Posted Wednesday, March 12/08 in General

34 years ago this month, the March 1974 issue of Car and Driver magazine ran an article about DIY modifications to improve fuel economy. The article was a direct response to the 1973/74 oil crisis - which was when people in North America first started seriously talking about improving fuel efficiency to address issues of energy security and high fuel prices.

But the magazine did a lot more than just talk about efficiency. They grabbed the bull by the horns (okay, a Ford Pinto by the bumper) and actually did something about it. Their story, Project Car: Crisis-Fighter Pinto, outlined six simple, mostly aerodynamic modifications which actually saved gas.

After the jump: the six modifications, in detail.

The Car & Driver guys didn't mess with the engine itself. Instead, they reduced the amount of work the engine had to do. Fuel is burned to overcome two main forces: rolling resistance and aerodynamic drag. At highway speeds, aero drag dominates, so that's where Car and Driver spent most of its effort - and eleven dollars on supplies (about $50, adjusted for inflation).

Showing the massive air dam, grille block and convex headlight covers

Mod #1: Front air dam.
They started by making & installing an air dam beneath the Pinto's front bumper to divert as much air flow as possible away from the car's aerodynamically dirty underside. That single change accounted for fully one quarter of their gains.

Mod #2: Partial grill block.
Another highly turbulent air pathway is the cooling system. Most cars' grill openings are sized to keep the engine cool in absolute worst-case conditions (think Death Valley, pulling a trailer). By blocking part of the Pinto's grill, they were able to improve efficiency without adversely affecting engine temperatures in normal driving.

Mod #3: Smoother nose.
Almost every new car sold today has a smoothly contoured front end. However, the Pinto left a lot to be desired. To partly address this, they made and installed convex plexiglass covers over the car's recessed headlights. That small change added 0.1 MPG.

Mod #4: Smoother tail.
The aerodynamically ideal shape at the rear of a vehicle is a gradual taper that helps minimize the size of the turbulent wake left behind. But the slope of the Pinto's rear window was too steep. By adding a six inch spoiler, they effectively changed the angle of air flow between the end of the roof and the back of the car. The result: a 7% MPG improvement.

Mod #5: Reduced parasitic loads.
Back in '74, most cars sported a belt-driven radiator fan. By removing two of the Pinto's four fan blades, it was made more efficient. Today, most vehicles have electric cooling fans that run on demand only.

Mod #6: Reduced rolling resistance.
The stock Pinto came with bias-ply tires. Switching to steel belted radials netted a 5% MPG improvement. While all new cars today come with radial tires, LRR (Low Rolling Resistance) versions are available which can offer a similar improvement over "standard" radials.

The Car & Driver Pinto demonstrated that even in a so-called "economy" vehicle, the auto maker had left a lot on the table in terms of potential efficiency improvements. The same remains true today, particularly regarding fuel-wasting, poor aerodynamics.

What's more... "...they are all the type of changes you can make - without going broke - and the type of change the car makers will have to make for the coming model years. Bluntly, this is the way it will be."

But perhaps the most interesting thing about the Crisis-Fighter Pinto is the fact that Phil Knox cites it as the catalyst that sparked his passion for DIY automotive aerodynamics. And since I can trace a line to the EV World article about Phil's aeromodded Toyota pickup truck that inspired me to learn about the same topic, ultimately I can thank the C&D article as well.

Resources

• Car and Driver magazine ecomods a car: MPG up +25% - discussion of this article at EcoModder.com
• Aero inspiration - MetroMPG.com article about wheel skirts and grille block where I credit Phil Knox for my newfound interest in aeromodding.