Let's Talk Miles per Gallon (Or Gallons per Mile)!

[wedg2go]

Before anyone beats me over the head and shoulders over this subject, "Yes, I know! I didn't buy my big block Challenger for gas mileage." However, look at this subject more as comparing "Apples to Apples" and nothing more.

Of course everyone should chime in on this subject in order to compare with other Mopar Brethren. Slant six owners all the way up the ladder to the mighty 426 HEMI. This subject should be interesting to most of us.

I'll start.

1970 Challenger R/T
4 speed
3.91 Ratio
440 Six Pack with - Stage III cast iron heads, Edelbrock intake, Comp Cam with .544 intake valve lift and 286 duration, all roller assembly, Hooker Super Comp Headers.

Best mileage to date and on the long stretch = 6 miles per gallon.

Future endeavors will find me jetting the inboard carb 3 sizes down since I brought it from 30 feet above sea level to 7300 feet above sea level. I just don't see this machine getting better than 8 mpg. None the less, I'm "Ok" with that...

 

[Mopars & Missiles]

Are you by chance running that engine without vacuum advance hooked up?

My '70 R/T SE is an auto trans with B&M converter 2400 rpm stall, 3.55 gears with a 383/426 stroker, 906 iron heads, 9.6 to 1 compression ratio, edelbrock performer RPM #7186 intake and #1407 edelbrock carb. Cam is Hughes flat tappet hydraulic #HEH2328BL with 223* intake, 228* exhaust duration, 539" lift intake, 558" lift exhaust. Stock cast iron exhaust manifolds. Ignition timing is about 15* initial, 35* w/mechanical all in by 2200 rpm, and 55* w/vacuum at cruise.

With this, my "mileage" is at 10 - 12 mpg with normal cruising/driving. With foot heavily engaged, more like what you are getting, mostly due to a lack of traction.

 

[wedg2go]

I am running a MSD setup. No vacuum. I do know the total is at 35 (so I was told when I bought the car) and where the initial is set is anyone's guess (Another thing todo when the snow starts flying).

 

[tonysrt]

71 Cuda, 472 Hemi, Dana 3.54, tremec 5 speed and 2 4barrels approx. 8-10 on a good day.

 

[dadeo1852]

70 Challenger R/T
440 six pack
4 speed
4:10 Dana
Stock heads/manifolds, same Hughes cam as Mopars & Missiles but 1.5 rockers
8-10 mpg if I stay off the highway, 6-7 on highway @ 55mph cranking rpms

 

[340challconvert]

Once owned a Challenger 440-6, automatic w 4:10 Dana, averaged 10-12 mpg totally stock settings, driving easy. Getting on it, dropped to 7-8. I once took it to a deserted industrial area to “try it out”. 8 runs at a quarter mile runs for fun and went through most of a tank of gas. Also ripped the left motor mount loose. Ah, the good old days!

 

[DetMatt1]

I don’t know what kind of mileage my Challenger gets since the rebuild because I don’t really drive it that much. My Imperial however has a bottom end that’s never really been apart and now has around 155K mikes on it, fresh 915 HP heads, a cam equivalent to a stock 375 hp stick, original log manifolds with dual exhaust with H pipe, cast iron intake with an Edelbrock 1411(for now) and Pertronix 1 ignition. It has 2.94 axel ratio which is perfect for the 4,800 lb coupe and I’ve put over 20K miles on it in the past 5 or 6 years with an average mileage of about 11 in the city and I think the best I did on the highway was 17 on one of the extended road trips we’ve taken in it.

 

[ebody70]

LOL Im jealous off all you guys , my 528 Hemi gets 3.5 mpg

 

[todd383]

I have a 383 stroker to 489 cu in, it has 580 hp and 615 tq, pump gas motor, 355s and 4 speed, 950 street hp Holley carb, I get 16 mpg!!!! I did not go crazy with a cam, I kept it mild, And I have vacuum advance hooked up. I also tuned it on a chassis Dyno.

 

[DetMatt1]

I have a 383 stroker to 489 cu in, it has 580 hp and 615 tq, pump gas motor, 355s and 4 speed, 950 street hp Holley carb, I get 16 mpg!!!! I did not go crazy with a cam, I kept it mild, And I have vacuum advance hooked up. I also tuned it on a chassis Dyno.

That’s impressive!

 

[budascuda]

I have a 383 stroker to 489 cu in, it has 580 hp and 615 tq, pump gas motor, 355s and 4 speed, 950 street hp Holley carb, I get 16 mpg!!!! I did not go crazy with a cam, I kept it mild, And I have vacuum advance hooked up. I also tuned it on a chassis Dyno.

Interesting, It gotta be the cam,
Can you recall the specs on the cam?

 

[70Barracuda]

I have a 383 stroker to 489 cu in, it has 580 hp and 615 tq, pump gas motor, 355s and 4 speed, 950 street hp Holley carb, I get 16 mpg!!!! I did not go crazy with a cam, I kept it mild, And I have vacuum advance hooked up. I also tuned it on a chassis Dyno.

what cam/ heads you got?

 

[wedg2go]

I starting to feel a little less concerned about my mileage after reading this thread. LOL!

 

[/sixchall]

Hi guys........I’m one of the hobbyists with a Slant6 E-body. My ‘70 Dodge Challenger, was a daily driver, from the time I bought it, to the time I retired it. I purchased it from Moss Motors Dodge, Riverside Ca. as a trade-in with 40K miles on it, for $1,100. in 1973. Fast forward through work and life to 2005 where I took it off the road with 562K miles later. During the time she was in service, she acquired a 2bbl OEM Super Six modification, Mopar Elect. Ign. Orange box and HO coil from Accel. Open element K&N 14x3 air filter. Hooker 3into1 Headers, real dual S/S, 2.25 with H pipe, (2) 26” glas-paks to the back. 904 Auto. W/ B&M shift improver to an 8 3/4, 742 case w/ 3.23 gear set. She will run perfectly fine on 87 at the pump and gets 18/19 mpg stop and go traffic. 22/23 on the freeway. Cruises just fine for me and as it passes that guy on the corner it’s still a cool looking ‘70 Challenger. Just cruises and shows now.

 

[David DiMartino]

73 Cuda 340, engine rebuilt to 69 specs. Holley 600 vacuum secondary carb, 727 trans 3:23 rear. Got 17 mpg driving from Fredneck, MD to Wilkes-Barre, PA every weekend for 6 months. North on Sunday, South on Friday. Don't imagine I'll do as well with the new cam.

 

[todd383]

what cam/ heads you got?

440 Source ported, comp solid cam 244-248@.050 580ish lift

 

[nvstorm]

In 1976 I bought a 1970 R/T S/E Challenger......guy I worked with had gotten the wife pregnant and she thought they needed a family car.....440 Magnum, 727, 3:55 rear end....every option, including the luggage rack on the trunk lid......In CA back then everything had smog inspections....the smog kit consisted of blocking off the vacuum advance and resetting the timing....I think that was on the car for 25 minutes....... speed limit, at that time, was 55.....anyway, I found, at a steady cruise of 60 or so, in traffic.....the damn thing would get 16 or even 17, with the a/c on, ran cool....dull as hell but I was amazed....get on it and you could see the gas gauge move....stock everything except I pulled the block off plates in the hood scoops and flipped over the top of the air cleaner and added what we then called "Highway Patrol" Mufflers.....Had that car for years.......sold it for what I then thought was "stupid" money

 

[DetMatt1]

In 1976 I bought a 1970 R/T S/E Challenger......guy I worked with had gotten the wife pregnant and she thought they needed a family car.....440 Magnum, 727, 3:55 rear end....every option, including the luggage rack on the trunk lid......In CA back then everything had smog inspections....the smog kit consisted of blocking off the vacuum advance and resetting the timing....I think that was on the car for 25 minutes....... speed limit, at that time, was 55.....anyway, I found, at a steady cruise of 60 or so, in traffic.....the damn thing would get 16 or even 17, with the a/c on, ran cool....dull as hell but I was amazed....get on it and you could see the gas gauge move....stock everything except I pulled the block off plates in the hood scoops and flipped over the top of the air cleaner and added what we then called "Highway Patrol" Mufflers.....Had that car for years.......sold it for what I then thought was "stupid" money

Any pictures of that one?

 

[340challconvert]

In 1976 I bought a 1970 R/T S/E Challenger......guy I worked with had gotten the wife pregnant and she thought they needed a family car.....440 Magnum, 727, 3:55 rear end....every option, including the luggage rack on the trunk lid......In CA back then everything had smog inspections....the smog kit consisted of blocking off the vacuum advance and resetting the timing....I think that was on the car for 25 minutes....... speed limit, at that time, was 55.....anyway, I found, at a steady cruise of 60 or so, in traffic.....the damn thing would get 16 or even 17, with the a/c on, ran cool....dull as hell but I was amazed....get on it and you could see the gas gauge move....stock everything except I pulled the block off plates in the hood scoops and flipped over the top of the air cleaner and added what we then called "Highway Patrol" Mufflers.....Had that car for years.......sold it for what I then thought was "stupid" money

nvstorm
Welcome to FEBO from New Jersey
Go to the new member section and introduce yourself.

 

[Dodgeboy]

1974 Challenger, 383/727, 4.30gears with 29.5inch tall tires (345/55R15). I get 6 mpg. 750 holley dp (bad tune/jetting, the pro's screwed up tuning it and I just assumed it was good....lol.....now trying a holley 850 track warrior, still playing with the jets. Cam is a Comp cam CRB 306S-10, lift is .555 I&E, duration @ .050 is 260, 3500 stall. 516 heads with bigger valves, fully ported. No idea what comp. Ratio is. Machine shop lost my blueprint.