Jim McCraw
May 10, 2010

Mustang owners worldwide will welcome the new-world V-6 engine for the Ford Mustang. The ancient 4.0-liter SOHC V-6 truck engine that was the base engine for the Mustang for years will finally take its place in history this spring when Ford introduces the 2011 Mustang with a brand-new V-6.

To get the skinny, MM&FF sat down with engineers Greg Johnson, Al Cockerill and Jim Mazuchowski at Ford's powertrain headquarters in Dearborn and we came away with all the details on the new engine, developed from start to finish in only 36 months.

Most importantly, the new Duratec 3.7-liter V-6 engine makes 305 hp at 6,500 rpm and 285 lb-ft of torque at 4,250 rpm, and is guaranteed to get 30 miles per gallon on the highway, or 480 miles per tank. By comparison, the old 4.0L was rated at 210 horsepower and 240 lb-ft of torque.

In terms of power efficiency, the new engine makes 82.5 horsepower per liter of displacement, versus the old engine's 52.5, a 57-percent improvement-and it weighs only 41 pounds per liter of displacement versus the old engine's 101. Compare the old 4.0 V-6's 1.93 pounds per horsepower to just under 1.2 pounds for the new engine. Fuel efficiency is almost 5-percent better overall, from 0.521 pounds per horsepower per hour down to 0.498.

Ford also says it's as much as two decibels quieter in operation throughout the rev range, which is not to say it doesn't sound angry and powerful when provoked. We've heard it run in the new Mustang, and it sounds great!

A 3.7-liter V-6 engine (95.5mm bore and 86.7mm stroke) was used previously in some of Ford's transversely mounted front-drive crossover applications, but now it has been turned into a longitudinal rear-drive engine for the Mustang that is all new except for the forged steel crankshaft, connecting rods, and a few small parts. It features new heads, a new heavily ribbed and reinforced cylinder block, 10.5:1 pistons flycut to make room for the valves at maximum lift, new front cover and accessory drive, new composite intake manifolding, and especially the new valvetrain.

This new engine is 41 pounds lighter, 20mm less tall, 30mm narrower, and 55mm shorter-far smaller and far more powerful than any base engine ever offered in a Mustang.

For starters, it's a 60-degree engine, so it's narrow. It's also all-aluminum as far as the block (which uses cast-in iron cylinder liners), cylinder heads and covers. The forged crank is held in place by six-bolt main bearings, four down and two at right angles on the sides of the block-like a proper race engine.

It uses four valves per cylinder and double-overhead camshafts, and not only that, the engine features what Ford calls Ti-VCT, variable valve timing on both intake and exhaust valves, a feature that allows a full 60 degrees of cam timing adjustment on the intake side and 50 degrees on the exhaust side, allowing the 3.7 to produce huge amounts of power, very clean emissions, a very smooth idle, and excellent fuel mileage all at the same time.

The Duratec 3.7 V-6 is actually what the engineers call a "mild Atkinson-cycle" engine, where the variable intake valve mechanism keeps the intake valve open much longer than in a standard engine for better mixing in the chamber, thus reduced pumping work and better fuel economy.

The new cylinder heads use an intake port design that is much higher and more direct, allowing the 29-lb/hr sequential fuel injectors to shoot fuel directly at the back of the intake valves when they are closed, or under high-load operating conditions, spray fuel into the chamber when the valves are open, to reduce knock.

The intake manifold is 100 percent composite to keep cost, weight, and noise down, and it's fitted with a 68mm throttle body-5 mm larger than the previous design. Because the engine has variable intake and exhaust valve timing, there is enough freedom built in so that the engine doesn't have flaps or valves built into the manifold for low-speed/high-speed operation. On the exhaust side, there are two high-silicon molybdenum cast iron alloy manifolds leading to the catalytic converters.