Marc Christ
Brand Manager, Modified Mustangs & Fords
June 13, 2012

When it comes to 5.0-liter Mustangs, there is a seemingly unlimited supply of aftermarket parts to make those 302 cubic inches as efficient as possible. You can bolt on top-end kits, better-flowing exhaust, and even power adders. But what if you like making as much power as possible without the help of a supercharger, turbo(s), or nitrous, and 302 cubes just isn't enough? The simple answer is an increase in displacement.

There are three major ways to increase displacement. First is cylinder boring. Oversized bores can increase displacement of an 8.2-inch-deck Windsor (302 ci) to 310 ci (0.060-over with a stock block). This is usually done out of necessity during a rebuild or when doing a stroker kit. If an engine failure or wear and tear scores the cylinder walls of the block, boring and/or honing can correct this. Another reason to bore is if you're racing in a sanctioning body that allows a maximum displacement, and you're trying to increase power output within the rules.

Another more popular way to increase displacement is by increasing stroke. By using a "stroker" crankshaft, the piston is pulled farther down the bore, increasing displacement. Stroker kits utilize a shorter, larger diameter piston and longer rods. This is an effective way to increase displacement without going as far as an engine swap.

Engine swaps are the third and most obvious way to increase displacement. For Fox-body Mustangs, the 351W swap is common, and there are many parts available to make it easier. The 351 beats out the 347 by a few cubic inches, but there are other issues, like hood clearance and accessory mounts, due to the taller deck of the block. There's always the big-block swap, but that's another story in itself.

Tall-Deck vs. Stroker

The first thing to understand before we start this comparison is the difference between a short-deck Windsor and a tall-deck Windsor. Short-deck refers to an 8.2-inch-tall deck, 302ci engine. The larger 9.5-inch Windsor is the base for the 351W. (There is a rare 9.2-inch-deck Windsor as well.) The two blocks are very similar, except the tall-deck block extends 1.3-inch higher than the short-deck. Difference in stroke (3.500 inch) and rod length allows the tall-deck engine to displace 351 ci with 4.000-inch pistons. A 5.0L 302 utilizes the same 4.000-inch pistons, but only has a 3.000-inch stroke. The 351W utilizes larger 3-inch mains, but also weighs in about 25 pounds heavier than a 302.

To achieve more stroke out of a short-deck block, a stroker crankshaft pulls the piston farther down into the bore, requiring some machining of the block. A typical 347 stroker utilizes a 3.400-inch stroke and 4.030-inch pistons. That has been the standard for 302-based big strokers for years.

FRPP 363

With Ford Racing Performance Parts' new Boss block, the same stroke can be combined with 4.125-inch bores, bringing displacement to 363 ci. To showcase this and provide its customers with a larger-cube engine in the same package as the 302, FRPP released a line of 363 engines. If you have a running 5-liter in your Mustang now and already have aftermarket heads, intake, and camshaft, then you could opt for the 363 short-block (PN M-6009-363; $4,899). Utilizing the Boss block, the FRPP team machines it to clear the stroker crankshaft and 4.125-inch pistons.

"The 363 was the natural next step for our crate engine lineup," says Jesse Kershaw of FRPP. "With the Boss 302 block, it makes sense to go bigger bore—it's free horsepower and torque! The 4.125-inch bore of the 363, as compared to a 347 engine with 4.030-inch, unshrouds the valves and really lets the engine breathe with 2.02-inch intake valve heads like our Z304."

Forged crankshaft and I-beam rods from Scat actuate forged-aluminum pistons from Mahle. The short-block is internally balanced and designed as a direct bolt-in part, though some parts, like head bolts, must be upgraded. The Boss block utilizes four-bolt mains and increased cylinder-wall thickness, making it far superior to a stock block in its ability to handle high-horsepower applications.

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