35 MPG Duster

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73Duster340

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Folks, with gas prices the way they are, it seems like a lot of old mopar muscle is sitting in garages these days. I am currently building a 73-76 V8 Duster that I am shooting for 35 mpg. It will look,sound, and drive like a hot rod (or better), yield significantly better MPG, and be fun. Is there any interest in a car like this? I have quite a bit of time in R&D and believe its do-able.
 
I would love to hear how it's done as I have a similar desire.
C
 
Not to steal the thread, but I had started this with a Duster a long while back and never finished...69 273, auto, with 2.94 gears...hmmm may have to digg that one out...should change it to a Passon OD 4 speed and lighten the car with some feather duster hood and trunk
 
Back in the day, my 318/904/2.73 7/25 rear Gold Duster could get as good as 25 mpg, says my Dad before he gave it to me. I never verified that, but believe it to be so. 35 would be quite an improvement, but very difficult, IMHO. My 2003 Honda 4 cylinder 5sp Accord gets 35 mpg on hwy, if I drive the speed limit.
 
jimmyray said:
Back in the day, my 318/904/2.73 7/25 rear Gold Duster could get as good as 25 mpg, says my Dad before he gave it to me. I never verified that, but believe it to be so. 35 would be quite an improvement, but very difficult, IMHO. My 2003 Honda 4 cylinder 5sp Accord gets 35 mpg on hwy, if I drive the speed limit.
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I think it's not too far fetched based on available tech and weight of vehicle. ( just expensive )
I would guess that it would need fuel injection, ignition computer and a 6 speed with some carefully calculated gearing and timing curve to make it accelerate quickly and be at a low enough rpm to get decent MPG at hwy speeds.
My best guess would be about 6K to buy the parts, but no clue on what the time would be to get it to work....but how long would it take to recoup the cost in gas???? but, but, viable alternative for "buying" a 35mpg car for 20K
 
I want to weigh in on this.
The Feather Duster and Dart Lite were rated at 36 MPG back in the day, but I question the reality of it today, and that would have to have been with the OD trans, no way on the 3 speed or auto Torqueflite There numbers were also obtained with the mildest Slant 6 Mopar could build, and with some lightweight components.
The standards were different, the number were probably "fudged" to make them look more impressive during the gas crisis.

I definately think that high 20's or low 30's is possible. But I believe it would take some definatly strong efforts to get there, and I believe the modifications needed to get there would be a compromised in many forms.

There are several guys on here that can document in low to mid 20's now, but keep this in mind. 22 mpg to 24 is only 2 mpg, but it is a 10% improvement. To go from an guessed average on a A body that is concerned with MPG of 18 to 35 mpg would require a 100% improvement, or double.... very hard to do.
I am interested in your MPG recipe.
 
I'd say a 225 with a small (or slightly bigger VNT) turbo and fuel injection off a 4.0L AMC/Jeep engine, hooked up to a Passon OD 4-speed and 8 1/4" rear with 3.23 gears. Also see about some minor aerodynamic mods to the body, depending on how bad the drag is on a Duster in the first place.
 
73Duster340 said:
Folks, with gas prices the way they are, it seems like a lot of old mopar muscle is sitting in garages these days. I am currently building a 73-76 V8 Duster that I am shooting for 35 mpg. It will look,sound, and drive like a hot rod (or better), yield significantly better MPG, and be fun. Is there any interest in a car like this? I have quite a bit of time in R&D and believe its do-able.
Click to expand...


I think you have our attention, can you give some details?
 
35 pmg's? Not out of a V-8. But I do think a turbo would help in the accelreation deaprtment.
Is there a cam out there smaller than the stock 318's?
 
Duster wet weight no more than 2500 lbs. I would go with a 273, but I have several 318's to play with and blow up/melt down if necessary, so I will use the extra 45 cubes for torque. Alum heads, 10.5-11.0 to 1 compr. custom cam, programmable fuel injection to squeeze a leaner mix. I plan on working the aero a little bit, nothing dramatic, but punching a little cleaner hole at 55-65 can make a huge difference(draft behind a semi and see) . Its going to be much lighter and the engine objective to be all in early in the power band. I got 20-22 mpg out of my original 70 318 Coronet Conv and my 72 318 Satellite. I know I am pushing, but I truly believe that if I can keep the motor together at an A/F mix of 16.1 or leaner, I will be close. Again, if I get close, its another reason to drive our old stuff versus the new cars that are straddled with all the emissions crap and extra weight. I will be starting with a dipped unibody, so I can keep track of the entire experience. We can always start a pool of what the final mpg's will be! Thanks for the input, FABO is the greatest.
 
Closed-chamber iron heads (Magnums?) will allow you to run almost the same compression with higher efficiency due to heat loss through the heads. Although they would be heavier...
 
There is claim to this :-k
Seen one this week end :-D
and hwy driving it will even get 35 mpg at 65 mph.:dontknow:

But this is what the owner said.

/6 at 35 mpg in the last picture on the side rear window

petit jean 004.jpg


petit jean 005.jpg


petit jean 006.jpg
 
In the mid 70's I was able to get consistent 25 mpg with a /6 and 3 on the tree 66 Dodge Coronet. I advanced the timing some, added CDI ignition, and replaced the air cleaner top with a piece of Plexiglas.

I also did the same with a 273 2-barrel 66 Barracuda with auto trans without modifications.

I think the modern gas with ethanol might be about a 8-10% penalty. Modern oils and tires may help offset the weak fuel.

If you use a programmable EFI use multi-port, not TBI. TBI may only be sightly better than a carb. Good ignition and the ability to tune it (RPM and MAP) is also important.

High compression may not be as efficient as a lower compression engine at light load conditions.
 
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