Sunday, April 26, 2015

2015 Nissan GT-R Le Mans

Unlike F1, Le Mans has a very liberal policy around race car engineering.

They're not quite there yet, but I think the model where you run what you want as long as you can finish the race on a set number of BTUs is the way to go. We’d see Pratt & Whitney helicopter gas turbines fueled with Jet A, 27 litre Allison V12 aircraft motors redlined at 1500 RPM and running on 105 octane avgas, 1 litre H16s screaming along at 30,000 RPM on a mix of methanol, nitrous oxide and toluene, 7 litre 2-stroke V-twin turbo Diesels running on home heating oil, whatever. You run out of BTUs, you’re out. Energy recovery suddenly becomes very important; photos of ceramic disc brakes glowing a dull orange as the driver desperately tries to dump precious BTUs heading into a corner are a thing of the past.

The bicycle racing arena is at least as rigid as F1. The rules for the Tour de France are extremely restrictive; I recently bought a road bike with hydraulic disc brakes which will outperform a TdF bike, but which the TdF riders can’t have because they stop too well. The argument is that if the guy in front of the peloton has hydraulic discs, and gets on them hard, he’ll be crushed by the pack behind him relying on Victorian-era cable-operated rim brakes that haven’t been improved since Tullio Campagnolo patented the quick-release hub in 1930. The string of Jaguar wins at Le Mans in the '50s were due entirely to two factors: Jaguar's adoption of disc brakes, and the refusal of some Italian guy named Enzo to do the same. Ferrari's high-revving, short stroke motors were decades ahead of the long-stroke Jaguar motor that were inspired by pre-war GP engines, but being able to brake later and harder was the trump card for wins by a string of C- and D-Types.

I once drove a car with cable brakes. It was a ~1950 Dellow trials car, and probably weighed about 600 kg. With a Ford Prefect 1172 cc (yes, that's 71.5 cubic inches) flathead motor augmented with a custom high compression head (I am going to guess 6.8:1 versus the standard 6.3:1) from one of those British ‘hot rod’ shops whose name escapes me now (Speedwell?), it probably made about 31 hp, and the three speed non-synchro box was geared for a top speed of well under 40 mph. Even in these circumstances the brakes were well and truly frightening, the inadequacies only matched by the thermo-siphon cooling system that could not handle repeated 0-30 mph sprints away from lights without boiling, which prevented me from further stressing the brakes as I had to pull over for a rest on my way back to the shop. A good thing too as I was probably additionally stressing the splash lubrication system, said splash lubrication system probably being the inspiration for the Briggs & Stratton 8 hp lawn mower engine, which is where it belongs. I would not have wanted to run the big ends on a customer car.
But I digress. Getting back to Le Mans: Porsche is running a V4 Diesel, everyone in LMP1 has hybrid systems, it’s getting very weird. But wait, it's about to get a lot weirder, to wit: Nissan is preparing a 3.0 litre turbo V6 making 625 hp for this year’s race. Pretty conventional so far; however it will be front engined (!) and FWD (!!) which is wild and crazy indeed. The advantage, they hope, is massively improved aero: air gets pulled in from underneath the front splitter, is routed through the forward engine compartment for heat management, and flows through large tunnels either side of the cockpit to the rear of the car, where it exits through what looks like an HVAC hot air vent off a downtown high-rise. The car has none of the usual vents, ducts, scoops, tabs and other drag-inducing stuff you find on the surface of the usual rear-engine cars; skinny little rear tires complete the picture, and the lack of an engine and transaxle  in the rear means the airflow is not constrained by mere mechanical bits. It will be interesting to see how many aero add-ons get pop-riveted onto it as they get the car ready for Le Mans, it’s all pretty sleek now.

According to Road and Track, Nissan will store power in a pair of flywheels under the drivers’ seat. Initial planning was for an added 1375 hp from the flywheels in 3-second bursts for a total of 2000 hp (!!) on tap at the exit of a corner. For reasons of reliability, they now have settled on only 625 hp from the flywheels, so a mere 1250 hp at peak (!). Yoiks. Let’s hope it all holds together.

Meanwhile F1 is back to 2.4 litre V6 turbos limited to 15,000 RPM, and NASCAR requires a pushrod (pushrod!) 368 cu. in. Chevy small block derivative with a restrictor plate under the carburetor (carburetor!). Seems to me the Chevy small block, while an excellent design, dates to about 1957, while the carburetor is a 19th century invention. Where's the innovations, guys?
So anyway Profil 24 has wasted no time in preparing a 1:24 model (possibly curbside) of the Nissan. I'm not sure how they do it but they do seem to have figured out what I need in my collection ... They are also preparing a model of the Aston Martin DB2 that ran in 1951 which I will tackle just as soon as I complete the DBR1 that Shelby used to win in 1959.

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