[jeffrey]

So I'm thinkin about an engine for my 7a io 360 or o-360, and where to buy one. Of course first thing I think about is buying one from Vans. Then I read that even Van himself didnt buy one from vans. ( RVaitor june 07 for his RV-10 ) But got one from aerosports. Susan at aerosports is great, but Im still up in the air about getting injection or carb. Can any one give me a good reason to go injection over carb, I know about carb ice but will injection give me any better fuel milage or any thing else to over come the extra cost?
thanks
Jeffrey
rv-7a 73050 building

 

[frankh]

This has been covered MANY times

Your better off doing a search of the archives.

Frank

 

[Kevin Horton]

If you spend some time matching the fuel injectors, a fuel injected engine can be run lean of peak EGT at lower powers (opinions vary, but I would probably not run lean of peak unless I was at 65% power or less). If you run lean of peak, you might achieve a fuel burn reduction of 10-15% less than a carburetted engine would have at the same power. This is the biggest reason to consider fuel injection, in my opinion.

If you want to do negative g aerobatics, a carburettor will not function, but a fuel injection system works just fine with negative g. But you would also need an inverted oil system, and a flop tube in a fuel tank. You can do all the usual "gentlemen" aerobatics without using negative g, so this is not a big deal.

 

[Walt]

Carb 4 me...

Simple, reliable and low pressure fuel supply. I also am able run lean of peak or at peak all the time (55-65% power) with dual light speed ignitions she runs beautifully

 

[rmartingt]

If you want to do negative g aerobatics, a carburettor will not function, but a fuel injection system works just fine with negative g.

You could use a throttle-body injector... works at any attitude, and is mechanically simpler than a traditional carb. Supposedly they're less susceptible to carb ice, but it can still happen. We've been running one for years and it works great.

 

[petehowell]

I'm with Walt

With Dual EI, a carb engine can be run LOP with good success. It requires a little more futzing - but it does save gas.

Hard to go wrong with a carb or FI. I am convinced that EI is the biggest driver of lean operations.

 

[robertahegy]

I have a Van's 0-360 Lycoming. Simple, works great, no problems, all of Van's accessories fit it correctly, performs great with the Hartzell BA prop, less cost, and works with only 0.5 psi fuel pressure.

Roberta

 

[dan]

Ask the carb folks what their cost per mile is. Those who run FI LOP (lean of peak) will be able to achieve lower cost per mile. For example, my average cost per mile on a recent 3000nm trip was 14 cents per mile (16 cents per nm). That was running full throttle. Can the folks running carbs get theirs that low? ...at the same speed?

I know some folks out there with carbs can run LOP, but most everybody I know personally with a carb can't run LOP smoothly. Just yesterday an RV-7A/O-360 pilot was in my hangar talking about converting to FI (and he's not even out of phase one yet!!!). He said his gami spread was 0.4-0.6 gph, but the engine was running pretty rough near peak. So he's forced to run that puppy rich. $$ out the window.

Thing is, the price of fuel is rapidly increasing, and the delta between carb cost per mile and FI cost per mile is growing right along with it. As fuel prices rise and that delta grows, any up front additional expense for, say, a high pressure boost pump, ends up being "paid for" much more quickly.

Now, you gotta ask yourself...how many hours are you likely to fly the airplane before you sell it? Will you ever "break even" on the up front add'l expense for FI? Ok, so say you'll probably only put 700 hours on the plane before you sell it. Well, even then I believe you'd break even...but let's say you didn't...by that point the price of fuel will be even higher, and a shrewd BUYER will appreciate the ability to run LOP and have a lower operating cost. Which means they're gonna a pick an IO-equipped RV over an O-equipped one. Put yourself in the position of an RV buyer. Which would you pick given the choice?

That's my philosophy and I'm stickin' to it. Let's talk in 3 years when the guys who are burning 9 gph are whining (or face it, just flying less!) and the guys burning 7 gph at the same speed are laughing all the way to the bank.

How much would you spend up front to lower your hourly operating cost by $10? What if, in 3-5 years, that delta is more like $15 per hour or more? How much would you spend NOW to save that THEN? Fuel ain't getting any cheaper!

Anyway, that's how I see all of this. I'd rather spend the money NOW, when prices are lower than they will ever be in the future, on the things that will save me (and every future owner) MONEY for the rest of the airplane's life.

 

[gmcjetpilot]

Ditto

Yes check the archives

Normally I'd say Carb for simplicity and cost to buy, but now I say FI. The cost difference in original purchase is no longer a big factor. FI is still a little more with the more expensive electric pump and more involved to set up (a little) but the fuel savings is a strong point now a days.

Fuel cost have gone up if you have been in a cave and not noticed, so yes any fuel saving no matter how little will add up faster, if you fly in a lean state (but not necessarily LOP). Go around wide open full rich it makes no difference. In other words how you fly has way more to do with your economy than just Carb or FI alone.

Highly Recommend a NAME brand engine builder, #1 choice would be Mattituck, followed by Aerosport. The next choice would be a ECI engine kit and do it yourself deal, if you want to save some money while learning how to assemble an engine. If deciding today the latter do-it-yourself ECI would probably be the way I'd go. The way I went was buying a Lyc O360 core, rebuilding myself with some hired help. It was a hassle, but I got a great core at a low price. Problem today is people want way to much for used cores now, so I would go new today without question. There are still used bragains but they are getting more rare. Besides the price saving can be small.

 

[db1yg]

Another Data Point

I was in the same position as you 3 years ago and did a great deal of research and balanced that info against my own real world experiences as well as those of friends.
My first airplane was a Cherokee 180 (0360/carb), never had to do much of anything to the engine or carb in the 500 hrs I flew that plane. My second airplane was a Mooney 201 (angle valve 360/FI), FI fuel servo was rebuilt twice and high pressure fuel pump once in the 1000 hrs I flew that plane. Cost to rebuild the servo was $800 the first time and about the same the second--cost to rebuild the high pressure pump was $600 although you can get high pressure experimental pumps for RVs for less. During that same time frame my brothers Piper Dakota (0540/carb) never had ANYTHING done to the engine or fuel system -- as a matter of fact when he sold the plane (to build an RV) it had over 2200 hrs on airframe and engine with nothing but normal maintenance on the engine. Is my experience with the FI worse than normal--don't know--maybe someone like Mahlon can comment on that. My point is that if you DO need maintenance on the FI system, it is going to cost you much more than a simple carb system--and that will negate some of the fuel savings from running LOP with the FI--not to mention the down time.

BTW, my ECi 0360 will also run lean of peak smoothly. I attribute it to the flow matching ECi does on their cylinders and the LS Plasma III ign I run on one side. As an example, last Saturday at 4500 ft indicated and a little less than 65% power I was lop on all cylinders (last to peak was lop by 5-10 degrees) and I was burning 7.8 gph. I think this is not the norm for carbs and therefore I would not count on it but it works for me. BTW, the airplane was still truing 154-156 ktas per my calibrated Dynon--ain't these machines great!!!

Regardless of which engine you select you are going to have a machine that puts one big grin on your face on every flight!!!

 

[dan]

Go around wide open full rich it makes no difference. In other words how you fly has way more to do with your economy than just Carb or FI alone.

Yeah, but if you fly around full rich (or relatively rich) you're probably racing. And if you're racing, you'd be out of your mind imho to go with a carb if you have a choice. How many RVs and Rockets that win the races have carbs?

 

[db1yg]

"And if you're racing you'd be out of your mind imho to go with a carb"


Oh my, this should liven up the afternoon----pass the popcorn!!

db

 

[Flyrod]

A strong vote for AFP IO

Its not just about economy and speed, don,t forget about worry free aerobatics. When I was training, I always bounced between IO and O 172s. The IOs needed a special routine starting but always seemed smoother. Maintenance could prove a little more demanding and hot ground operations not as smooth but when you put the lever to the metal, that precision fuel distribution is going to feel good. Its also nice to know that no matter what the attitude of the aircraft or G forces involved, fuel will remain flowing in precision.

I like the AFP injection that I am using and it has not been a maintenance problem at all. Also, I think the fuel return on the AFP is a great safety feature. I can bring 90% of the system to full pressure and 30% flow during pre-flight and check for leaks.

 

[osxuser]

Well, as far as carb reliability. We've had to buy a new carb on our O-360 A1A once, and the new one has an annoying dead spot around 1400rpm that we can't get rid of. MUCH prefer FI if only we could put it in our C177.

 

[RV7ator]

FI beats carbs when upside down (do you have inverted oil and flops?). Other than that, I believe the life cycle cost of a carbed engine can't be beat. Also, simple to install, maintain, get parts. Consider spending your money on flow matching by a builder who knows what they're doing, like LyCon. My O-360 is lighter than an IO and produced 204 hp on the dyno, before adding EI.

John Siebold
Boise, ID

 

[dan]

"And if you're racing you'd be out of your mind imho to go with a carb"

Oh my, this should liven up the afternoon----pass the popcorn!!

Yeah, I figured that would kick things up a notch. Just messing around. Hey, how about Tracy Saylor or Dave Anders? Did/do they run a hopped up O-360, or were they IOs? I honestly don't know. Something tells me those guys ran carbs, but I don't know the details.

 

[petehowell]

O-320 Carb Numbers - YMMV

The -9A is a lot different than the the -7, and has a different mission, but my numbers are not too bad. Now I might have an odd duck engine that runs smooth lean, and I know the 360's are faster, but for what I do with my plane, the carb was not a bad choice. Not much racing or upside down in the -9A I have an O-320 with dual EI. If all out performance is the key, I agree FI is the way to go.

Fuel flows are from my Dynon EMS flowscan which is very close at each fill up and TAS is from my D10A that I calibrated and verified with the help of Kevin Horton (thanks again, Kevin).

Filled up on Pancakes and 100LL ($3.49) this morning at the Amery, WI fly-in - so I used that for a fuel price.

Here are my favorite places to run my engine depending on what I am doing. GMC-George is right, the key to savings is using the red knob every chance you get.

- 7500 ft WOT/2300 to go places

- 21.5/2200 to fly locally

- 16.5/2200 when just smashing bugs with my daughter

 

[Kevin Horton]

Yeah, I figured that would kick things up a notch. Just messing around. Hey, how about Tracy Saylor or Dave Anders? Did/do they run a hopped up O-360, or were they IOs? I honestly don't know. Something tells me those guys ran carbs, but I don't know the details.

I don't know about Tracy Saylor, but Dave Anders' RV-4 has a modified IO-360-A1B6. Details at Cafe Foundation.

 

[gmcjetpilot]

Yep, but no on the GO

Yeah, but if you fly around full rich (or relatively rich) you're probably racing. And if you're racing, you'd be out of your mind imho to go with a carb if you have a choice. How many RVs and Rockets that win the races have carbs?

This is splitting hairs but........

Carbs are not slow, that has never or never will be an issue. Most drag cars have what, Carbs. In theory FI could in theory make a HP more or two more at most (due to better fuel distribution), but it's unlikely to make much difference in power when running full rich (full power). When you are racing, running full rich, small variations in fuel distribution makes little difference in power.

However when lean, a little better fuel distribution does translate into a little fuel savings of a few percent (your milage may vary). As pointed out by my fellow Carb buddies, Carbs still do a bang up job, even in econ mode and are simple (possibly less maintenance).

Yes Tracy Saylor has a Carb and Dave Anders FI, again it does not matter when it comes to making power.


My point is either FI or Carb, if the pilot is not judicious with that black and red knob it really does not matter. A guy who can really manage his plane and engine well will win fuel burn contest. Speed wise no super advantage with either.

I use to be a Carb guy but the nod goes to FI overall now, no debate, in my opinion (if not on super tight budget). FI set-up use to cost way more than a Carb, but now its only a $1000 option at most if going with a new set-up.

When gas was a Buck-n-half, the FI potential advantage in fuel savings was not a big deal. The cheaper carb set-up was the way to go in my opinion than. Now with fuel so high, FI gets the edge in my opinion. Plus as a bonus you get away from any Carb ice issue.

Still a Carb is simple, works and is fast. I have a Carb and love it, but I bought a used O-360, making the decision easier. I would not swap out an existing Carb set up due to cost, about $3,000.

 

[Ron Lee]

Cylinder flow matching

RV7ator, that issue is one that is hard to get factual info on. Places like Performance Engines feel that it is useful and Light Plane Maintenance had an article extolling the process. Is that the only mod to your engine or did you go to higher compression pistons and high performance camshaft?