Old school FE 1967 Cutlass

[ALS]

Just for fun looking back to what GM was trying for better fuel mileage.



They were pulling 19 mpg back then. Imagine what a front spoiler, a four speed automatic OD transmission with a locking torque converter and modern radial tires inflated to 36 psi could have pulled at 65 mph. I'd guess 24 mpg could be possible and 26-28 mpg at 55 mph.

AUTO INDUSTRY observers long have predicted Detroit would build cars specially designed for long-distance, high-speed cruising on tomorrow's super highways. These cars would be considerably different from cars intended for normal city-suburban transportation. They would be designed for smooth, effortless cruising at 60-90 mph, with a minimum of engine vibration and noise. Fuel consumption at 80-90 mph would be what owners now expect at 50-60 mph. The handling would have to be firm and stable, especially in crosswinds, but without a harsh, choppy sports car ride. Very important, the acceleration in the normal passing range, from 50-70 mph, would have to be up to current 400-cu. in. engine standards, with no great compromise for high-speed fuel consumption.

Just such a car is available now at Oldsmobile dealers. The car represents Detroit's first serious effort at a specific car design to meet the challenge of the 41,000-mile network of interstate super highways to be completed early in the 1970s. Efficient, high-speed, long-distance travel on these highways calls for a very special combination of equipment that cannot be readily "designed" on current option order forms.

Carlife_apr67

Another article comparing the Turnpike Cruiser and the 442.
Carlife article

[MetroMPG]

This Olds was one of the earliest manufacturer-ecomodded cars I had read about.

I compared it to the Metro XFi:

They modified several of the same things that engineers would later do in the Metro to create the XFi, including using a taller final drive ratio and - surprise, surprise - a special "efficiency cam".

Noting that "internal engine friction increases roughly as the square of rpm, and is relatively unaffected by the load on the engine or the degree of throttle opening," the goal of the Oldsmobile's engineers was to create a car with good torque at low RPM - just like the XFi.



To permit loafing the engine along while maintaining acceptable driveability, the Olds engine included several other improvements from the stock motor [which they don't describe] , but of all the mods, "the camshaft is the key."

Like the XFi's cam 25 years later, the economy cam in the Olds used lower lift, shorter duration, and advanced timing. As a result of the increased lift rates, both the Olds and the XFi also have somewhat less peak power compared to their less efficient siblings (because the redline is lowered due to the potential for valves to float at high RPM).

[Big Dave]

Ahhhh! Gear lust! 2.41:1 gears.

Oh! for the days when you could actually get custom-hobbed hypoid gears.

How good would this car be with a T-56 manual?

[Christ]

Darin -

Imagine if they could precisely control the engine's torque output so that it was flat between, say 700-1500 RPM (peak) and used a very long 4 speed to keep it in that range even at 55-60 MPH...

Something about a 800 RPM range of peak operation makes me think medium speed diesel, though. It would probably have a RPM limit of 2000-2500, even as a gasoline engine.

[Frank Lee]

Kinda gettin into that optimal piston speed thing again

[robertwb70]

I had a 1980 Chevy Malibu "wanna be" hot rod back in the early 90's that had 2.29 gears. Even with the 3 speed auto (no lockup) it would run 85 MPH in first gear (at a conservative 5,500 RPMs) but the motor was so worn out it was drag limited at about 150 MPH. Even on the highway it could only manage about 15 MPG with a Holley carb, later changed to an Edelbrock and got 17 MPG, probably single digits around town...but it was fun none the less.

[99LeCouch]

My Buick with 2.86 gears is pretty killer with highway FE. It gets >30 at 65 mph, and I've seen 37-39 mpg at 55-60 mph. The engine is loafing at highway speeds. At 75 mph the engine is just touching 2000 RPM.

Around town is a different story.

[wagonman76]

Wonder what my Celebrity would do with a 3.06 or 2.84 final drive, in a nice flat area like the plains (warm temps would be nice too). It has numerically the highest they offered, 3.33. But between the 3.1 and the gearing, it does give the torque to climb most any hill at like 1500 RPM in OD, and there are a lot of hills around here.

[jcp123]

I get around 20mpg on the open road with my Mustang, lacking overdrive, with a best of nearly 22.

Conversions using Ford's AOD transmission, featuring a ,67:1 overdrive gear and lockup, are reasonably common and tend to yield around 25ish mpg with a 302, and about the same with a T5 5-speed stick.

[bgd73]

there really is a means for big v8 downdraft to go to the 20s mpg. I miss most of my v8s. "They" (oem) did not let them have power, they did not let them fire completely, and their gearing was a chinese socialist in similarity (exactly perfectly power killing wrong..all while letting rpms and power curves happen anyway).

I could repeat history of my own past even better, any v8 I owned, as said, lock up convertor, fuel refining discipline of today, and some carb makers that have not given up, ignition alone is at least 5-10+ mpg with plugs and other tune up stuff...

but I still can't afford even 20s mpg...

not when there is 50.