Carb Vs Ellison TBI?

In order to keep things simple and light I'm moving away from the IO-320 in favour of the O-320. The question is to use a carburettor OR the Ellison TBI?
I understand that auto fuel cannot be use (which is a great pity) and that they do/do not suffer from carb.icing, opinions seem to differ from pilot to pilot. It is a never ending debate of Fuel injected Vs Carb. but I've not seen a great deal about the Ellison TBI. What experiences, advantages and /or disadvantages are there with Carb. Vs ETBI?
Will it fit the standard O-320 cowl and FAB without modification?

Andy
#4411

Andy, Although I don't have personal experience with the Ellison TBI, I know of several people who have tried it. Without exception, all had a great deal of trouble getting things set right. All also eventually gave up and went back to carbs. These are all people I know directly and not just heresay. These people were trying the TBI on RVs, Glasairs and a Glass Goose. I've been running an O-320 with carb in my RV for 13 years. It is simple, and it works well. If you decide to go with the Ellison, be prepared for some tinkering and let me know how it works out. The concept is great.
Mel...DAR

On my previous RV-8, I started with a carb, then switched to an Ellison when I installed the inverted oil system. I ended up selling the plane about 30 flight hours later, but during the time I flew the Ellison, it worked great.

The only quirk it had was when shutting down the engine. You had to bring up the rpms to 2000 or so, then shut the mixture off. If you left it at idle, it would keep getting enough fuel to continue stumbling along. Otherwise, it was perfect. You could indeed lean farther than with the carb, and it didn't miss a beat inverted.

Now that I'm building another RV-8, did I choose the Ellison? No, but it was close. The real decision was whether I wanted another inverted oil system, and I finally decided not to go that route. For normal positive G flying, I think the carb is a better choice overall, particularly if you plan to run any auto fuel. Not only is the Ellison restricted from using it, but if you did manage to get some vapor bubbles in the fuel line, it would cause a temporary loss of power with the Ellison. FWIW, if I had decided to go with inverted oil, then I would have gone with the Ellison over the fuel injection.

I had the exact same thoughts awhile back, Ellison vs. carb... decided to stay with the carb due to the reasons Mel listed, plus I'd like to be able to run auto fuel from time to time.

Has anyone used an Aero Carb from the Aeroconversion/Sonex guys? They have a large size that'll fit an O-320; I asked if it'd fit an O-360, but no luck, not quite big enough. It looks simple and light, and only $395? Man, that's cheap!

http://www.aeroconversions.com/carb_index.html

Regarding the aerocarb, I've never seen one for a lycoming, but a friend with a Sonex/Jabiru eventually replaced his with a conventional carb because of sticking issues. His Aerocarb used a plate that slid back and forth in a slot to control airflow. This was Aerocarb's substitute for the butterfly valve most carb's have. The problem was that the push-pull connection for the plate was off center and when force was applied, the plate would torque in the slot and jam.

Repeat discussions with Aerocarb, several replacement parts later, and a few months down the road, the problem was never solved. Since it was a flight safety issue (jammed carb = no ability to change throttle settings), he replaced it.

My logic for considering fuel injection first was for the inverted flight option, since I'm not intending to incorporate an inverted oil system there seems to be little point in progressing down this route, particularly with regard to added weight, expense and complexity.

The option of having a few more seconds of inverted flight at very little extra expense or complexity does appeal, but this is far outweighed by the inability for the Ellison TBI to run on autogas! Long term availability of 100LL is in question and at this stage I'm not quite sure what the alternatives will be here in the UK.

As pointed out earlier, the Carb option is simple, robust and not fussy about what you run through it. Like most builders it's nice to include modern high efficiency systems into our machines but apart from FI the choices of how we get accurately scheduled fuel to the engine is limited. The tried and tested Carburettor seems to have more pluses than minuses in this respect!

Thank you for your inputs so far,

Andy
#4411
Wings 95% complete
Fuselage 80% complete

Ellison

I have been running with an EFS-5 on my O-360 RV-4 for the past 100hrs or so. Yes, I have had to fiddle with it (and there isn't much to fiddle with). Fiting to the RV cowl was fairly easy, andt he installation is neat and simple cf. FI. I started with a vapor return line but removed it for all Ellison's reasons later, with no ill effect. Shutdown will be possible on mixture alone if the idle mixture is set lean enough. Sometimes if you need it richer through the whole range you do this by enriching the the idle mixture, but this then keeps the engine bumping along when you try and stop it. Backing up with mags to OFF is now my normal technique to get a clean cut. I believe some variability of running that people compain about, me included, with the Ellison is due to fuel gumming up the holes in the airflow sensor tube. This then prevents the diaphram fully opening the valves that supply the main metering tube. I notice this, I think, after the aircarft has not been flow for a while. Access for a shot of carb cleaner would be nice. I fitted carb heat, I think this is wise, I'd hate to be a low power poking around below cloud trying to get to an aerobatic comp without it...
Inverted ops - it works great. Auto fuel - I can't say, though there isn't many seals/o-rings in there to react poorly with it. I'm sure if Ellison wanted to they could make it autofuel compatible. Another plus is being able to hand start with an Ellison easier than FI. I'd use one again.

Ellison on 0-360

I have on O-360 with the Ellison and have had no problems to this point other than a slight surging when powering back in the pattern....I'm beginning to think that this is a harmonic problem though.
I am running a Catto 3-Blade prop and heve never had any issues at start up or shut down as far as the engine still running.....I am quite happy with our decision to use the Ellison.
When I purchased my engine used....it came with both the carb and Ellison. I received more positive comments than negative from the matronics list guys at the time I made my choice.

Carb or Ellison

[In answer to the question Carb or Ellison? I had a Bendix PS5 so I put it on my Mattituck XP360 and have been competely satisfied, but that being said if I had not already had the carb I would definetly put the Ellison unit on. I know Vans has had some problems with them but I know people who have them on RV4s and have had no problems. Roger Moore RV4DRVR@aol

Re: Ellison vs Marvel...

After 1500 hours in my 0-320 powered RV4 with a Carb I can safely say this: Carbs Work! No jetting issues, easy starting hot or cold and yes I do positive G acro alot and still have alot of fun. I helped a friend install an Ellison in a clip wing Tcraft and it took us many hours to get it dialed in and it still doesn't work as well as the carb it replaced. If I had the option to do it again I would still go with a carb, it's simple, relatively cheap and cheerful in all weathers...

Rob Ray

I like my Ellison. 365 hrs. on an RV6 180 hp CS, with inverted oil. Ideally it likes two clicks difference on the adjustment between summer and winter. I usually leave it in the middle year round. Runs lean near idle in winter(pops sometimes when you pull the power off on the downwind). Rich in summer(diesels at shut down sometimes, pull mixture and push in throttle and it dies). At cruise I have plenty of mixture control. There is no float, so if you get bubbles in the fuel line from a quick turn around in the summer, it will skip when they work their way through. That problem will show itself with low fuel pressure and can be solved by leaving the boost pump on for climb out. Turn the pump off for good when pressure stablizes at 6psi with it off. To get even distribution to the cylinders I had to set wide open throttle with the rod end bearing adjusted to hold the slide slightly shy of wide open. Covered in the install manual. Sounds like a lot but I haven't touched it in five years. I didn't have to buy the high pressure(expensive) pump like other inverted systems require, and I can run with some quick RVs. 191kts @ 1400msl. WOT.
If anyone is not happy with theirs and the price is right I am building an 8A that could use it.
Don

Ellison

Don, good to hear a good report of the ETBI. I would use one again too. Can't see the reason for $$$FI with all the hi-pres pump costs and increase in plumbing. Yes, mine goes a bit lean (?) at WOT, better to pull it a smidge of the stops.