Has anyone considered using a POSA style carburetor on their engine? I
  recall the older Lake Injector carbs receiving their share of bad press
  due
  to the sensitivity of the floatless system to head pressure. While this
is
  a
  problem on gravity feed fuel system, using a very low pressure import
  type
  electric fuel pump would eliminate the tuning complications as fuel
levels
  changed.
  To my understanding, here is a list of the core components needed for
such
  a
  system to properly work;

  1 Either a AeroCarb
  http://www.aeroconversions.com/products/aerocarb/index.html or Revmaster



http://www.revmasteraviation.com/products/revflow_injector_carburetor/index.htm

  carburetor. Cost is $395 and $330 respectively.

  2 Custom intake manifold. I can't really guess a price but since the POSA
  style carbs can be mounted as downdraft, sidedraft or updraft, you would
  have more design flexibility and potentially save some money.
  3 Very low pressure electric fuel pump. Units like the Mr. Gasket 42S
  http://beta.summitracing.com/parts/MRG-42S/, Professional Products 10701

  http://beta.summitracing.com/parts/PFS-10701/ and Facet 40105
  http://www.aircraftspruce.com/catalog/eppages/facetpumps.php would work
  and
  keep the costs reletively low at $37, $40 and $32 respectively.

  4 Very low pressure fuel regulator such as the Mr. Gasket 9710
  http://beta.summitracing.com/parts/MRG-9710/ for $26 or Holley 12-804
  http://beta.summitracing.com/parts/HLY-12-804/ for $28.
  This list excludes items such as fuel filters, gascolator, fuel lines,
  etc.
  due to their universal nature.
  Plumbing a carburetor heat system should be easier since the carb can be
  mounted in different orientations and much less critical since POSA
  carburetors lack venturi.
  Vlad

  We looked at it for a long long time.
  They are very susceptible to vapor lock as the fuel pressure
  is down around 1 psi. Even the VW guys don't recommend them any more :
  Go with a float bowl. Float bowl Carbs have it all. Mass airflow sensor,
  fuel pressure regulator and fuel injector all rolled up into one :

  Paul Lamar

 Vlad,
 The POSA was the original slide carb, then came the Aero Carb copy of the
 POSA and some other carb was further developed by someone leaving Aero
 Carb
 or so I have been told. The Aero Carb looks good and the flat ground
 needle is the way to go IMHO, however no two needles are the same from
what
 I have read on the internet discussion groups. This is Ok for a single
carb
 on a single rotor but would need some care in matching the needles in a 2
 carb set-up.

 Aero Carb recommend 35mm for up to 120hp and 38 mm for up to 160hp - no
 venturi.

 Revmaster 40mm carb will flow 166cfm at 10"water

 Edelbrock recommends 42mm for up to 125hp.
 Mukuni recommends 48mm  42 venturi for anything over 120hp

 38mm Lectron carbs flows 161cfm at 10" water
 40mm 186cfm at 10"water
 44 flows 217cfm at 10"water

 All carbs without a float bowl require low fuel boost pump.

 Can't remember all the different carbs and their venturi sizes, but
appears
 a venturi does two things- increases inlet speed and acts at a restrictor
 at
 some point.

 It was a fun exercise I didn't find anything that was exactly what I
 wanted,
 so started making my own- and still not finished.
 George down under



Wow George, I'm very impressed with the homework you've done. Seeing as
you're far more acquainted with the design, can I ask you a couple of
questions? I understand that the POSA style was first designed to be
gravity
feed only and it seems that the more recent companies aero & revmaster are
still keeping up with that tradition. Why can't the carb be designed to
operate with higher fuel pressures? I don't mean EFI range pressures, but
at
least the common 4-7psi range associated with most domestic carbs Holley
2300 for instance. Even if the 4-7psi range is too high for whatever
fundamental reason, perhaps the 1-4psi import range could be used. Do you
have any pictures or specs of your little project? In any case, thanks for
the interesting info.
Vlad


OK guys I am going to give you the basic data to see if
low pressure non float bowl carbs are going to work well in aircraft
engines.  Do your homework and ask questions later. Then write an article on low
pressure carbs.

------------------------------------------

Here is a better chart of fuel flow.

Paul Lamar


I see. My apologies. I'll refrain from asking questions from now on.
Vlad

I don't think you do.
I told you the problems but you choose to ignore them. Just like George
Lendrich ignores them. A lot of what he told you he learned on here.
You both waste my time when you do that.

By all means ask question but do your homework first. If what I say does not
seem right then follow up on the leads I provide. This does not just come off the
top of my head. Google is your best friend.


Paul Lamar