Automobile Magazine / Marc Noordeloos / June 10, 2019
Ford is still keeping quiet about the final output numbers for the mega Mustang Shelby GT500 supercharged, 5.2-liter V-8 engine but we do know it will top 700 horsepower. A dual-clutch gearbox is the transmission of choice, a first for the Mustang and a first for any muscle car. Ford Performance powertrain manager Patrick Morgan has more than 30 years of experience developing engines, including time at Jaguar, Aston Martin, and Cosworth. We recently sat down with him to talk about the development of the GT500's new 'Predator' V-8.
Automobile Magazine: How is this new GT500 engine related to the 5.0-liter Coyote in the GT/Bullitt, and the GT350?s high-revving, 5.2-liter Voodoo version?
Patrick Morgan: The core architecture is the same. It's built at the Romeo [Michigan] engine plant and based on the that Coyote architecture. The bore and stroke are the same as the Voodoo. We've gone through it and said, "How do we handle 125 bar [1813 psi] of firing pressure for the supercharged engine?" We increased strength in the block and heads. We went to longer head bolts and deeper columns. We also added a fourth active layer to the head gasket and additional casting structure in the head. In the interest of commonality and efficiency, we're rolling those changes into Voodoo too. The [GT500?s cross-plane] crankshaft is an interesting story. Because it's supercharged, we're not so sensitive to tuning. As you know, the GT350 has a flat-plane crank and it's lauded for its high-speed tune. We are affectionate and love the flat-plane crank with the sound and feel, but it does bring with it some very interesting challenges when it comes to vibration.
It's its own love affair with Ford and the enthusiasts. We're constantly looking at our product line and where it sits. I can't elaborate on our plans going forward. But we do love that engine!
What other advancements have been made to the GT500 engine?
We've put a lot of effort into the fundamentals. It uses a bar-plate cooler - a low-temp intercooler above the supercharger rotors. A tremendous amount of effort went in to make sure we had the right capacity to keep the charge air temps down on the track. We really wanted to maintain the performance. In the bottom end, you start looking long and hard at dry sump with the g loads we're pulling. We're right on the cusp. But we looked at the weight and cost as well as the development time and said, "Are we sure there isn't a better way?" We were able to put together a structural [wet-sump] oil pan that ties to the dual-clutch transmission. Inside the oil pan are trap-door baffles - one-way baffles on hinges. It traps the oil from running up the other side of the pan during high g loads. Also, we ended up using an aluminum viscous damper for the crank damper. That's to handle the supercharged loads on the nose of the crank and all the torsional loads. It's a nice solution to get weight off the nose of the engine and thus the nose of the car.
What are the compression ratio, redline, and max boost pressure?
It has a 9.5:1 compression ratio, a 7500-rpm redline, and about 12 psi of max boost.
What's involved getting a 700-plus-hp engine to play nicely with a DCT?
The biggest challenge is taking an engine that flows a massive amount of air and then have torque management down to just a few foot-pounds, in order to get smooth shifts. Our engine calibration team and Tremec's DCT calibration team have worked so well together. We have a couple of [Tremec] calibrators that basically live with us in Dearborn. We've had umpteen number of trips with people coming over from Belgium to work with our technical leaders making sure our torque management works well and plays nicely with the Tremec shift strategy. We have shifts that are under 100 milliseconds. Yet under light load it drives like any automatic.
What specific cars and engines did you benchmark?
You always benchmark the pony cars - that?s obvious. Then for the various subsystems, you tend to look further out. We looked at AMG and we always pay attention to features on the Corvette. Porsche is a huge benchmark from a transmission perspective; its DCT [marketed as PDK] is phenomenal. I'm always personally paying attention to the competitive V-8 engines - AMG, BMW, and Audi. How they do their boosting systems, how they do the bottom-end design, their solutions to valvetrain, etc.
The GT500 is the only supercharged engine at a company that?s all about EcoBoost turbocharging. Why?
It's a different project to go after raw performance that can span from, say, 2000 rpm to 7000 rpm and couple nicely with a DCT. Supercharging was the right solution for us. We have to work within the constraints and timing, and also have to make something that's affordable for the customer. With turbocharging, you can make an engine with lots and lots of torque. Look at the 3.5-liter EcoBoost in the F-series pickup. It's fantastic. But it kind of runs out of energy around 6000 or 6500 rpm. You say that you want a high-revving turbo engine? I can do that. Just look at the same basic engine in the Ford GT: 647 horsepower. But then you have to do some special things to get it to drive nicely down at lower speeds. With a supercharger, especially this 2650 Eaton supercharger, it breathes nicely everywhere.
But what about the emissions and fuel-economy challenges of supercharging?
The GT500 is about where you'd expect any muscle car to be today. We're studying what to do as next steps, same as everyone else. This engine is still port fuel-injected, so it does really well with particulates. It doesn't have direct injection. The engine is kind of at the end of its box for the technology it needs to take the next step, but fortunately, some of those new technologies are "and solutions," meaning you can still pick up a bit of fuel-economy and emissions improvements.