 was 1/2 inch less.



Straight and level, WOT, MAP in the '04 Tiger was 7/10 inches less.

I've thought for a long time that the design of the carb air inlet on 

the AG5B was stupid.  Now I'm convinced.

________________________________________________________________________ 	


 ================================================

 Gary:

  

 Where is the manifold pressure being taken from for each gage?

  

 What I'm thinking is: Since we know the poor configuration and fuel distribution that the intake manifold offers, could it be this, that is showing the difference between your gages.

  

 Then again they are only gages.  Made by different manufactures and I believe the JPI uses a transducer while the planes gage is a Boron(sp) Tube.  Lots of mechanical differences their also.  There is also the scales range to consider.  What is the advertised accuracy of the each of the gages?  Are the reading differences between the gages within that accuracy range?

  

 GAUD!  I hate being so QA Analytical.

  

  

  

 Barry

"Chop'd Liver"

  [quote][b]

flyv35b(at)minetfiber.com
Guest

Posted: Sun Oct 29, 2006 4:47 am Post subject: Manifold pressure

[quote] ---

flyv35b(at)minetfiber.com
Guest

Posted: Sun Oct 29, 2006 4:53 am Post subject: Manifold pressure

Barry, 

  

 Read his email again.  Both  planes had JPI instrumentation and used the same transducer in all  likelihood.  Also, they both indicated the same MP on the ground.   That sounds as if the instrumentation is NOT a factor to me.  At any rate  I'd be willing to buy Gary's theory about the poor induction system on the AG5B  models.

  

 BTW, it's bourdon tube.  But I'm  not sure if that's the type gauge the AG5B used or not.

  

 Cliff

 [quote]   ---

flyv35b(at)minetfiber.com
Guest

Posted: Sun Oct 29, 2006 8:03 am Post subject: Manifold pressure

Disregard the last comment.  None  of the single engine Grummans ever had MP gauges from the  factory.

  

 Cliff

 [quote]   ---

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Sun Oct 29, 2006 10:16 am Post subject: Manifold pressure

I thought I made it clear that both planes have a JPI 800.  Same 

instrumentation.  Same transducers.  The pressure is being measured 

 from the fuel injection port on the #3 cylinder on both planes.  The 

length of tubing to the MAP transducer is the same.

--

_________________
Gary
AuCountry Aviation
Home of Team Grumman

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Sun Oct 29, 2006 10:23 am Post subject: Manifold pressure

I need a test AG5B to create an STC for a diffferent inlet.  The same 

(stupid) air filter and airbox will be used.



--

_________________
Gary
AuCountry Aviation
Home of Team Grumman

923te(at)cox.net
Guest

Posted: Sun Oct 29, 2006 11:44 am Post subject: Manifold pressure

I have one...how long do yu need it for?



---

FLYaDIVE(at)aol.com
Guest

Posted: Sun Oct 29, 2006 2:20 pm Post subject: Manifold pressure

In a message dated 10/29/2006 11:04:44 AM Eastern Standard Time, flyv35b(at)minetfiber.com writes:

 [quote] Disregard the last comment.  None of the single engine Grummans ever had MP gauges from the factory.

  

 Cliff

 [quote] ---

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Mon Oct 30, 2006 9:33 am Post subject: Manifold pressure

Well, based on how long the FAA is taking with the cowling .... TBD.  I 

wish you lived closer.

--

_________________
Gary
AuCountry Aviation
Home of Team Grumman

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