383 The Right Way

Building the best-performing stroker small-block is a balancing act

- Barry Kluczyk

In the Great Ideas Hall of Fame, the first builder to create the ubiquitous 383 stroker combination is right up there with whoever invented s’mores and Philippe Kahn, the guy who stuffed a camera in a cell phone.

Along with the 33 additional cubic inches over a 350 engine, the 383’s complementing advantage is torque. The bore/stroke ratio of a stock, oversquare 350, with its 4.000-inch bores and 3.480-inch stroke is 1.15:1. The 383 is still oversquare, with a larger bore dimension than the stroke, but it comes much closer to square with an improved stroke ratio of 1.07:1, which enhances torque production.

Let’s take a look at another example for comparison: Chevrolet’s new 6.6L gas V-8, found in the latest heavy-duty trucks, versus the 6.0L engine it replaces. Almost all of the 6.6L’s greater displacement comes via a longer stroke: 3.860 inches versus 3.620 inches. That’s a nearly 7 percent increase, while the bore dimension is essentially unchanged. The result is 401 horsepower and 464 lb-ft of torque, compared to 360 horses and 380 lb-ft for the 6.0-liter engine.

That’s nearly 11.5 percent greater horsepower and 22 percent more torque for the 6.6L. It’s important to note that, thanks to direct injection, the 6.6L has a higher compression of 10.8:1 versus the 6.0L’s 9.4:1, but it primarily enhances horsepower. It’s the significant increase in stroke that really amplifies the torque output.

In fact, the stroke ratio for the 6.6L is 1.05:1, which is on par with the 383. So, that original builder was on to something with that first stroked small-block.