Efficiency, personality and good bang-for-the-buck are hallmarks of the Ward’s 10 Best Engines, so it should not be a surprise the supercharged V-8 in Ford’s 200-mph (322 km/h) Shelby GT500 Mustang made our list this year.
It is not cheap, and it does not exactly sip fuel, but if you are looking for a 662-hp engine in a vehicle priced under $55,000 without a gas guzzler tax, it’s the only game in town.
The engine’s prodigious output makes it the world’s most powerful production V-8, beating countless exotics costing many times the price of the GT500, as well as Ford’s cross-town rival, the Chevy Camaro ZL1.
Some judges found the ZL1 easier to drive because its 580-hp engine is less prone to overwhelming its chassis than the GT500, but the Camaro’s 6.2L V-8’s lower horsepower rating, larger displacement and significantly lower specific output of 94 hp/L and 14/19 mpg (16.8-12.3 L/100 km) city/highway fuel economy put it at a disadvantage in our evaluations.
Plus, the Camaro is saddled with up to a $2,600 gas-guzzler tax, which has been the kiss of death for contenders in recent years.
The 82-hp stronger GT500 escapes the guzzler penalty with significantly better fuel economy of 15/24 mpg (15.7-9.8 L/100 km) city/highway.
The Ford 5.8L’s superior output numbers also helped it edge out Ford’s Boss 302 V-8, which made the list the past two years. The naturally aspirated 5.0L Boss still impresses us with its 444 hp, 380 lb.-ft. (515 Nm) of torque and magnificent exhaust note, but its specific output of 89 hp/L is dwarfed by the GT500’s 114 hp/L and asphalt-melting 631 lb.-ft. (856 Nm) of torque.
And even though the GT500 is priced more than $13,000 higher, the bigger engine wins the dollar-for-horsepower battle. The Boss 302 weighed in last year with a base sticker of $41,000, while our ’13 GT500’s $54,200 base price just squeaks in under our $55,000 cap. Even so, it wins at $82 per hp, compared with the Boss’$92 per hp.
Another interesting statistic is sales volume: With sales of roughly 4,900 units in 2012, the GT500 handily outsells the Boss, which will see about 3,750 deliveries in its final year of production.
But even with these statistical strengths, we would not have put the 5.8L on our list if Ford simply had bored out the previous 5.4L engine and cranked up the boost pressure on the supercharger to make 112 more hp.
Ford actually added significant technology. For one, it achieved the increased displacement by eliminating conventional steel cylinder liners with a patented plasma transfer wire arc process that applies a thin iron/iron oxide coating on the internal surfaces of the cylinder bores. Eliminating the liners increased cylinder bore 3.3 mm (0.13 ins.) and saved more than 8.5 lbs. (3.9 kg), keeping weight within 1 lb. (0.45 kg) of the previous 5.4L engine. The coating also improves heat transfer between the combustion chamber and coolant while reducing friction between the piston rings and cylinder bore.
Lower friction along with a higher 9:1 compression ratio helped improve fuel efficiency, but engineers also are quick to point out body and chassis improvements played a significant role,including optimized gearing, low-friction axle lube and a single-piece carbon-fiber drive shaft that eliminates center bearing friction and reduces weight by 14 lbs. (6.4 kg).
