Can I add GAMI injectors to a G-REG

[stuartforrest]

Hi

I wondered if anyone know if you can put gami injectors on a G registered plane on does it have to be on the N reg.

The plane is a 1993 A36 Bonanza. Also does anyone have any reports on real world fuel savings after they have added them and where did they get them added?

Thanks in advance.

Stuart Forrest

[IO540]

I had them fitted to a G-reg TB20GT in 2003 by Air Touring Ltd.

The paperwork went down the plughole when they went bust but they must have got CAA approval for it. Also if you search the CAA AAN database you will find some approvals there.

The fuel savings (if any) come from being able to run at peak EGT without the engine running rough (if you are looking for a one-line explanation).

LOP operation benefits even more from matched cylinder performance but you don't get more MPG from LOP unless you allow the IAS to drop off a bit, which will obviously deliver more MPG as a result of the lower speed.

Compared to flying say 100F ROP which most people do, you save 10-15% on fuel.

I always fly at 65% or below, and always fly peak EGT or slightly LOP.

Some notes here (http://www.peter2000.co.uk/aviation/engine-management/index.html)

[vanHorck]

I had GAMI's on my Seneca which combined well with the JPI. It was G registered, so there should be no issue.

The next best thing i did was to have the props balanced dynamically. Although static balancing is done a lot, I understand few people bother with dynamic balancing these days but I think it made for noticeably smoother flying

The combination made for extremely smooth LOP flying

[IO540]

Dynamic prop balancing is IMHO essential, especially with a 3 blade prop. I have had two new Hartzell 3B props and both were way way out when new.

For some reason the 2B props are not so critical; perhaps the harmonics are less objectionable.

However, I have done a lot of vibration analysis in flight (an accelerometer and a digital storage scope) and the data suggests that most vibration which is actually felt on the airframe and the windows comes from the prop-blade-frequency related "lumps" in the slipstream, not from the engine via its mounting frame. But it's hard to tell for sure.

[stuartforrest]

The "if any" comment makes me wonder if it is worth my while. I will need to save a bit on fuel to make it worthwhile. My bonanza has done 700 hours in 7 years. Savings of 2 gallons per hour would have yielded something like seven thousands pounds in savings. I wonder how likely 2 gallons per hour actually would be.

I guess gamis and an engine monitor would be best part of 5k.

[Zulu Alpha]

All that GAMI do is sell you a set of matched standard injectors.

They have some sort of rig that measures each one and then they put a set together to match your engine requirements.

Therefore you are not fitting anything other than a standard part. You have to send your old ones back (I suspect the re use them) otherwise they charge you.

So as far as paperwork is concerned it is just a dismantle and then a remantle.

[IO540]

It has been argued in the USA that the reason GAMI "had" to get an STC for their injectors was because they do sometimes open them up beyond the Lyco factory spec. In most cases they don't, but sometimes they have to to get a proper fuel flow match for a particular engine. I vaguely recall they actually told me this in an email.

Obviously if you just fitted them, nobody would notice because they look just the same as the stock ones, but the little labels (which make sure they go into the right cylinders) might give the game away :)

I bet you there is some generic CAA approval from about 10 years ago. Search the AAN database for "GAMI" and other similar terms (the database is inconsistent and full of typos so you have to search for various terms) and stuff will definitely turn up.

I guess gamis and an engine monitor would be best part of 5k.

If you do serious flying without an engine monitor then you are wasting loads of juice.

[NutLoose]

The ANN would need to be specific to the A36 Bonanza to be accepted I think you will find...... had this issue before with an EGT monitor, had been fitted to a Cessna 172 if memory serves me correctly and there was an STC... HOWEVER it was not accepted on a Reims Cessna 172 version which wasn't on the STC nor the AAN when applied for, because that is a French aircraft and in La La land is counted as a different aircraft!!

Best bet is go through the German website, they tend to have fitted this type of stuff before if you cannot find an AAN.

[dirkdj]

The US STC for Gamijectors was accepted by the BelgianCAA in 1997 or so on my A36. All previously accepted STCs in any member state are grandfathered under EASA.

Stuart, you may want to read my presentation on engine management on the PPLIR website to find out about the advantages of LOP operation beside the savings. On my engine, the LOP savings alone pay for the engine overhaul at TBO time at current fuel prices.

[IO540]

I have now flown some 1100hrs in the TB20, and apart from running-in, 100% were flown at peak EGT or just slightly LOP. When the engine was opened at 700hrs for the crank swap, it was found to be spotless. The only items which were outside new limits were the exhaust valve stems which were about 0.001" out of new limits (I have the old valves here). I don't understand why there are still so many people who fly "the old way" :) Avgas costs enough...

[dirkdj]

The way Gamijectors work is as follows (briefly):

On the TCM IO520 and similar engines, the induction air flows from back to front of the engine. The injectors spray a continuous flow of fuel-air in the induction tubes while the intake valve opens up only 1/4 of the time.

Because of this continuous spray in the induction tubes, and the induction air travelling from back to front, the middle cylinder row gets its 'own' fuel spray plus some fuel-mist laden air coming from the rear. The front cylinder row gets its 'own' fuel spray plus fuel-mist laden air from the front and middle cylinder rows.

What GAMI did was make matched injector sets per cylinder row that give less fuel for the middle row and even less for the front row. to compensate for this hidden fuel transfer between cylinder rows.

The OEM provided similar injector sizes for all cylinder for ease of manufacturing. When running ROP this difference in mixture between cylinder banks doesn't show up because the power curve is very flat ROP so you can get away with mixture imbalance. When LOP the power curve is directly related to fuel flow and imbalance between cylinder rows shows up as a rough running engine.

If you want a smooth engine running LOP you need a perfect 'conforming' engine with tight induction tubes (no leaks), good ignition harness and spark plugs, good mags etc. An all-cylinder engine analyser is invaluable for troubleshooting and keeping the system in top condition.

[IO540]

Dirk above is right.

You can buy GAMIs in two ways:

(1) Without EDM flight data. They will sell you a set which tries to even out the fuel/air distribution to a given engine type, based on the known front-to-rear uneveness. This sometimes works. This is what Dirk is describing above.

(2) With EDM flight data. They will sell you a set of injectors whose orifices are matched to make all cylinders peak at the same common fuel flow. This balances power delivery in the engine. This usually works; occassionally you need to have a second go at it (which IIRC they do at no extra charge).

Option (2) is a lot more likely to deliver a good result.

[stuartforrest]

Thanks. I cant access that report as I am not a PPLIR member. You dont have the text of it do you?

Thanks

Stuart

[dirkdj]

Send your email address by PM and I will send a link where you can download it.