Stupid question

Don Lindsay · #1 12-01-2007, 12:43 AM

I've only flown carbureted planes. What controls does a fuel injected RV need on its panel ?

Specifically, is there anything besides Throttle that needs to be on a throttle quadrant ?? Can't be carb heat ...

BuckWynd · #2 12-01-2007, 01:21 AM

Mixture (Red).
Prop Control (Blue), if you're using a constant-speed prop.

These, along with the Throttle (Black) are the standard three that make up the actual throttle quadrant.

Other engine controls will depend on your particular situation: A couple of fairly common ones you'll see on RVs are an "Alternate Air" control, and an oil cooler shutter control.

Nope, no carb heat needed.

Pirkka · #3 12-01-2007, 03:25 AM

As we got good start let's continue with 'stupid questions'. Why there is mixture control for FI engines?! I don't have one in my car and I can't undestand why we would have FI unless it takes care of fuel flow to cylinders which IMHO is same as 'mixture'. So where do I go wrong? To make FI really do it's job, we should connect it to EGT? I assume it already knows air flow...

SvingenB · #4 12-01-2007, 04:06 AM

The fi used on lycomings are mechanical, not electronic or digital as they are in modern cars. It is only a simple regulator injecting fuel based on the flowrate of air into the engine, with no other feedback for fine tuning of the combustion. This means that manual mixture is needed to manually adjust the setpoint of the controller based on the logics of the brain basically

jmartinez443 · #5 12-01-2007, 04:29 AM

Quote:

Originally Posted by Pirkka

As we got good start let's continue with 'stupid questions'. Why there is mixture control for FI engines?! I don't have one in my car and I can't undestand why we would have FI unless it takes care of fuel flow to cylinders which IMHO is same as 'mixture'. So where do I go wrong? To make FI really do it's job, we should connect it to EGT? I assume it already knows air flow...

Your car has a computer that measures the air density and adjusts the mixture. Ever see the check engine light come on in your car? 9 times out of ten it's because your O2 sensor is going goofy. Mechanics out there please refrain from correcting me on my 9/10 figure, I pulled that # out of my butt.

Because in your plane it is mechanical fuel injection, you play the role of the computer. Now if you step up to an electronic fuel injection (like FADEC or a system like precision's EMS) then you lose the mixture control.

SvingenB · #6 12-01-2007, 08:55 AM

You can read about how this fi works here
http://www.precisionairmotive.com/Pu...s/15-812_b.pdf

Pirkka · #7 12-03-2007, 12:30 AM

Thanks for the info. I'll sure will read that .pdf through to understand the basics of fuel injection in aircraft engines.

When I did started my project, I knew more about engines than I did from metal building, now the engines are the weakest part. I don't know yet how to solve engine issues but we'll see. It would be nice to get new engine and assemble it in the 'school' to make myself more familiar of them.