We weren't so sure about this engine's qualifications for WEOTD status, not because it doesn't measure up in the awesomeness department but because it's damn near impossible to figure out whether those perfectionist Porsche engineers have completely blank-sheet-of-paper redesigned the thing repeatedly (keeping only the general layout, mounting hardware, and the bore centers). If we agree that the boxer six-banger from Stuttgart has been essentially the same engine with a constant series of upgrades, then its ancestry stretches all the way back to the early 1960s. We'll let tipster Jason weigh in with his arguments after the jump...
Says Jason: First conceived in 1961 for the T7 prototype, and later installed in a 911 in 1964, the little 2.0L flat six turned out a whooping 130 hp. Fast forward to 1998, and the last air-cooled 911 (turbo) was cranking out 400 hp. The race flat-6 motors in the 935 were cranking out in excess of 950hp with water-cooled heads.
But this motor didn't just power 911s, it covers 914s, 959s, and a slew of race cars... including the 934, 935, 956, 962, and Porsche's first Indy car in the 1970s, along with the 936...
Not only was this motor in a street car for 34 years, it has won races and championships for Porsche for nearly as long... including 24hrs of LeMans, 24hrs of Daytona, 12hrs of Sebring, Targa Florio, MonteCarlo, and Paris-Dakar (Twice).
Does it need mentioning that the 956 with a flat-6 "911" motor currently holds the all-time fastest lap record at the Nürburgring-Nordschleife of 6:11:13?
The 'engine' has been essentially the same... I think the same bore centers based on the research, but the cylinders are external to the block (being air-cooled)... the air-cooled motors have had water-cooled heads, esp. within motorsports, and the cylinders have changed over time to increase displacement... I do know for a fact, that you can take an old 911 'T' beater, strip the 2.2, or 2.4L motor out and drop in a 3.0L or 3.2L with 'ease'... the mounting hardware is very similar.
That being said, Porsche has also changed the casting material, from magnesium to Al because on the 2.7L motor they found the head-studs had a tendency to pull, esp. with the higher temps. from having the thermal reactor installed (for cleaning up emissions).
Porsche as a firm has long since been of mind of reusing parts & technology, putting various motors into the same racing chassis (904 with 4-cam 4-cyl, the 911 6-cyl, and the 8-cyl F1 engine)... initially the 917 motor (called type 912) was started with 2 6-cyl. siamesed...
From that first flat-6 that was installed into a 911 (The T7 had 2 axial fans) the basic layout has not changed until 1994's 996 water-pumper. It had the same type of split-case, crank, dry-sump oiling, cyl. arrangement, (oil) cooling... the heads have changed greatly, esp. with Turbocharging, and later variocam/ram systems to alter valve timing... the 935 had its cooling fan switched from vertical to laying horizontally on-top of the motor, but that came from the prototype racers. (speaking of which, the 956/962C twins gave their motor to the 959... and the only difference between the 956 and 962 is where the front axle was rel. to the driver's feet... BUT the IMSA version of the 962 had a single turbo, vs the twin turbos of the Group C cars...) Also, the first 1970's foray into Indy, Porsche had a 2.86L Turbo flat-6 and then used that motor in the old 936 chassis to create a new 936 that won LeMans... well you get the idea.