Automotive V8, Fuel Filters, 100LL

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Toobuilder

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In aircraft use, do folks ever remove the screens installed in the injectors? If the screen area is really small, it might be preferable to put a large area, "good enough" XX micron filter before the injectors and eliminate the chokepoint at the injector itself.
Of course if the electronic injector does crud up and choke, is that any worse than when it hapens on a Bendix injector or the line breaks and it throws raw fuel on the top of the engine? Both are quite common among the GA fleet and considered "par for the course".

Frankly, a pluged EFI injector scares me a lot less than the mechanical stuff.
 

rv7charlie

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Another question to ask is, 'Why did the auto mfgr put that little screen in there, if removing it doesn't cause any harm?' Maybe an injector getting stuck *open* due to trash (while being fed 40-60 psi fuel) might be worse than it getting clogged? Until we know the reason for something being designed the way it was, it's often better to not change it. Especially if it could be flight-critical.
 

TFF

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In reality, you have to care where you get your gas. The filter is there to save the engine not your life. Unless there is a bypass for a clogged filter, the engine will stop when the filter does its job.

The good news is fuel is usually clean; very clean. 99% fuel is perfect. My two1% experiences. From one fuel stop in 15 minutes, the filter went into bypass. Turbine helicopter. Filter looked like a wad of cotton was shoved in there. Without the bypass it would have been an auto. Number two was hot fueling during maintenance. The owner’s helicopter was normally fuel from his own tank which was shelling out small pieces of steel from the gears. Normally it laid at the bottom of the aircraft tanks and could not be picked up. Dumping fuel in the tank while running stirred it up and it went through the system. The gascolator did not grab any of it and what it did was foul the plugs. It was the only time I thought there was a real emergency going on. I know of one other from a coworker who filled up and the farm tank float sunk and pumped 300 gal of water off the bottom into his tanks. Stared up and taxied and it all quit. Big aircraft don’t sump but during maintenance. My experience is fuel filters are always clean until they are not, and are not is clogged completely. Clean enough that you can get complacent checking them.
 

Protech Racing

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I use a bunch of filters with diesel and 112 fuel . FWIW the remote oil filter adapters that are 3/4 16 will allow filters to be fitted easily. (Chevy Duramax). E mail Wix or Lubefiner and ask for the data for best fit . This is for the prefilter. IMHO . Good chance that separator designed for diesel will do the same for AV gas.
The delivery filter can be almost any inline 8-10 micron. 1991 BMW 318I for example is clamp on both ends, , runs at 60-80 psi .
********* Lay this filter on its side ****** This promotes **** falling to the bottom . It works, .
112 leaded will run for about 60 hrs or more before messing up the O 2 sensor , most of the time. I wouild hope that any AC will be run in open loop with map feedback only .
 

skydawg

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We did considerable testing with gas filters on our C172 V8 project and may have already played test pilot on your set up. First, what type of fuel pumps and injectors are you using? This is really the factor that will drive your filter option, as some pumps and injectors are more prone and sensitive to contamination. Some lower pressure pumps may need a feed pump to maintain pre pressure, especiallly with higher G loading, such as aerobatics. If using a higher pressure EFI setup, reference that any suction side filter element needs to be strong enough not to collapse even if saturated and blocked. …. This can be an issue with paper elements.

as far as lead, or TEL, goes relative to a filter, we did not see any issues but were only using 100 and 40u elements, but cut them open on a regular basis for inspection. I don’t like paper elements for a number of reasons, but if you do use them, I’d suggest cutting it open to see the actual size of element. Many of these type filters use deceptive small elements inside big sized canisters…. Was told it allows manufacturers to be able to use same elements in many different filters. I’d suggest finding the largest surface area element that can prolong period to saturation which may allow you to catch a problem between inspection samples. Also, you may notice many elements are not reinforced while others incorporate rigid mesh…. This helps resist collapse.

many EFI systems bypass 2/3 flow back to tank, so filters are really filtering 3x-5x the engine consumption rate, so remember this when looking at filter flow specs. I have seen builds where filters were only rated for the fuel consumption, and caused issues.

I would not underestimate water contamination even if not burning ethanol. Having a low point to sample is really a good idea. There are a couple of companies that make spin on type filters with a pet cock drain that can be safety wired. Water easily can accumulate in a filter and displace and block fuel from flowing to a failed engine.

without knowing your design, I would suggest consider some form of filter bypass in case elements clogs….. pretty easy to make and could even incorporate a filter,…. Trick is knowing when you start bypassing. A redundant system even better. There’s a few photos of how we did it on our website www.corsairV8.com. …. But every system is different and there is no one way to do it.

I don’t have much specific first hand knowledge of paper elements with lead fuel, but expect paper was used in cars that burned leaded gas for decades. We mostly fly with 85 octane ethanol mogas, and stray from AVGAS unless it’s only option (mostly because of cost, not needing engine run up to burn plugs clean, and longer oil change intervals…. And the environment). Hope this helps. Good luck on the build.
 
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