Ellison TBI question

rocketbob · #1 08-06-2009, 10:06 PM

For the guys running Ellison's... Since the Ellison TBI doesn't have an accelerator pump, how is the throttle response?

pvans · #2 08-06-2009, 10:11 PM

Works fine!

WillyEyeBall · #3 08-07-2009, 06:38 AM

Quote:

Originally Posted by rocketbob

For the guys running Ellison's... Since the Ellison TBI doesn't have an accelerator pump, how is the throttle response?

Super fast, both ways. Best thing out there without going FI.

Bill McLean
RV-4
Sky Dancer

Low Pass · #4 08-07-2009, 07:07 AM

Regarding the Ellison product, can anyone speak first-hand to the distribution of fuel to the cylinders (EGT/CHT spreads)? Intuitively, I would think they perform much better than a conventional carb but woud like some actual operating observations.

Thanks in advance.

Alan Carroll · #5 08-07-2009, 07:58 AM

Quote:

Originally Posted by Low Pass

Regarding the Ellison product, can anyone speak first-hand to the distribution of fuel to the cylinders (EGT/CHT spreads)? Intuitively, I would think they perform much better than a conventional carb but woud like some actual operating observations.

Thanks in advance.

I recently experimented with an Ellison in place of my carb, to see if it would allow me to lean further and use less gas. After some adjusting it worked fine and ran smoothly during idle, takeoff, and cruise. However, the EGT spreads and minimum fuel flows during cruise were essentially unchanged or maybe a bit worse than with the carb. I've put the carb back on for now but may do some more experimenting in the future.

I'd be very curious to hear more about how others have set theirs up; it seems that the Ellison is highly sensitive to inlet geometry. Mine was bolted where the carb would go, with a ~1.5" spacer between it and the Vans FAB (there is a 1.5" difference in height between the MA4-5 carb and the Ellison). I mounted it with the slide parallel to the aircraft longitudinal axis, because this allowed use of the same throttle and mixture cables. Ben Ellison recommends mounting the slide perpendicular to the longitudinal axis, but gives no concrete reason why this should work better. Ken Krueger at Van's mounted his the same way I did, and reports good results.

N941WR · #6 08-07-2009, 10:09 AM

Alan,

Correct me if I'm wrong, doesn't the Ellison TBI use the same low pressure fuel pump as the carb?

If that is the case, it sounds like a "simple" change.

Everything else being equal, I might look into buying one for my new engine since my MA3 carb is now suspect, along with the rest of the engine.

cawmd82 · #7 08-07-2009, 10:16 AM

Rotec introduced a TBI for Lycotypes at OSH. Apparently there are a few flying already. Might be a consideration for those considering the Ellison. Anyone see it or have firsthand experience? Certainly their craftmanship with the little radials is up to the task......

My main interest would be for the alleged and intuitive improvement of
distribution for LOP operation.

Alan Carroll · #8 08-07-2009, 10:36 AM

Quote:

Originally Posted by N941WR

Alan,

Correct me if I'm wrong, doesn't the Ellison TBI use the same low pressure fuel pump as the carb?

If that is the case, it sounds like a "simple" change.

Bill,

Yes, it uses the same low pressure fuel pump and boost pump. The main fuel system change they require is the addition of a 70 micron fuel filter. I have an Andair gascolator that already has a 70 micron screen, and according to Ben Ellison this is sufficient. You'll also need a primer system if one is not already installed.

The hardest part of the installation is routing the control cables. Unlike a carb, the throttle and mixture controls move at 90? to each other. The throttle cable is easy to attach to the TBI using a bracket that Ellison sells, but the mixture attachment is up to your own ingenuity. Ken Krueger says he worked out a bellcrank system for this. I brought the mixture cable in from the left side, using a custom-made bracket.

Overall all it seems like a good, simple system, and is a pound or two lighter than the carb.

petehowell · #9 08-07-2009, 10:49 AM

Don't mean to Hijack the Thread - move if required......

I am working out the installation details now. Hangar-mate supreme Alex P engineered an adaptor to match the height of the Rotec TBI to the carb, allowing use of the same airbox. it was machined this week. Cable rework will come next.

The unit is a gem to look at. Nice machining with Viton seals to allow use with Mogas. Intro price of less than $600.

Some photos of the Rotec unit.

Metering Holes produce "Fuel Fog"

Partial Throttle

I have a great data baseline for my carb, including extensive LOP ops. We will be measuring the performance of the TBI carefully and with great interest.

Install will be a few weeks out.

rocketbob · #10 08-07-2009, 10:50 AM

Quote:

Originally Posted by cawmd82

Rotec introduced a TBI for Lycotypes at OSH. Apparently there are a few flying already. Might be a consideration for those considering the Ellison. Anyone see it or have firsthand experience? Certainly their craftmanship with the little radials is up to the task......

My main interest would be for the alleged and intuitive improvement of
distribution for LOP operation.

It looked great and led me to discussions with them about a larger version, which they are making for me. Stay tuned...