don_w
Dyno Numbers - Who Cares?
+1... but I never actually look at that display.
What doe the bars on the instantaneous fuel economy gauge mean?
- Thread starter Chris B.
- Start date
You artificial air pushing/pulling guys have a bunch of fancy, snazzy gages you need to pay attention to - fuel economy should be the last thing on your minds.
ixtlan
Senior Member
Chris your gonna love this post.
Especially since you made it into the Tech Thread of the Day.
And you slammers are gonna feel sooo doltish (Ya ya can look that word up too).
Someone actually hit the bar thing right on the money.
It is Vacuum!!!!
In the 70's this was a bit of a fad in the Hot Rod industry.
But we used tubes filled with iodine as our "Measurin Sticks".
The higher the vacuum the better the mileage, The lower the worse.
It is actually a little bit handy if your trying to pull some mileage out of the car.
But we used it back in those days to give us an indication of our throttle opening.
Now think 4bbl carb and secondaries. Especially Vacuum Secondaries.
Low vacuum (small bars) equates into low air flow into the engine and therefore less fuel draw. The vacuum effect is less or supply for air is more than the engine can draw in for the given instant in time.
In the carb world that meant the secondaries were opening too soon and the mixture may be too rich.
In these modern cars it is more of a supply exceeds the demand gauge.
Sort of a holdover from the true Muscle Car era, and a mileage detector.
Now you know "The Rest of the Story".
Especially since you made it into the Tech Thread of the Day.
And you slammers are gonna feel sooo doltish (Ya ya can look that word up too).
Someone actually hit the bar thing right on the money.
It is Vacuum!!!!
In the 70's this was a bit of a fad in the Hot Rod industry.
But we used tubes filled with iodine as our "Measurin Sticks".
The higher the vacuum the better the mileage, The lower the worse.
It is actually a little bit handy if your trying to pull some mileage out of the car.
But we used it back in those days to give us an indication of our throttle opening.
Now think 4bbl carb and secondaries. Especially Vacuum Secondaries.
Low vacuum (small bars) equates into low air flow into the engine and therefore less fuel draw. The vacuum effect is less or supply for air is more than the engine can draw in for the given instant in time.
In the carb world that meant the secondaries were opening too soon and the mixture may be too rich.
In these modern cars it is more of a supply exceeds the demand gauge.
Sort of a holdover from the true Muscle Car era, and a mileage detector.
Now you know "The Rest of the Story".
I think you have that backwards. More vacuum equals better fuel economy. More throttle = less vacuum= crappy mpg's.
Back on topic though, I don't pay much attention to the bars either. When I look at that stuff I click over to the average mpg selection
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