It seems like in today’s high performance market power adders are the easiest way to make a lot of horsepower without completely rebuilding the engine. But added horsepower puts more stress on the bolts that hold the head to the block. Studs can solve this problem.
Many manufacturers are now offering bolt on added horsepower of anywhere from 50 to 300 extra horsepower for the very popular Ford Mustang 4.6 Modular Engines by bolting on a supercharger, turbocharger, or nitrous oxide. The consumer is under the impression that it really is just a bolt on and go kit. And in a lot of cases it can be. Especially with the milder horsepower upgrades, driven conservatively, a kit might be well suited for no additional add ons other than a tuning upgrade. ls engine builders
Whenever I give a quote for a 4.6 Ford Modular Engine being built for use with a power adder I always recommend that the engine be upgraded to include aftermarket head bolt studs. The factory head fasteners are not capable of enough clamping force to hold the head securely to the block for the increased cylinder head pressures caused by the power adder. When the engine is producing more horsepower and has more cylinder pressure, the head is trying to “lift” off the block with each explosion in the head chamber.
Remember in high school when they told you about Newton’s Third Law of Motion? The third law states that for every action (force) in nature there is an equal and opposite reaction. In this case the “reaction” is the force trying to “lift” the head off the block. As the force to push the piston down increases so does the force to “lift” the head increase. Make sense?
It becomes the “vicious cycle” of engine building. The stock fasteners can’t hold the head properly so you blow a head gasket. The head has some damage and you have it machined a few thousandths. Now the head is more susceptible to blow another head gasket because the compression has increased a bit from the machining. Again you shave the head and the process repeats itself until one day someone suggests that you use an aftermarket set of head studs that can provide enough clamping force preventing the head from lifting off the block.
Head studs should be installed on any Ford Modular 4.6 and 5.4 Engine where a power adder has been installed. Head studs are available for all Modular engines. The most popular head studs are manufactured by ARP and are available through the link at the end of this article.