Carbies and Throttle Bodies

[matty88]

What's the main differences between the two? I know that carbies can go on any car that doesn't have an ECU. Does the TB mix the air and fuel just like a carbie?

[Burt_vn]

Well the throttle body just sends air into the cylinders, and the fuel is injected directly to the cylinder. In a carby, the flow of air moving through the carby creates a vacuum which then sucks the corresponding amount of fuel down with it. Thats why it doesnt need an ECU. I'm not even sure i answered your question, but oh well.

[DANNY8]

I wouldn't say a throttle body sends the air into the cylinders,..it just lets a certain amount through depending on how far it's open.

[Burt_vn]

Just my way of explaining it to someone who doesnt seem to mechanically minded. Obviously its point of entry is the valves, but hes not asking about valves, i meant it as a comparison to a carby, which takes the fuel with the air, and how a throttle body only controls the amount of air getting into the engine, and the computer then adjusts the amount of fuel injected.

[Not_An_Abba_Fan]

Throttle bodies are found on EFI and Diesels and carbies are on well....carburetted cars. The throttle body has a butterfly that opens and closes when the accellerator is depressed and lets in the corresponding amount of air to match the fuel being delivered through the injectors. A carby works on engine vacuum, it also has a butterfly, or two and even 4, in the case of twin throat and quads that adjusts the amount of air let in and that teams with a plunger, jets and atomising nozzles to suck the fuel into the engine.

Not a very technical explanation but hopefully understandable.

[matty88]

I get it now

The throttle bodies seem very large, although the fuel ingetcors must pump a hellova lotta petrol.

[shaggerz]

Throttle bodies must be quite large yes... remember that you need 14.7 times more air than fuel for complete combustion!

I recommend http://www.howstuffworks.com

That site has answered so many of my questions check out the Auto section.

Heres a couple relevant to the topic...

http://auto.howstuffworks.com/question377.htm - how carburetor's work

http://auto.howstuffworks.com/fuel-injection.htm - how fuel injection works

http://auto.howstuffworks.com/engine.htm - how car engines work

There is a massive amount of information on that site that tells you just whats what in words that you can understand... I love it hehe.