Surprise Performance: Fast Cars With Suspect Horsepower Ratings

Vukasin Herbez June 22, 2020

3. Pontiac 400 Ram Air IV

Back in the late ’60s, Pontiac’s Ram Air engines were one of the hottest mills in the muscle car class. This engine featured a four-barrel carburetor with the famous Ram Air induction system. The ratings were 360 HP in its RA III form. They installed those engines in GTOs, making them the perfect street racers of the era. However, in 1969, Pontiac presented the Ram Air IV version of the same engine with the same advertised horsepower rating of 360 HP. The two engines looked the same, but the RA IV had much different internals underneath.

It had different engine heads, camshafts, and valves. It also had more compression and a higher rev limit. The Ram Air IV was capable of much more than 400 HP. However, the factory decided to rate it at 360 HP for insurance reasons. Unfortunately, the Ram Air IV was an expensive option so Pontiac didn’t make many of them.

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2. Ford Mustang SVT Cobra

Inspired by the wild SVT Cobra R’s from the ’90s, they didn’t name the 2003 model “R” since it wasn’t limited in production. Ford made it available to the public rather than just racing drivers and private teams. However, this SVT Cobra was an interesting, important model for the Mustang dynasty since it featured two firsts. It was the first factory supercharged engine with an independent rear suspension. For the SVT, Ford took the standard 4.6-liter block and mounted different heads and a supercharger to get 390 HP and 390 lb-ft of torque.

They named the engine the “Terminator.” The rumor was that it delivered more than the advertised 390 HP. In fact, it was much closer to 430 HP. To handle all that power and torque, Ford equipped the SVT Cobra with an independent rear suspension setup like the first Ford GT. This helped stability at high speeds and hard launches, making this Mustang handle like a dream.

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1. Buick GNX

The ’80s were the dark ages of muscle cars and American performance, but there were a few bright moments. One of the cars that restored faith in muscle car movement in the ’80s was the mighty Buick GNX. The story of this model is an interesting one. Back in 1982, Buick started experimenting with turbocharging its line of standard V6 engines. The results were satisfying, so engineers got permission to develop a performance version with better acceleration figures. Soon there was a Buick Grand National with 175 HP, which wasn’t impressive but was a start.

In the next couple of years, the Grand National got a bigger engine and more power, jumping from 175 HP to 200 HP and finally to 235 HP. With those numbers came the acceleration times of under six seconds. Those black Grand Nationals were quick cars. But in 1987 came the ultimate version Buick called the Grand National Experimental, or GNX for short. It featured the same 3.8-liter turbocharged V6 but with 275 HP and 0 to 60 mph times of 4.7 seconds. Lots of car enthusiasts claimed the GNX produced at least 300 HP since it was extremely fast. At that moment, Buick GNX was the fastest accelerating production model in the world. At $29,000 it wasn’t a bargain, but there is a widespread legend about owners who paid the lease on these cars by street racing them for money.

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Surprise Performance: Fast Cars With Suspect Horsepower Ratings

3. Pontiac 400 Ram Air IV

2. Ford Mustang SVT Cobra

1. Buick GNX

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