Fuel Injection vs Carb

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PilotPaul

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PilotPaul
Just curious as to everyone's opinion on fuel injection engines vs carb. I have been looking at a really nice Mooney M20C. I am just wondering if I should wait to find an E model which is fuel injected. Opinions?
 
PilotPaul said:
Just curious as to everyone's opinion on fuel injection engines vs carb. I have been looking at a really nice Mooney M20C. I am just wondering if I should wait to find an E model which is fuel injected. Opinions?
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Pros and cons to both. You do eliminate carb ice as a threat with injection, but I experienced that in my M20C only once or twice in over 1,000 hours and 12 years of Minnesota-based flying.

Usually a bit more maintenance and hot start issues with injection, but a minor difference at best.
 
The E model has a 200 HP engine instead of a 180 HP engine, so you'll have a faster plane with an E. I would personally get an E over a C for that reason.

Fuel injection is more complex, but so long as you clean your injectors, nothing significant. Plus it let's you run LOP better, where most carbs won't give you the required mixture distribution to do it well. Hot starts are harder, but not difficult if you know the technique.

In about 3,000 hours of injected engine run time in aircraft (and way more on stands), the only issue I ever had was an engine-driven fuel pump went out, which it could just as easily do on a carbed engine.

I'd go with an injected engine any day.
 
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In that particular airframe, it means the difference of 20HP and about 8-10 knots of speed. In this case, I'd wait for the E model if all other things are equal. Some planes there is little difference.
 
I'd prefer injected simply because it is a better technology.

Not that there's anything wrong with carbs, though!
 
The E model is better for sure, but you can get more panel for the same money with a C. I would say that it depends on your mission. There were also more C's out there, when I was looking.
 
PilotPaul said:
Just curious as to everyone's opinion on fuel injection engines vs carb. I have been looking at a really nice Mooney M20C. I am just wondering if I should wait to find an E model which is fuel injected. Opinions?
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The engine you want is the FI 180hp engine. It will be able to go forward on 94UL with little issue. You could also register Exp R&D and drop a turbo normallized IO 470 in it and fly it like that.;) I think that would be the ultimate engine package for a Mooney, a very nice blend in overall cost per mile effectiveness. Even no turbos would still be good.
 
Now Henning, tell us how simple it is to convert a certified aircraft to experimental? The answer, for those curious, is that it's easier to understand tax code.
 
If you want to talk maintenance costs try comparing the prices of a Carb, and a fuel servo.

And yes, fuel servos get replaced.
 
HerrGruyere said:
I'd prefer injected simply because it is a better technology.

Not that there's anything wrong with carbs, though!
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I tend to feel this way, too.

It's also more expensive technology.
 
An IO-470 engine is going to fit in a Mooney cowl? Could be interesting to see. I also believe the FI Lyc 360 engine has the same C/R as most of the carbed models. Don't know why the carb model won't like UL94 unless there's a concern with the float materials.
 
Ted DuPuis said:
Now Henning, tell us how simple it is to convert a certified aircraft to experimental?.
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The FAA will not allow you to do that, they will require you do the 1 time STC route, with all the engineering and testing to gain approval.
 
Ted DuPuis said:
Now Henning, tell us how simple it is to convert a certified aircraft to experimental? The answer, for those curious, is that it's easier to understand tax code.
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Simple, you file for a Research Exp certificate to gather the data required in accordance with FAR... In the furtherance of attaining STC issuance. That's the same way there is a Twin Commander flying around on a pair of big block Chevys for the last 20 years. You just have to put up with the restrictions which are much like any other Exp restrictions in that they diminish with time flown.
 
I have an "E". Before I had a Cherokee. The injector is very primitive tech. compared to our autos with the computer controlled engines. Of course the Carb is way older. I really miss the Carb on the hot start. The injector really blows in that situation. After about 700 hr. I think I have it. I also rarely use those extra horses except on takeoff. It is a kick in the A## though. The 94UL is also an issue down the road, however you may need bladders because the sealed wing may not handle the additives. You should get the C at a good price. Check e-bay and barnstormers as I have a friend selling an E for a good price in NJ.
 
94UL is not an issue of fuel injection. 94UL is an issue with the higher compression FI allowed. Remember, we're only talking 9.5:1 at the maximum, many more at 8.5:1. We run run 87 octane in cars with any of those, heck, I've run it with 10.25:1. The thing is timing and the low RPM restriction. In a car you shift down and pick up RPM keeping you out of detonation. Personally if I do a gear reduction I'll do it through a Lenco.
 
docmirror said:
An IO-470 engine is going to fit in a Mooney cowl? Could be interesting to see. I also believe the FI Lyc 360 engine has the same C/R as most of the carbed models. Don't know why the carb model won't like UL94 unless there's a concern with the float materials.
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Because the 200 HP engine has higher flow heads than the 180 HP version (that's where the extra power comes from) and that makes for higher ICPs, leading to a need for higher knock resistance from the fuel.

Now, there are opinions as to whether or not the 200 HP engine truly needs more than 93 or 94, and that's another thread.
 
Henning said:
Simple, you file for a Research Exp certificate to gather the data required in accordance with FAR... In the furtherance of attaining STC issuance. That's the same way there is a Twin Commander flying around on a pair of big block Chevys for the last 20 years. You just have to put up with the restrictions which are much like any other Exp restrictions in that they diminish with time flown.
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If you think that sounds simple, you're in the minority. You have to actually have a path to STC, and then there's whether or not they'd go for it. The Orenda engines in the Commander are definitely a special case. I don't know if that plane is flying or not. It does say it has a valid airworthiness certificate in experimental. But according to FlightAware, the last flight was 14 years ago. Also, a picture of it on FlightAware from 2 years ago shows it parked with no engines installed.

Now, let's say the Southwest ACO was alright with that. They're known for being easier in that regard than other ACOs, and there's a big difference between having a major STC program and just an individual who says "I want a bigger engine in my Mooney."

We'll ignore the fact that they're not too keen on increasing power in certified aircraft these days.
 
docmirror said:
In that particular airframe, it means the difference of 20HP and about 8-10 knots of speed. In this case, I'd wait for the E model if all other things are equal. Some planes there is little difference.
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This seems not quite right to me.

A Cherokee 140 with 150 hp gets 105 knots and add 85 hp to Cherokee 235 and top speed is 130 knots so if 85 hp gives you 25 knots 20 hp might give 5.

Where is my logic wrong??
 
Drag is a quadratic equation, as in if you want to go twice as fast you need 4x the power. It's why it's easier and cheaper to usually cut down on drag before adding ponies.
 
PilotPaul said:
I have been looking at a really nice Mooney M20C. Opinions?
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IMO- it is really difficult to find a good air plane for the money and for your budget. If the only reason you would pass on this plane is FI then hell no, I would not wait on a FI airplane. of all the things to prevent buying an airplane I do not think FI even enters the list.

Sooner you get an airplane the sooner you start your new adventure.
 
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I intentionally looked for an older travel air with carbs. I've had enough of $2k fuel servo adventures
 
Henning said:
94UL is not an issue of fuel injection. 94UL is an issue with the higher compression FI allowed. Remember, we're only talking 9.5:1 at the maximum, many more at 8.5:1. We run run 87 octane in cars with any of those, heck, I've run it with 10.25:1. The thing is timing and the low RPM restriction. In a car you shift down and pick up RPM keeping you out of detonation. Personally if I do a gear reduction I'll do it through a Lenco.
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Well the 200 injected IO360 Calls out for 100 Octane minimum. As to weather that is really necessary.....? The bigger issue is the glue sealing the tanks. Minimum would be bladders, and extensive testing on the 200 hp engine, or limited MP,... along with stc for both paths. Sounds like an opportunity if you have more money than sense.
 
Tony_Scarpelli said:
This seems not quite right to me.

A Cherokee 140 with 150 hp gets 105 knots and add 85 hp to Cherokee 235 and top speed is 130 knots so if 85 hp gives you 25 knots 20 hp might give 5.

Where is my logic wrong??
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Ask Mooney, they spec them that way. M20C = 150kts, M20E = 160kts. I just report, not design or explain.
 
Knock control with a vibration detector and electronic ignition retard is now common in autos. Air cooled engines present a somewhat more challenging path but that is what I would approach if I were to do the redesign. Of course, this is well past the question of the OP, but it wouldn't be that much trouble to find a detector that could work on an air cooled engine, and an ignition map to suit the fuel avail.

An 8.5 C/R engine with better flowing heads can run fine on 94 octane with the proper controls. It's the fixed advance spark that is killing the whole program. Retarding the fixed timing is not the answer either as that will take away continuous power.

The real fly in the ointment is 'guaranteed T/O power'. It could be different under load with 100LL or 94 if the controller sensed a series of pings and retarded the timing at a critical time.
 
Not a huge difference, the carbed engines are easier and cheaper to work on, I like them better in the heat and D/A if I'm going to be starting and stopping a bunch, less vapor lock. Vapor lock is not that big of a deal to clear, just annoying.


LDJones said:
....and hot start issues with injection.
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I got a good bit in injected and carbed.

You have to do a hot section inspection on that??? (jk)
 
docmirror said:
Knock control with a vibration detector and electronic ignition retard is now common in autos. Air cooled engines present a somewhat more challenging path but that is what I would approach if I were to do the redesign. Of course, this is well past the question of the OP, but it wouldn't be that much trouble to find a detector that could work on an air cooled engine, and an ignition map to suit the fuel avail.

An 8.5 C/R engine with better flowing heads can run fine on 94 octane with the proper controls. It's the fixed advance spark that is killing the whole program. Retarding the fixed timing is not the answer either as that will take away continuous power.

The real fly in the ointment is 'guaranteed T/O power'. It could be different under load with 100LL or 94 if the controller sensed a series of pings and retarded the timing at a critical time.
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Agreed. But just like any modern EFI engine, full throttle timing and mixture maps would be tailored to the operational requirements, meaning "full rich" with a retarded timing curve for full throttle, with timing advances and a leaner curve on cruise for better cruise power and efficiency.

Nothing problematic with adapting EFI, digital spark control and adaptive knock sensing to air cooled engines. It's done on larger air cooled motorcycle engines.
 
Henning said:
Simple, you file for a Research Exp certificate to gather the data required in accordance with FAR... In the furtherance of attaining STC issuance. That's the same way there is a Twin Commander flying around on a pair of big block Chevys for the last 20 years. You just have to put up with the restrictions which are much like any other Exp restrictions in that they diminish with time flown.
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You pretty much have to be a corp. trying to gain certification to get that approved.
 
Ted DuPuis said:
If you think that sounds simple, you're in the minority. You have to actually have a path to STC, and then there's whether or not they'd go for it. The Orenda engines in the Commander are definitely a special case. I don't know if that plane is flying or not. It does say it has a valid airworthiness certificate in experimental. But according to FlightAware, the last flight was 14 years ago. Also, a picture of it on FlightAware from 2 years ago shows it parked with no engines installed.

Now, let's say the Southwest ACO was alright with that. They're known for being easier in that regard than other ACOs, and there's a big difference between having a major STC program and just an individual who says "I want a bigger engine in my Mooney."

We'll ignore the fact that they're not too keen on increasing power in certified aircraft these days.
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It sure is, I see it at airshows all the time, last time I saw it was at AOPA Summit. I talked to the guy about it, it's not that difficult, just fill out the paperwork properly, he's been flying it with just the minimal Non Commercial restrictions for over a decade.
 
Henning said:
It sure is, I see it at airshows all the time, last time I saw it was at AOPA Summit. I talked to the guy about it, it's not that difficult, just fill out the paperwork properly, he's been flying it with just the minimal Non Commercial restrictions for over a decade.
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When I see you do it to the 310, I'll believe that it's not that difficult. Until then, I'll believe everyone else I've talked to who's tried. :)
 
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