It was inevitable. EcoBoost is invading Ford – you see it on the side of the new NASCAR Ford Fusions and it is coming to Mustangs in 2015. It’s smart that Ford gets the racing community bought in first, and they are making that step with the Cobra Jet Twin Turbo concept.
While there aren’t any official talk of making this a production vehicle, there’s no doubt that we think the twin turbo Cobra Jet will sell more units than it’s former supercharged competitor. Is Ford also queuing Mustang fanatics on a 5.0 EcoBoost option? Only time will tell.
“When a new generation of Cobra Jets arrived four decades later, they immediately began winning with a modern, fuel-injected 5.4-liter V8 topped with a belt-driven supercharger,” recalls Jesse Kershaw, Ford drag racing competition manager. “Over the past four years, the Cobra Jet has gone on to become both a fan and competitor favorite, the most successful late-model vehicle in drag racing.”
“Racing predates Ford Motor Company. Henry Ford himself raced the 999 and won in 1901 to generate interest for the new company,” said Jamie Allison, director of Ford Racing Technologies. “We haven’t stopped since. We’ve competed in almost every category of auto racing, from deserts to road courses to ovals and drag strips over the past 111 years, often with cars and trucks based on our production models, including the Mustang.”
In 2011, the Mustang GT’s all-new 5.0-liter V8 found a home in the Cobra Jet, both with and without a supercharger. “Despite its smaller displacement, the improved breathing of the 5.0-liter with its twin independent variable camshaft timing and Boss 302 cylinder heads provided comparable performance while showcasing the high technology available in street Mustangs today,” said Rob Deneweth, Cobra Jet powertrain development engineer.
While the naturally aspirated Cobra Jet wasn’t a huge success from a sales perspective. it proved a lot to naysayers on what the 5.0 was capable of. If Ford were to produce a twin turbo Cobra Jet in 2014, will production be split between it’s supercharged brethren, or will both cars retain the factory production allotment?
NHRA competition rules for the stock classes Cobra Jet races in require parts like turbochargers to be derived from production components. Borg-Warner has supplied smaller, more efficient turbochargers based on the units used in the Focus ST for the Cobra Jet concept. Smaller than those found in most other drag racing applications, the turbine wheels are made from titanium aluminide that reduces the rotational inertia by 50 percent. Along with a shaft riding on low-friction ball bearings, the compressors can spin up to 150,000 rpm almost instantly.
The same integrated, electronically controlled wastegates used on production EcoBoost engines enable the turbos to keep spinning and generating the boost pressure needed for low elapsed times and high trap speeds at the strip.
One of the top reasons for a car company to go racing is the rapid learning curve it provides and the lessons that can be fed back into the vehicles customers drive every day.
“We’re already using ball bearings in the turbocharger of the 6.7-liter Power Stroke diesel V8 in Super Duty trucks,” says Born. “We’re also evaluating materials like titanium aluminide for the turbine, and it could find its way into future production programs as the costs come down.”
Q&A With Jesse Kershaw
Power Automedia: What was done differently on the internals for the turbo versus supercharged engine? Cam phasing/duration/compression, etc?
Jesse Kershaw: “The long block is virtually identical as far as rotating assembly goes. We are in the process of validating a new sportsman block (M-4010-M50CJ) with added bracing for the cylinder wall so that part validation is part of developing the twin turbo concept. For now the cams are the same as the 2013 supercharged Cobra Jet. That could change if the Twin Turbo goes from concept to production, but with variable cam timing the need for changing to a turbo cam is greatly minimized.”
PAM: Can you give us some insight into track or horsepower differences? What are the boost levels compared to the SC combo?
JK: “Being a concept we don’t have that level of detail fully calibrated. With the variable cam timing the boost varies greatly depending on calibration. I can tell you that the car would fit in a 6.5lbs/hp or 7lbs/hp class in NHRA Super Stock.”
PAM: What are your personal pros and cons on the turbo versus supercharged combinations?
JK: “Superchargers are easier to package and the induction system is simpler. The downside is that it takes horsepower to turn them. A turbo does not take that horsepower to turn but is much more complex for packaging. For example the Twin Turbo Concept has both oil and coolant fed to the turbos, combine that with the location of the turbos and you need an oil return pump. With Ford’s experience in turbocharging in production we saw this as an opportunity to experiment with the Cobra Jet.”
PAM: What were some of the challenges you had to overcome when designing the first ever twin turbo Cobra Jet?
JK: “There was a learning curve on many small details. We did our research combining the production team’s experience with drag racing know-how. Powertrain engineer Rob Deneweth and I spent considerable time going through pro mod racers pits asking questions. Larry Larson shared some feedback from his many years of Hot Rod Drag Week success.”
“Inside Ford, Dave Born, who is our turbo tech specialist was critical in working with the production supplier, Borg Warner, to get us a production based turbo that met our demands. Even with the hardware sorted out calibration proved difficult with a relatively small mass air flow housing diameter and lots of air coming through. We had a fairly short period of time to deliver but an exciting program like this gets people excited, we pulled together to make it a “one Ford” effort.”