The Murphy Builders Site

I have used both the AeroCarb and the Rotec TBI-40.

I liked the AeroCarb, after customizing the needle shape, but in my
particular physical setup it was not possible to achieve acceptable
push-pull throttle cable routing. (That's particularly important because all
throttle body carbs exhibit some degree of internal resistance to opening
the throttle, as the increasing engine suction pulls the slide back to a
closed position.) Because it has essentially no venturi, The AeroCarb is
highly resistant to carb icing. The new version ("Aero Injector") is
smaller, but requires a quadrant-style throttle wire system.

Many people find the AeroCarb requires quite active mixture mgmt. at the
high and low RPM extremes, with aggressive leaning required to start and
idle, which can make approaches interesting if you're used to going full
rich to land. However, after tweaking the needle profile for my engine,
operation became pretty easy. The AeroCarb's virtue is its extreme
simplicity, but the downside of that is it has no internal fuel shutoff
mechanism like a float bowl carb does, and will drip fuel unless you close
your fuel valve promptly on shutdown. I still have the AeroCarb but unless I
have some grand inspiration about throttle cable routing -- that dozens of
hours of cogitation has not yet produced -- I'll probably sell it.

The TBI-40 is quite different, borrowing the Ellison's rotating, perforated
tube for fuel delivery and mixture control, and adding an upstream diaphragm
regulator/valve. It has somewhat less slide friction than the AeroCarb. With
the TBI-40 I now have good cable routing and smooth action, but am still
working on fine tuning some air turbulence at the TBI intake, which does
have a bell shape and venturi characteristics -- though I've never
experienced carb icing yet. The TBI's fuel mgmt. operation is more automated
than the AeroCarb, and is very easy to fly. The regulator/valve shuts off
fuel flow on shutdown, but can also be overridden for a priming function.
Standard procedure is to start & run at full rich and leave it there unless
you chose to lean for economy cruise at altitude. I'm very pleased with it.

There's more to say, of course, but that's the nitty gritty of my
experience.

Ron



On Sat, Mar 12, 2011 at 9:18 PM, <kpierson@dcsol.com> wrote:

I have been looking, with interest, at the Aero Conversion throttle
body injector. I was wondering if any one has had experience with
a throttle body injector-carb?

Thank you. Keith P. Tail draggers forever.

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

Ron: Thanks for your reply. I think that I will look into the TBI-40 by
Rotec, I like the idea of a built in fuel shut off. I have been known to forget
insignificnat items such as that. But with aviation fuel "only" $5.00 a gal.
who cares right!!!

Keith P.

On 3/12/2011 10:16 PM, rshannon@cruzcom.com wrote to rebel-builders:

-> I have used both the AeroCarb and the Rotec TBI-40.
->
-> I liked the AeroCarb, after customizing the needle shape, but in my
-> particular physical setup it was not possible to achieve acceptable
-> push-pull throttle cable routing. (That's particularly important because all
-> throttle body carbs exhibit some degree of internal resistance to opening
-> the throttle, as the increasing engine suction pulls the slide back to a
-> closed position.) Because it has essentially no venturi, The AeroCarb is
-> highly resistant to carb icing. The new version ("Aero Injector") is
-> smaller, but requires a quadrant-style throttle wire system.
->
-> Many people find the AeroCarb requires quite active mixture mgmt. at the
-> high and low RPM extremes, with aggressive leaning required to start and
-> idle, which can make approaches interesting if you're used to going full
-> rich to land. However, after tweaking the needle profile for my engine,
-> operation became pretty easy. The AeroCarb's virtue is its extreme
-> simplicity, but the downside of that is it has no internal fuel shutoff
-> mechanism like a float bowl carb does, and will drip fuel unless you close
-> your fuel valve promptly on shutdown. I still have the AeroCarb but unless I
-> have some grand inspiration about throttle cable routing -- that dozens of
-> hours of cogitation has not yet produced -- I'll probably sell it.
->
-> The TBI-40 is quite different, borrowing the Ellison's rotating, perforated
-> tube for fuel delivery and mixture control, and adding an upstream
diaphragm
-> regulator/valve. It has somewhat less slide friction than the AeroCarb. With
-> the TBI-40 I now have good cable routing and smooth action, but am still
-> working on fine tuning some air turbulence at the TBI intake, which does
-> have a bell shape and venturi characteristics -- though I've never
-> experienced carb icing yet. The TBI's fuel mgmt. operation is more
automated
-> than the AeroCarb, and is very easy to fly. The regulator/valve shuts off
-> fuel flow on shutdown, but can also be overridden for a priming function.
-> Standard procedure is to start & run at full rich and leave it there unless
-> you chose to lean for economy cruise at altitude. I'm very pleased with it.
->
-> There's more to say, of course, but that's the nitty gritty of my
-> experience.
->
-> Ron
->
->
->
-> On Sat, Mar 12, 2011 at 9:18 PM, <kpierson@dcsol.com> wrote:
->
-> > I have been looking, with interest, at the Aero Conversion throttle
-> > body injector. I was wondering if any one has had experience with
-> > a throttle body injector-carb?
-> >
-> > Thank you. Keith P. Tail draggers forever.
-> >
-> >
-> >
-> >
-> >
->




-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------