Quote:
Originally Posted by dweyant
Roberta,
I.e. how do I build a simple fuel system, for a fuel injected RV-9, and allow for the potential vapor lock issues with burning mogas?
-Dan
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For me, it was not just about the plumbing, but the fuel system as a whole. I wanted a simple system that was easily adaptable to future fuels while allowing me to get the optimum performance and economy out of my engine without all the voodoo that gets talked about on this forum or the $1000+ seminars that try to explain the voodoo. I wanted a simple, easy to install and maintain system that provided feedback that all is well and functioning normally.
I am using Precision's Eagle EMS (mfg of certified FI and Experimental Silverhawk FI) in my IO-320 C/S RV-9A. It provides both dual electronic Ignition and electronic fuel injection in a single system. It was a good route for me to simplify my fuel system and better support future fuels, including mogas, while managing my Ignition and air/fuel ratio to provide best power and best economy cruise without the voodoo. I am given a lean pot to lean by a percentage, but for mine full lean automatically sets it up for best economy cruise, not matter what power setting or altitude. Should I try to over lean and cause the cylinders to rise over 400 degrees, it will ignore my input and adjust timing and fuel to keep temps down. It's simply to install and made to be a direct replacement for other Mag/EI and carb/FI installations.
I used standard hard-pipe plumbing from the wings through the fuel selector to the firewall. On the engine side, I used professionally custom-built fuel lines from the firewall to the mechanical pump and than to the fuel block on top of the cylinders. Unlike standard/mechanical FI, this is NO hose from the mech pump to the throttle body, thus no line going from the throttle body between the cylinders (cooking the fuel) to the distributor block. Note: This isn't really a distributor block per se, it contains a micro filter and dual pressure sensors.
Each injector is individually pulsed at a much higher pressure than mech FI, thus quickly clearing out any vapors. Injectors lines are larger and insulated/fire sleeved. There is no need for a fuel flow sensor spliced into your main fuel line since the computers(s) know exactly how much fuel was consumed bases on the pulse length and fuel pressure. Much more accurate than traditional flow sensors. The throttle body is the same as the Silverhawk, except it has dual MAP/Temp sensors connected to it.
I flew to AirVenture2012 and landed at airports that were above 100+ degrees with high density altitudes. Engine had plenty time to heat soak, but it started just like a car and immediately adjusted for density alt. On take-off/climb, it always maintained best power until reaching cruising alt when I switched to best economy cruise.
Although not everyone wants to try something new, I would do the following regardless of what fuel system I would install. I would
personally avoid anything that adds more fuel lines and/or connections. I wouldn't add a aux tank or use any FI system requiring a return line. It only complicates the fuel system, adds more connections that could leak or fail and makes it difficult to manage/calculate fuel consumed from each tank, especially with return lines.
If you want to use mogas, I would use as much hard pipe as possible unless you are willing to replace your fuel hoses on a regular/scheduled interval. Also, have a pro make your hoses!! Confirm that the mfg of your mech pump and fuel system are ok with mogas.
NOTE: I am
not a A&P nor do I pretend to be. These are just my personal comments based on my experience or lack there of. However, I have stayed at a Holiday Inn numerous times!
My .02 cents worth, good luck.
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