Three years have passed since the last installment of Project Z and there's good reason. The car's been such a tank and so spectacular to drive, we found little reason to mess with it further. It almost cleared 100,000 miles of boosted abuse by various hard-driving editors-ranging from drift monkeys to the mechanically unsympathetic-and we were determined to squeeze every last mile we could out of it. We missed the mark by just 2500 miles, when the bottom end finally succumbed to excess blow-by and oil consumption.
However, we'd long anticipated the demise of our supercharged stock block. Arrangements had already been made for a newly built, low-compression, Jim Wolf twin-turbo engine package, assembled by Violent Racing Technologies-now called Verified Racing Technologies (VRT)-in El Cajon, California.
As much as we loved the predictability of the 330 wheel-hp delivered by the Vortech supercharger kit, we knew we would need to make more power in order to take on a Corvette Z06 in a shoot-out. While a low-compression engine, with the same supercharger running more boost, could easily have met the 500hp target we were shooting for, making low-end torque comparable to a small-block V8 would be an issue with the centrifugal supercharger, as it requires revs for boost. A pair of smaller turbos should spool quicker and provide more boost through the middle of the powerband.
To minimize downtime, we sent a spare VQ35DE long-block down to VRT to be torn down, machined and built with Pauter E-4340 connecting rods and JE 8.5:1 compression pistons. The plan was to drive Project Z to VRT on its last leg and have the built motor and Jim Wolf Technology (JWT) twin-turbo kit ready to drop in.
Things never work out as planned. On the big day, the car was just on the verge of spinning a bearing or two. I took the keys the night before, having been assured by its former driver that he checked the oil level regularly, even though the oil pressure warning light was already flashing intermittently when I fired the car up.
Figuring pressure was down because of blow-by degradation and the oil was just a little low, I stopped at the local gas station for some thick, el-cheapo stuff to last the 90-mile drive to VRT. Three trips to the cashier and four quarts later, I finally got enough into the motor to register on the dipstick, but the damage was already done. The faint rattle I heard earlier had developed into a full-on knock. Project Z only made it 10 miles down the freeway the next morning before the rod knock got so out of hand that we were at risk of damaging the original block (which we might re-use at a later date). The remaining 80 miles were made on the back of a tow truck at $5 a mile.
Modes Of Failure
Before building the new engine, we needed to figure out what happened to our original block, so the same mistakes wouldn't be repeated. As a starting point, the VQ is a tremendously stout engine, able to withstand endless beating under drift and race conditions. But we've seen and heard of two consistent signs of weakness from the people within Nissan Motorsports.
VQs and previous generations of Nissan motors, stretching from the QR to the RB series, all use a modern-style bearing material that's fairly intolerant to heat. While older engines used a tri-metal, lead-based alloy (designated F-770 internally by Nissan) that held up well at elevated temperatures, newer bearings use a lead-free material (for environmental reasons) that's far less tolerant of high oil temperatures. This is why most new Nissans from Sentras to Skylines all use oil coolers and bearing failure is so common for track-bound GT-Rs and 350Zs. At temperatures below 300 degrees F, where most synthetic oils are still stable, the newer lead-free bearing material has already changed chemically and been damaged permanently. Even at 250 degrees F, these bearings have lost significant load-bearing capacity.