2019 Porsche 911 Speedster: 7 Powertrain Points
Why Porsche considers this the third generation of this engine architecture
Porsche is kissing its 991-generation 911 goodbye with a series of 1,948 very special cars, and we can now reveal more about what's under the hood. The wraps were pulled off two new 911 GT3-based Speedster models—the first to be prepared by Porsche's GT-car department—at the 2019 New York auto show. One was a $275,750 "base" model in Guards Red; the other was a Heritage Edition version resplendent in GT Silver and decorated with $24,510 worth of additional vintage racing graphics, badging, and a two-tone black and cognac interior.
Recently, we spent some quality time with the engineers and learned quite a bit more about the powertrain motivating these special cars. It is indeed GT3-based, but this was no mere engine swap. In fact, there is so much new engineering involved that Porsche considers it the third generation of this engine architecture.
The three main engineering revisions are for compliance with stricter European emissions regulations—particularly the particulate standards. To prevent these dangerous particles from forming in the first place, you want the fuel spray droplets to be extraordinarily fine. Toward this end, new injectors operate at higher pressure (3,626 psi versus 2,901) and spray a different pattern of fuel into air that enters via individual throttle bodies. (These are also credited with improving throttle response.)
Exhaust now exits the engine through a new super-thin-wall exhaust system that integrates the forward silencers. Particulate filters live in a cylindrical housing that is brazed using an innovative nickel-steel solder capable of withstanding the intense heat of an exhaust system. This saves a few precious grams over the welding process that Porsche formerly used to fabricate the exhaust. In all, the system weighs 22 pounds less than its predecessor, and pounds shaved off the very back of a rear-mounted engine bring compounded benefits in terms of weight distributions and polar moment of inertia. Note that in place of the particulate filters, U.S.-bound cars will get an inert substrate that simulates the filters' back pressure.
These changes boost output to 502 hp at 8,400 rpm and 346 lb-ft of torque at 6,250 rpm. The 2018 GT3 engine produced 493 hp at 8,250 rpm and 339 lb-ft at 6,000 rpm. Note that the second-gen GT3 engine's metric horsepower rating of 500 was previously reported as 500 SAE hp, but the real improvement is 9 hp.
As in the last-gen GT3 4.0-liter, the valves operate without hydraulic lash adjusters, yet the factory-set shim valve adjustment is expected to last the life of the engine, so there are no access plates to service them.
