GT3.8

Also from Issue 157

  • Preview: Ruf’s 700-hp, 235-mph CTR3
  • The Unpublished IROC Story
  • Driver Jack McAfee Remembered
  • A Day Inside of Weissach
  • Three 356 Concours Kings
  • Ferry Porsche’s Carrera RS 2.7
  • Survivor: The Risky Business 928
  • Market Update: 1974-89 911s
  • Interview: Bobby Rahal
  • 911 SC Targa Turns into a Speedster
  • Mess-Less Oil Filter for 924S/944/968
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RUF RGT 1
RUF RGT 2
RUF RGT 3
RUF RGT 4
RUF RGT 5
RUF RGT 6
RUF RGT 7

A new rear engine lid provides better venting than a stock 997 and is comparable to the GT3’s design. As with the factory 996 GT3 RS, 997 GT3, and 997 GT3 RS, the quoted dyno figures do not take into account the supercharging effects of the ram air intake on the engine lid, which only works at high speed. Porsche claims another 15 bhp from this effect, but Ruf is only willing to put his name to a more conservative 10 bhp. The big rear wing balances the looks and also saves the weight and complexity of a motorized spoiler. It is three-position adjustable via a bolt-and-hole system — with the most extreme rake for use on tracks where downforce is critical. However, if you are going to use the more aggressive angles, Alois Ruf recommends rebalancing the RGT aerodynamically with an optional front splitter.

The competition-based 3.6-liter flat six in the latest 997 GT3 RS leaves the factory making 415 bhp at 7600 rpm and 298 lb-ft of torque at 5500 rpm. Alois Ruf feels that an engine without a supercharger or turbocharger strapped to it should have a decent cubic capacity and 3.8 liters was his target. The GT3 3.6 is stripped before new 102-mm diameter Mahle pistons are attached to a fully balanced steel crankshaft via lightened titanium connecting rods. The stroke remains 96.4 mm, but displacement goes up to 3746 cc with the same 12.0:1 compression ratio utilized by the standard 997 GT3.

Deeper breathing comes thanks to subtle improvements from a custom set of high-lift camshafts and a sport exhaust system. The Bosch Motronic ME 7.8 ECU is remapped to cope with these changes and for a single-mass flywheel borrowed from the GT3 RS. The lighter flywheel means the ignition timing can be more aggressive at low rpm. The result, says typically conservative Ruf, is 445 bhp at 7600 rpm and 310 lb-ft of torque at 5100. To put this in perspective, 445 bhp from a normally-aspirated flat six was unthinkable back in 1988 — when Porsche’s 3.3-liter 911 Turbo made 282 bhp and Ruf’s own twin-turbocharged, 3.4-liter CTR Yellow Bird was rated for 469 bhp.

The Ruf RGT is capable of rocketing from rest to 62 mph in 4.2 seconds before reaching 124 mph in a total of 13.5 seconds. Top speed? An impressive 196 mph. None of these numbers will beat the old Yellow Bird, but more frontal area, more weight, and a lot less torque make that unavoidable. The payoff is the RGT’s docile behavior in normal driving. It pulls smoothly from 1200 rpm in sixth all the way to its top speed — yet remains a car you can conceivably enjoy daily, something no one will ever say about the original CTR.

Weight has become the watchword for car enthusiasts of late, and an even more important one than “power.” Porsche says the standard GT3 weighs 3,075 pounds, while its GT3 RS is supposed to check in 44 pounds lighter. With aluminum hood and doors, Ruf says this RGT tips in at 3,163 pounds — the extra weight largely due to the IRC cage and its trim.

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