Carb, Injection or Throttle Body?

[Charles Davis]

Just wondering what everyone thought.

Injection seems like the best option, but the most expensive (not only for the injection, but the high pressure fuel pump).  I also worry about the high pressure fuel if I were to develop a small leak in the fuel line.  Is this a valid concern?

I've heard a lot about Ellison TB's being tempermental, or very difficult to properly tune.  Is this a valid concern?  Is there a better alternative to an Ellison TB?  Does a TB need a carb heat box?

Much thanks.

My LongEZ should be flying by next summer.  Here's the numbers:

Engine: O-320E2D, downdraft cooling, 8" extension, 2-blade prop, 4-4 exhaust, one mag, one electronic ign, 40A+20A B&C alt's, light starter.

Airframe: Long nose (Davenport), Roncz, Wilhelmson nose lift, Wortmann gear legs, tall rudders, beefed up headrest, Andair fuel valve, oil cooler cabin heat.

Electric/Avionics: All electric dual alt, dual batt, split bus.  Day/night VFR, Efis-Lite with mini steam gage AS, ALT and T&B backups, lowrance airmap 1000c, vision micro vm1000.

We started with an 80/200 project (80% done, 200% to complete).  My brother is doing the structural work in TN, and had previously complete two very nice Cozy MK4's.  I just write the checks, do the electric and machined parts, and nitpick.  It's been a great excuse for Mike and I to spend a lot of quality time yaking about something we both love.

I live in SD a few miles north of Miramar and plan to base at Ramona, Gillespie or French Valley.  Anyone looking to share a hanger?

[Bruce Hughes]

Hi, Charles

I did not post earlier because I know VERY little about engines.   Also
I have been told to keep my uninformed opinions to myself by someone
who is known by many in the canard pusher group.   He said that I was a
hazard to uninformed people.

Having said that, my OPINION is the carburetors are a hazard and should
have been banned by the FAA.   The throttle body is a bit better but it
can ice up.   The difference is that carburetors ice up gradually so you do
not realize it is happening until the engine is about to quit or quits.   If
it quits, where will you get carb heat?

I live in western Washington where the humidity goes through a lot of variation daily but it is often very high.   I had a little ice on a C-152 when I was TAXIING out to the runway, once.

The Ellison can ice up but it does it in a different way; the ice tends to
slip off and go into the engine causing one cylinder to misfire.   That
gets your attention.   It is less likely to ice up compared to the carbs.

You could also fly inverted with an Ellison, if you make the other changes
necessary for fuel flow.   I think one of the ideas in developing the Ellison
was to give a more even distribution of fuel to the various cylinders.
Unfortunately it does not do that whereas the fuel injection system does,
I think.

I have an Ellison but the Longeze has not been off the ground yet.

Fuel injection is good, too.   The Ellison is a lot cheaper.   If you want to
hear minor details, call me at 808-250-0939.

[Charles Davis]

Thanks for the reply.

I've decided to go with the silverhawk fuel injection.  AC Spruce sells them for $2389 for the Lyc 0-320.  You need a high pressure fuel pump, which can be expensive ($600+) but we're looking for alternatives to the TSO'd stuff; maybe something used by the automotive industry.

IMHO the improvement in safety, fuel economy, and HP make this a good investment.

[Drew]

I think that I have seen some carb heats that are electric.  I have seen many insist on monitoring the carb throat temperature.  Once it gets into the icing range, they apply carb heat whether they notice the oncoming effects or not.  I am not an expert at either one of these----having flown with neither----and currently have fuel injection.

[Jack]

Hi, Charles


Having said that, my OPINION is the carburetors are a hazard and should
have been banned by the FAA.   .

I have flown heavy recips from 1975 off and on. 2800s, 1820s, and the much smaller GA motors.  In all cases you have to know the operating ranges of your motor and in the case of icing, ensure you use carb heat as required.  Sure you can get carb icing up to 78F in certain conditions. I have flown heavy recips over the Northern Atlantic in winter time and the Pacific.  

If you don't know your equipment, no doubt you could have a very bad day.

When I am flying my EZ, on the cold days I tend to add some carb heat up to 10C and this allows a little more efficiency on the engine without visible moisture around.

A carb is a pretty simple piece of equipment and it's been around for decades.  Just know the performance data for it and it will last a long time.

Jack