Dumb question - What are the advantages of a carb engine?

[Shadrach]

10 hours ago, DCarlton said:

I never check my fuel pressure during hot starts (since I don't use the pump).  I'll start doing that now.  Curious thanks.  

You don’t need fuel pressure for a hot start. The fuel that is starting the engine is downstream of the spider. it has already been purged from the lines and into the manifold.  I’m sure you’ve heard the squirting sound from the top of the engine after shut down. That sound is the fuel boiling out of the injector lines and into the manifold.The heat is ostensibly pre-priming your engine.

Edited July 2, 2021 by Shadrach

[DCarlton]

20 hours ago, carusoam said:

The challenge with automotive fuels… the unknown alcohol that may get in the system….

All of our rubber bits… seals and sealant make this a NoGo….

 

As far as why I bought the carb’d M20C over the M20E when I had the chance…

The M20E cost 10 AMUs more than the M20C… in Y2K dollars…

 

The M20E… with a decent engine monitor….  Produces 10%more hp than the M20C, and is fun to run LOP…

 

I kept my CB status for a very long time… 

Best regards,

-a-

I actually buy the non-ethanol fuel for my boat for the same reasons mentioned above particularly when the ambient temps are 100-120 degrees.  Volvo fuel pumps are too dang expensive and vapor lock and hot starts can suck too.  

Some folks may think this is a lame question but I was actually surprised that you could buy a new airplane with a new carbureted engine.  My head started turning... Why?  Do folks want this if they live in remote locations and may need to use MOGAS?  Is starting more reliable if you're landing in remote locations?  Or is it about upfront, operating and maintenance costs.  The benefits of fuel injection seem far more obvious.  But hey, I haven't swapped the carb on my old Camaro to FI either.  

[carusoam]

So many choices…

So many costs…

So many things that just work well… enough…

Learning about carburetors is pretty challenging…

Adjusting airflow and fuel flow per cylinder is pretty challenging…

Knowledge about air distribution for your engine is hard to come by…

Having a decent engine monitor and getting data out of it helps…

 

Lots to take in…. Not everyone is that interested…

Best regards,

 -a-

[A64Pilot]

Specifically to the Maule, any aircraft that can be put on floats needs to start right now, as your floating down river backwards heading for a tree overhanging or just maybe rocks, you don’t want to be playing hot start games.

Secondly a carb if your in the boonies is a whole lot easier to clean or work on period, if your a high wing airplane often with a carburetor you don’t even have a fuel pump, the fuel just drains into the carburetor. (Maule’s however have fuel pumps, two I believe for the auto gas as well as an additional air scoop I think.)

Maule’s specifically were designed to be easy and cheap to maintain, the wings and flight control surfaces are put together with hardware store pop rivets for example, there is no plastic inside of the airplane, the interior is like a 1060’s car, as such they don’t look as modern, but if you live in the boonies, they are a whole lot easier to maintain with simple tools

However my Maule was an IO, and I liked my IO, it made 235 HP a couple of hundred RPM less than the carb 540 did, my redline was 2400, the low compression carb motor took 2600 to make the same power I believe. The higher compression motor burned slightly less fuel too, high compression is more efficient as can be seen by its lower EGT.

An older test pilot friend worked at University of Tn flight dept years ago and they flew a C-310 in testing with one engine running (gasohol) what auto fuel with Ethanol was called back then and he said it ran fine. I assume there were some fuel system mods to deal with vapor lock, but the engine ran just fine, he just flew it and I don’t think he knew if any timing adjustments etc were made or not.

‘I may have heard of someone who more as an experiment than anything else ran his IO Maule with alcohol free high test in one wing and 100 LL in the other, made takeoffs on 100LL. He experienced no difference in running, but he did run ROP and no differences at all, until he re-fueled at Deland on a Summer day and experienced starting difficulties. he was still on auto gas when he shut down.

On restart the fuel PSI was bouncing around so obviously vapor lock 

‘My personal belief is if 100LL becomes not available, our NA Lycomings can run off of 93 Octane car gas, if we reduce timing by a few degrees, and maybe limit manifold pressure?

Edited July 2, 2021 by A64Pilot

[A64Pilot]

Oh, and pressurized carburetors make a carb motor so they can pull neg G’s, and there is a whole lot more to it than that, go pull neg G’s in your Mooney and after landing you will see oil streaming down the left side all of the way to the tail. 

Yes, the Spit in its original form was actually a pretty primitive airplane, it was a old design.

Ref the Spitfire, the BF-109’s would have torn them up if not for two American modifications made just before the battle, first was a constant speed  prop made under a US license, (Hamilton Standard) prior Spits ran fixed pitch props, or some two speed maybe even wood props?

Secondly was 100 Octane fuel, the high Octane fuel really allowed the Merlin to come into its own, I think it increased speed by 15 kts?

Later on the German’s discovered the 100 Octane fuel, but the Daimler engine couldn’t make enough boost to make its use worthwhile. The German’s ran Nitrous Oxide for a quick emergency boost

‘The Merlin was made in the US of course later by Packard, and Packard made some changes and it was considered a better motor than the original RR Merlin, it’s a whole lot easier to improve an existing design that it is to develop it from scratch. Packard built I think over 55,000 motors, they weren’t Merlin’s they had a different designation V-1650’s or something 

Edited July 2, 2021 by A64Pilot