Pistons
"A lot changed in the piston industry due to advancements in CNC machining and diamond cutters. Pistons can be made much more accurately now, so whether they're forged or hypereutectic, they will fit very tightly in the bore. That means piston slap associated with forged pistons doesn't necessarily compromise durability, as previously thought. However, we actually use hypereutectic pistons in many of our motors because they're more rigid and fit slightly tighter in the bore, which can reduce blow-by and noise at startup. Hypereutectic pistons are very rigid and strong, but once you reach a certain power output, they'll break. On the other hand, forged pistons will flex and move because the material is much softer, which is why they can handle more power. Ultimately, it's a trade-off."
The Other 383
Smeding's 383 packages use a 3.800-inch crank over the more common 3.750-inch cranks. While Smeding's crankshafts are custom, GMPP offers 3.800-inch-stroke units as well. Since this less common stroke requires a custom piston, is there any performance advantage to using it over a 3.750-inch stroke? "The main reason we have our cranks custom made is so we can set our clearances more precisely and tailor the counterweights to be more in balance with our components," explains Ben. "Since we're doing that, you might as well take advantage of the extra stroke of a 3.800-inch crank. This allows us to run higher compression with lower-grade fuel due to the improved quench. In theory, a longer stroke should rotate easier because of the additional leverage, which reduces stress, improves durability, and might improve gas mileage as well."
Break-In
Some engine builders say break-in isn't necessary due to advancements in ring technology, while other suggest a stringent break-in procedure. So who's right? "It all depends on the honing technique and the type of rings and bearings used, which is why there are so many different opinions on break-in procedure," says Ben. "Since we run every motor we build on the dyno, they're 90-95 percent done right out of the crate, and our customers don't need to do anything. Whichever break-in procedure you should adhere to is up to your engine builder or machinist to determine. There isn't a universal answer."
Octane
Anything greater than 91-octane pump gas is hard to find out west. Consequently, whether it's blower kits or crate motors, most engine components are now tuned to be compatible with 91-octane fuel. Rest assured, Ben says the drawbacks of a few octane points are minuscule. "If you have access to 92- or 93-octane fuel and bump up the timing accordingly, the benefit is so small that it's not even worth doing. There's always a trade-off. Advancing timing can boost midrange torque but will also sacrifice some top-end power."
Blower Motors
Forced induction calls for lower compression, but there are other engine parameters that must be tweaked to make it compatible with boost. In addition to thicker compression heights and stronger wrist pins, forced induction requires different bearing clearances, ring packs, spring pressures, and exhaust valves and guides. "Forced induction makes blow-by worse, so standard-tension rings help improve oil control better than the low-tension rings used in many naturally aspirated motors," explains Ben. "Larger bearing clearances improve oil flow, and valvespring pressures must be increased since boost tries to blow the valves open. The additional heat of a blower motor also mandates the use of additional valveguide clearance and wider seats."