Project FR-S: Adding a Turbo to Our Salvage Auction Find

Update by Tom Suddard to the Scion FR-S project car
Mar 3, 2020

Story and Photography by Wayne Presley and Tom Suddard

Thanks to a weekend in the garage and some bolt-on suspension parts, our Scion FR-S, salvaged from the clutches of a Copart auction, now had a chassis appropriate to that sleek sheet metal. Now it was time to make the car go as well as it turned.

The FR-S/BRZ engine is rated at just 200 horsepower from the factory, along with a torque curve that leaves a lot to be desired: There’s a big low spot from about 3200 rpm to 4700 rpm, right in the meat of the engine’s operating range. 

How do we fix it? We could go with a tune and mild bolt-ons, but we have a somewhat lofty goal here: Run down Porsche Caymans.

Because of our FR-S’s high compression, good-flowing heads and variable cam timing, bolt-ons weren’t going to give us huge gains. That left us only one option: forced induction, either through supercharging or turbocharging. Both supply boost, but the turbocharger’s efficiency won us over.

 

Prepare for Launch

Before we could make any further changes, we needed to gather some baseline data. We strapped the FR-S to our Mustang chassis dyno, where it spun the rollers to the tune of 167 horsepower with 139 lb.-ft. of torque. Not bad for a car saved from an insurance salvage auction. 

We had already installed our uprated Xclutch clutch kit–as detailed in the first installment–so now it was time to order that boost. Hello, Treadstone Performance Engineering? This parts manufacturer makes an intercooler kit for the FR-S that’s designed around the BorgWarner 6258 EFR turbo.

That turbo can support 450 horsepower and still spools up quickly. It features a water-cooled ball bearing center section, ensuring a long life, while the billet impeller spins in an anti-surge compressor housing that provides max of airflow. Plus, the turbo offers electronic boost control, meaning just a two-wire hookup.

The kit also includes an equal-length header, stainless-steel hot pipes, mandrel-bent aluminum cold pipes, and all the fittings and clamps to bolt it into the car. The price? $4895, including the turbo and everything needed–well, except instructions.

Why not engineer our own turbo setup? Refer to Part 1 of this series: This is a daily driver, meaning when it rolls into the garage late Friday, it must be ready to head out Monday morning. Here’s how we turbocharged our Scion.

After adding some sport to our Scion’s chassis, it was time for the next step: installing a turbocharger. Is this the way the car should have come from the factory?

First, we removed the front bumper and laid out Treadstone Performance Engineering’s turbo kit to figure out each component would go. 

Before installing the header, up-pipe and downpipe, we coated them for thermal protection with a Cerakote air-dry ceramic. It sprays on like paint and provides a very hard, durable coating. 

We removed the stock header and oil pan, which we no longer needed. Treadstone Performance Engineering provided a new oil pan with the turbo oil return fitting TIG-welded in.

Time to install the header and up-pipe before test-fitting the turbo. This BorgWarner turbo’s housing can be rotated to any angle without affecting the wastegate actuator location.

The compressor housing was removed so we could install the speed sensor for the TSG-1 Turbo Speed Gauge. We ran all of the cooling lines for the center section to the heater feed and return lines. We installed the downpipe, then stepped back to see how things were fitting. Making progress. 

BorgWarner makes this TSG-1 Turbo Speed Gauge, which also features a built-in boost gauge. The unit is pre-programmed for the BorgWarner turbos and can be configured for others as well. The gauge is compatible with 3, 3.5 or 5 bar MAP sensors. Knowing the compressor speed shows when the turbo is operating in the optimum range. We installed the gauge in a CravenSpeed mount that attached to the steering column shroud. Why not use the typical A-pillar mount? In a car with side-curtain air bags, A-pillar mounted gauges become projectiles in a crash.

The Treadstone downpipe was about an inch too long to mate with our midpipe, but luckily the fix only required a 14-inch abrasive cut-off saw and a TIG welder. 

Now that the hot side of the setup was together, we could work on the intercooler and the cold-side tubing. The intercooler is a Treadstone piece featuring a 3-inch-thick core that bolts to the front bumper bar. The cold piping installed easily with high-quality silicone connectors and T-bolt clamps. 

The last pipe before the throttle body has a welded-in bracket for the stock mass airflow meter.

We clearanced the splash shield beneath the front bumper to provide room for the intercooler core. 

Thanks to that extra three-quarters of an inch, the front bumper cover fit perfectly. 

The 4 bar map sensor plugs into the top of the intake manifold and uses the stock connector for an OEM fitment. The intake manifold has only one available vacuum port for connecting the bypass valve, and it’s not easily accessible. We removed the throttle body to reach it. One tip: Put a hose clamp on that vacuum line. When it falls off the intake manifold, the engine will run very poorly, meaning the entire job will have to be done again. (Ask us how we know.) The electronic boost control solenoid is controlled by the stock ECU via the CPC solenoid–we just had to extend the wire a bit. 

The last piece of the puzzle is a higher-capacity fuel pump to keep up with the turbo’s extra air. The supplied pump wasn’t a direct replacement, so we needed to carefully trim it a bit to fit our FR-S’s stock fuel pump bowl. 

But we weren’t careful enough and caused a fuel leak. We replaced it with an AEM drop-in pump. 

 

Dyno Tuning

Our FR-S now had a turbo, but that wouldn’t be much good without a tune. We hooked up an ECUtek programmer and had William Knose from Delicious Tuning in San Diego tune the car remotely. Why not tune it ourselves? Remote tuning allowed us to work with an expert without the cost of airplane flights. After six rounds of flashing, logging, emailing and reflashing, our FR-S put down 243 horsepower with 230 lb.-ft of torque at the rear wheels. One neat party trick: We can switch between three different boost levels on the fly with a special flick of the car’s cruise control lever. 

What’s the limit? Our data logs show the boost falling off above 5500 rpm. We believe the stock exhaust system is too restrictive. It’s on the to-do list.

 

How's It Drive?

Out on the road, the car feels completely transformed: extra power without any delay. The engine makes nearly 90% more power at 4000 rpm than stock. 

The hole in the powerband is gone, replaced by a big fat torque curve that allows it to squirt through traffic with ease. And downshifting to pass people on the highway? Yeah, that’s a thing of the past. 

The relatively small turbo–remember, we chose the BorgWarner 6258–means we’ll never make 600 horsepower, but we do have an OE feel and very little turbo lag. 

Of course, we have another goal: Cayman hunting. We’ll go looking for crocodiles in the next installment.

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