What Makes A Fully Built Engine? Photo Gallery
Industry experts weigh in on what exactly the age-old term means
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| When it comes to cylinder liners and aftermarket sleeves, whether or not they’re part of the definition is up for debate. In Honda-land, where the factory cylinders start coming apart somewhere around the 400hp range, they’re a part of the equation. For engines like Toyota’s 2JZ or Nissan’s RB, though, perhaps not so much. (photo courtesy LA Sleeve)
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| Historically, the term “fully built” has been used to describe the degree to which an engine’s been strengthened by way of stronger internal components, and according to Ron Bergenholtz of Bergenholtz Racing, typically consists of things like forged pistons and connecting rods, more durable head studs or bolts, and a heavy-duty valvetrain.
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| Cast-aluminum pistons are typically the first to fail when it comes to bottom-end catastrophes, which means that no matter your definition of a fully built engine, it ought to include pistons that are forged.
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| Low-budget pistons or those from some obscure Chinese parts peddler might seem like a good idea while browsing eBay but will never measure up to the sort of quality and durability you’ll get from, say, a company like Tomei. (photo courtesy Tomei)
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| The fully built definition starts to get a bit foggy when you start talking cylinder heads. Some say it includes porting, some say it’s only got to do with things that’ll make that engine more durable, like stainless steel valves, for example
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| Hardware like head studs or bolts as well as main caps and their fasteners also have to be included in the fully built definition. After all, a forged connecting rod is only as strong as the bolts that hold it together.
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| When it comes to cylinder liners and aftermarket sleeves, whether or not they’re part of the definition is up for debate. In Honda-land, where the factory cylinders start coming apart somewhere around the 400hp range, they’re a part of the equation. For engines like Toyota’s 2JZ or Nissan’s RB, though, perhaps not so much. (photo courtesy LA Sleeve)
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| A properly built engine goes beyond parts selection. Knowing what that engine will be used for is critical to the sort of bearing clearances and piston ring endgaps you ought to use.
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| Proper planning and a detailed assembly are also just as important as you paying for those forged bits. You might have the fanciest pistons around, but if nobody bothers with things like giving them the right amount of clearance within those cylinders, none of that’ll matter. (photo courtesy Tomei)
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| There is no fine line between what’s considered fully built and what’s not. Half of our experts say it ought to include things like cylinder head porting and combustion chamber shaping, both of which have no bearing on engine strength but’ll certainly affect horsepower. (photo courtesy Tomei)
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| Nobody disagrees on whether or not proper machining ought to take place. Any time an engine’s been torn apart, its block and head should be resurfaced, among other things, depending on the circumstances. (photo courtesy Tomei)
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| There are worse mistakes you can make, but going overkill on parts you don’t need will never be a good thing. Yes, solid-deck cylinder liners are just about the strongest modification you can make to a short-block. And no, your 220hp K-series doesn’t need it. LA Sleeve’s Dave Metchkoff goes on to say that even a fully built and sleeved engine isn’t foolproof. “A sleeved motor is meant to survive short-term abuse,” he says. “In the long run, its fiercest enemy is the soft aluminum engine block. Through thousands of heat cycles, some blocks simply soften and sleeves can drop a few thousandths of an inch. Once dropped, the head gaskets simply cannot hold coolant.” (photo courtesy LA Sleeve)
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| You can throw all the expensively forged parts you want at the engine of yours, but if you don’t know what you’re doing when it comes time to assemble it, your definition of fully built might take on a whole new meaning. (photo courtesy Tomei)
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