1970 Porsche 917K

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1970 Porsche 917K

August 24th, 2018 Leave a comment Go to comments

Model of a legendary Le Mans race car. Features suspension, drivetrain and steering system, dihedral doors, a working steering wheel, lights and custom stickers.

Datasheet:

Completion date: 23/08/2018
Power: electric (BuWizz 2.0)
Dimensions: length 68 studs / width 32 studs / height 16 studs
Weight: 2.088 kg
Suspension: double wishbone independent
Propulsion: 4 x LEGO RC motor geared 1.66:1
Motors: 4 x LEGO RC motor, 1 x PF Servo

When I’m not busy loving tanks, I also have a fondness for classic race cars. And by classic I mean 1960’s and early 70’s. This was the golden age of Le Mans, this was when monsters capable of speeds above 300 km/h were built by hand, without using computers, with still incomplete understanding of aerodynamics, with nothing but engineers’ intuition and drivers’ experience to rely on – and, incredibly, the resulting cars were things of beauty. I heartily recommend seeing the video below to feel what I’m talking about: it’s incredible to see hammer marks on a 300+ km/h capable vehicle. Modern race cars just don’t have this kind of craftsmanship. I also recommend the “Go like Hell!” book which tells the story of rivalry between Ferrari and Ford in the 60’s, which led to the creation of Ford GT40. It was a fascinating age, due in no small part to the bravery of drivers who knew that pretty much any error while racing such a car would be fatal. I strongly suspect that the main reason why Porsche 917K’s cabin has only one seat in it is to leave room for driver’s balls.

The Porsche 917 doesn’t seem to be a particularly famous car, which is a pity considering that it has single-handedly installed Porsche as a top racing brand. The car was launched in the 1969 season, where it performed poorly and killed one driver due to severe stability problems. After that season, Porsche handed the car over to the Gulf team for testing and development. The Gulf drivers have noticed that the pattern of dead gnats that appears over the body after a few laps doesn’t include the car’s tail, proving that the air does not flow over the tail like it’s supposed to. A new, shorter tail was, as Wikipedia puts it: “cobbled-up on the spot in the pits with aluminium sheets taped together” and it improved the car’s performance drastically. Thus a 917K (Kurzheck for “short tail” Porsche was born and it went on to crush the 1970 racing season by winning 7 out of 8 races it was entered in. An underdog for decades, the Porsche was suddenly a leading racing team and it maintained its domination for years by introducing new 917 versions. I, however, like the original 1970 version in Gulf livery most, and I used it for my model, along with markings taken from Steve McQueen’s 917K from the “Le Mans” movie.

The model was directly inspired by the LEGO Tumbler tires and by the introduction of medium blue Technic pieces. I knew that I’ve seen this particular color somewhere, but it wasn’t until seeing this photo that I’ve made the connection:

The legendary Gulf livery has appeared on many legendary cars, and for me the Ford GT40 would be the first choice, except that I’ve already built one. So I went with the 917K and completed it after many months of ordering rare medium blue and orange pieces from the Bricklink. At one point I’ve put together some Bricklink catalog screenshots to keep as a guide of what pieces I can and can’t use. The medium blue is a really rare LEGO color, with only 698 types of pieces available at the moment of writing this post, as compared to 3212 types of pieces available in regular blue. The model’s silhouette also presented a challenge, because it’s extremely low, flat and offers very limited room inside. I did experiment with putting 6 LEGO RC motors inside, but there was no way to actually control them all. It would take six SBricks with six batteries to power all these motors, requiring essentially a huge trailer to fit in, and while BuWizz 2.0 can handle two RC motors per unit, it was not yet possible to control more than two BuWizz units simultaneously.

Technically, the model was fairly simple – after my highly overengineered Pagani Huayra model I just wanted a car that looks well and moves quickly. The rear axle was driven by 4 LEGO RC motors powered from two BuWizz 2.0 units, while a PF Servo motor steered the front axle. Both axles had double wishbone independent suspension; the front suspension was extremely hard, while the rear one was using long wishbones from the LEGO F1 sets, as well as adjustable shock absorbers. The model appeared to be very agile for its size, with great acceleration and surprisingly tight cornering, but its actual top speed was around 6.5 km/h, which I consider fairly disappointing.

On the aesthetic side, there was a number of challenges to the 917K, especially when it came to the shaping of cabin’s roof and doors. I did what I could given the limited choice of medium blue and orange pieces. The tires were also problematic, because the Tumbler tires looked right but were too narrow, and it showed when seen from behind. The front tires, which are about 10% smaller than the rear ones in the real car, were intentionally undersized for two reasons. First, I wanted to use tires with rounded profile, to look like the real ones, so the flat-profiled tires that come in many LEGO versions were out of equation. Second, the real 917K has thin front fenders that the front wheels can fit right under. The LEGO version has front fenders 1 stud thick, because there are no medium blue panels of appropriate shape, so I had to reduce the size of the front tires to make them fit under such thick fenders without rubbing against them. Finally, the rear axle is about 1 stud too wide because of the long wishbone pieces, and I had to make cutouts in the sides of the body to make the rear tires fit. However, probably the greatest challenge was setting the front hood panel in such a way that the slit in it fit the row of grille pieces in the chassis perfectly.

The finished model turned out to look well and appear agile, even if its top speed was actually not that great. I also think that the ground clearance was insufficient in front. Still, it was an interesting exercise in building with limited choice of pieces, and in combining Technic and System pieces together.