Ellison TBI

[Graybird]

Considering an Ellison TBI for my O-200 Verieze. Can someone who's gone this way let me know if they saw any performance increase? How about any change in fuel economy? I'm now using the Marvel/shevler 3spa. Thanks

[Bruce Hughes]

Hi, "Greybird"

You are asking the wrong question.    The question should be
"Are carburetors safe to use?"   OR  "Do carburetors have icing
problems".    YES, they have icing problems.

I bought an Ellison because I will (it is not flying yet) fly in a high
humidity environment.   I have already iced up a carburetor
WHILE TAXIING OUT TO TAKEOFF.   That was in a Cessna 152.

The Ellison WILL ice up.   But not in the way that a carburetor
ices up; it gives you a lot of warning.  

Let Cessna/Piper/etc use the carburetors.   If you cannot afford
fuel injection, get an Ellison.

I don't know if you get better perfomance from an Ellison; have
not flown it yet.

[Tom]

I might be incorrect, but I dont think the VE can use the ellison system without an additional fuel pump.  ( There is not enough head pressure between the tanks and the unit)

Anyone else have any experience with this??

[Bruce Hughes]

Yes, I think you are right.   Thank you for pointing that out.

As you can see, I have a Longeze.  2 fuel pumps - one electric
and one mechanical.   I forgot the Variezes do not depend on
fuel pumps.

Fly safe.

[mwilli7119]

Actually, a lot of folks are using an Ellison on a Varieze without a fuel pump. Gary Hertzler recently told me that he does. He said that you have to make sure the vent is well outside of the boundry layer and change the control cables to push/pull type which requires modifying the throtlle quadrant.

[Jack]

Hi, "Greybird"

  I have already iced up a carburetor
WHILE TAXIING OUT TO TAKEOFF.   That was in a Cessna 152.

The Ellison WILL ice up.   But not in the way that a carburetor
ices up; it gives you a lot of warning.  

.

So what's your point??  Carbs give plenty of warning and you should be aware of icing conditions when your flying??  Carbs have been around a long time and longer than most folks have been flying.  It's like any other piece of equipment, you have to know how to use it.

Jack

[NWade]

Okay, I don't even have my pilot's license yet - so I may catch some flak for even sticking my nose into this conversation...  But before anyone starts yelling at me to sit down, let me just say that I have a few years' experience as an auto-racing mechanic; and I've dealt with both carburetors and fuel-injection systems.

By far, fuel-injection systems require less unscheduled maintenance (at least in auto applications).  And yes, I know the Ellison isn't a "direct" injection system.  But I've had to deal with jetting and float problems and a myriad of other carb issues (some of which matter to airplanes and others don't)...  If you then add icing risks on top of the standard carb issues, I don't see any reason (other than cost) NOT to use injection systems if at all possible.  The increased adaptability and reliability of injection systems just makes sense to this novice.

Carbs have been around a long time and longer than most folks have been flying. It's like any other piece of equipment, you have to know how to use it.

Injection systems are not "new" and have been around for 30+ years.  If a better solution exists, WHY do we have to settle for an inferior one and "know how to use it"?  Especially when that inferior solution involves serious risks like an engine-out condition even when the unit is in good mechanical working condition?  Does this also mean I shouldn't use GPS and rely only on LORAN?  Please understand I'm not sneering at you personally, Jack - but I fail to see the logic in this argument.

If you're comfortable with a carb and want to use one, fine.  The PIC should always be familiar with all of the equipment in the aircraft in order to operate it safely.  But criticizing a solution and implying that older equipment is better just because its been around longer strikes a false chord with me.

Let's debate equipment not based on its age, but rather on its track-record and proven performance specs.  I'm still hoping someone will respond to this thread with some concrete numbers.

The technology and comparison photos to traditional carbs can be seen here:  
http://www.ellison-fluid-systems.com/article/notaposa/notaposa.htm

--Noel

[Bruce Hughes]

The following is what I HAVE BEEN TOLD BY PEOPLE THAT I RESPECT.
I have absolutely NO personal experience in this comparison.

___________________________________________________________

The Ellison CAN ice up BUT it GIVES YOU A LOT MORE WARNING
compared to a carb.   The carb ices up gradually and the tachometer
gradually goes down.   New guys may not notice that.


The Ellison gets a little ice which falls into the airflow and causes a
lot of coughing by the engine.   THAT gets your attention.

___________________________________________________________

[Jack]

Okay, I don't even have my pilot's license yet - so I may catch some flak for even sticking my nose into this conversation...  But before anyone starts ye Please understand I'm not sneering at you personally, Jack - but I fail to see the logic in this argument.

l

Give you some hints, after 10,000 plus hours of flying approaching 40 years and 12 of that flying Navy crap including heavy recips that just happened to have carbs in them.  I am very leery of new tech that doesn't have a million hours of time on it.  I flew single seats to 4 motor birds.

My logic is based on all of my body parts are attached after doing some serious maintenance check flights in the Navy, flying old aircraft into and out of Davis Monthan, depot level maintenance and 3 first time flights in homebuilts.  

I use to fly out of Mojave back in the early 80s and I met and knew most of the players in homebuilding.  KISS is always good.

Jack

[Graybird]

Hello everyone: I've flown carbs for a long time as well-- in planes and Helicopters--with no problems. Yes they can ice up. They just require a bit more cockpit management than other options--there's nothing wrong with them.. I have a carb temp gauge on my Verieze. My original post was to see if there are any performance gains and/or economy gains, and if any how much? The ellison also requires a priming system and in some aircraft maybe a fuel pump of 2-6 psi. If there are performance or economy gains I'd consider one. If not I'll stay with my m.s.3spa.
If you have a fear of carb icing--by  all means--use something else. If you've iced a carb taxiing-- maybe there was a lesson either failed to have been taught or one that was failed to be learned--if either is the case it can surely be overcome with extra training. My M/S 3spa works fine, but, with the cost of fuel these days I wouldn't mind saving a few bucks and maybe going a little faster as well. That's why I asked the original question. Thanks

[NWade]

Just a clarification:  I wasn't saying that carbs are bad.  I was saying that newness isn't (in and of itself) a reason to reject a possibly better solution.

And the Ellison TBI supposedly has *fewer* parts; so KISS definitely applies to it (yes, I know the fuel-PSI issue adds "complexity" - but most low-wing planes have fuel pumps anyways, right?).  The points about icing and flow-alteration due to the butterfly valve in a conventional carb (mentioned in the article I linked to previously) all make good sense.  This does not mean the TBI is automatically better - just that it has the potential to be that way, with fewer parts & complications.

...Still hoping fuel & reliability numbers will appear, to make a *good* argument for one system over the other... ;-)

Take care,

--Noel

[maprather]

I don't have any performance numbers.

However, the Ellison should yield higher manifold pressure because it doesn't require much (any) venturi (restriction) to create a vacuum signal to deliver fuel.  All of this may mean more horsepower is available, which might give better takeoff and climb performance.

The other benefit of the Ellison is that it may allow for an installation that has better mixture distribution.  This may mean that your airplane will get slightly better fuel economy.

The downsides I have seen with the Ellison are that it seems to be more susceptible to fuel contamination, and may be more sensitive to turbulent airflow entering the unit (causing weird mixture issues).  A friend has an Ellison on his LongEZ, and it seems like his might suffer from the last issue I mention.  He can't seem to get it to have stable mixture over the full range of throttle movement.  Transition from idle to part throttle seems problematic, along with overly rich full throttle mixture.

Also, the Ellison doesn't have an accelerator pump, and so (as has been mentioned) it will likely require some kind of primer system.  Lacking an accelerator pump may also cause the engine to stumble if the throttle is racked open quickly.  The pump on the carburetor acts as an enrichment device in such a situation.

One final disadvantage of the Ellison is that if you have a problem with it while on a trip, you may have trouble getting parts for it, or getting an A&P to work on/troubleshoot it.  I would hazard a guess that every A&P has worked on a Schebler, but not nearly as many have played with an Ellison.  Probably not a big deal, but something worth considering..

One final thing about the Ellison..  It isn't new.  It's been around at least since the early '80s..  I think all of the issues with it are known and documented.


Matt-

[Jack]

 The points about icing and flow-alteration due to the butterfly valve in a conventional carb (mentioned in the article I linked to previously) all make good sense.  
--Noel

Most pilots are really clueless about icing and carbs.  Let alone the difference from anti or de icing gear.  Yeah a carb can ice up at 78F in certain conditions, by the same token it might not ice up at minus 9C with visible moisture present.  

I have flown the Atlantic in a Convair 440 in the middle of Winter and was sweating range with a serious headwind.  Using carb heat down at 6,000' cost me 10% of range.  With the gauges on the Convair I could detect carb icing prior to it impacting the carb.  I also knew the same motor on DC-6s never had a carb icing problem because of the manifold setup and the 6 was certified for severe icing.

Prevention and SA will keep you flying another day.  I am still waiting for a freaking motor to replace your typical Lyc or Cont motor in a homebuilt.

Cheers;

Jack