M

Moura

Well Known Member
Hi

I am plannig on the engine for a RV10 and have been talking to a couple of friends that are argueing that I would be better off with a carburated engine (O-540) instead of the fuel injected option (IO). They argued that The carburated would be more fuel efficient and much better to start when hot (that is very hard to start a hot fuel injected io540) and so on. Considering I live in Brazil and fly mostly down here (tropical weather), what would be my best shot?

Thank you

Moura
 
Don?t listen to them, they have obviously not used a FI engine before and there full of BS, Given the choice I would never chose a carb over FI.

Fuel economy will be better with the FI even if it?s only balanced average, balance it well and you get the idea.

They all have there reluctance to start hot, carb or FI, either way you will find the sweet method to get it started.
 
FI is the way to go. Read up on the benefits of running lean of peak and that is reason enough. Hot start is just not that big of a deal - its all in the technique.

erich
 
If the support is all the same then get FI as you will get better fuel economy, but if your able to get carb parts much easier then that may be a factor.
 
I went thru this same fear factor from friends who had never flown FI, discounted same and have been flying with injection going on 3 years. I would NEVER want to go back to carb.

Cheers,
 
WOW, you guys are fast. Well, so far I have not seen any advantages of the carburated over the injected, except that it masy be easier to get parts for it. Are there any other advantages of carb over FI? Do you guys users of FI have any trouble hot starting your engines? What are the methods used for hot starting a IO540?
What about troubles, we know sometimes (perhaps quite often) in aviation the simpler the better and we know carbs are very simple and proven design. FI users are facing or have faced any kind of troubles with your IOs?
Sorry to insist but I am trying to understand the advantages and disadvantages of each option because once the option is make, it will be to late to change the mind. So far FI are way ahead, lol.

Thank you

Moura
 
Moura said:
Do you guys users of FI have any trouble hot starting your engines? What are the methods used for hot starting a IO540?
Click to expand...

If you use a purge valve, the hot fuel is pumped back in to the tank and cold fuel is used to start.
 
It's very similar to the F/P vs. C/S argument. Both have advantages and disadvantages. Carb is cheaper, easier "hot" starting, and runs with much less fuel pressure. FI has better distribution, very low risk of induction icing, allows for inverted operations (so long as you have inverted oil and fuel pick-ups), and slightly better operating economy.
 
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No one mentioned that you cannot get 'carb ice' with an FI system. Carb ice can form even in tropical climates.
 
gpiney said:
No one mentioned that you cannot get 'carb ice' with an FI system. Carb ice can form even in tropical climates.
Click to expand...
CAUTION! Induction icing is still possible with fuel injection even though it is extremely rare.
 
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Moura said:
... Do you guys users of FI have any trouble hot starting your engines? What are the methods used for hot starting a IO540?
Click to expand...

There is an art to the FI hotstart, but even without a purge valve it can be learned. The problem is that the process is a little different for each airplane. Most of the time when you see someone grinding away on the starter after a quick fuel stop, it's going to be a rental pilot who does not know the airplane. I know my FI airplane very well and but even without a purge valve I can get it running on the first few blades about 99.9% of the time. If I happen to "miss it" on the first try, I will always get it on the second.


Moura said:
... What about troubles, we know sometimes (perhaps quite often) in aviation the simpler the better and we know carbs are very simple and proven design.
Click to expand...

FI systems are also very simple (just different), and very reliable. As long as you don't run a lot of trash through the system (dirt, debris), you should get years of trouble free service.
 
There is an article in the Firewall Forward section of VAF by Stein Bruch, entitled "Carb vs Fuel Injection". What makes this article different from the other comments in this thread is that Stein has had both carb and FI RVs, so is speaking from personal experience.

I had chosen FI and am comfortable with that, but I value Stein's opinion and he makes some valid points.
 
I see no advantages anymore with carbs. They used to be cheaper and are almost at parity now. Running lean of peak with a carb is a c*** shoot. You cannot balance a maniflold, you can change injectors to balance fuel injection. So you can end up with a hot cylinder with a carb.

Had a Cessna 150 and a Grumman Tiger with carbs and a T-34 and Bonanza with FI. Starting after you learn the procedure for any engine is not a problem. There just isn't anything in the advantage column for a carb anymore.

Just my $.02.
 
jlk said:
I see no advantages anymore with carbs. They used to be cheaper and are almost at parity now.
Click to expand...

I must be missing something. Going to Van's website I see an average delta of $5-6k difference between carb/FI engines of the same dash number. Then add to that a $500 difference between the price of the boost pumps. Looks to me like there's quite a difference in price.
 
Buggsy2 said:
I looked high and I looked low and didn't find this article, can you post a link? Thanks!
Click to expand...

Found the text mentioned and pasted below:

Carb vs Fuel Injection
posted in the VAF Yahoo Group by Stein Bruch (http://groups.yahoo.com/group/vansairforce/)

I've been reading this thread with interest, and noticed that lots of advice has come from people not yet flying...So...here's my 2 cents. And YES, I do have some experience in this area. Here's my setip. I have BOTH carb and FI...

RV6 - AEIO-360 (Inverted) with Bendix Injection
RV6 - O-320 with Marvel Carb.

FI....First, let's get all this "icing" stuff out of the way. Number one, no one in their right mind is going to mount a filter downstream of the servo in an RV, so that debate can quit. The Bendix units are not prone to icing, but the filter is still prone to collecting snow/ice, so an "alternate air source" should still be installed.

Second, it's a mechanical system that is constant flow, injecting fuel into the intake ports aimed at the intake valve in all 4 cylinders at the same time.

Benefits to the FI....
1.You can get a pretty good balance between all 4 cylinders and can lean the **** out of the engines accurately. That being said, it rarely happens without changing/tinkering with the various injectors to get them all balanced.
2.Little to no worry about icing in the servo itself.
3.No stuck needle/seat assemblies.
4.YOU CAN FLY UPSIDE DOWN!

Benefits of the Carb...
1.CHEAP-Just overhauled my MA4 for around $200.00
2.EASY Install. Van's makes a simple bracket for the cables. The FI was a pain.
3.WAYYYYY easier starting. Since the FI injection tubes rest on top of the engine, when you shut it off hot, they flood themselves. No matter what the installation, or what fishing stories people tell you, I've never seen a FI engine start as well as a carb when hot.
4.Very little to break.
5.Lower Fuel Pressure (2-5lbs vs. 25-30lbs for FI). Oh, and yes you do need a high pressure boost pump ($$$$), bypass, and high pressure engine driven pump for FI.
6.Lower Overhaul costs. FI=$750-1000.00, Carb=$200-450.00

In the end, it's pretty hard to justify a FI based on most peoples arguments. It's kind of like the TD/Nose Dragger, TipUP/Slider, 320/360, blah, blah, blah debates. The fact is that a carb will perform just as well, and produce nearly the same fuel flow as FI does. I've flown along side all of the above combinations and Carb vs. FI are usually within .5 gph of each other, assuming you have a good engine monitor which allows you to monitor all 4 cyl's CHT/EGT for leaning. If you can afford it and want it, buy it.

My first RV had FI, now my newest has a carb, because I'm cheap, and like the easy starting. That's just my 2 cents so take it for what it's worth. Drop me a note offline and I'd be happy to discuss either system.

Here's a good hint based on one of our "local" engine gods. He has an RV4 that puts out over 230+HP, Constant Speed Prop, and he works on Lycomings for a living, is a DAR, and guess what...uses a carb.

Cheers,
Stein Bruch, A&P
RV6-N664SB, IO-360 FP
RV6-N64YU, O-320 FP


Moura
 
Hi Mel,

This is what I was looking at from Van's:

Experimental O-320 160HP
Part Number = EA XO-320-D1A RT
Price = $23200.00

Experimental IO-320 160HP
Part Number = EA XIO-320-D1A RT
Price = $23600.00

less than 2% unless I am missing something.
 
jlk said:
Running lean of peak with a carb is a c*** shoot.
Click to expand...

Hi, so running lean on peak on FI engines may be a little more forgiven in comparisson to carb engine, is that what this post meant? If so, why?
Thanks
 
Hi Sebastiao..

...The risk in running LOP with a carb is that you have a hard time balancing cylinders (if at all possible, even) because of the difference in fuel/air flows through the intake system. One point (the carb) feeds them all....some running leaner than others.

With FI, the injectors can be balanced and give a more uniform fuel delivery.

Best,
 
Hi Pierre

pierre smith said:
...The risk in running LOP with a carb is that you have a hard time balancing cylinders (if at all possible, even) because of the difference in fuel/air flows through the intake system. One point (the carb) feeds them all....some running leaner than others.

With FI, the injectors can be balanced and give a more uniform fuel delivery.

Best,
Click to expand...

How Can the FI system be balanced? Isnt the fuel delyvered through that spider thing equally, just like carbs?
It is probably a stupid question and I apologize for that but then again, a way to learn.

Thanks

Moura
 
...To add to Mel...

FI delivers fuel under hydraulic pressure to the intake port - True, it's from the same source, but the final metering is done at the individual nozzles. With a carb, the fuel is carried to the combustion chamber along with the air through a torturous path that is not only of variable length, but shape as well. As a result, the fuel will drop out of suspension along the way and cause a large variation in the mixture that is seen by each cylinder. This large variation in spread is why running LOP is such a challenge with a carb.
 
Gami injectors are available for most engines, but they are somewhat expensive for what they are. They are balanced based on the engine model. The are numbered and I believe the number correspond to numercal drill or reamer sizes.
 
Well, you guys were great!! Thank you very much for the timelly answer... I rest assured that Ill go with the FI.

Thanks
 
jlk said:
Gami injectors are available for most engines, but they are somewhat expensive for what they are. They are balanced based on the engine model. The are numbered and I believe the number correspond to numercal drill or reamer sizes.
Click to expand...

No reason to spend that kind of bloated expense on the RV's...Don Rivera from AFP provides balanced injectors, customized to your engine for a MUCH lower cost/price point, and he'll go over you specific engine data to get it right. Can't beat his service when it comes to balancing injectors or for services related to injection sysetms in general. Unfortuneatly the certified guys don't have that option, but we do! :)

Cheers,
Stein
 
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