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bgd73 06-08-2010 06:00 PM

down the gasoline trail (1935)
75 year old film, explaining basics of a carbed gasoline engine.. with a cartoon.
75 years later, I am still hypermiling with their concept, on a 23 year old carbed engine, never rebuilt yet.

to sum it up:
cold fuel, last minute expansion venturi (claims of faster than the speed of sound) where it gains air, expands, runs through warm intake... and burns.
today, injection kills venturi, there is no atomization, gadgets pretend to be on top of it natural transformation into super stoichial.

any arguments?
love to chat about this. it is not even funny anymore.:rolleyes:

dcb 06-08-2010 06:14 PM

ok, vacuum computers are painfully slow compared to electronic ones. They don't make a whole lot of o2 sensors that output in vacuum so you have to add electronics to a carburetor just to make a rough approximation of stoich.

A wideband o2 sensor with the right EFI software can hold stoich, or any mixture that makes sense, over almost the whole operating range. A pure carb cannot adapt, if you change elevation you run lean or rich. If it is moist out, your mixture is affected, or if the temperature changes, or if the composition or temp of the fuel changes.

feedback is a good thing when done right. and a EFI can also "lead the target" in some cases, rather than lagging the airflow, with some random amount of additional fuel squirted in when you move the pedal.

I'm not saying all EFI were done terrifically, but all were able to pass emissions that a carb couldn't touch, due to much finer control over the fuel delivery.

NeilBlanchard 06-08-2010 07:34 PM

Another point is that fuel injection can be shut off for downshifting, and this saves fuel. The mixture can be adjusted for elevation/atmosphere pressure change. The mixture can be adjusted for air/engine/exhaust temperature. What about detonation? What about tuneups? Most modern cars can go 100,000 miles without a tuneup. It doesn't really matter how dirty the air filter gets (within reason).

I can tell when I'm driving behind an old car, without even seeing it -- the smell of raw gas/rich exhaust is pretty obvious on lots of old cars. Most of these around here anyway, are very well maintained/fully restored "classic" cars, so it isn't that. Most carbureted cars are not designed for economy/efficiency -- gas was 29 cents for about 25 years, right?

The last carbureted car that I owned was a 1970 Volvo (twin Strombergs) and by the end of the car's life, it was burning up the paper air filters (by backfiring) and I never heard it. It had a manual choke, that you had to learn how to use.

The next car I owned was a 1987 VW Golf, which had EFI. The engine was virtually flawless, and lasted a lot longer than the Volvo.

dcb 06-08-2010 08:12 PM

lol, the choke, what a rig :)

jamesqf 06-09-2010 12:16 PM

I remember the problems I'd have trying to get my older carburetted cars to pass their emissions tests. Had an '85 Toyota pickup that I'd done a lot of work on (over several years) - rings, valves, rebuilt carb, replaced all the vacuum lines - and it'd still barely squeak through. Also had some interesting times starting in cold weather, or after being parked for a month or two.

Finally traded it for an '88: almost exactly the same truck except that the engine is EFI. Have done no engine work on it in the four years I've had it. Goes through smog checks with numbers way at the low end of the range, and starts first time, every time.

Oh, yeah, and then there are the joys of mixture control (and carb icing, though that's seldom a problem here) on a carburetted Piper Cherokee...

gone-ot 06-09-2010 09:59 PM

...hmm, I wonder what the ECU equivalent of "CTRL-ALT-DEL" is?

dcb 06-09-2010 10:12 PM

I'm confused? Do you think every electronic device is running windows?!? ;)

mpgx2 06-10-2010 09:10 AM

FYI, ctrl+alt+del is a pc interrupt.. and Car ECU's do have interrupts..

Who told you CTRL-ALT-DEL is part of windows? It isn't.

CTRL-ALT-DEL works under Linux too on a PC, did you
ever bother to try it?

It's actually implemented as a hardware interrupt on the
PC environment.

Car ECU's do have interrupts, but perphaps not mapped
to that key combination, because last time I looked, few
cars have keyboards built in. So it makes no sense.

Car ECU's do have a point where *they do* need to
be reset. It is called an error condition.

If one of these error condition occurs the car/ecu needs
to go to the mechanic to have the code reset. This
happens commonly on German cars because they use
that system a lot.


dcb 06-10-2010 10:41 AM

I was kidding around with Tele. Not looking for a history of the pc lecture in the middle of a carb vs efi thread , but thanks.

jamesqf 06-10-2010 02:29 PM


Originally Posted by Old Tele man (Post 178335)
...hmm, I wonder what the ECU equivalent of "CTRL-ALT-DEL" is?

Turning the key off, of course :-)

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