In its simplest form, an engine is nothing more than an air pump. Cramming the cylinders full of air as efficiently and densely as possible equates to horsepower. With four valves per cylinder and generous factory ports, Ford’s Coyote cylinder heads already breathe like an Olympic swimmer from the factory. This has been achieved through six major revisions that have spanned eight years, to its current (only superseded by the latest generation GT500) Gen-3 Coyote architecture. Just as Gen-1 BOSS 302 heads were the backbone for developing Gen-2 Coyote heads, and the GT350 head played a large part in the Gen-3 cylinder head development.
Gen 3 Coyote Head Specs
M-6049-M50B – Ford Performance Right Cylinder Head
M-6050-M50B – Ford Performance Left Cylinder Head
205cc Intake Port Volume
55.9cc Chamber Volume (smaller versus 15-17 57cc)
37.7mm Intake Valve – 1.484-inch (.4mm larger than 15-17)
32mm Exhaust Valve -1.259-inch (.2mm larger than 15-17)
The Parts We Used
26125CTS-KIT COMP Cams Valve Spring Kit with tool steel retainers
4673-32 – COMP Cams spring seats for MPR bronze valve guides
Maximizing Power Potential
When it came to porting our Gen-3 heads, we turned to MPR Engines. “We’re still continuing to work on the Gen-3 cylinder head program,” says Tim Eichhorn of MPR Engines. “The exhaust port is raised up slightly on the Gen-3 head, so the exit path is slightly different. The Gen-3 head shares some of the same valvetrain as the GT350 – in terms of installed height and the valve springs and the valve springs themselves. If the Gen-3 head didn’t have the direct injection and would fit on a Gen-1 or -2, it would really be the head to have. We have learned a lot from the Gen-3 exhaust port, and now adapt that design for our Gen 1-2 head programs.”
Eichhorn continued, “We first find out the application the heads will be used for — naturally aspirated, blower, or turbo. Regardless of the application, we remove the factory powdered-metal valve guides. The naturally aspirated port has a little longer and straighter intake port, whereas the exhaust port on the blower program is as big as we can get it. Most of the machining time, though, is spent on the valve job machine. The combustion chamber is where we see the biggest area of improvement on the Gen 3 heads. We actually haven’t had to go as far as swapping seats out on the Gen-3 heads for considerably larger valves because they flow so well from the factory. Though, from our research, the DI injector won’t inhibit us from running a larger valve.”
While the stock Gen-3 Coyote valvetrain is suitable for bolt-on modifications, we knew that our eventual plan was to throw a bunch of boost at our test mule (watch for a future story on that). In addition to our MPR port job, we equipped the cylinder heads with a set of stock diameter Ferrea stainless-steel valves and finished off the valvetrain with a spring and tool-steel retainer kit from COMP Cams. “Even if someone doesn’t want to do a port job, we at least recommend that they do bronze guides, new valves, and a valve job if they plan to make a lot of power,” says Eichhorn.
Assembly and Dyno
L&R Engines in Santa Fe Springs, CA helped us swap over our ported Gen-3 heads. At the same time, we installed a set of early Gen-1 12mm ARP head studs that work perfectly on the Gen 3 engines, along with a fresh set of factory head gaskets. Our engine was already equipped with COMP Stage-II camshafts, MMR guides, MMR billet oil pump gears, and MMR HD secondary chains. We then transported our engine to Westech Performance where Palm Beach Dyno assumed tuning roles through our HP Tuners MPVI2 on pump E85.
After 10 years of circulating reused tap water while dyno testing, our electric water pump had finally given up the ghost when it was time to dyno. Westech is typically scheduled out for over two months at a time, and we were strapped in the day before. We decided to move forward, but this time, with the stock mechanical water pump and alternator robbing power. We’ve seen this give up 12-15 horsepower in previous testing.
At the end of the day, we managed to make 617.3 horsepower and 471.7 lb-ft of torque with the mechanical water pump and alternator. Normalized for the difference between accessories, we netted 630.6 horsepower and 479.8 lb-ft, giving us an overall corrected gain of 26.5 horsepower and loss of 5.4 lb-ft. The low-speed torque loss was expected as our larger port carries a slightly slower port velocity when compared to the stock castings. Despite this slight drop, torque on the MPR port wins above 5,900 rpm. For the record, our runs on the stock heads and Meziere water pump were 604.1 horsepower and 485.2 lb-ft. With solid naturally aspirated gains shown, the next round of testing for this Gen-3 Coyote is with boost. So stay tuned!