Though you may not realize it, Ford Motor Company has been in the stroker business since the early '60s. In 1962, the Blue Oval boys introduced the 221 V8 that featured a 3.50-inch bore, a 2.87-inch stroke and was installed in lightweight Fairlanes (and later Falcons). By the late '60s, Ford cars grew in size (and weight) and the small-block followed suit. It was first enlarged to 260 cubic inches and then to 289 inches. In 1968 the little V8 grew one final time to 302 cubic inches, still using the same basic block design.
At the time, the 302-inch small-block was factory rated at 230 horsepower (with a 4-barrel carb), but it was not considered a performance engine-at least not considering the power of the hot 390 and 428 engines in the Mustang's lineup. With a 4-inch bore and a 3-inch stroke, the 302 had the potential to make great power, but it was all at high rpm. When Ford found the need for a more powerful small-block with lots of low-end torque, it went with the 351 Windsor, a derivative of the 302, albeit with a raised deck to accommodate a longer stroke. Additionally, the 351 used a different crankshaft main journal size (3.00-inches compared to 2.248-inches), but the basic block design is the same as the 289/302 and cylinder heads are interchangeable.
In the time since the late '60s, engine builders have gone past the standard bore and stroke specifications of the 302 (and 351 and big-block engines, too) using modified and aftermarket cranks, pistons and rods to gain cubic inch displacement. With the current list of available aftermarket parts you can now take a 302 or 289 engine and make it as large as 355 cubic inches. And when using the Ford Racing (M-6010-S351 or M-6010-W351) 351-based 9.5-inch blocks, you can achieve a maximum displacement of 454 cubic inches, all with a great amount of user friendliness.
The reason for increasing engine size is simple-cubic inches equal horsepower. It doesn't matter if you're racing or if you're into street performance, a larger engine will usually outperform a small one. And by stroking your small-block, rather than switching to a big-block, you get the benefit of more engine size while maintaining lighter and smaller packaging. When you turn your 302 into a 331 or 347 you can use the stock hood, stock engine accessories, intake, fuel system and headers. However, in order to reap all the benefits, your stroker engine must be properly designed, built well and run efficiently.
One question you may ask is how big should I make my stroker? The answer is easy, as long as you have a plan of attack. If you're going heads-up racing, you'll be restricted to class limitations that will dictate maximum or minimum engine size. If you race with the NMRA or the FFW it's likely you'll be limited to 310, 360 or 400 cubic inches, depending on which class you run. In the case of NHRA, engine size is dictated by the bore and stroke rather than actual displacement (like in Stock or Super Stock), or by a cubic inch to weight factor, such as in Competition Eliminator.
Either way, remember there has to be a balance between the parts. Building a 347 stroker will do you no good if you're going to use stock heads on top of it and a stock cam in it. Obviously, combination is extremely important.
Thankfully, we can build virtually any variety of cubic-inch size you wish. And you can top your stroker with a myriad of heads and intake combinations to get your small-block screaming.
Internal Combustion
Over time, much has been written about the Otto 4-cycle (or 4-stroke) internal combustion engine. Performance magazines and most books refer to engines as air pumps because they do pump air, but making copious amounts of reliable horsepower takes a little more understanding and a little knowledge about engine combinations and engine tuning.
The combustion process begins with the engine at top dead center (TDC) and with the intake valve slightly open. As the engine turns, the intake continues to open and air enters the engine and is mixed with the fuel in the carburetor (or in the intake ports, as would be the case with fuel injection). The mixture is then drawn into the individual cylinders as the piston swings down on the intake stroke. It's important to know that a pressure difference exists between the cylinder and the intake manifold (and ports in the heads) which causes the mixture to rush in when the valve opens. Naturally, we can pack in more air and gas with turbochargers, blowers and nitrous kits, but this basic example refers to naturally-aspirated engines.