Gas mileage...?

[CHARGERMAN2007_69]

i have a 71 charger and it has a 400 4bbl   i get 8

[Lost Sheep]

I got a 68 Charger with a 383 2 Barrel and an automatic.......... (i dont recall gear ratio) but I can usually get about 16-18 out of him(i drive 60 usually unless im in a hurry).

[learical1]

In the old days, my Hemi SuperBird would average 16 mpg on the road trips (Phoenix to LA and back, Phoenix to Denver and back.)  Stock 3.54 Dana, F60-15 bias plies.  Unless I found some loony in a 280Z that thought he was bad.  Mileage would plummet once you got off the primaries of the rear carb and opened up all 8 bbls.  Of course, that was when you'd put in a quarter tank of leaded regular along with 3/4 tank premium unleaded.  (and get change back from your $20)  

[69charger2002]

I just dug up a receipt from my trip over to St. Louis last year. In my 69 Charger 500 with a 440 and 4.11 rear gears, I averaged 12.9 miles to the gallon on the interstate cruising at 70 mph.

My car ran on the gas fumes from your car all the way home... Mine dropped to around 22 that trip - must have been the turbulence.

Troy

wait wait wait.. the cuda gets 22 mpg? or were you in a dodge stratus? 
trav

[Troy]

I just dug up a receipt from my trip over to St. Louis last year. In my 69 Charger 500 with a 440 and 4.11 rear gears, I averaged 12.9 miles to the gallon on the interstate cruising at 70 mph.

My car ran on the gas fumes from your car all the way home... Mine dropped to around 22 that trip - must have been the turbulence.

Troy

wait wait wait.. the cuda gets 22 mpg? or were you in a dodge stratus? 
trav

It used to get 23+. That's on 89 octane too. What'd you do to it?

Troy

[Rolling_Thunder]

27mpg on the highway...     1970 Superbird    440 six pack   OD 4-speed   and 3.54SG Dana     

[oldcarnut]

Looks like most responces are from carb. engines.  Has anyone that converted over to one of the FI kits noticed a mileage increase from the changeover that makes it worth the installation cost?. 

[69charger2002]

I just dug up a receipt from my trip over to St. Louis last year. In my 69 Charger 500 with a 440 and 4.11 rear gears, I averaged 12.9 miles to the gallon on the interstate cruising at 70 mph.

My car ran on the gas fumes from your car all the way home... Mine dropped to around 22 that trip - must have been the turbulence.

Troy

wait wait wait.. the cuda gets 22 mpg? or were you in a dodge stratus? 
trav

It used to get 23+. That's on 89 octane too. What'd you do to it?

Troy

well the main problem is that in 2 months i don't think i've run a complete tank out of it lol. but if it gets 23, man that's better than any vehicle i own bar none!
trav

[mikesbbody]

I don't even look anymore.

The way I look at it is
It's a weekend having fun thing for the most part with collector plates so I just look the other way when filling it up at the gas station.

It's a hobby

I couldnt agree more! if it were a serious problem for us, we wouldnt be into these cars  interesting to know though. I dont know what my gas mileage is (warmed over 440, auto, 3.55's 28 inch tire) i just tell people 8-12 mpg does that sound about right? 

[Mike DC]

I think EFI tends to buy you about 2 mpg over a carb on a mild street motor.  That's assuming a port-injection EFI setup and comparing to a carb that is tuned & sized very well. 

In the real world of street cruisers, I wouldn't be shocked if it was at least 4 mpg on a muscular 440-500" big block.  EFI really starts to show the difference if you drive the car in varying weather/altitude/temperatures, and if you do a lot of short trips around town when the motor isn't really warmed up.


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A lot of the EFI gains come from just getting separate "barrels" for each cylinder with the port-injection setups.  I don't think the throttle-body EFI setups are worth the conversion costs because they're much closer to being a carb in that sense. 

And more of the gains come from the fact that the motor is being tuned for various temps & altitudes.  With a carb, you have to pretty much pick one setting and stick with it until you climb under the hood again to change something. 

Carbs have to always err on the side off too rich whenever anything can't be perfect so that you don't hurt the motor.   That goes for varying coditions as well as varying amounts of airflow to different cylinders because of the engine's manifold shaping. 

This is one of the reasons that race cars don't always see the huge benefits from EFI conversions:  Race motors are wrenched on a lot, and they're set up to be already pretty near their peak efficiency with the carbs.  EFI's benefits are much more about bringing a motor's average efficiency up closer to peak efficiency all the time.  Much more relevant on a daily-driver motor that you run in varying conditions and don't retune all the time.   

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EFI allowing leaner settings on average, it also means the cylinder walls don't get fuel-washed as much.  Way better for long-term wear on the cylinder walls.  (This issue has a lot to do with why modern motors can go 150,000 miles without showing much bore wear.)