Revving high reduces fuel consumption?

[Christ]

Hmm... you could also have something partially blocking your jets, making you run leaner at higher RPM..

That or your fuel system might not be flowing as much as it could... either way, you want to be careful of leaning out while revving high.

[guudasitgets]

The advantage to injection is that IT is run and adjusted by a computer. A carb is run and ajdusted totaly dependant on manifold vacuum, which is why they are less efficiant.

[MetroMPG]

Much different drivetrain (obviously), but FYI:



And:



Source: Showdown: testing RPM vs. MPG at a fixed speed - MetroMPG.com

[Christ]

Originally Posted by guudasitgets

The advantage to injection is that IT is run and adjusted by a computer. A carb is run and ajdusted totaly dependant on manifold vacuum, which is why they are less efficiant.

and yet, there are still older carb'd cars that get better gas mileage than FI cars do w/ the same engines.

Weird.

I totally prefer injection and an ECU... but in some cases, I'd rather have carbs.. it's just ideal to have a carb on a lawnmower instead of 300lbs of FI apparatus, ya know?

[guudasitgets]

and yet, there are still older carb'd cars that get better gas mileage than FI cars do w/ the same engines

Ya, name one?

[Christ]

Ford Escort/Mercury Lynx/Lincoln Bobcat vs. Ford Escort FI/Mercury Tracer

I chose these cars because they still ran the same series of engine, regardless of the induction type used. Some were 1.6, some were 1.9.

Of course, this claim is based on my experience, not what the EPA says. I could give a damn about the EPA's estimates, they've never been correct in my experience.

They're (at best) an average based on what the NTSB says people are doing while they're driving.

[guudasitgets]

I had carb versions of those for fleet use, my brother still has his fuel injected escort theres about a 2 to 3mpg better fuel burn, but the later escorts had 1800. Carbs are not as efficient has EFI, that goes without saying. If were baseing this on what you got from your car, we have no way to varify it. The data is out there on the escort take it or leave it but there are plenty of them to compare. So that car choice is out. Got any other guesses?

[Christ]

Properly tuned, I agree that carbs are not as efficient as injection... FI can use leaner mixtures to achieve the same result.

I'm just saying in stock config, nothing changed, I got 40+ in my carb'd 1.9 escort, and less than 35 in my FI 1.9 escort, both wagons.

The part that really concerned me was that the FI version of the escort has better (visually) aero. I never compared the Cd, because back then, I never really cared.

[93Cobra#2771]

I'll wager when you compare the weight difference between the old and newer escort, you will find the culprit. I did have a bookmark showing weights of different year escorts but I'm not sure where it went. I want to say there was at least 100# different.

Often, as carbed engines age, their a/f will start going leaner (vacuum leaks will cause this often). A carb cannot compensate for a vacuum leak, while FI can and often does compensate.

[Christ]

Originally Posted by 93Cobra#2771

A carb cannot compensate for a vacuum leak, while FI can and often does compensate.

I know that to be true from my Honda... and there are times I wish it didn't.

PS, I didn't really factor the weight into it, It didn't seem that much different.