If you subscribe to the notion that too much power is just enough, then we have a book for you. Every day, engine builders are pushing the limits of making power with large displacement small blocks. What was once the realm of exotic race engines has now become fair game for street enthusiasts and those looking for what the late road racer and engineer Mark Donohue called “The Unfair Advantage.”
This book will deal strictly with street small-block engine combinations that are based on the first generation small-block Chevy. We will investigate all the different bore and stroke combinations, look at a few of the better parts combinations, and we’ll even run through a few power tests to show you what kind of power you can expect from your next small-block adventure. Every small-block part and engine combination will be aimed at street operation. Some combinations will be more adventuresome than others, but we hope to point you in the right direction and give you some ideas about which cylinder heads, camshafts, and induction systems we have found work best in these large displacement applications.
This Tech Tip is From the Full Book “HOW TO BUILD BIG-INCH CHEVY SMALL-BLOCKS“. For a comprehensive guide on this entire subject you can visit this link:
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Perhaps the biggest question is not whether to build a stroker small block but rather what style of engine to build. For any single displacement, you could build that engine two or three dozen different ways, ranging from an extremely mild combination that makes excellent off-idle torque, all the way up to an ultra-exotic engine with all the latest race technology for limited street use.
The key then becomes defining exactly how you plan to use this engine. If your next engine is intended to climb mountains all day pulling a horse trailer or a race car, it will be drastically different from a 434ci small block for the drag strip or road course that can push the RPM band way up. There are also various street engine combinations that fall somewhere in between these two ends of the performance spectrum. Being honest about your plans and expectations will go a long way toward achieving your goals. Keep in mind that being conservative and compromising on some of the more radical expectations will probably get your farther in the long run.
The edge that the big-inch small block enjoys is the subterfuge factor. Savvy street guys know there are certain production 400ci blocks with only two freeze plugs per side. Add an internally balanced stroker crank, and you could construct a 420ci small block that appears to all the world like a 350. Even with a lumpy cam, no one would expect a 350 to run like a big block, but 500 hp and gobs of torque are easy goals to attain when you start with a bunch more cubic inches.
The only limitation to going big is the depth of your wallet. Even a very conservative 1.2 hp per cubic inch (ci) factor will deliver 520 hp from a 434ci engine compared to only 426 hp from a 355. But beyond the horsepower is the torque that is generated by large displacement engines.
Displacement generates torque. That’s why earthmovers and big trucks employ huge displacement engines that spin very slowly. They don’t make much in the way of horsepower, but they do make loads of torque. The beauty of this concept is that you can build a rather mild, larger displacement small block that can generate exceptional torque and still have an engine with an almost-stock idle quality. This engine could be capable of quick e.t.s and production-like part-throttle operation with lightning quick throttle response.
This book will address any small block larger than 355ci as a large displacement engine. The most popular upgrade is the 383, which is the easiest stroker small block you can build. Take one production 350 block, bore it 0.030- inch oversize, add a 3.75-inch stroke crank from a 400 small block, and that will give you a 383. In the early days of this swap, the 400 crank’s main journals had to be ground down to the smaller 350 diameter. This displacement upgrade has become so popular that you don’t even have to bother looking for a used crank, since companies like Eagle, Scat, Crower, Callies, and many others now offer dropin 3.75-inch stroke cranks in numerous configurations and materials. We’ll get into more detail in the chapter on crankshafts. The point is that these engines are incredibly easy to build, the parts are available, and the milder versions of some of these stroker motors can cost only slightly more than a stock small-block rebuild. When you have an opportunity like that, it’s hard to pass it up.
Of course, for each displacement, you have literally hundreds of options. For truck towing or off-road, rockcrawling applications, a 383, 406, or larger small block with small heads and a mild cam can offer big-block torque capability without the weight or cost penalties. Take those same displacement engines, add slightly larger heads, a more aggressive cam, and a good dual plane intake manifold, and you the opportunity to make impressive torque and horsepower without sacrificing mid-range power. For example, you could build a 383 using mid-sized heads like a set of Airflow Research 195cc heads or the excellent castings from Canfield or TFS and create a stormin’ small block that could easily generate in excess of 500 ft-lb of torque and 450- plus horsepower. This would be a slightly more expensive engine since it would employ a hydraulic roller camshaft, but it could still be affordable (well below $7,000 from carburetor to oil pan).
Of course, there’s also the big-inch, max-output engines that everybody dreams of building. We like to call these efforts “bottom of the page” engines because these guys just go straight to the bottom of the catalog page for the biggest heads, the biggest cam, and the tallest intake manifold to construct a monster engine that will make killer power. The scary part about this plan is that it is so easy to do. Most of the exotic parts are available right off the shelf. Dart builds 23-degree CNC-machined heads that push into the 230cc intake port range! That’s only slightly smaller than an oval port big-block cylinder head. If you really want to get exotic, you could also step up to the race-oriented 15-degree, 18-degree, and SB-2- style heads that stand the valves more vertical for even better flow.
We’re not even talking about custom, one-off castings, but about parts that are currently sitting on the shelf. You can also expect to get into some serious coin when you start shopping on the NHRA drag racing and Winston Cup shelves, but you can believe that a set of SB2.2 heads on a 454ci small-block with 10.5:1 compression and a single 4-barrel carburetor (or a state of the art EFI package) could easily be worth over 700 hp and in excess of 600 ft-lb of torque.
So where does all this lead us? Right back to parts catalogs and the question of what kind of engine you want to build. We will look at what’s available, where to find the parts, and their cost. We’ll also identify the best parts and pencil out a few engine combinations to help you assemble a small block that you’d love to thrash. Along the way, you’ll also get an idea of the importance of the proper combination of parts. One goal for this book is to introduce the concept of the systems approach to engine designing. We use that word because that’s what you’re doing. Assembling an engine is just screwing it together. The important part is designing each part to work with the next to create a system that makes the most power for the least investment. Assemble the right collection of parts, and you can end up with a solid small block that will run like a rat, impress all your friends, and cost much less than the price of a new car.
Written by Graham Hansen and Posted with Permission of CarTechBooks