The R35 GT- R might be regarded as one of the best cars to ever come out of Japan, but that doesn’t mean you can’t improve on perfection. Cars are there to be modified, after all …
Three hours is a long time to be doing anything, especially when you start talking about circulating a car non-stop at race pace around a racing circuit. Most sprint races last 10 to 20 laps, and when you crunch the numbers for a three-hour enduro on any New Zealand track, you can expect that number to total between 100 and 200 laps. This presents a special set of parameters when building a car, as no longer are you looking for outright speed and stressing the car to achieve that performance, it’s about reliability and balancing the power output to ensure the car’s fast enough to run at the front of the field, but not so fast that you burn up tyres and fuel quicker than you need to. That old saying, to finish first, first you must finish, was surely penned with endurance racing in mind. If you watch the recently televised Highlands 101 (effectively Highlands Motorsport Park’s three-hour race) you will know exactly what we’re talking about.
All this makes for a very challenging build, and is perhaps why endurance racing is such a popular sport here in New Zealand, attracting some of our biggest fields — and prize purses. Auckland’s International Motorsport is well versed in enduro racing, having built and run countless machines over the years, but this would be its first R35 GT-R.
The project began when the owners, one of whom has a heavily modified R35 street car, realised everyone was racing a Porsche GT3, and no one had an R35. “The way the Skyline is set up makes the car the perfect option for those weekend warriors, as it’s a little easier to drive. There’s a good amount of driver aids, good straight-line speed and four big wheels on it, with plenty of mechanical grip,” explained IMS fabricator Ricky.
The GT-R was purchased as a fresh import from a friend, with only 5000km on the clock when it was rolled into the IMS workshop and stripped to a near bare shell. Stepping into the unknown was a challenge for the team, as surprisingly not many people run R35s in endurance racing anywhere in the world. Plenty compete in sprint race and weekend-warrior track days, but not endurance racing. However both IMS and the owners were confident it could work, as Ricky explained. “The good thing about this build was the budget. They didn’t want to mess around with doing anything half way, so the easiest thing to do was over-engineer stuff. We knew the car was going to be heavy, so we weren’t too worried about weight, we wanted to make it reliable and safe for the enduro stuff.”
With such a well-constructed chassis to begin with, not too much was needed in the way of chassis stiffening. An extensive roll cage was constructed, and the rear alloy bracing was replaced with a tube structure, which would also act as a bracket for the 120-litre special-order Fuel Safe fuel cell.
“The way the Skyline is set up makes the car the perfect option for those weekend warriors, as it’s a little easier to drive. There’s a good amount of driver aids, good straight-line speed and four big wheels on it, with plenty of mechanical grip,”
The VR38DET, which had barely been broken in from factory, received very little in the way of upgrades. The factory turbos had new cores fitted locally, and American company AMS — which would end up supplying plenty of pieces for the project — sent over its largest GT-R-specific intercooler, along with its piping and a fuel rail kit, to house the ID1000 injectors. AMS also supplied the 3.5-inch turbo downpipes, with IMS building a five-inch side-exit exhaust.
These few basic upgrades are controlled by the MoTeC ECU, and see the 3.8-litre produce more power than needed, somewhere around 410kW (550hp), depending on the ECU map chosen via the adjustment on the dash.
The gearbox is the factory-fitted item, although its ECU has had a lot of attention to upgrade the way it functions, as Ricky explained. “We are lucky to have have Linney Tuning and EcuTek on board, they have adjusted the way it shifts, hydraulic line pressures and clutch-pack pressures. They do a
These few basic upgrades are controlled by the MoTeC ECU, and see the 3.8-litre produce more power than needed, somewhere around 410kW (550hp), depending on the ECU map chosen via the adjustment on the dash
lot to take it away from how the road car version shifts, making it a lot harsher, which reduces the heat.” In addition, a large rear-mounted gearbox cooler ducts air up through the rear diffuser and out through the opening in the rear bumper. This and the coolers for both front and rear diffs all have their own pumps, and are temperature controlled by the MoTeC ECU. It’s factors like this you just wouldn’t bother with for a sprint-race car, but banging out in excess of 100 laps — as you do when endurance racing at some tracks — translates to thousands of gear changes, and you don’t want to leave anything up to chance.
Other over-engineered areas include the braking kit, one item they knew would need overkill — as R35s are known to be hard on brakes — but then again, any car weighing over 1700kg will be hard on brakes. “Everyone with a GT-R complains that you can’t make the brakes last longer than six laps, you just cook them. So the owner went out and said “what’s the biggest and baddest brake package we can get”, and Endless came up with this — 400 by 36mm two-piece rotors up front and 387 by 37mm on the rear, with huge six-pot Endless racing Mono6 calipers front and rear.
The brake ducting draws down through the bonnet to feed the rotors nice cold air, and it seems to be working really well. The special enduro pads are getting 1mm of wear an hour. The boys are raving about how well the brakes work, so we are rapt.” To put the size of the brake rotors in proportion, that’s just shy of 16 inches, add the caliper on top of that and you’re going to need a big wheel, in this case a set of special-order 19x10.5-inch Wedsports wrapped in 305/690R19 Pirelli slicks, the type normally found on Ferrari Challenge cars.
The suspension package again comes from Endless and AMS, with a set of Endless Super Function coilovers, and a full titanium adjustable-arm kit imported through AMS. This has seen the car find a good base tune rather quickly, but the IMS team has battled the likes of front tyre wear and lack of front aero grip. The large Tuner Group rear wing and carbon diffuser are working well, but the front fell short. As a result the car soon transformed into an even more aggressive looking machine, with a new front bumper, front guards and side skirts, all aimed at increasing aerodynamic grip ahead of the full assault on both the North and the South Island Endurance series next year. “It’s a competitive car — whether or not it’s a winning car is still to be found out, but it’s definitely competitive. Getting it to go fast over a long period of time is what it is all about.”
There is no denying that the guys at Nissan designed and built the R35 as one of the world’s greatest cars, and certainly one of the greatest to ever leave Japan, but just like the stock versions of any of the cars featured in this magazine, there is always room to improve on what was once perfection in someone’s eye. Modifying a car like this is a brave move, but we have a sneaking suspicion that this coming season we’ll be shown just how competitive the Endless/IMS R35 GT-R can be. Watch this space.
“It’s a competitive car, whether or not it’s a winning car is still to be found out, but it’s definitely competitive. Getting it to go fast over a long period of time is what it is all about.”
Endurance racing means on-the-fly driver changes, so the harness is attached to this stretch cord system that pulls each belt out of the way, so the next driver jumping in does not need to hunt for every strap
With fuel saving a must in endurance racing, this dial allows on-the-go power delivery changes by switching the map in the MoTeC ECU.
There is a surprising 200kW of adjustment, but generally the GT-R runs around the 410kW mark to all four wheels
Cooling is a serious business, and the car has two engine-oil coolers, plus radiator, AMS intercooler, power steering, front diff, large trans and rear diff coolers. Each cooler temp is logged, and has an electric pump controlled by the MoTeC and PDM
Conserving fuel to work within pit stop strategies is a big part of race-day antics, as fuel stops are fitted into the mandatory two driver changes. To run the distance a special order 120-litre Fuel Safe bladder sits inside an alloy case and feeds via a dry break fuel filler
The huge braking package supplied from Endless uses 400x36mm two-piece rotors
up front, 387x34mm twopiece rotors on the rear, and Mono6 calipers front and rear. This is a bolt-on kit, and works in conjunction with the stock pedal box so as not to affect the inbuilt