For the past eight months, we've been following the latest go-fast goodies for the Coyote 5.0L-powered Mustang. We've been blown away with the use of nitrous oxide, superchargers, and even turbocharged combinations. In that time it seems as if
MM&FF has covered dozens of bolt-ons, experimental parts, and power adders of all flavors from a wide variety of manufacturers. Each time we walk away more impressed with the gains and performance.
The moment has finally come for us to remove the cam covers and get to the juicy stuff. With that, we follow along as JPC Racing adds a set of its CNC-ported heads to Joe Marini's naturally-aspirated 2011 Mustang GT. Adding a power adder was out of the question for Joe, and so this is next logical step in his quest for power.
JPC Racing turned to Rich...
JPC Racing turned to Rich Groh Racing to design and CNC-port stock Coyote 5.0L heads. We tested Stage 1 and JPC will be releasing Stages 2 and 3 by the time you read this issue. The Stage 1 price tag is $1,495 with core exchange.
Marini's '11 Mustang GT is a veteran of the
MM&FF 5.0L Shootout that was run in the Feb. '11 issue. It features all the latest and greatest parts like Kooks 1 3/4-inch, long-tube headers and 3-inch, X-style midpipe, 3-inch MagnaFlow after-cat exhaust, JLT cold-air kit, and custom JPC tune (DiabloSport Trinity). The suspension is hooked up for drag racing and the car has run 11.19 at 119 mph. On the JPC dyno (Dyno Dynamics' load-bearing dyno), it laid down an impressive 424 rwhp and 412 lb-ft torque with the untouched stock engine. Our task was to swap over to the JPC CNC-ported heads and chart the gains.
This CNC-porting job is a JPC exclusive designed by Rich Groh Racing (RGR)-a shop that isn't a stranger to horsepower, as evidenced by the nearly dozen NMRA championship victories credited to its engines. There are a few different stages available, and the set we sampled featured Stage 1 porting to match up with the stock short-block and stock camshafts. Stage 1 features opened intake and exhaust ports, five-angle valve job, and shimmed valvesprings. This stage utilizes the stock valves (37mm intake and 31mm exhaust), springs, locks, and retainers. Stage 1 heads go for $1,495 with core exchange, and RGR is currently working on Stages 2 and 3, which will include bronze valveguides, larger valves, and upgraded springs. Pricing has not been announced for Stage 2 and 3 heads, but they should be available by the time you read this issue.
The top-half was stripped...
The top-half was stripped off the Coyote 5.0L short-block. The engine compartment is large enough to allow the head swap to happen with the short-block in the car.
JPC's Brian Clauss and Wayne Bryant were able to swap the heads without removing the engine. The spacious engine compartment of the S197 Mustang (released in 2005) is a distinct advantage over the previous generations. Long-tube headers and other bulky aftermarket parts just seem to be easier to install on the Three-Valve mod motor and the current Coyote 5.0L than previous Two-Valve and Four-Valve-equipped engines. We'd call this swap a two-day (or less) ordeal if you have mechanical experience. The chains are similar to the earlier mod motors in that you have to line up markings in order to keep the timing correct. At the time of our head swap, aftermarket bolt and stud kits for the Coyote were not available. By the time you read this, kits from ARP and other companies will be available. We used a set of Cometic multi-layer head gaskets that were just released at SEMA, as well as a pair of its exhaust gaskets.
So what's it worth? The quick answer is the CNC-ported heads brought peak numbers to 446 rwhp and 422 lb-ft torque. That's 22 rwhp and 10 lb-ft torque gain over the slightly modded but mostly stock engine. This is about what a typical head swap yields on a Three-Valve engine.
Here is a view of a 5.0 DOHC...
Here is a view of a 5.0 DOHC piston. You can see the unique design in order to accommodate the four valves and still help produce a 11:1 compression ratio.
But the story goes much deeper than the just peak gains with the JPC heads. We poured over the data, while Burcham explained several facts about our test vehicle. The peak rwhp with the stock heads was 422 at roughly 6,400 rpm; on track, the car runs quickest when it's shifted at 7,400 rpm. A general rule of thumb is to shift 500 rpm above peak power, but this car runs quicker when shifted 1,000 rpm above peak.
"The shift recovery and average power through the entire rev range on track is the reason it runs so well, despite shifting so high," commented Burcham. He reports the car pulls strong to that rpm without dropping off. Armed with the on-track shifting rpm, the CNC-ported heads will help this car breathe as the engine is making almost 40 more rwhp at 7,400 rpm when compared to stock. The curve is more aggressive, which is going to lead to even quicker times.
Knock sensors are mounted...
Knock sensors are mounted in the valley of the engine, similar to previous Mustang engines.
We are disappointed that these heads weren't available when the weather was warmer (at least in the North) and the tracks in the Northeast were open. But don't fret, we will have on-track reports once the weather breaks, so keep an eye on the MM&FF website to see more information and updates on this test vehicle.
By the Numbers
| Flow Testing JPC Racing Stage 1 |
| CNC-ported Coyote 5.0L Heads |
| Lift Intake | CFM JPC | CFM Stock |
| 0.100 | 54 | 49 |
| 0.200 | 197 | 180 |
| 0.300 | 266 | 243 |
| 0.400 | 303 | 280 |
| 0.500 | 321 | 289 |
| 0.600 | 335 | 298 |
| Exhaust | JPC | Stock |
| 0.100 | 37 | 32 |
| 0.200 | 158 | 147 |
| 0.300 | 201 | 180 |
| 0.400 | 213 | 189 |
| 0.500 | 224 | 201 |
| 0.600 | 232 | 207 |
Notes: All cylinder head flow testing was performed with a 92.2mm (3.63-inch) bore, which is the stock Coyote 5.0L bore size. RGR utilizes a Super-Flow 600 flow bench, 28 inches of water, and the exhaust ports were measured using a 1 3/4-inch pipe.
The intake port was opened...
The intake port was opened up and the port divider was sharpened. The intake volume port is 207 cc.
A look inside the exhaust...
A look inside the exhaust side of the head reveals the modified port. The exhaust port volume is 93 cc.
Four valves per cylinder are...
Four valves per cylinder are standard on the Coyote 5.0L. The intake valves measure 37 mm, while the exhaust valves are 31 mm. In comparison, the stock Three-Valve intake valves are 34 mm, while a single exhaust valve measures 37.5 mm.
According to Burcham, the...
According to Burcham, the valvesprings have light pressure, only 50 pounds on the seat. JPC shims the springs to 65 pounds on the seat for more control at higher rpm and big boost levels. Burcham did say that the Coyote valvetrain is very light compared to the other OHC engines in the Ford family.
We used Cometic multi-layer...
We used Cometic multi-layer gaskets when putting the engine back together. The head gaskets featured the same thickness as stock gaskets (0.040-inch), so the compression ratio would remain identical with our before/after testing. They retail for $139.99 (each) from JPC Racing.
Here is the Coyote valvetrain...
Here is the Coyote valvetrain at a glance.
The heads were bolted down...
The heads were bolted down using stock head bolts; Bryant torqued them using the step-method. First, he hit them with 18 lb-ft, then 30 lb-ft, and then turned all the bolts 90 degrees, only to follow up with another round of a 90-degree turn.
Always use the inside-to-outside...
Always use the inside-to-outside technique and tighten in steps for even compression of the head gasket.
The cam caps are bolted down...
The cam caps are bolted down with 53 in-lb and a 45-degree turn.
Yours truly slowed the head...
Yours truly slowed the head swap process when I moved the cams for a photo-op. Bryant, unfortunately, had laid them down in a specific order. We learned, after a few phone calls, that the intake cams feature three dots while the exhaust cams have two dots.
A filter is inserted in the...
A filter is inserted in the camshaft before the cam phaser/weighted end is bolted on.
The cams are connected in...
The cams are connected in a similar fashion to the other DOHC engines from Ford.
This one, however, uses a...
This one, however, uses a cam phaser to adjust the camshaft timing.
The cam phaser/weighted end...
The cam phaser/weighted end is secured using 133 in-lb and a 90-degree turn.
The cam follower and lash...
The cam follower and lash adjuster are connected as one unit.
The front chains utilize a...
The front chains utilize a similar tension system as the Three-Valve engines. The chains are also reinstalled in a similar manner by lining up the dots.
Cam phaser sensors are located...
Cam phaser sensors are located in the front cover, which is different than the Three-Valve engine where the sensor is bolted on to the cylinder head.
Clauss puts the finishing...
Clauss puts the finishing touches on the engine before moving underneath the car to install the exhaust system.
When reinstalling the Kook's...
When reinstalling the Kook's long-tube headers, we used Cometic's new exhaust gaskets...
... as well as a Kook's 3-inch,...
... as well as a Kook's 3-inch, X-style midpipe with cats and a MagnaFlow after-cat exhaust.
JPC Racing uses a Dyno Dynamics...
JPC Racing uses a Dyno Dynamics chassis dyno and here are the two power curves. You can see how aggressive the horsepower curve becomes as rpm increases, and torque output was consistently above the baseline from start to finish.
JPC has released a line of...
JPC has released a line of camshaft profiles for naturally aspirated and supercharged combinations. Pricing and specs weren't available at press time, but we will be checking out these sticks in a future issue.