Short-Stroke Shootout

In search of the small-bore sweet spot, we sample three early 911s with 2.2, 2.5, and 2.8 liters of displacement.

October 1, 2009

Also from Issue 177

  • 996 GT3 vs. 997 GT3
  • 2009 Panamera S, 4S, and Turbo
  • Mille Miglia with Gijs van Lennep
  • Rare 964 Turbo S2 Driven
  • 930-powered 356
  • Interview: Paul Ritchie of PMNA
  • Market Update: 911 Turbo
  • Porsche Icon: 911 GT1-98
  • $0.79 911 Foggy Headlight Fix
  • Project 914 3.6: Details, and First Drive
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Short-Stroke Shootout 1
Short-Stroke Shootout 2
Short-Stroke Shootout 3
Short-Stroke Shootout 4
Short-Stroke Shootout 5
Short-Stroke Shootout 6
Short-Stroke Shootout 7

Don’t bring a knife to a gunfight.” When talking cars, that bit of wisdom translates roughly as “there’s no replacement for displacement.” Early 911 hot-rodders tend to agree, and they’ve been reaching for bigger guns for a long time now. The result is a rash of long-hood 911s with 3.6- and 3.8-liter flat sixes.

Porsche laid the groundwork for such swaps long ago. Stuttgart first added displacement to its air-cooled flat six for the 1970 model year, when the 1965–69 2.0-liter grew to 2.2 liters on a bore increase. In the quest to build ever faster 911s, however, Por­sche began to increase stroke, as well, creating 2.4-, 2.7-, 3.0-, 3.2-, 3.6-, and 3.8-liter engines between 1972 and 1998. One thing all of them have in common? Their “long-stroke” crankshafts.

The first long-stroke 911 crank was the 70.4-mm unit used by the 2.4 (1972), 2.7 (1973), and 3.0 (1974). Then came the 74.4-mm crank used in the 3.2 (1984), followed by the 76.4-mm unit found in the 3.6 (1989) and 3.8 (1993). With so many long-stroke options available, what would compel someone to build a short-stroke 911 engine based on the earliest, 66-mm crankshaft? Build­ing a short-stroke 911 is like thrusting through swinging saloon doors and into a shootout while packing a .22 instead of a Colt 45. That said, there’s something to be said for a .22. Like accuracy.

Maybe it’s just me, but the thought of a high-revving, short-stroke six in an early 911 is seductive. Many of the great 911 race cars won on 66-mm cranks, among them the 911R with its high-strung 220-hp 2.0 and the 911 S-Ts with their 2.3s and 2.5s. What short-stroke flat sixes give up in power, they make up for in the way they spin. They seem not just willing but desperate to rev. They’re a little sharper, a little more precise, and a little more responsive than the bigger sixes.

Then there’s the sound. A small-bore 911 coming on cam is an audible history of the 911R at Monza and the S-T at the Nür­burg­ring. Call it romanticism if you will, but let me assure you: I’ve never been accused of being a romantic (just ask my wife!). But I am a huge fan of tradition.

While considering a short-stroke flat six myself, a unique opportunity to evaluate three different combinations presented itself. Friends were planning a road trip to California and I would have at my disposal several short-stroke 911s. Car number one is my own, a 2.2-liter S with a short-ratio gearbox and a limited-slip diff. Car number two is Curt Egerer’s 1971 911T Targa with an old-school 2.5 and Weber carbs. Car number three is Randy Sten­son’s 1971 911T with a twin-plugged, 2.8-liter beast of an engine. I would spend time driving each on the freeways and back roads of the wild west before meeting early 911 hotshoe Randy Wells at The Streets of Willow.

Day 1 1970 911S 2.2

Let me get this out of the way up front: Impartiality is impossible. I love this car! I’ve owned this S for six years and have racked up nearly 15,000 miles on club trips alone. It rarely sits idle during the abbreviated driving season typical of the Midwest, which is nothing new for “Olivia,” as my wife and I call her.

The previous owner bought her in the mid-1970s and did a lot of track days and auto­cross­es over his 25-year tenure. So she’s well broken in, much like your first baseball glove or that pair of jeans you can’t bear to part with — or wash. Olivia’s got plenty of rock chips, a few minor oil leaks, and maybe even a stray French fry beneath her seats.

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