Old School Engines and Fuel Efficiency

[pounsfos]

well lets take my starlet, its 29 years old, it gets 40mpg (us) and i usually just drive it around normally without hypermiling, i find p&g decreases my FE, maybe im doing it wrong,


one day im going to get it to 50mpg and it will be through performance mods and a little common sence.

[davidgrey50]

Slant Six Forum is a fabulous source for info on the...well, slant six. Even a how-to for DIY fuel injection.

[cRiPpLe_rOoStEr]

A 4-speed transmission might not be so bad at all, since it would be a little lighter and have fewer internal frictions too, but the gear spread and the differential ratio also have a key role on that matter. The close-ratio 5-speed and 6-speed manual transmissions which become prevalent nowadays have been geared to fare well in the EPA test procedures but it doesn't lead to any outstanding real-world mileage improvement.

Regarding engines, even some flatheads could still be kinda efficient in spite of their flow limitations.
Born-again Flathead | Hemmings Motor News

[sirchris]

I had , and got back, long story, a.'67 Charger. It was the first body style, fastback, and I could get 20mpg on the highway. No ac, no mods

[iveyjh]

In 1968 I had a 1964 Ford Fairlane 2 door 289 sports coupe 4 speed with 3.30 differential. I got over 24 mpg driving 65-75 mph from Dothan, Alabama to Watertown, NY. I thought that was pretty good for a 225hp 289ci engine with a Holly 4 barrel carb.

[Hersbird]

The special edition mid 70's Feather Duster supposedly got in the 30's stock with the 4 speed manual and slant 6 motor. They had some light weight parts and a lean burn tune on the small carb. Too bad most came with the non-overdrive automatic option and then got hacked up turned into drag cars with their lightweight partts.

From allpar.com
"The Feather Duster included aluminum replacements for the inner hood, trunk bracing, bumper brackets, and intake manifold, cutting weight by 180 lb (around 5%). It had a smaller single barrel carburetor, economy distributor calibration, large exhaust, and a 2.8:1 rear axle ratio, with a choice of three-speed automatic or four-speed overdrive manual transmission.

While acceleration was compromised, the Feather Duster was now rated at 22 mpg city, 31 highway with the automatic (a stunning 24 city, 36 highway with the manual), and was larger inside than many other economy cars, though acceleration took a hit. The Feather Duster was a fine alternative to the extra-slow Japanese imports that customers were waiting to buy, at list price; or at least it would have been, had more people considered it over the quick-rusting Coronas, Civics, and Datsuns of the time."

[kafer65]

Originally Posted by davidgrey50

Slant Six Forum is a fabulous source for info on the...well, slant six. Even a how-to for DIY fuel injection.

Yeah, I like it too! I put a orange box on my Dodge slant 6 truck 9 years ago and compatible distributor and dream of fuel injection. Its the last year of the slant in the truck and it was lean burn new. I removed the computer myself since the Carter carb was long gone. There was a vacuum line that went to a vacuum can that was mounted on the lean burn computer. After 20 years the diaphram would crack and it wouldn't read properly. I'm told that even though the automatic is very durable there is more than a 20 percent loss in efficiency over a manual. I have a 70s Chevy truck vacuum switch to use the overdrive which makes the gearing pretty good otherwise. I've got the weight down to around 3900 pounds for a long bed with helper springs. Front air dam and magnesium wheels installed as well. It would get 17 mpg new. I get 12 in traffic now. Love the ride and sound. I'm pretty sure that even if I had a good kamm back cap and belly pan I'd still get 12mpg with this Holley carb I have on it now. Trivia: the 225 slant 6 weight is about the same as the 2 liter VW TDI engine

[kafer65]

The Duster/Demon cars didn't weigh that much to start with. My 72 Demon weight was around 2800 pounds. A manual and a better final drive ratio would have made all the difference in the mpg. I'd love to lighten the hood, doors, and K member on my pickup. It has a 3.55 rear end ratio but the tires are not conducive to economy.

[user removed]

My light green 4dr 63 Valiant with a 170 would push 28 mpg if driven reasonably and that was on recaps. Add another gear and some radials, 35-40.

regards
mech

[cRiPpLe_rOoStEr]

Originally Posted by kafer65

the 225 slant 6 weight is about the same as the 2 liter VW TDI engine

Comparing a gasser straight-6 to a 4-pot turbodiesel sounds kinda like comparing apples and oranges, but many older engine designs are really lighter than modern ones. To make a fair comparison, let's look at the Chevy 350cu.in. small-block and the first Lexus V8: even with an iron block vs. the aluminium block of the Lexus, and a displacement 42.5% higher, due to its simpler layout it was not just a little lighter but also physically smaller outside.