945LSTANG

i can push start my car so i have no clue what youre talking about.

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GreyStang

I think what hea means is.. you can't push start an EFI car if your battery is competely dead.

No battery = no ECU = no start

67mustang302

EFI is not a better system hands down. For those of you who don't know much or anything about how carbs REALLY work, you need to stop dispensing advice, because it's wrong.

Carburetors have several advantages over EFI and EFI has several advantages over carburetion.

EFI is obviously more precise at metering fuel, which helps with power production but also with emissions and mileage. EFI cars are MUCH less sensitive in operation to how a car runs on a dyno vs the real world, so you can dial the tune on a dyno and it's pretty much good to go, adjusting in actual driving to reach optimum.

Carbs on the other hand aren't quite as precise at fuel metering, but a good carb with a good tuner can get them REALLY close. Their biggest drawback is that they are totally at the mercy or the person tuning it, so it's never going to run any better than that person can get it to. Their very slight imprecision in metering however is more than offset by their power producing advantages. Carburetors emulsify fuel before they introduce it into the airstream, so the fuel is closer to a vaporization point, and fuel needs to vaporize to combust properly and completely. Also having the fuel in the intake gives it slightly more time to atmoise homogeneously, which also leads to better combustion, and the emulsion helps with atomisation as well. They also take advantage of the Joule-Thompson effect, which helps to give them a slightly denser air/fuel charge.

All things being equal, carburetors generally will make a bit more power, and EFI generally will get better mileage and emisions. They both have excellent drivability, the proper carburetor set up properly will have every bit as much drivability and throttle response as an equivalant EFI setup. Carburetor setups are cheaper when starting from scratch and are more reliable since there's less to go wrong, but again, are at the mercy of the meat-head who's working with it. EFI is more user friendly, especially these days with good carb tuners being hard to find. Most shops now can tune EFI cars, or you can buy canned tunes.

For anyone who is considering a carburetor setup, I give the same advice, if you don't understand how a carburetor really works or you don't know someone who does, then you might want to stay away from it. A carb's advantages are only realised by someone who knows how to get them to work right.

GreyStang

That's a great summary '67! [8D]

A question about this part...
I guess a throttle body fuel injection system would take advantage of this concept just as well as a carb? But the advantage must not havebe enough reason to keep that setup, because (I think) all EFIcars now are port injected?

67mustang302

Yes, throttle body injection does have that same advantage. All factory production vehicles are port injection these days, but Formula 1 cars run throttle body injection with individual injectors and stacks for each cylinder. So on an F1 car they tune each individual cylinder like a port injection running MPFI but it's a TBI system. Those are the only EFI cars in the world I'm aware of that can match or exceed the efficiency levels of NHRA Pro Stock and NASCAR Nextel Cup engines, both of which are carbed. All 3 are naturally aspirated.

The one biggest drawback to a TBI system is that a wet flow intake like a carburetor setup, though it has advantages, has disadvantages as well - airflow velocity in the intake. Both carb and TBI require the intake charge to maintain high velocity and/or have high vacuum, without which the fuel can fall out of suspension from the airstream and splat against the intake runner wall/floor and collect into fuel puddles. It either plates out onto the runner and you get a dry air charge into the cylinder resulting in misfire, or wet fuel dribbling into the cylinder which may also result in misfire, and sometimes fouled plugs. That's the single biggest reason that carbed cars with large intakes and carbs often run like dog poo at low rpm. The velocity is so low that the fuel either atomises very poorly, or starts to fall out of suspension. Power is lost from extremely poor combustion.

blake77

CARB!!!!!!!!!!!!!! first off htey r really easy to work onim a 14 year old kid who races stock cars i tookmy carb offmy 65 289 cleaned it took it apart looked at it and put it back it n0w runs 5 times better than it did b4
u can save gas with 4 bolts and a couiple lines by puttin ga 2 barrel also u can gain hp with a 4 barrel
u can also save gas by using smaller jet
name 1 racing series that dont use a carb
ok the asians drift with a fuel injected just because they can play with computers and change almost every thing with it
they neaver but a nuckel
carb all the way

GreyStang

Top Fuel drag racing. The highest horsepower (ground) engines on the planet

67mustang302

The fuel injection system on a Fuel car though is a totally different animal. They run injectors and pumps that dump fuel into the cylinders like a firehose, and that is not an exageration. EFI is used a lot in racing, but so is carb. Properly set up, either system can be competative.

JD1969

Yea we could tell by how you type.
Many race series have rules that mandate a carb. Nextell Cup teams would love to use fuel injection, I bey the Pro Stock guys would as well.

strangedemon

if your wanting to be a decently somewhat economical daily driver go with efi. For extreme power and ball haulinggo with carb, your not going to be unsatisfied either way so really it doesn't matter, you want a big airfilter under your hood to look at or a large intake manifold with an inlet tube to look at haha