Ghost two-six
Member
Fuel Injection - should I want that ? Why or why not ?
I have flown several carb'ed RVs and the #1 issue I always see is un-even fuel distribution as displayed by a 4 point CHT / EGT indication system, especially at partial throttle. Usually at W/O throttle the CHT/ EGT split is fairly even, anything less than that may cause a "front / rear" split. The 1/2 cylinders can run as much 300 deg cooler EGT than the 3/4 cylinders, which run hot anyway, at certain throttle plate positions. One has to wonder how healthy that is for the engine and how much power is being made in such a condition. The issue of O-360 sumps on O-320 engines and the corresponding lip just above the carb may also contribute to the un-even fuel distribution. With a carb, the fuel is introduced at one central point, the carb. Irregularities in the induction system can result in un-even flow. With F/I, the fuel is injected directly at the cylinder, resulting in very consistent CHT/EGT and the ability to run LOP. I have been very happy with the AFP FM series of F/I units. Once you understand the purge valve, hot starts are simple and reliable. No carb ice issues and the ability to pull sustained negative G are also in favor of the F/I system. Initial build cost and simplicity of installation seem to favor the Carb, but the long term fuel efficiency and safety (carb ice) seem to favor the F/I system.
... Sure, I would like to have FI, but thinking through that installation, plumbing, electrical etc. was time/money I chose to avoid. Still like the simplicity of the carb. Fires up every time, no primer installed either.
+1 for fuel injection. Saves money and pays for itself in no time if you fly it right.
Besides, when was the last time you saw a new car with a carb? 'nuf said!
I don't mind the mixture knob. Most of the time the power is at a given level and I like having control. If we had a good electronic injection that had backup like the PMAG, I might consider it on a new engine.
Why not look at the current EFII system? Just because the backup generator would be a separate item instead of physically built into the unit is no reason to disregard it. Plus, in adding that separate backup generator/battery, you gain redundant power for any EFIS you might install as well. You're going to need it for the fuel pumps anyway...
My thought on the mixture knob (which probably won't be popular round these parts) is that it's a distraction from flying the airplane. The "benefits" of manually-controlled mixture over a decent automatic system are vastly overstated, and do not outweigh the large potential for the mixture knob actuator to improperly actuate the knob (with consequences ranging from burning too much fuel, to early TBO or a failure from cumulative damage, to an engine failure in the very near term).
The mixture knob was "part of flying" for so long not because it's the ideal way to do things or because it's impossible to fly without one, but rather because it was the best way of achieving good engine operation and fuel economy at the time it was implemented. We now have better ways of doing things. Manually babysitting the engine doesn't make one a pilot; it makes one a flight engineer.The mixture control has been part of flying since aviation was invented just like a tail wheel, rudder, elevator or aileron.
No, I'm suggesting that every second the pilot is heads-down fiddling with the mixture knob is one second not spent scanning for traffic, maintaining situational awareness, navigating, etc.; and every mental clock cycle devoted to babysitting the engine is one less devoted to more important tasks. Once properly set up, an automatic system like EFII won't forget to adjust the mixture, won't forget carb heat, and won't improperly set the engine due to inattention or miseducation. How many engines get ruined, how many airplanes crash, because the pilot forgot the carb heat or mis-leaned the engine?Are you suggesting the typical pilot is dumbing down, like mentally incapable of managing a mixture knob?
I want boring; that's why I've decided to go with EFII. No magic black art to starting, just turn things on and crank. No fiddling with a mixture knob every time I change the power; it does that itself. No carb heat to worry about or forget to apply. More time to look out the canopy and enjoy the view I'll spend the extra time and complexity and fiddle-time once, up front, rather than keeping it "simple" and making the operation more complex on every flight.I've flown with EFII with the Sub H6, it was boring.
I have a carb on my O-360 with dual P-mags and can easily fly LoP.I've been flying my IO-360 FI RV6 since 2001 and thoroughly enjoy flying with FI. Flying LOP at 5 gph is a leisurely way to enjoy the local scenery. Recently I replace a magneto and Lightspeed with two P-Mags. On my first flight I leaned to 4.4 gph. I dub the setting Rotax mode.
Fuel injection servos can be mounted vertically (with the lower cowl scoop) or horizontally (with the duct or snorkel inside the cowling with the filter in the pilot's side cooling air inlet) depending on which sump you specify.
When I ordered my finish kit (same time as fuse kit) I bought the cowl with the scoop as I planned on using the carb because I wanted simple and inexpensive. Now that I've read through this thread, I'm seriously thinking of going FI.
At least I can still use the same cowl!