Subject: Inverted flight with TBI

From: Fausto Tongiorgi Sent: 2nd February 2011

The engine is a Rotax 912s

A Rotec TBI is fitted.

Result of the tests: The engine runs perfectly inverted,

Customer reaction: The TBI performs flawlessly...

Great photographs showing great ingenuity!

< Click on the thumbnail to enlarge the photo...


Date 26th May 2010
Paul Lee - Paul's Site for his full SQ2000 Project detailed here
Rotec TBI-48-4/5 on his Franklin 6A-350

The Rotec TBI sure looks tiny compared to the bulky Franklin MA-5 carb which sticks out significantly more below the oil pan.

I tried a static run outside of the hangar and it ran well up to full static RPM. For whatever reason the engine seemed to run smoother than with the carb.

Please click on the thumbnails to enlarge ...

The unique feature on the Rotec model (missing on Ellison) is a primer button on the pressure regulator. When that is depressed it releases extra fuel into intake tubes to help with cold starting.

With the aid of a spring / mechanical slide I implemented a unique linkage that permits the mixture control cable to go beyond the rich mix stop and activate the primer button. That makes it easy to regulate the mixture and prime the cold engine with only one control cable.

As you may see I installed extra brackets to hold the pressure regulator in place to the TBI. I did not trust the AN fittings alone to hold the regulator sufficiently against engine vibration.

Rotec comment: Well done Paul! Outstanding workmanship and clever innovation.

JabiruTBIInstallation on a Jabiru.

Rotec TBI-40-S For all Jabiru engines.

Replacement for Bing Carb - note the rubber coupling used is taken from the Bing.





Simon's O320
Installation on a O-320

Owner: Simon Bromley.

Aircraft: RV7





Nick Colemans Install TBI-40-3 in a Swick T

As promised here is some pictures of my TBI install on my O-320 powered Swick-T.

When I first got the TBI out of the box I thought there is no way this thing can work very well. It is too small, too light, it did not cost me an arm and a leg, and there is only two moving parts.

However, on a leap of faith I pulled off the piece of #$@$%* PS-5C pressure carb that I have run for years and set about installing your TBI.

I was completely shocked when the engine started on the fourth blade on the initial start. I have about five hours flying it now and I cannot be more pleased. It starts right up every time, hot or cold. My engine runs smoother and quieter than it ever has.

I do not have the specific numbers yet, but I am using a significant less amount of fuel per hour.

While doing aerobatics in a practice box my ground observer even noticed that my engine seemed to running be much quieter and smoother than it had in the past. I cannot tell you thanks enough, it just works great. If you have any customers looking for recommendations please feel free to have them contact me.

Thanks again,

Nick Coleman

Nick's Install Photographs

Please click on each thumnail to enlarge - when done close the window to return here.

TBI on O32 .TBI on O32.TBI on O32

TBI on O32 .TBI on O32
Please click on each thumnail to enlarge - when done close the window to return here.

Lynn Mattison's Comments on Performance & More

(Jabiru + Rotec's TBI-40-S)

Email Exchange between Lyn and the Rotec Factory (November '09)

-----Original Message-----
From: Lynn Matteson [mailto:lynnmatt@jps.net]
Sent: Tuesday, 10 November 2009 1:19 AM
To: Rotec Factory
Subject: Engine stoppage during takeoff

Hi Paul-

The TBI-40 that I bought from you at Oshkosh has been running great on my Jabiru 2200 engine, but I have a question.

While taking off the other day, the engine quit, (prop stopped) but I was able to re-start it within about 6 seconds, after check of switches, valves etc. The conditions were as follows: WINDY!The wind was very gusty...about 22 knots reported on the ground, and worse at 2000 MSL. The airport sits at about 1100 feet MSL, and I was about 400-500 AGL when the engine quit. During the takeoff, I was getting huge gains in lift from the wind gusts. ( I didn't notice what the VSI was reporting during these vertical jumps in altitude...too busy flying the plane) As soon as it quit, I checked that the main fuel valve was still turned on, the ignition switches were both on, and figured I'd give re-starting a try. It started immediately, and I flew 30 miles home without incident.

My question is this....could it be that the sudden and somewhat dramatic lifts in altitude could have caused the fuel to not flow due to inertia (bodies at rest tend to stay at rest), and that momentarily the fuel did not come out of the discharge tube? Or could the same condition have affected the regulator? My system is entirely gravity flow, and I had about 20 gallons aboard in the two high-wing tanks (10 gallons each) at the time. I've never encountered this (engine out) condition in the 90 hours of flight since I installed the TBI-40. Yesterday I tried to duplicate the steepness of takeoff attitude...at 4000 feet AGL, for safety...and practically stood the plane on its' tail in several power-on stalls, but the engine ran perfectly. So the only condition change between the day of the engine- out to the next days' power-on stalls, was the lack of gusty winds.

Any ideas?

Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062, 810.9 hrs
Countdown to 1000 hrs~190 to go
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying (and learning)

On Nov 9, 2009, at 7:01 PM, Rotec Factory wrote:

Hi Lynn,

I bet the lack of positive fuel pressure combined with the sudden varying flight conditions, would be probable causes for lost fuel pressure and resultant fuel starvation.

These things come to mind which are not ideal are as follows.

1. Gravity feed system only, so your line pressure is not as positive as a mechanical pump. A positive pump is not as affected by external forces.

2. Steeper angle of climb which put the low fuel level in the tank at a level closer to the TBI so head pressure further reduced.

3. Gusts of wind causing bumps which would cause momentary zero or even negative gravity state. Under these conditions you would have zero or negative fuel pressure. At full power the engine would quickly starve of fuel.

I think it would be a VERY good idea to add a small boost pump for take off and go arounds etc. Once you climb to a safe height you can switch off the boost pump and run on gravity alone.

I don't think the column of fuel in the fuel line between the outlet of the reg and the TBI is the problem. However this distance should be kept as short as possible. To reduce forces acting on the fuel after the regulator.

Q1: During your tests at 4000', If you had the plane hanging on the prop would at this point the tanks not be lower than the TBI, and thus offer no fuel pressure at all? Is your plane a Jabiru or are just use a Jabiru engine?

Q2: Do you have a cockpit diaphragm over ride primer fitted to the reg? If yes you do relies that this will be less effective as a primer with out a boost pump?

Hope some of this helps get you gears turning?

Regards, Paul.

Lynn's reply to Rotec's Paul:

Hi Paul-

Thanks for the suggestions, and no, I do not have a boost pump at this time. I had one, and removed it during the "Bing era". : ) I've had other folks suggest that I reinstate it, so I probably will do that.

My plane is a high-wing Kitfox, and as such the wing tanks are above the TBI. I did some more 4000' power-on stalls today, and the engine ran extremely well including when I had to push it over and recover flying speed.

Yes to the cockpit "primer actuator" control....it works just fine with the gravity-only fuel feed. Just for a test, I tried starting the engine without using the "primer" today and it didn't start right away, but pulling on the control cable (depressing the overridespring) gave the engine the prime it needed and it started right up. My habit is to do as you suggested at Oshkosh, and give it a prime for the first start of the day, and after that no prime is needed.

Thanks again for the suggestions, and keep up the good work. Several people have mentioned to me that they got good advice from you regarding their installations. Good show, mate!


These Comments by Lyn were posted on the Matronics Forum.



Lynn Matteson
Kitfox IV Speedster, tail dragger
Jabiru 2200, #2062, 727.5 hrs
Sensenich 62"x46" Wood prop
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: TBI installation done...tests flights underway
On Aug 10, 2009

... the addition of the Rotec TBI-40 mechanical fuel injection system will enable the pilot to
control the EGT's rather well. I've been test flying mine over the last several days, and I've seen EGT's as close together as (today's flight) 41 degrees F., and CHT's as close together as 7 degrees F. It's nice to be able to adjust the mixture with this device, and also to see the fuel flow read down as low as 2.9 gph at about 80 mph ground speed into a 12 mph wind at 2700 rpm.

I've been playing with "lean off peak" with this device, which is one reason that I bought it. It amazed me that you can see the EGT's go down after reaching peak temperature....I was a skeptic as first, but if the engine lives, I'll be a believer. Even without the ability to go lean of peak, just being able to adjust the mixture on the fly is worth the added workload on this pilot during takeoff and landing.

=== End Extract

Contributions and Updates Sought:

Please send in your TBI install photos along with any installation comments, with or without, performance comments to Jim's email roteceng@optusnet.com.au.com


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