Cant we invent carburetors that atomize fuel as good as fuel injectors by now?

[The motor guy]

Maybe they do, just on things with more lax emissions requirements. I know on my ztr mower parts of the carburetor are like ice cold. I just forgot the name of the area that gets cold, so maybe they already do a good job at atomizing the fuel

 

[Nick1994]

TBI?

 

[The motor guy]

TBI?

Oh...is that as close as we got? Guess we did that 40 years ago

 

[eljefino]

Atomize? Yes. Control the amount and exact timing? No way.

 

[demarpaint]

With the big push to go green, I doubt there are many companies that want to waste the time or the money to do so. Especially for small engines used for things like OPE.

 

[97prizm]

Maybe they do, just on things with more lax emissions requirements. I know on my ztr mower parts of the carburetor are like ice cold. I just forgot the name of the area that gets cold, so maybe they already do a good job at atomizing the fuel

The biggest thing is you'll never have is the efficiency on a carburetor that you'll have on fuel injection or direct injection. Plus add in computers which helped immensely as computers are always tuning the engine several times per second.

 

[Astro14]

Atomization in a carburetor happens from vacuum pulling the fuel through an orifice.

Atomization in a FI system happens from pressure pushing the fuel through a smaller orifice. DI has even high pressures.

So, with the pressure advantage of FI?

Nah, carbs will never get there.

 

[vwmaniaman]

I know history has erased the Motorcraft variable venturi carb but I had one one a land barge Ford Country Squire station wagon I think in the early 80's. It was a company car and On the highway that thing would get over 32mpg with a 302 v8. I heard of people getting 50+ mpg in the smaller cars with that motor and carb . That was an amazing combination since it performed flawlessly and returned great performance and mileage.

 

[Cujet]

I know history has erased the Motorcraft variable venturi carb

Motorcycles used CV (constant velocity) carbs for years and I believe there are still a few models that may have them (Suzuki DR650 for example). They have a variable venturi and do provide better control over the air/fuel ratio than conventional fixed diameter venturi carbs.

I don't know that I noticed any massive gain in MPG with them. I did notice a decrease in throttle response when compared to a conventional carb. We would try all sorts of tricks to make the vacuum operated slide (variable venturi) pull up or open faster.

These carbs did not work well for hard core dirt bike riding, such as a dual sport bike ridden on a motocross track, as the slide's weight would 'close' the carb when landing from a jump. Causing the engine to lose power just when needed and when traction was highest.

I converted my KLR600 from a Mikuni CV carb to a conventional Del'Orto pumper carb of the same size. The difference was remarkable. The variable venturi carb was not ideal for good performance.

Back in college, I had a '66 Mustang with downdraft Weber carbs. They worked really well with stunningly great throttle response, they would ice up though. MPG was acceptable, and peak power was on par with a single plane intake manifold and big Holley carb, with much better low end and no bogging. Today, the setup is again popular, and my old college roommate's brand new 347 cubic inch Ford small block makes a solid 550+HP.

EDIT: I guess my point is that such carb setups can be designed to provide even fuel distribution for each cylinder. And/or can be designed to provide excellent atomization. 2 strokes often use very crude carbs with great results. The air/fuel movement through reed valves, around the hot crankshaft, and through hot transfer ports helps with atomization.

 

[Cujet]

 

[b_b]

everything was computer controlled injection when I was growing up, so I've never had much experience with carbs. small engines had them, but I wasn't old enough at that time to really understand. my lawn equipment has carbs, but I've never had to work on them to learn.

 

[spasm3]

A carb can't adjust for varying barometric pressures and temperatures like FI can.

 

[Propflux01]

GM almost did it with the Computer Command Control carburetor. They actually worked pretty good for the time once you understood how they worked. Putting them with today’s electronics and sensors would probably work even better.

 

[emmett442]

Carburetors atomize fuel VERY well, and even have an advantage in that the fuel/air mix moving through the low pressure is cooled dramatically.

On the dyno, a properly set up carb will actually outperform FI, even if barely.

It's the difficulty in adaptability and maintaining precise control that hurts it for mainstream use.

 

[Burt]

Can’t we invent vinyl records that last as long as digital recordings? How about a filament light bulb that is efficient as LED? Why?

 

[KrisZ]

Carbs have no problems with atomizing fuel, that's a common misconception. Motorcycles probably took the cab tech the furthest and when many models switched to FI they actually lost HP and we started seeing choppy throttle and unpredictable response.

But FI is much better for emissions and fuel economy, so naturally manufacturers dropped carbs.

 

[Mechanician]

Even with a perfect carburetor, the intake manifold couldn't deliver the perfection.
It's nearly impossible to deliver the mixture evenly, to all the cylinders.
You could put a carb on each cylinder, like a motorcycle. But then you have to tune/match the carbs, instead of the intake runners.

 

[KrisZ]

Even with a perfect carburetor, the intake manifold couldn't deliver the perfection.
It's nearly impossible to deliver the mixture evenly, to all the cylinders.
You could put a carb on each cylinder, like a motorcycle. But then you have to tune/match the carbs, instead of the intake runners.

You still need to do the same with the throttle bodies. FI doesn't solve this problem.

 

[D60]

A carb can't adjust for varying barometric pressures and temperatures like FI can.

As someone who immediately saw the advantages of EFI growing up on the trails of CO, this would be my concern.

I had my Ford EEC-IV at sea level on the PCH and at 14,100 on Mt Antero. It always just ran like a clock. It would start immediately at -20F or 110F.

I have to wonder if some of today's backlash is more because of CAN-BUS etc. A standalone EFI system is really not complicated and typically dead-reliable. All you really want your PCM to do is control stoich and maybe shift points. The rest is just humans meddling because we think we're smart and WE CAN.

 

[72C10]

Carburetors can be tuned decently enough, I think for many cases, but generally they just aren't tuned well at all. It seems almost every time I'm around a classic vehicle with a carburetor, you can smell the excess fuel burning.