RobertL18C wrote:
would agree in a turbocharged engine a multi probe engine monitor is good insurance. For a de rated normally aspirated engine that will operate below 65% when leaned, I would rather spend the money on preventive maintenance and oil analysis.
Turbo / non-turbo they can both suffer the same problems.
Imagine – doing a runup test. On one magneto your engine runs rough. What do you do? What do you check? Is it magneto? Sparkplug? If sparkplug then which one? Maybe fuel injector? You basically have no idea.
With an engine monitor and a bit of knowledge – you can make your diagnosis within a minute!
I remember flying a 210 once where the mechanic had put the GAMI injectors back in randomly disregarding the cylinder numbering… It ran. But not great!
The installation cost of an “EDM700” type product depends on how much you are doing and the type of plane.
I once saw a shop spend a couple of weeks pulling the thermocouple wires through tiny orifices in the airframe of a twin. So that job was expensive. In a TB20, it is probably a day’s work to drill the exhaust and fit all the probes. Maybe 3 days, with installing an extra CB and other messing about. The fuel flow option is quite a bit more work but I would use a separate instrument for that; the user interface of an EDM700 is horrible enough already and not interacting with it (as is the case for engine temp monitoring) is a bonus.
The imbalance described by NCyankee exists in Lycos too although no doubt differently. GAMI will sell you a kit of injectors which try to balance up that imbalance and it ought to improve things quite a bit even if you never do the leaning check flight / data collection exercise.
Yes, and the most valuable, since it is usually not there….
ch.ess wrote:
cylinder set of EGT & CHT probes including cabling thru the firewall in 2 days, i.e. approx. 16hrs
They are the easy ones to do….
I do not know where the installation figures come from or what extra work has been included… I installed (under A/P supervision) a 6 cylinder set of EGT & CHT probes including cabling thru the firewall in 2 days, i.e. approx. 16hrs (strict shop opening times), during an annual. The 3’’ instrument in the panel was another 3hrs.
And I was focused, but very careful with every step….
boscomantico wrote:
That doesn’t make much sense. AFAIK, you really can’t do that anyway. Installing GAMIs requires fine tuning them, but you can’t do that if you don’t know the single EGTs/peaks.Even if you could, having an engine monitor is more valuable than having the GAMIs. Some aircraft run quite OK LOP with stock injectors.
I don’t agree with the first comment. Installing GAMI injectors will improve engine operation on a Bonanza regardless if they are tuned. Of course, tuning can help and you would need a multi probe EGT to do the tuning. My experience (I have installed about 25 sets) is that most engines don’t require tuning, but that it is available. GAMI will provide replacement injectors at any time for tuning purposes, so one can install them, get better performance now and later if one installs an engine analyzer and determines that tuning would benefit the installation, GAMI will provide the fine tuned injectors.
The real value of an engine analyzer is troubleshooting when something is out of whack. I don’t use my JPI for leaning, I just set fuel flow. If the engine runs rough or has other indications, I use the JPI to troubleshoot.
Peter wrote:
I don’t know why Contis should be different from Lycos, for the GAMI injector benefit.
The reason the TCM engines benefit from GAMI has much to do with the air induction on these engines. In the IO-520B/550B series, the induction plenums provide airflow to the cylinders from the rear of the engine and are below the cylinder with a small feeder from below to the cylinder. So air flows from the rear to the front in the plenum. The injectors are on the top side of the engine and are continuously providing fuel into the intake chamber. When the intake valve is open, air and the fuel mixture are pulled into the cylinder, but when the intake valve is closed, the lower pressure aided by gravity from the air passing by the rear cylinder in the plenum, draws the fuel from the cylinder above thru the small runner into the plenum. Thus the forward cylinders get some of the fuel intended for the rear’er cylinders. This makes the rear cylinder run the leanest, the middle cylinder runs richer, and the forward cylinder runs extra richer. The GAMI injectors adjust for this imbalance in fuel distributed thru the intake plenum. At the front of the plenum, there is a small cross tube that I understand is to balance the air pressure side to side. See the attached photo. You can see the front cylinder air with the small runner to the forward cylinder. Remember the air comes from the rear of the engine and underneath to feed the plenum.
Here is a diagram of an IO 470 U engine illustrating the air flow with the red arrows and the injectors circled in green.
Not all TCM engines have this induction system, but those that do are found in Bonanzas. TCM has also developed what they call balanced induction system which feeds from the top with central distribution to each cylinder. The GAMI injectors provide a much greater benefit for the type of engines with the bottom plenum. For a typical Bonanza engine, the imbalance wastes up to a gallon per hour when ROP and allows smooth operation LOP, where fuel savings can be as much as 3 GPH.
@boscomantico good points, single probe EGT and CHT with standard injectors it is.
@Raven would agree in a turbocharged engine a multi probe engine monitor is good insurance. For a de rated normally aspirated engine that will operate below 65% when leaned, I would rather spend the money on preventive maintenance and oil analysis.
RobertL18C wrote:
Am planning to fit GAMI injectors but no engine analyser
That doesn’t make much sense. AFAIK, you really can’t do that anyway. Installing GAMIs requires fine tuning them, but you can’t do that if you don’t know the single EGTs/peaks.
Even if you could, having an engine monitor is more valuable than having the GAMIs. Some aircraft run quite OK LOP with stock injectors.
