When you first consider the idea of comparing a Time Attack car to a wheel-to-wheel circuit car, you'd think there wouldn't be many similarities. The HKS GT1000+ Nissan R35 GT-R was built with the HKS catalog, while the World Challenge (WC) AutomotiveForums.com R34 GT-R was built to fit within the SCCA's homologation requirements. Deep down, though, these cars came out to be very similar; remove all the stickers and they could both still be road-worthy cars.
First, there needs to be a little backstory on the R34 driven by Igor Sushko in the SCCA World Challenge Series GT-class back in 2006. Originally when it was purchased it started out life as a Super Taikyu Class One car in Japan that was operated by the Fujitsubo team. Well, actually and unfortunately not the car you see before you — on a test weekend at Moroso Motorsports Park (now known as Palm Beach International Raceway) that car crashed and needed to be rebuilt before its first race at Sebring International Raceway, which had to be done only five days. Instead, Sushko's team had a spare car mostly as a shell that was once sponsored by Altia in the same Super Taikyu class.
Fortunately, the roll cage and body were ready to go save for the pieces that had to be bolted on. Over those five days, the team that included Sean Morris (now with International Vehicle Importers) had taken the parts from the Fujitsubo car and transplanted them to the Altia car. The only thing that didn't transfer over was the coilovers they originally used. Instead, they found a set of Ohlins high-end street dampers from a local shop. With as much done to the car as they could, the GT-R took its first competitive laps at Sebring — 16 seconds slower than the top 11 cars. Why so far off the pace? Super Taikyu regulated engine output to no more than 420 horsepower on a car that weighed nearly 3,300 pounds. The SCCA, however, mandated GT cars remain at 3,000 pounds and 500 horsepower, though in reality was more like 2,700 pounds and 550 horsepower to be competitive. Then there was Cadillac.
Even at its best, the R34 GT-R was putting out 400 horsepower with 16 psi of boost pressure. It wasn't like this wasn't a well-built engine; it was a NISMO-built power plant made exactly to Super Taikyu specifications. It's just in a field of factory backed CTS-Vs, Porsches, and veteran-built Corvettes, there wasn't much a brand new team with a very limited budget could do. The ATESSA All-Wheel-Drive system of the GT-R, mandated to remain in place by SCCA for homologation, certainly helped at the starts but once cars got going and along long straights, the GT-R's weight and lower power meant it was getting left behind.
The main idea of the Super Taikyu and SCCA World Challenge GT-class was to maintain cars that still remained very close to their street-driven counterparts. Many parts that were installed, in both series, had to be approved before use — including bumpers, wings, wheels, engine parts, and more. Essentially, anyone with a good budget should be able to produce either a Super Taikyu or a World Challenge car. For that reason, this R34 and the HKS GT1000+ R35 GT-R have a very similar build principal.
The parts installed on both the WC GT-R and the HKS GT-R can all be found for public purchase. Both engines can be built and purchased by anyone with enough cash, the aerodynamics can be bought and applied to street cars, the wheels are both sets you can purchase from your Rays or Yokohama Wheel dealers, both still use Nissan's AWD systems — the point is both of these cars could be street driven and you wouldn't know they were actually racing cars, provided you took the graphics off. When it comes down to it, it's an amazing result that the HKS GT-R was able to be as competitive as it was at The Speed Ring.
What amazed me as I took pictures of the HKS GT-R was the fact it still has power windows that work — a car built to go as fast as it does still has a creature comfort like that. It even has power door locks that still function. Yes, it has carbon fiber parts, including both doors, but the things most people ditch in the pursuit of building a lightweight racer — like power windows, locks, basically anything that's considered "dead weight" — many of those things remain in place. The HKS GT-R is definitely a very Japanese approach to car builds that aren't tube chassis. If it works on the street car and the engineers designed it that way, why remove it? It's only when they knew something could be made better that they took it out of the car and replaced it. It's why much of the car remains stock where it does — they didn't find a way to make it better and even worked with it.
Both cars are not impossible to replicate — expensive, but not impossible. Indeed, one of the things that make these cars special is the idea that anyone could build them. You take a look at each car and you can see a majority of each is not a one-of-one build. You see the parts installed on these cars and they are all pulled from catalogs, past and present. The turbos, the engine internals, tires, steering wheels, lights — it's all stuff you can buy or could have bought.
There are some key differences between both cars, however. This is where having no universal rulebook really starts to show. The engines are pretty much a given, with the WC GT-R's displacement at 2.6 liters in an inline-6 design and the HKS GT-R at 4.3 liters in a V-6. The HKS car also makes 802 horsepower more than the WC GT-R (the GT1000+ is rated at 1,252hp). The WC car had to make do with a spec tire from Toyo; on the front and the rear are Proxes RA1s sized in 305/35ZR18, meaning the Volk Racing TE37 Time Attack wheels are 18X11 +18 (originally, it had a set of TE37s in 18x10.5 with a 275 width tire). The HKS car? A set of Yokohama Advan GTs in 20x10.5 +24 with Advan A005 slicks coming in at 290/710R20. That's roughly the equivalent of a 295/35R20 when you take percentage errors most tire makers fit within — even Yokohama advertises the A005 with a 707mm-overall diameter and 291mm tread width despite being a 290/710 on the sidewall — though this is probably a discussion best left for another tech article.
Another key difference, and one I'm a particular stickler for, is roll cage design. Both cars, before the WC GT-R was brought up to SCCA specifications, would have actually been very close here as well. However, the SCCA (and most sanctioning bodies in the US) requires a harness bar when you use a five- or six-point harness where most Japanese sanctions don't. There is also the "NASCAR" style door bar on the R34. The HKS GT-R has neither, but the one I find most surprising to see missing is that harness bar.
In principal, a harness bar should be installed on a car that uses a four-, five-, or six-point harness, principally because it keeps the shoulder belts angled at 45 degrees or less. Anything more is considered unsafe because it can cause spinal compression in a crash as the belts stop securing you in the forward direction and begin to try and pull you down. The shoulder harnesses are designed to stop you from moving forward, even in off-road — it's the lap belt that keeps you from flying up out of the seat. The belts in the HKS GT-R are right at that acceptable forty-five-degree angle, so I'm probably nitpicking.
One other departure is fuel pumps. The R34 has a primary, secondary, and slosh tank pump for a total of three fuel pumps. In the HKS R35 there are two Bosch 044 fuel pumps to feed the slosh tank and three more 044s to feed the engine for a total of five fuel pumps. For reference, a single 044 pump can push out up to 300 liters per hour; tie them up as a pair in series, you get 600. HKS is running three; that's 900 liters per hour to feed the engine and its 1,252 horsepower — which incidentally would also fill a 1,220-cubic-inch pool with 7,200 gallons of water in about eight hours. This set up is based on engine need more than anything else. At 450 horsepower, a single pump at 300 lph is more than enough.
The final difference? The character of the teams. You see it in the build of each GT-R; the HKS car is serious — all business. It knows the job and you don't ask it any questions. The R34 is a bit more lighthearted, and its team had to be. As mentioned earlier, this was a squad that was on a low budget and taking on the likes of Porsche, Cadillac, and Corvette in a professional series. At 19 years old, Igor was also still fairly young, so there was some inexperience the team had to somehow leverage in its favor. Since he was a part of the original Gran Turismo generation, on the center dash where the computer gauges used to reside is a 100-yen "coin slot," and used to feature a "track map" of the Nurburgring. By his right hand is an arcade button to "select" a "multiplayer game." If they couldn't win, at least they could have fun and say they took on factory teams on their $500,000 budget. It's a fact these guys still relish, even today.
While these two GT-Rs took on the world in different ways, it's important to see how far automotive technology has come in just 10 years. What are basically stock cars took on vehicles that would be considered truer racecars than these two. While the R34 wasn't able to dominate, the technology Nissan researched and implemented into the R35 made it an amazing car out of the box. Then HKS used its own publicly available aftermarket parts to augment, and its GT-R became one of the fastest cars in the world that you might still just be able to drive home in. Believe me; I've seen "street cars" with fewer amenities and harsher engines than either one of these.