It looks that in today’s high-performance market the power improvement is the easiest way to generate a lot of horsepower without absolutely rebuilding the engine. But the added horsepower puts greater stress on the bolts that hold the head to the block. Buttons can solve this problem.
Many producers are now offering bolt-on added horsepower of somewhere from 50 to 300 extra horsepower for the very popular Ford Mustang 4.6 Modular Engines by using bolting on a supercharger, turbocharger, or nitrous oxide. The consumer is under the influence that it is just a bolt-on and go kit. And in most cases, it can happen. Especially with the milder horsepower upgrades, driven conservatively, a kit may be well suited for no extra add ons other than a tuning upgrade.
Whenever I give a quote for a 4.6 Ford Modular Engine being constructed for use with a power adder I always advocate that the engine be upgraded to include aftermarket head bolt studs. The factory head fasteners are now not capable of enough clamping pressure to hold the head securely to the block for the increased cylinder head pressures induced by the power adder. When the engine is producing greater horsepower and has more cylinder pressure, the head is trying to “lift” off the block with every explosion in the head chamber.
Remember in high school when they advised you about Newton’s Third Law of Motion? The third law states that for each action (force) in nature there is an equal and opposite reaction. In this case, the “reaction” is the pressure trying to “lift” the head off the block. As the force to push the piston down will increase so does the force to “lift” the head increase. Make sense?
It becomes the “vicious cycle” of engine building. The inventory fasteners can’t hold the head good so you blow a head gasket. The head has some damage and you have it machined a few thousandths. Now the head is more prone to blow another head gasket because the compression has multiplied a bit from the machining. Again you shave the head and the process is repeated until one day anybody suggests that you use an aftermarket set of Duramax Head studs which can provide enough clamping force to prevent the head from lifting off the block.
Head studs should be mounted on any Ford Modular 4.6 and 5.4 Engine where a power adder has been installed. Head studs are reachable for all Modular engines.