Text and photography by Nigel Petrie / Engineered To Slide
It’s not uncommon these days to talk about horsepower levels in the thousands, but today I have something a little different for you. I am Nigel Petrie, and this is my 1989 Nissan PS13 Silvia.
12 years ago, I picked this car up as an unfinished project. It started life as an CA18-powered, automatic-transmission, two-tone PS13 that was imported from Japan to Australia. A lot has happened over that 12 year span, but there have been a few significant moments that have led this car to become what it is today.
Initially I kept the CA engine in place and added a few parts like a full Trust TD06 turbo kit, HKS cams, intercooler, ECU and exhaust to make a respectable amount of power. I enjoyed this stage of the car’s modifications, but felt like I could improve it with an SR20DET powerplant in place of the CA18.
A friend was heading overseas and had offered me his freshly built SR20DET engine, so I took it off his hands and begun the process of swapping motors and adapting a VG30DETT transmission to the car. I mounted up a Trust TD06 turbo, made up a new inlet plenum and started taking the car to the track, where my drifting bug started to return. After a few track days and a little rear quarter panel damage, I rethought my direction for this car and decided to store it at my parents’ place while I built my Red 180SX for drifting duties.
A few years later I began to build my Hilux and basically pulled this car down to a bare shell to use the parts for the Hilux build. Over the three years it took me to build the Hilux, the Silvia sat motionless, but I had some plans for it.
Those plans were to build a naturally aspirated SR20-equipped race car, and the process began when I picked it up from my parents’ place and began to find my way down the long road to reconstruct it.
Firstly, I had to cut everything out that I had previously modified, and the lessons and skills I learnt in the fabrication process of the Hilux build allowed me to build this car into my dream machine.
I cut the entire firewall out, the entire engine bay leaving just the chassis rails, the center floor section and boot floor. Over the next few months I would construct a new engine bay, a firewall that is shifted further rearward, a new trans tunnel, roll cage and flat trunk floor.
As the chassis was coming together, I started to focus on the engine setup. I continued the DIY nature of this build into the engine development phase. A friend of mine developed a set of short throttle body adapters with fuel rail provision and set about CNC machining them out of billet alloy. Mounted to those adapters are 52mm throttles, and the whole package mounts to an S13 SR20DET head that has been ported, polished, and had oversized valves fitted. Tomei ProCams operate a solid lifter arrangement with heavy-duty Tomei valve springs.
I have never been a fan of the stock Nissan optical cam trigger arrangement, so I had a friend help me develop a Hall effect sensor that reads a single trigger on the exhaust cam and the RPM via the crank trigger.
The bottom end is a bone stock S13-chassis SR20DE; these are basically free here in Australia. I gave this motor a good clean and inspection then fitted a set of ARP head studs, Nismo 1mm headgasket and bolted the head on with a set of vernier adjustable cam gears.
The idea behind the car was to have a light and simple race car, so I had no need for power steering. Since I only needed the water pump and alternator to be driven off the crank, I machined my stock balancer down, fitted a trigger wheel for the RPM signal, bought a bunch of old NASCAR dry sump CV Racing pulleys off eBay, then proceeded to develop my own drive system. I love the compact setup, and it has been faultless.
You may notice that the engine sits back in the engine bay thanks to the new firewall. This presented a heap of issues that required all the crossmembers be made from scratch out of chromoly tube. I have three: one that mounts the engine with custom made engine mounts, one that holds the now-manual power steering rack and lower control arms, and one that mounts the caster rods and PWR radiator. Clearing all of this is a SR-Miata conversion sump that solved my problem without having to make one from scratch.
Oh, and how could I forget that 1.75-inch 4-into-1 header pipe that really finishes off this engine bay. This exhaust was a key component and something that I built with function and looks in mind. from the merge collector into the single 2.5-inch stainless exhaust all the way to the resonator and then merging back out into twin 2.5-inch tips.
Other details in the engine bay are an oil breather tank and custom coolant header tank with a KTM motorcycle thermostat to reduce flow and allow the motor to warm up and stay warm (believe me, it’s an issue with naturally aspirated cars).
All of this equates to 118kw at the wheels, which travels through an S15 Nismo clutch that spins a stock S15 six-speed transmission, custom tailshaft and R200 diff with 4.9:1 diff gears.
Stepping inside and through the comprehensive new roll cage, you find a pair of Bride ZIEG III seats set back inside the cabin. I extended the steering column 200mm to facilitate the new seating position, which also welcomed a Tilton 6000 series pedal box.
With this ultra-low seating position, I needed a dash that would suit the new roll cage and also allow me to see the Defi gauges through the Personal suede steering wheel. I shaped this out of timber and foam then took a fibreglass mould off it to produce my fibreglass dash. This was finished off with some black felt from my local haberdashery store.
Apart from the six-speed gear selector (using a spare gearknob off my Hilux’s Quaife Sequential 6 speed) there is a handbrake lever, a pair of Cusco 3-inch harnesses, smooth door cards with small custom door openers and an electrical switch panel.
Speaking of electrics, I wired the entire car myself using a LINK ECU with inputs from the throttle position sensor, engine temp sensor, air temp sensor, crank and cam trigger. The switch panel houses a start button, ignition, indicators, electric window controls and headlights.
On the outside it is a mix of 1980s styling and current day Time Attack attributes. I have long been a fan of the original body and this was optioned from the factory with the OEM Aero front bumper (now replaced with a less droopy FRP item) and OEM Aero sideskirts.
Additions to the body are mostly Origin items with an FRP Type 2 bonnet with self made carbon louvers, Origin Type 1 Carbon trunk wing, Origin Carbon weather strips, Origin Carbon roof wing, Carbon rear diffuser panel, East Bear mirrors, custom Carbon Canards and an R32 GTR Carbon Abflug front splitter.
The factory metal fenders have been massaged (and need some work still) to clear the Rays Engineering TE37 rims in 17×9.5+12 up front and 17×10+18 in the rear.
Tyres are Advan A050 and measure 245/40/17 at the front and 255/40/17 at the rear, with 6 degrees of negative camber at the front and 1.5 degree negative in the rear it sticks to the racetrack impressively well.
Suspension arms are all custom chromoly with adjustable alluminium heim joints, front knuckles are custom S15 items that I had optimised for this car. I retained the length so that the steering wasn’t so heavy but reduced the Ackerman a little.
The uprights are JIC Magic with the rears sitting lower than usual inside some machined cups that I integrated into the chassis.
Overall the car is a modern take on something that you might have found at the racetrack in Japan in the late 1990s. It combines so many elements that I love, all fabricated into one complete car.
Yes, it only makes 118kw at the wheels, but on the racetrack with a 6 speed transmission and 4.9 diff gears it’s the most fun I have had in a long time. Combine that with the simplicity of the raw naturally aspirated engine, it’s also easy to work on.
So is it finished? Yes, for now. In the future, I will finish off the bodywork and repaint it in the original two-tone colours, maybe add a stroked high compression bottom end and a dry sump then call it complete!
For any more details head over to Engineered to Slide for the complete build progress.
Thanks for reading.