The Nissan SR20 turbo is one of the most famous Japanese engines of all time, predominantly from its delivery in Nissan’s S-chassis platform (S13, S14 and S15 Silvia/200SX). But what some may not know is there was an earlier, forgotten sibling.

First published in the March 2024 issue of Street Machine

That engine is the CA18, also a turbocharged, dual-overhead-cam turbo four. The 1.8-litre mill bears a much closer resemblance to the straight-six RB25 platform than the SR20, leading to it being dubbed the ‘baby RB’ to those in the know. Sadly, the CA seems to have got lost in the shadow of the SR, which I reckon is a bit of a shame.

Paul Sant and his crew at ProFlo Performance recently built a belter CA18 for customer Rob Ward’s Datsun 1200 coupe, giving us the perfect excuse to shed some light on this ripper little engine. With the right gear, these little screamers can pack plenty of punch.

For this package, the standard crank and block were used, with Spool rods and CP pistons added to retain the 1.8-litre capacity. A factory eight-port head was given a massage by Charlie Sant, and is clamped down with ARP gear over a Cometic head gasket. It also has a new pair of Tighe Cams camshafts, matched with a set of Tomei valve springs.

The cold side uses a standard intake paired with a Hypertune throttlebody, and a Plazmaman fuel rail will feed the whole show with E85. Hot-side goodies include a Steadfast Garage manifold, Garrett hairdryer and Turbosmart 40mm wastegate.

Paul reckons this thing will see upwards of 30psi. “The goal the owner wanted was around the 500rwhp mark, so we’ll put somewhere between 20-30psi in it for that,” he says. “It’s for a street car, so that’s why we retained a lot of standard gear like the factory wet sump system.”

The ignition system on these old 80s Nissans isn’t much chop, especially once you start shoving more power down their throats. So, this CA has rightfully been updated and brought into the 21st century with a Platinum Racing Products trigger kit. “We wanted the cam gears exposed, and the kit is designed to work with the factory cover, so we had to make our own bracket to suit,” Paul says. A good trigger kit will keep everything happy as the CA mill sings to 8000rpm, with brain power from a FuelTech FT550 ECU.

Building a slightly left-of-field engine like this does come with its challenges, with the ingredients a tad harder to track down. “Parts were a bit tricky; you couldn’t just do a one-stop shop like with a V8 or RB,” Paul says. “They are out there, but you need to dig around to find them and do a fair bit of picking and choosing from different places.”

With 500rwhp and bugger-all weight on the nose, the Datto 1200 that’s going to receive this thing will be one formidable street demon. “I believe the owner is just going to be keeping the car fairly standard-looking on the outside with a tricked engine bay, so it should be a neat thing,” Paul says.

FAMILY TIES

Much like the SR20, the CA18 found its way into a bunch of Nissans during its production run. Made in both turbo and atmo form, it could be found in rear-wheel-drive S12 and S13 Silvias/180SXs, or in front-wheel-drive EXAs. The CA18 shares loose similarities with the hilariously slow, twin-spark, single-cam, CA20 variant found locally in R31 Pintaras and Nissan Gazelles.

ProFo Performance
Campbelltown, NSW