Driving at 10,000 RPM with Steve O'Hara
When it comes to fast cars 4 cylinder motors tend to not be thought of by the average enthusiast as fast. The F20C, F22C, and 4A-GE are small displacement motors in a sea of 1,000 horsepower W16s and twin turbo V8s producing a gazillion horsepower. So how does this car go faster than cars that make quadruple the ponies and what is it like to drive? This is one interview you don’t want to miss.
September 29, 2017
Formula Atlantic 4A-GE
I first heard of these engines from the Japanese show Initial D. The 4 valve 1.6L engine is fed by dual Weber 48DCOE side draft two-barrel carburetors that have a very narrow power band. Steve described how they would stumble before revving violently to the limiter, “In a low gear like 1st gear coming off the queen's hairpin at Long Beach the car would go from 7,000rpm to 10,000rpm in just about 1 second. So you're countersteering towards the wall with one hand while you reach over with your other hand to shift up.” The performance gets even more impressive from here…
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The Machine as a Whole
250 horsepower doesn’t sound substantial until you remember the car only weighs 1,125lbs with driver and all fluids topped off. The result is a 0-60 sprint of 2.2-seconds and 3.8G of cornering force. The car can almost generate 3G in braking zones as well thanks to AP Racing 4 piston calibers and 10 inch vented rotors. The master cylinder comes from AP Racing and Tilton supplies the adjustable brake bias system. One of the unique features on the car is a bladed sway bar that can be adjusted on the fly for changing conditions on the track or tires. Very trick stuff, but all simple and mechanical.
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Max Venturis
Forged in the era of unrestricted underbody design the Swift DB4 features venturi shaped underbody tunnels for a maximum downforce rating of 2,500lbs. “In an Atlantic car I can go 150 mph through turn 9 at Willow Springs,” Steve says. I almost spit out the water I’m drinking in disbelief only to rephrase the question with a more inquiring tone. O’Hara simply responded, “Flat out. Hundred and fifty.” Now I start to understand how different a purpose-built racing machine is. Lap times for this car at WSIR are in the 1 minute 12 second range putting it multiple seconds ahead of the fastest time attack cars in the world.
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Adapting
How different is it to drive from a normal sedan? “In a sedan type car the faster you go the less grip you have. In the Formula Atlantic the faster you go the more grip you have. You’ll never slide one of these things at 140 or 150 mph,” the hall of fame drive replies. “It’s easier to get loose at low speeds and harder to get loose in high-speed defying everything you thought you knew before driving one.”
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Underbody Detail
This amazing performance comes from the shape of the underbody. Most cars at the track have a flat bottom or a flat bottom that extends into a rear diffuser. In these Swift DB4s, the entire underbody of the car is shaped like a diffuser so the only flat part of the car is essentially just under the nose. The rest of the car works as a giant expansion chamber to produce negative lift or low pressure underneath the car. As the car moves faster the pressure drop increases sucking the car right to the ground. In the photo above the car is entering a corner at 140 mph.
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Summary
I thought it would be cool to share how fast small displacement 4 cylinder engines can be when a machine is truly built around them. While many articles exist online about them, few of these articles highlight the Formula Atlantic 4A-GE in its natural habitat. The speeds are massive and the skills required to drive them to their limit are epic. I hope you enjoyed reading about this incredible car and have a new perspective on how fast ground effect cars really are!
>>Join the conversation on Small Displacement Motors and Steve O'Hara right here in the S2Ki Forum!
