Roush Performance's Ford 427 crate enginesRoush Performance offers three small-block Ford-based 427-cubic-inch V8 crate engines that produce over 500 horsepower. The 427 SR crate engine provides 510 horsepower, the 427 R has 550 horsepower, and the 427 IR delivers 560 horsepower and 540 lb-ft of torque using premium fuel.The Roush 427 IR features a cast-iron engine block with four-bolt main bearing caps, a 9.5-inch deck height, and CNC-ported aluminum cylinder heads. The rotating assembly consists of a steel crankshaft, steel H-beam connecting rods, and forged aluminum pistons. The valve train assembly consists of a hydraulic roller camshaft with undisclosed lift and duration that Roush points out will have a rougher idle than normal. The aluminum "8-stack" intake manifold is among the Roush 427 IR crate engine's most striking features.Unlike the Ford Performance 427 Boss crate engine above, the Roush 427 IR is delivered as a complete and turn-key crate engine. It's also protected by a two-year or 24,000-mile warranty. However, those interested in purchasing a Roush 427 IR crate engine should understand that these high-performance engines have characteristics that differ from traditional production engines. Some of these, which are not covered by the warranty, include: excess mechanical noise, increased heat generation, and higher oil and fuel consumption. They also may not be street legal, depending on the configuration.