What is the best possible fuel mileage for a mopar

[johnnycharger]

Hi Guys
Just wondering... has anyone put fuel injection on a 318 in a cool mopar? What MPGs are you getting? I currently commute with an SRT4(25mpg +/_) but have been thinking it would be fun (maybe not practical) to get an A or E body with a 318 and try to maximize the fuel efficiency with it. I think (I don't know for certain ) that adding Fuel Injection to it would be a big step in the right direction...
Have any of you guys tried this?

[Kern Dog]

In 1976, Ma Mopar built 2 A body cars with high fuel economy in mind.
The Dart Lite and Feather Duster were EPA rated at 36 mpg highway!  Slant six, one barrel, 4 speed manual overdrive with a 2.94 axle ratio. NO A/C. Aluminum transmission case, aluminum bumper brackets. The underhood and deck lid stampings were supposed to be of aluminum too.
You could take an early A body Valiant or Dart that weighs at or around 3000 lbs and fit a 318, a lockup 999 trans and a 2.76 or a 2.94 and do quite well. A well tuned Thermoquad would be more thrifty than a 2 barrel if driven responsibly.  The 999 trans is basically a 904 but has a lower 1st gear ratio to get you out of the hole with the tall axle gears. It was a quickie fix as a holdover until Mopar could build an overdrive transmission.
Skinny tires, something like a 195 or 205 75 14 would allow less drag and weight.
If one were inclined, they could use a FITech system for economy instead of the reasons that other guys go that way. My guess is that 22-24 mpg should be attainable.

[303 Mopar]

In my '69 Satty vert 318 2 bbl I get around 18 mph at 5300' altitude.

[JR]

I'm going to assume you're starting with something like a 318 powered 70 Dart.

Bolting on EFI with no other changes MAY give you 2mpg over the old carb setup. Bolting on something like a FItech/Sniper/Atomic EFI alone won't make a drastic increase in fuel mileage.

For the sake of discussion, if you want to go all out on a fuel efficient hot rod, I would take a junkyard 5.7 Hemi, add some form of O/D transmission, a 2.76-3.23 rear gear,  lightweight  wheels,, and any weight reduction you could live with.

I could see something like that getting 20mpg. Possibly a little more.

And just thinking out loud here, has anyone done a 3.6 Pentastar swap in an old Mopar before?  That would be an easy 20mpg plus 300hp combo.
I don't see anyway a boat anchor LA 318 could manage much over 20mpg.

EDIT: Well I'll be damned, someone's already building this. He makes a pretty good case for it.

325lb engine, 300hp, flat torque curve, this could be interesting. And most likely, a 20mpg plus combo with the Tremec 5 speed.

https://www.forabodiesonly.com/mopar/threads/72-dart-swinger-3-6l-pentastar-t5.361683/

[Alaskan_TA]

My all stock 1970 Valiant 4-door has a 318, 3-speed manual stick shift & 3.23 gears.

It averages 21.5 MPG just as it is.

[Mike DC]

Somebody once said, "15 mpg is the most you're likely to get from any old carb'd V8 in a fun car."  That's true for anything much over 300 cubic inches and 3000 lbs.  You might pull off 20 mpg on the highway but not 25 or 30. 
 
Skinny tires and lowered highway speeds will make a big difference.  We don't wanna hear it but it's true.  Economy cars in the gas crisis era ran stuff like 14x5" wheels.  The Federal speed limit was 55 mph (everywhere).  The cars' speedos only charted up to 85 mph.

-------------------


I'm waiting for somebody to retrofit a G3 Hemi with the displacement-on-demand operational.

The DoD feature has a rep for being ineffective because the factory made it 100% unnoticeable to the driver.  That would throw away most of the gains.  If you had that thing on a toggle switch, and tolerated the car feeling like a 4-banger while it was in Clark Kent mode . .  should be a very different story.  

[Kern Dog]

Chrysler called it MDS. Multi Displacement System.   The DOD sounds like a Chevy term.

[toocheaptosmoke]

I put a newer magnum 318 into my charger, NV3500 5 speed, 3.73 rear end.  With a carb the best I was able to do was on a trip to Carlisle and back, 22 mpg at around ~70 mph.  Mixed driving to work was around 16-18 mpg.  Last year I installed FiTech on it, never really had a chance to do a good highway trip with it, but average mixed driving was 17-19 mpg.   I think a little higher gear ratio would be just right for max mpg.   I would like to get 25 mpg on a tank one time just to do it, keep it under 60 on the highway and I think it's possible. 

[Mike DC]

 
That sounds do-able.  You might make 25 mpg on the highway with a 318 + EFI + manual trans + overdrive gear + under 60 mph.

[johnnycharger]

Lots of great information for me to learn from! Thanks guys!
I never would have thought of a modern v6. That's an interesting build!

[alfaitalia]

Well.... fairly interesting....but the problem here is that anyone caught fitting a 68-70 Charger with a motor with less than eight cylinders is legally bound to be beaten to death with a Ford camshaft and then eaten whilst his family are forced to watch.....so let that be a warning to you!

[A383Wing]

I get 16.5 mpg with my 66 Charger 383......

I have pulled 24.5 mpg out of the Daytona once...can get 18 all day long on the freeway

[johnnycharger]

Well.... fairly interesting....but the problem here is that anyone caught fitting a 68-70 Charger with a motor with less than eight cylinders is legally bound to be beaten to death with a Ford camshaft and then eaten whilst his family are forced to watch.....so let that be a warning to you!

Bwahahahahaa!

[A383Wing]

Well.... fairly interesting....but the problem here is that anyone caught fitting a 68-70 Charger with a motor with less than eight cylinders is legally bound to be beaten to death with a Ford camshaft and then eaten whilst his family are forced to watch.....so let that be a warning to you!

They were fitted with 6 cylinder engines from the factory

[Kern Dog]

Thanks, Captain Obvious...
The man was joking about how nobody would intentionally put anything but a V8 in one of these cars.  I see the slanty Chargers as interesting to see but there is no way I'd keep a slant  sick in any Charger.

[cooldude]

I remember the fuel crisis of the 1970s, the gas rationing and the lines at the gas stations, and the tidal wave of environmentalist greenies talking about how we were going to run out of fossil fuels, seems like, about 1996 or something like that. Much like the global warming hype going around now a days.

I have to question, if we were running out of oil in the early 1970s, why have we kept right on pumping it since then and not run out?

Why is everyone concerned with fuel economy to start with? Other than saving a few cents per gallon on our fuel bill, is there even any point to thinking seriously about fuel economy?   

[alfaitalia]

There is when its about $8 a gallon over here (UK)!......was over $10 a while back. I don't worry about it in my Charger which I recon might get 10 MPG when its done as it wont do enough miles to matter....but do think about it in my DD which gets about 35mpg....would like to get more which is why its for sale to get something with even better gas mileage. The less I spend on fuel....the more I have for my resto!

Not saying I'm a tree hugger either but I don't think any rational mind could put up a very convincing argument for Global warming being just hype these days....evidence is pretty clear. Never used to care less to be honest.....think about it a little more since I became a father.

The reason we have not run out of fuel yet (and are unlikely to in our life times) is because of massive new reserves found since the 70s. Back then (based on known reserves at the time) I'm sure they did think they would run out soon.

[Mike DC]

  
The amount of oil on earth isn't a straightforward thing.  It's not like a giant underground bathtub that will one day get bone-dry.  

How much are we willing to spend (per-barrel) to get it?  50-100 years ago Jed Clampett could shoot a shotgun at the ground and the stuff bubbled right up.  Today we are drilling down miles underwater with giant floating oil rigs.   There are oilfields all over the planet that were abandoned with 50-80% of the stuff never recovered, or the field was never pumped at all, because the costs were too high.  

If we spend more per-barrel the amount of "economically recoverable reserves" goes up.  The earlier estimates weren't "wrong" they were just built around a lower price figure.  In the future we will keep "finding" more oil because the prices will keep climbing. 

[cooldude]

There is when its about $8 a gallon over here (UK)!......was over $10 a while back. I don't worry about it in my Charger which I recon might get 10 MPG when its done as it wont do enough miles to matter....but do think about it in my DD which gets about 35mpg....would like to get more which is why its for sale to get something with even better gas mileage. The less I spend on fuel....the more I have for my resto!

Not saying I'm a tree hugger either but I don't think any rational mind could put up a very convincing argument for Global warming being just hype these days....evidence is pretty clear. Never used to care less to be honest.....think about it a little more since I became a father.

The reason we have not run out of fuel yet (and are unlikely to in our life times) is because of massive new reserves found since the 70s. Back then (based on known reserves at the time) I'm sure they did think they would run out soon.

Its really hard to tell what science is real these days, and what is just made up to support a political agenda.

The academic world is forced into lockstep, and any desenters are thrown out of a job. These days, the term "Peer Reviewed" just means they grade each others papers.

But, all these years of burning hydrocarbons cant really be all that good. I remember talk of the great London smog of 1952, I think it was.

But, it went away and things cleared up after London stopped burning so much coal. Wasnt permanent.

As for the price of gasoline, well now, that is another matter. Economics isnt Earth science, its human being  science. And greed is usually the lowest common denominator. And that drives politics, which drives academic trends and agendas, etc etc etc.

Im sure the global warming thing is serving the interest of the rich and powerful, otherwise it would have been quietly shelved years ago, and some new and urgent agenda would have been devised to serve their interest.

[odcics2]

 
The amount of oil on earth isn't a straightforward thing.  It's not like a giant underground bathtub that will one day get bone-dry.  

How much are we willing to spend (per-barrel) to get it?  50-100 years ago Jed Clampett could shoot a shotgun at the ground and the stuff bubbled right up.  Today we are drilling down miles underwater with giant floating oil rigs.   There are oilfields all over the planet that were abandoned with 50-80% of the stuff never recovered, or the field was never pumped at all, because the costs were too high.  

If we spend more per-barrel the amount of "economically recoverable reserves" goes up.  The earlier estimates weren't "wrong" they were just built around a lower price figure.  In the future we will keep "finding" more oil because the prices will keep climbing. 

Ask the good folks of Oklahoma how much fun fracking can be.   Look up "earthquakes in oklahoma". 

[ACUDANUT]

Might try a Fiat 4 Cylinder diesel engine that they put in the new Rams.
Wait..  Muscle cars and fuel mileage    Find another hobby.

[Mike DC]

  

Ask the good folks of Oklahoma how much fun fracking can be.   Look up "earthquakes in oklahoma".

Yeah, it's a mess.  

Our whole civilization has serious energy problems.  


Subtracting about 6 of the 7 billion people on earth would help a lot of things.

[cooldude]

Any of you guys believe the rumors going around back in the day, about a guy that invented a carb that could get 100 mpg on a v8? But some oil company bought the rights to it, and shut it up?

[birdsandbees]

NOPE!! Absolute BS !

[JB400]

Honestly, I have yet to see anyone do a full on eco build to see what the fuel economy actually would be.  With the shape of the old cars, I could see where they may get over 25.  My blueprint is still in the works.