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RB26 260

A road/race Datsun 260Z with the hidden performance of an ex-GT-R tweaked RB26DETT!

Words by Michael Knowling, Pix by Julian Edgar

Click on pics to view larger images

At a glance...

  • 1976 Datsun 260Z
  • Skyline GT-R engine conversion
  • Water-to-air intercooler
  • Skyline/Commodore brakes and custom suspension
  • 448hp (329kW) at the wheels!
  • Road and track spec
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This article was first published in 2005.

When you’re a car enthusiast who has owned the same machine for almost 20 years, chances are there isn’t much left on the car that remains unmodified.

Just take John Whittaker’s 1976 Datsun 260Z for example. The suspension and brakes are f-a-r removed from the standard Datto parts – and you’d better be ready for a surprise when you pop the bonnet...

There’s a tuned Skyline GT-R motor hiding in there!

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John is the owner/manager of Brisbane Tuning and Turbo Centre and, as you might imagine, he’s had petrol pumping through his veins for many years. Back in the late ‘70s, John purchased this RS30-series 260Z from its original owner and proceeded to give it the performance to run with the hot cars of the day – namely, Toranas, Monaros, Falcons and Chargers. The first serious round of mods saw the original L26 in-line six equipped with a draw-through carby turbo set-up. John says this set-up made quite good power - about 260hp (191kW) at the wheels - but it lacked the oomph to make it a real on-road ego basher.

After about four years of running a boosted L26, John decided to step up to the L28 engine (as fitted to the later series Zed). A new engine was pieced together with a ported head and some beefed-up parts and John achieved his goal of improving flexibility and torque.

Now fast-forward to the start of the current millennium.

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As a workshop owner, John didn’t want to get left behind by the current breed of performance cars so he took the big plunge – fitment of an R32 Skyline GT-R engine (RB26DETT). John says there was a lot of work that had to be done to accommodate the DOHC twin-turbo donk but the similarities between the L-series and RB-series bottom-end helped make it achievable. John recognised the limits of the factory engine mounting arrangement and added an upper engine brace to keep everything sitting where it should.

The RB26DETT was slid into the Zed together with the accompanying GT-R gearbox. To suit its adaptation into a rear-wheel-drive car, John removed the front-drive section of the ‘box and performed some custom mods. A modified HKS single-plate clutch is sandwiched between the engine and ‘box.

The Datto IRS has been revised with Nissan R31 Skyline LSD (R200) rear suspension running custom driveshafts. John says it’s unlikely the standard driveshafts would’ve lasted under the stress of a boosted RB26.

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A squiz around the engine bay reveals some power-up mods to take the RB26DETT well beyond its standard 280hp (206kW) power level. The inlet to the compressors is virtually restriction-free thanks to twin K&N filters and the turbochargers are based on HKS 25/10s. John says he ran the engine with the turbos as supplied from Japan, but after fiddling with the wheels and housings, he managed to pick up torque at both the bottom and top ends of the rev range. A 3 inch mandrel bent exhaust lets the turbines breathe.

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An air-to-air intercooler was initially used in the car but the front-mount placement of the big core didn’t do any favours in terms of maintaining coolant temperature. The alternative was to switch to a compact water-to-air intercooler set-up using a PWR heat-exchanger, electric pump and dedicated front radiator. John isn’t entirely happy with the set-up on the track – some experimentation with pump flow and radiator heat-exchange properties might be needed. The intercooler plumbing is made from mandrel bent stainless tube and twin GT-R blow-off valves are fitted.

To avoid engine destruction on the racetrack, John has upgraded to a thick core aluminium radiator with a large diameter electric fan. An Odyssey battery, isolator switch and oil catch can are neatly nestled into the rear of the engine bay.

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The task of controlling fuel, timing and boost pressure is given to an Autronic programmable management system. Fuel is supplied by a set of six Mazda RX-7 (Series 4) injectors and a 700hp Bosch Motorsport fuel pump drinking from a swirl pot. The ignition system is stock with the addition of an Autronic CDI.

Boost pressure is limited to 1.2 Bar (17.6 psi) and you’ll find a maximum of 448hp (329kW) at the wheels. John says peak power is attained at 7000 rpm but with the recent turbo tweaking and careful tuning, the car produces strong torque all the way through the rev range. There’s plenty of punch available to kick the rear-end sideways on corner exit.

“The car is pretty neutral in terms of handling,” says John.

“It’s quite controllable and, when you want it, you can make it power oversteer,” he says.

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The all independent strut suspension uses coil-overs that are custom made by Brisbane Tuning and Turbo Centre using adjustable Koni dampers as the base. Custom adjustable swaybars were also fabricated and a carefully chosen group of bushes are replaced with Nolathane items. John says the car is still driven every day and it was important to maintain an acceptable ride quality.

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Braking is improved thanks to R32 Skyline calipers and discs together with a Holden VL rear discs. John also added a larger brake master cylinder and braided lines but fell short of installing a hydraulic handbrake – he’d prefer to keep the original cable-operated system. Despite the substantial improvement, John says the brakes are still pretty marginal – he plans to switch to R33 Brembos or AP monster anchors.

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The classic Zed body is standard with a fresh splash of original green pain courtesy of a friend. An aftermarket front lip was added back in the late ‘70s/early ‘80s and a new rear bumper was about to be fitted after our shoot. The previous one got a li’l bent at a recent track outing...

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Inside, John has kept much of the '70s Datto feel. The dashboard is standard and retains the factory tacho (using an adaptor off the Autronic ECU) and an oil pressure gauge is integrated where there's normally a clock. A boost gauge and shift light are also added to the steering column. The standard steering wheel remains and there's an aftermarket driver's seat and harness for track purposes. A new set of race seats are soon to be fitted. The area behind the front seats has been stripped and a custom rear suspension tower brace is installed.

Rolling on its 16 x 8 alloys and Toyo road-legal slicks (which have now been replaced with Silverstones), John has taken numerous trophies in the historic racing class. And we know what you’re thinking – it won against old HR Holdens, Anglias and Minis. Wrong! This machine has snatched glory from hairy-chested monsters such as replica Ford GT40s - get the picture?!

John is justifiably proud that the car has been built entirely in-house and is frequently street driven. With a move to Silverstone semi-slicks he’s hoping for a bit more adhesion to further reduce lap times. And it’ll need all the adhesion it can get when John follows through with his plan to build a RB30/RB26 hybrid engine.

“I think it will arrive somewhere around 650hp (478kW) at the wheels and I want to make plenty down low – 200hp (147kW) at 2000 rpm is what I’m after,” he says.

Contact:

Brisbane Tuning and Turbo Centre
+61 7 3393 1588

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