When Ford rolled out the Ford GT supercar in Detroit in January 2015, enthusiasts worldwide let out a collective gasp. Finished in Liquid Blue, the futuristic supercar showed its winning pedigree. There was no questioning the race-inspired design, and with rumors of Ford heading to Le Mans, the new GT style was quite fitting. What we weren’t expecting was a V6 powerplant to be sitting under the trapezoidal fuselage. OK, Ford is winning with the 3.5L EcoBoost, but is it proper for a road-going supercar?
Know one thing: Ford is committed to the EcoBoost, and its 3.5L (213ci) variant has been a smashing success both on and off the track. The twin-turbo, direct-injected V6 powers everything from the Taurus SHO to F-150 trucks. It also powered winning Ford race cars at the Rolex 24 Hours of Daytona and the 12 Hours of Sebring, beating the best from Europe and the United States.
What you may not know is that the 600hp race version—built by Roush Yates Racing Engines (RYRE)—uses a production block, heads, direct injection, cam drive, gaskets and valvesprings. It also uses stock bore and stroke, compression ratio, and valve sizes.
“We ran the 5.0L Cammer V8 for 12 years,” said John Maddox, Sports Car Engine Program manager for RYRE. “But it no longer has relevance. We wanted Ford to support our program for the Daytona Prototype cars, so we moved forward with this, and [Ford] really liked the idea of EcoBoost being in a professional racing category. We’ve run [unrestricted] dyno tests close to 1,000 hp. When we set the 223-mph speed record at Daytona, the V6 was making 800 hp. And we ran 10 miles at WOT.” They’ve also run more than 14,000 simulated miles at Daytona. But IMSA rules limit the engine to about 600 hp with the use of 33.2mm restrictor plates fitted before each turbo. With such immense power and reliability, Ford realized this was the engine for the next GT supercar.
“The 3.5L EcoBoost makes 365 hp in production trim,” said Ford Performance Racing Supervisor Dave Simon. “We’ve increased output by 40 percent, which is significant, especially on an endurance engine. This project has embodied the spirit of Ford Performance. We formed one team between Ford Global Engineering, Ford Performance, and Roush Yates.”
“Ford has an extreme depth in engineering,” Maddox said. “Having access to things like crank-fatigue simulation and analysis help us immensely. We’re just constantly developing. We’re looking to reduce internal friction—that’s the biggest enemy. But we also work on air inlet, calibration, and engine control.”
While our sources couldn’t give up the goods on the Ford GT, we’re speculating it will utilize a race-style engine and fall in the 600–650hp range. The current Daytona Prototype cars weigh 2,350 pounds and run more than 190 mph. So we can guess the GT will need similar power, if not more, to go faster than 200–220 mph. But perhaps the coolest part is how Ford turned a production engine into a winning race engine—and back again to evolve the 3.5L EcoBoost into a production engine with more than 600 ponies, where it will power the Ford GT.
Block and Heads
The foundation of the RYRE 3.5L EcoBoost race engine starts with a production aluminum engine block and aluminum cylinder heads sourced directly from Ford’s Cleveland Engine Plant. The blocks are machined before assembly and set up for dry-sump oiling, while the heads receive mild porting. Bore and stroke is stock (92.5x86.7mm).
The factory 3.5L EcoBoost V6 uses a DOHC configuration with four valves per cylinder and variable-cam timing. The race engine uses aftermarket valves with the stock sizes (intake: 37mm, exhaust 31mm), however, the IMSA TUDOR series doesn’t allow variable-cam timing, so the cams are “locked out” with fixed sprockets. RYRE uses specific race cams as well. Chaindrives are mostly stock, along with the valvetrain, including factory springs, locks, and retainers.
The 3.5L engine sits low and the radiator even lower. This requires a “header tank” (commonly called a swirl tank or de-gas tank) that’s located high in the engine bay on the left side of the firewall. This header tank removes air and gases from the cooling system, and coolant flow is handled by a stock water pump.
The race engine utilizes Ford’s factory high-pressure direct-injection system, albeit with race-style injectors (one per cylinder). Fuel is fed with a single low-pressure pump that feeds twin Bosch injection pumps (one per cylinder head, mounted on each cam cover, and driven by a cam lobe) that supplies VP 100 E10 gasoline at 2,900 psi. Injector architecture and mounting location are stock—tuning is manipulated with injection timing and duration, not pressure.
Intake air enters through a common rear-mounted filter that feeds inlet tubes. Air must then pass through two 33.2mm restrictors (mandated by the sanctioning body) located just ahead of the turbos. The induction also uses twin 57mm throttle-bodies sourced from the 2.0L EcoBoost, along with a race manifold (which constantly evolves). The carbon-fiber plenums are removable and bolt to a composite plastic individual runner unit that’s built with rapid prototyping. “We changed the manifold in 2015 to reduce weight and plenum volume,” Simon said. “It greatly improved transient response from low-to-high throttle position as well.” We expect the Ford GT intake to be much lower to fit under the bodywork.
Twin air-to-air intercoolers provide a temperature drop of the incoming air charge. The team wouldn’t speak much about them, but stated they closely monitor incoming air temperature in real time. While rules prevent tuning in real time, the data is used to tweak the engine tune for power, driveability, and, no doubt, reliability.
The race engine is boosted with twin Honeywell Motorsport (parent company of Garrett) 60mm compressor turbos with 54mm turbines. They feature billet-machined compressor wheels and proprietary Inconel turbine wheels. They also use ceramic bearings, a lightweight housing, and V-band flanges on the exhaust side. Surprisingly, the engine only runs about 10 psi of boost pressure.
A forged-steel crankshaft was designed by Ford (but built by an aftermarket supplier) to work with forged steel H-beam rods and high-temperature billet alloy pistons. Compression ratio is stock, at 10.0:1.
Ford’s passenger-car and truck EcoBoost 3.5L V6 produces 365 hp at 5,500 rpm and 350 lb-ft of torque at 1,500 to 5,000 rpm (6,700-rpm redline). The RYRE 3.5L nearly doubles that with 600 hp (restricted) at 7,300 rpm and 540 lb-ft of torque at 5,600 rpm (7,500-rpm redline).
While Roush Yates builds the 3.5 EcoBoost race engine, the teams are responsible for the transaxle. According to Simon, Chip Ganassi’s team currently runs a Xtrac sequential six-speed. We presume the Ford GT will use a racing-style transaxle suited to street use with as many as seven to eight forward speeds.
Engineers calibrate the engine using a Bosch Motorsports 5.0 ECU with C50 data-logging. The system transmits data in real time so the team can monitor manifold pressure, temperature, and all other vitals. In addition, the race engine uses stock ignition coils and racing spark plugs.