Pete Epple Technical Editor
March 9, 2012

Step one: disconnect battery. Step two: remove engine. Step three: install ported heads and camshafts. Step four: enjoy!

OK, maybe the installation isn't that easy, but the end result is the same. Until last month, our '11 AMSOIL GT's power has come from a stock Coyote motor with a Ford Racing 2.3-liter twin-screw supercharger and a full exhaust from Kook's Custom Headers. The engine and transmission tuning has brought us to 595 rwhp, which has equated to a best e.t. of 10.48 at 130 mph.

Unfortunately, we've come close to the limit of the stock fuel pump, so power gains have been halted. After we cracked open the 5-liter and replaced the stock cylinder heads with a ported version from Total Engine Airflow (TEA), we also added a set of bumpsticks from Comp Cams to take advantage of the higher flow rates of the CNC-ported stock castings. This month it's all about tuning.

Before the additio of the CNC-ported cylinder heads from Total Engine Airflow and Comp Cams camshaft, our AMSOIL GT laid down 595 rwhp and 519 lb-ft of torque.

Justin Starkey, owner of VMP Tuning, made the trip from Deltona, Florida, to our Snap-on Tech Center in Tampa to see how much power we could make. With the AMSOIL GT strapped to our Dynojet 224XLC chassis dyno, Starkey started manipulating fuel and spark tables in the Copperhead ECU.

We were excited to see the gains available from ported heads and bigger cams, but the results came in at 594 rwhp and 402 lb-ft of torque—1 hp and 17 lb-ft lower than our previous numbers. Starkey spent the better part of a day adjusting timing tables and the variable valve timing tying to find power, but in the end we ended up with 600 rwhp and 500 lb-ft of torque.

Shocked, we did some research and came to a conclusion. The increased efficiency of the DOHC 5.0-liter powerplant is night-and-day different than its 5.0L predecessor from the '80s and '90s. The gains you saw then (and also today) when modding a pushrod V-8 are not what you'll get from a late-model engine. But that didn't stop us from building more power.

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If you recall, our last dyno session with Starkey ended with us sacrificing a few ponies and reinstalling the stock airbox to keep the air/fuel mixture in a safe zone. With our new Blow-By Racing Jackal fuel system, fuel delivery is no longer a limiting factor.

Although the stock airbox is a very efficient piece, it still becomes a restriction as horsepower increases. We didn't know how much of a restriction it was until we reinstalled the JLT Performance Big Air Kit. With the addition of the 123mm mass air housing, power jumped to 640 rwhp and 527 lb-ft of torque.

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"I've seen the JLT intakes pick as much as 28 rwhp," explains Jay Tucker, owner of JLT Performance. "But 40 is a little high. The Big Air kit is less a restriction than the stock airbox, but the increased airflow is probably letting the ported heads and bigger camshafts do what they are supposed to do."

At the end of the day, we were up 45 rwhp and 8 lb-ft of torque peak to peak. We were still running the 47-lb/hr injectors that came in the Ford Racing supercharger kit, and although the air/fuel ratio looked OK, we wanted to add more boost, which made us nervous with such small injectors.

Luckily for us, Jim D'Amore of JDM Engineering was in town, and was nice enough to bring a set of Ford Racing Performance Parts 80-lb/hr injectors. These high-impedance injectors flow close to double the flow of our old injectors. This means we can run less fuel pressure and make more power in the long run.

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Once D'Amore arrive, we strapped the AMSOIL GT back to the dyno and swapped our 3.00-inch supercharger pulley for a smaller 2.875-inch pulley. While we were working on swapping the parts, D'Amore wrote his tune. He spent the better part of three days inside the Copperhead adjusting table after table. Cam timing, ignition timing, load tables, torque management, throttle sensitivity, and fuel tables are just some of the parameters that were altered. Once the driveability and idle were set, D'Amore turned his attention to making power. When all was said and done, our AMSOIL GT laid down a healthy 683 rwhp and 557 lb-ft of torque.

Since our testing was completed right around the holidays, a track outing was not in the cards. But rest assured—we're itching to see how our gains on the dyno relate to quarter-mile e.t. improvements on track!

10. D'Amore spent the better part of three days working on driveability and max power. When he was finished, our GT laid down 683 rwhp and 557 lb-ft of torque for a total gain of 88 rwhp and 38 lb-ft of torque. Once our local track reopens for 2012, we’ll get some quarter-mile numbers and report back.