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rv6ejguy

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Questioning the "better starting" comment, especially with a hot engine.


BJC
Depends on what type of fuel injection you're talking about. Bendix style with its low fuel pressure during cranking and idle can sometimes cause issues. With EFI, no issues like that.

EFI generally improves power over a carb due to superior mixture distribution, even at WOT. Seeing 2-4% more power on the dyno is not uncommon. Some of the 540 intakes are quite poor designs with unequal runner lengths, entry angles and virtually no plenum volume.

EFI throttle bodies don't have the inlet restrictions of carb venturis or Bendix/AFP metering servos so they have lower pressure drop and higher mass flow. This can pick up additional power at high rpms in many cases.
 
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BJC

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Apart from the cost, it would be useful to install an injection instead of the carburetor?
... Fuel Injection ... gives You a better Starting Engine,...
Depends on what type of fuel injection you're talking about. Bendix style with its low fuel pressure during cranking and idle can sometimes cause issues. With EFI, no issues like that.
Thanks. I am familiar with the benefits of EFI and electronic ignition over the standard mags and Bendix-type injection. I took the question to be about installing a Bendix-type injection, which makes hot starting more difficult, even with the "proper" technique, so I was curious about the better starting engine comment.


BJC
 

Armilite

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Questioning the "better starting" comment, especially with a hot engine.


BJC
=========================================================

First, I was assuming EFI being used which don't have them problems, and Why would anyone want to use any Fuel Injection that does have problems on any Plane?
For what they charge for Commerical made Fuel Injection for planes it better be 100% fool proof!
 

TFF

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Bendix FI is super reliable. Hot starting in some planes is more of a factor of the airframe company wanting to run the fuel lines in the hottest place possible. Mooneys, and of course lots of RVs, running a fuel line between cylinders is stupid. Hot starting a Mooney is miserable, but trusting the simplicity is great. Key start mag switch makes it worse. If you can spin a Bendix FI engine with mags off and purge the vapor lock, starting becomes a non issue. I don't not believe in EFI, but the old mechanical works fine.
 

rv6ejguy

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Bendix FI is super reliable. Hot starting in some planes is more of a factor of the airframe company wanting to run the fuel lines in the hottest place possible. Mooneys, and of course lots of RVs, running a fuel line between cylinders is stupid. Hot starting a Mooney is miserable, but trusting the simplicity is great. Key start mag switch makes it worse. If you can spin a Bendix FI engine with mags off and purge the vapor lock, starting becomes a non issue. I don't not believe in EFI, but the old mechanical works fine.
Some like to hold onto the old ways and I understand that. Fortunately for us, the world has seen the light in Experimental aviation making a wholesale switch from carbs and Bendix/AFP mechanical injection just as the rest of the world has long ago switched car production over from carbs and mechanical injection. 2016 was our best year ever in aviation EFI/EI by far. A lot of RV guys no more want carbs, mags and Bendix injection on their new builds than they want steam gauges in the panel anymore. Even the STOL, bush, Cub guys are starting to fit the new stuff. Step into the light, the future is EFI.
 

Battson

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New Zealand
For these 540 Spec's I used 8.5cr. But using these same Spec's but just changing the CR used, you can see how it affects your HP.

7.0cr = 270hp at 3500rpms
7.5cr = 282hp at 3500rpms = +12hp
8.0cr = 293hp at 3500rpms = +23hp
8.5cr = 302hp at 3500rpms = +32hp
9.0cr = 311hp at 3500rpms = +41hp
9.5cr = 320hp at 3500rpms = +50hp
10.0cr = 327hp at 3500rpms = +57hp
10.5cr = 334hp at 3500rpms = +64hp
11.0cr = 341hp at 3500rpms = +71hp
That kind or RPM might be attractive in a hotrod race plane, where the engine lasts for a few dozen hours with a special propellor to transfer the power...
I think running an engine in such an extreme and expensive configuration unnecessary and unattractive for 99.99% of homebuilders.
 
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