rocketbob

rocketbob

Well Known Member
For the guys running Ellison's... Since the Ellison TBI doesn't have an accelerator pump, how is the throttle response?
 
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.
 
EGT/CHT spreads

Low Pass said:
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.
Click to expand...

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.
 
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.
 
Rotec TBI

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.
 
N941WR said:
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.
Click to expand...

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.
 
Rotec - I have one....

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.

Rotec%20TBi.jpg


Metering Holes produce "Fuel Fog"
Rotec%20TBi%20006.jpg


Partial Throttle
Rotec%20TBi%20007.jpg


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.
 
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cawmd82 said:
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.
Click to expand...

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

Pete, I look forward to hearing your test results. If Ellison and the Carbs and perhaps this new one all still have variation in EGTs it will suggest there is another factor causing the difference. I have heard that insulating the intake tubes will help. If some intake tubes run hotter, say #3 and #4, the mixture will be richer due to the same gas and thinner air in those tubes. Maybe that is the cause of the variation. Anyone tried insulating the intake tubes?
 
Variation in EGTs

EGT variation really is not the metric to look at. It is the fuel flow where EGTs peak on each cylinder while leaning that matters. The "Gami spread" or in my case the "tractor carb" spread is the key.

The carb has challenges atomizing/vaporizing the fuel. I have found ways to use the FAB carb heat (and partial carb heat) to intoduce heat and turbulence that allows better vaporization of the fuel and gets more even distribution of the mixture to each of the cylinders. It works pretty well, but it costs you some MP and the extra heat reduces the charge density - meaning less power. I get good economy - but I am always looking to do better.

I'd be remiss not to mention that I have dual EI - in my eyes, that is he key to LOP ops - the hotter spark and programmed advance are key.

Lots more, including graphs in the archives.
 
Temperature variations

RV7AV8R said:
Pete, I look forward to hearing your test results. If Ellison and the Carbs and perhaps this new one all still have variation in EGTs it will suggest there is another factor causing the difference. I have heard that insulating the intake tubes will help. If some intake tubes run hotter, say #3 and #4, the mixture will be richer due to the same gas and thinner air in those tubes. Maybe that is the cause of the variation. Anyone tried insulating the intake tubes?
Click to expand...

I did not think to test this on my installation. The variation is mostly between left and right (1-3 vs. 2-4). My initial thinking was that its caused the the airbox being slightly offset to avoid the left side of the cowl.
 
Looks just like the Ellison

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

Pete,

This unit looks virtually identical to the Ellison mechanically, right down to the pattern of the metering holes. The differences appear to be the machined outer surface, Viton seals, and price. Is Rotec licensing it from Ellison? Otherwise I don't see how they avoid patent infringement.

Does look like a beautiful unit; I'll be curious to hear how it works out.
 
Ellison running fine

I have had my 8 flying from day one with the Ellison and it is smooth as silk, never had any problems at all.
Just before install I sent it in for a lookover by Ellison as it was aquired with my engine a few years before I had my first flight.
But no problems at all since first flight
Doug
 
glfrdug said:
I have had my 8 flying from day one with the Ellison and it is smooth as silk, never had any problems at all.
Just before install I sent it in for a lookover by Ellison as it was aquired with my engine a few years before I had my first flight.
But no problems at all since first flight
Doug
Click to expand...

Doug,

Are you using the Vans FAB?
 
Expired patent

petehowell said:
I think the patent may have expired - and these guys are in Oz.
Click to expand...

Pete,

The patent number than Ellison lists on their web site was issued in 1985, so it does appear to be expired. Rotec seems to be offering an improved version of the same product for much less money. I'd guess that Ellison is either going to have to drop their price dramatically or else go out of business.
 
petehowell said:
EGT variation really is not the metric to look at. It is the fuel flow where EGTs peak on each cylinder while leaning that matters. The "Gami spread" or in my case the "tractor carb" spread is the key.
Click to expand...
I should have stated that my primary need/concern is improved fuel distribution. If the fuel distribution is better, then I believe improved efficiency and general performance will follow (along with proper leaning). Relative fuel distribution is roughly indicated by relative EGT. Am I missing something?
 
Vans FAB Airbox

Yes I am using it. A little modification but no big deal.
I need to take some pics for another builder and I will try to get some poted.
Doug
 
EGT probe position

HI Bryan,

As I understand it, EGT probe position has a big effect on the EGT reading, so it is hard to use the absolute reading as a measure of balance. I could have a perfectly balanced mixture distribution to each cyl and have EGT readings all over the board. Now - If the EGTs peaked at the same Fuel Flow - the CHTs should be close (if cooling is uniform) and each cylinder should be producing similar power.

If this is what you meant by relative EGT, we are on the same page!

Experts - jump in and correct me- I could be way off here.
 
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Pete is this adapter placed on the intake side? And it looks like you just followed the tapper of the TBI, correct? Do you know if the minimum diameter of the throat is about the same as a MA 4-5 (the 360 carb)? And sorry for so many questions but this TBI interests me, what price is it? Oops, I see you said it was less than $600 !!
 
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Adapter

Hi John,

I have the MA-4 carb - so not sure about the 4-5. The adapter we made is on the airbox side and we did our best to match the taper to get good airflow.

I paid the intro price, but they said that was a pre-OSH price and they were going up. I don't know if they raised the price. Here is the website.

If you have a O-360, it looks like RocketBob got them to make one for the bigger engines, he might have more details.
 
Pete,

What is the other part in this picture?
001SimonBromleyO320.jpg


Just a side note, that installation doesn't look very safe. I would be afraid that aluminum 90 degree fitting would break after a while due to the engine vibration.
 
return line needed?

Do the Ellison or Rotec TBI systems require a return line back to the tank?

I'm planning a carb (probably an experimental Volare) but this might be better.....
 
Fuel Regulator

Bill,

It is the diaphragm fuel regulator. Mine will be mounted to a bracket - my guess is Simon might change his mounting,too. I don't think he is flying yet.

Hey Dave - Vapor return line is not required, but is the last resort to solving vapor lock issues per Ellison.
 
Alan Carroll said:
On the Ellison this part is built into the throttle body. Not sure what the advantage is of making it separate part?
Click to expand...
It was explained to me this allows the throttle body to be oriented in any direction. The Ellison restricts the mounting so the slide moves laterally back and forth, needing a wide space. This would not fit the carb space allotted in my cowl without major modifications. By having the diaphragm separate this limitation is removed allowing the slide to align with the longitudinal axis.
 
zzapp said:
It was explained to me this allows the throttle body to be oriented in any direction. The Ellison restricts the mounting so the slide moves laterally back and forth, needing a wide space. This would not fit the carb space allotted in my cowl without major modifications. By having the diaphragm separate this limitation is removed allowing the slide to align with the longitudinal axis.
Click to expand...

Chris,

Actually Ellison says you can mount it either way, although they recommend mounting with the slide running perpendicular to the aircraft longitudinal axis. The position of the diaphram/regulator doesn't really seem to be related to this, unless I'm missing something.

According to the website the Rotec TBI has a provision to mount the throttle cable from either end of the slide, a handy feature that the Ellison lacks.
 
petehowell said:
If you have a O-360, it looks like RocketBob got them to make one for the bigger engines, he might have more details.
Click to expand...

Yep TBI-48-4... this is something in the works from the last few days so there's really no data or pics to post yet. I suspect I am the first to order these. 1-7/8" bore, equivalent to the EFS-4-5.
 
Version for 180HP 0-360 available

Just received a very quick response from Paul Chemikeeff at Rotec on my inquiry about a TBI for 0-360's.
As of today, 8/8/09 there is ten days left till expiration of a introductory price of $595.00 with free shipping for a TBI to fit the 0-360.
There is a two week lead time and they only accept Visa or MC .
I was always interested in the Ellison but was concerned about the price.
These look really nice. Might be the answer.
 
Only eight days left and confused

Only eight days left to get the lower price on the Rotec TBI's.
To you guys out there who have been running the Ellison I have a question.
When all's said and done, are TBI's really that better than a carb. If you had it to do over would you spend the extra cash. They seem to be better. Less moving parts, claims that they run smoother, run inverted, I think they even slice bread. I'm thinking I could maybe have a safer plane here but then I know I read in the past somewhere that there very hard to get adjusted at first but once set up there great. I dunno. Any regretful owners out there want to put your two bits in here. Seems like people either love them or hate them with no in between.
 
confused too

I'm confused about this... On the Rotec web page they say about the throttle body:

"The TBI-40 can be mounted at any attitude and at any angle. ... making the TBI-40 the perfect aerobatic fuel systems."

But then about the remote regulator (separate on the Rotec, is integrated with the throttle body on the Ellison):

"This is important. Do not position the TBI regulator LOWER than the throttle body."

Obviously, with acro, no matter where you put the regulator, it's going to be below the throttle body some of the time. So, like I said, I'm confused.

--Paul
 
Garage Guy said:
I'm confused about this... On the Rotec web page they say about the throttle body:

"The TBI-40 can be mounted at any attitude and at any angle. ... making the TBI-40 the perfect aerobatic fuel systems."

But then about the remote regulator (separate on the Rotec, is integrated with the throttle body on the Ellison):

"This is important. Do not position the TBI regulator LOWER than the throttle body."

Obviously, with acro, no matter where you put the regulator, it's going to be below the throttle body some of the time. So, like I said, I'm confused.

--Paul
Click to expand...

The regulator not lower than the unit is an issue while the plane is at rest and for starting. While fuel is flowing in flight - it should not be an issue. (I think)

Send them the question - I found them to be very responsive.
 
regulator placement

Pete, you're right about them being responsive. I got this reply back pretty fast:

"The regulator is actually quite tolerant to
G's. Just so long as it mounted in a neutral position to start with, the
change of position of the TBI reg will have almost immeasurable effect.
HOWEVER: If you start off the reg in a bad spot i.e. too high or low or too
far away, then this will get worse once the aircraft is placed in an unusual
attitude and will alter the fuel supply.

Not only should the height of the reg be level with the TBI fuel inlet but
also the fuel line connecting the reg to the TBI body should be kept as
short as possible. If kept under 8" long and you can do all the aero's you
like with next to zero effect."

--Paul
 
Delivery

rocketbob said:
Yep TBI-48-4... this is something in the works from the last few days so there's really no data or pics to post yet. I suspect I am the first to order these. 1-7/8" bore, equivalent to the EFS-4-5.
Click to expand...

Hey Bob did Rotec give you any estimate on when your TBI will be delivered?
There offering free FedEx shipping from way down under. They seem like pretty nice guys.
 
Thanks Chuck

cawmd82 said:
Rotec introduced a TBI for Lycotypes at OSH.
Click to expand...

In all the confusion that is "OSH" I somehow missed the Rotec TBI display.:eek:
I've since investigated the product and company and find that it's exactly the type of business I like to deal with. This is a family operation run by airplane people who love what they do and not just collecting a paycheck. Seems like those businesses are harder to find now a days. Like dealing with friends.;)
Anyway my TBI is ordered. Always wanted one. Just couldn't justify the higher priced Ellison. Thanks for bringing it to my attention Chuck.:)
 
A couple of TBI notes

I have an Ellison TBI on my Kitfox with over 700 hours on it. Its a good piece of hardware and works well. In cold weather, I did note a fuel distribution issue of the left and right sides, but insulating the intake header helped a lot.

If you do decide to go with a TBI (anybody's), one thing to keep in mind is that they can get 'carburetor ' icing. Maybe not as bad or as quickly as a carb, but they can definitely since the injection is not directly into cylinders.
 
I did note a fuel distribution issue of the left and right sides said:
Harold, I would like to try insulation on my Carbed engine, can you tell me how you insulated the intakes? I was thinking of wraping with insulation and using safety wire to overwrap and secure it, any comments?
Click to expand...
 
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