Short-Stroke Shootout

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
Buy Excellence-177-cover
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

While my 911S was rebuilt to factory specs, the Gray Wolf’s previous owner wanted more power. In 1979, there were few choices for larger pistons and cylinders. A common up­grade was to replace the 87-mm pistons and cylinders with 90-mm Mahles as used in the Carrera RS 2.7. With the 66-mm crank, this yielded a displacement of just over 2.5 liters.

The downside is that the resulting compression ratio is typically 7.5:1. Tru­man claimed 8.1:1, which is still mild. Curt has found an upside: He typically uses the cheapest gas he can find. 87 octane is the norm, which makes fill-ups a bit more palatable. Curt jokes that he’d buy 85 if they sold it at the pump.

Pulling onto the freeway, I quickly settle into a groove in the Gray Wolf. With­out question, there’s more torque on tap. Useful torque is available lower in the rpm range and less effort is required to gain similar speed. With Solex cams and an S distributor replacing the original T items, the 2.5 can be spun to 7300 rpm, although that might be a questionable policy considering that the original, non-counterweighted crankshaft still resides within the magnesium case.

Passing through Amarillo, Texas and switching from Interstate to more scenic four-lane state routes towards New Mexico, I struggle with how to describe the 2.5. It makes more power and feels stronger than the 2.2S, but the increases are subtle. It’s faster, but not a lot faster. Weight isn’t a factor; due to its lightweight seats and trim, this 2,300-pound T Targa is only 25 pounds heavier than my S coupe. If you swapped its custom 15×6.5-inch steel wheels for Fuchs and dropped the “rally bits,” they’d be dead even.

Repeating the same fourth-gear pull I did in the 2.2 S, the 2.5 is only about half a second faster from 60 to 100 mph. The 2.5 is actually slower for the first few seconds due to its stock gearing. But, as the century mark nears, 2.5 surpasses 2.2. The extra torque is most noticeable as the 2.5 easily overcomes aero drag.

All up, the 2.5 feels like a T (which it is) with more power across the board (which it has). The T was always touted as the more comfortable grand touring car, requiring less work and fewer shifts. The problem with 911Ts is that they cry out for more power. This 2.5 fixes that but retains the manners of a 2.2 T.

Curt, when asked to describe what he likes about the combo as well as what he would change, thinks for a moment. “If I ever blow this engine up,” he says, “I will rebuild it exactly as it is, except I will bump the compression to 9 or 9.5:1. That would make it just a bit more responsive. But honestly, I don’t need more power… it’s fast enough as is!”

115,000 miles have passed beneath the tires of the Gray Wolf since the 2.5 was built, so it will need to be freshened again at some point. Until then, Curt is satisfied. Unfortunately, satisfaction with the power I have is one of those life-lessons I’ve never been able to learn. I’m eager to drive the 2.8 to see what a little more displacement and a lot more compression feel like! Tomorrow, I’ll do just that.

Day 3 1971 911T 2.8

Our third day begins with breakfast at a small Mexican restaurant on the edge of Ruidoso, New Mexico. Curiously, it’s called the “All-American Diner.” As I chew on what may be the finest breakfast burrito ever constructed, I’m thinking about the 2.8-liter, twin-plug beast in the parking lot. I soon discover that it’s easier to separate a bear cub from its mother than it is to separate the keys from Ran­dy’s fist. It’s not that he’s afraid to let me drive, it’s just that this is the first real trip Randy has done with the 2.8 and he’s having too much fun in the car.

I’m now able to sympathize with all the mothers who have had to pry their child off of the mechanical pony outside of Kmart! The kicking, the screaming, the begging — by both parties. It’s quite embarrassing, actually. Taking a page from the parental handbook, I back off, knowing that my adversary will become more cooperative when he gets sleepy. It works. Somewhere in northern Arizona, I convince Randy he could use some rest.

Connect with Excellence:   Facebook Twitter