Performance Modifications for the 4.9
There's not much performance aftermarket support for the 4.9 for obvious reasons. However some common hot-rodding techniques can be used. My performance 4.9 project started with a reground camshaft. The mustang guys may recognize this as the popular Ford Motorsport E303 roller cam profile for a 5.0.
Advertised duration: 282 intake/282 exhaust
Duration at .050 in. cam lift: 220 intake/220 exhaust
Gross valve lift: .498 in. intake/.498 exhaust
Lobe separation: 110 degrees
Peak horsepower rpm: 5,500
Peak torque rpm: 2,500
The regrind on the cam was very inexpensive, but the increased valve lift results in several other required modifications. The stock valve springs will coil bind at 1.3125", or .4175" cam lift. The spring retainers will also contact the valve seals at about .435" lift. To allow .498" lift I needed to use different springs, and machine the valve guides to lower the seals. There are very few springs that will provide the acceptable open and closed pressure on the valve and still fit within the machined area of the head, so the spring seats also need to be machined. While I was doing all of this machining, I also decided to shave the heads to get the compression ratio up to about 10.5:1. I also ported and polished the heads. There's actually quite a bit of material that can be removed to open up the ports and improve flow. In the combustion chambers I un-shrouded the valves, knocked down any sharp corners, and polished the surface. The intake manifold was ported and polished to match the heads. There is some restriction that can be removed where the runners get narrow for the pushrods to pass through the intake. I fabricated an adapter to use an LT-1 or TPI throttle body and I bored the intake to match the adapter. I also radiused the bottom of the bores into the runners and removed some excess material. I installed a set of Angus Racing Ford roller rocker arms by machining the rocker mounting rails to accept the new pedestals. This resulted in the rockers hitting the valve covers, so I raised the valve covers by making 1/4" spacers. The rockers have adjustable pushrod seats, which eliminates the need for custom length pushrods.
I also ported two Seville front side exhaust manifolds for this engine. I have 2" pipe coming off the manifolds into a 3" Y collector behind the engine, and into a Flowmaster muffler. Pictures can be seen in the exhaust section.