What Is a Crate Engine?

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Ask Kevin Cameron (Cycle World/)

CW reader Odal asks, “What is a crate engine?” In the US auto industry, remanufactured auto engines are a $2.5 billion industry, and new special-purpose engines sold separately from a vehicle are a similar enterprise. In both cases the engines are built in a dedicated facility by professionals.

Reman engines allow continued economical use of a car that needs an engine rebuild, but at about 10 percent of the price of a new vehicle. Individuals or even large dealers are unlikely to have crankshaft-grinding, deck-milling, and align-boring equipment that is essential to remanufacturing an engine that can bear a warranty.

PULL QUOTE: The idea of trackside people needing engine-building skills was becoming as strange as a do-it-yourself appendectomy.

On the hot-rod side there is a market for assembled, ready-to-run high-performance engines for those engine users who lack the facilities and/or skills to build their own engines. In the past, I read countless stories in Hot Rod magazine about romantically rushing around from one flourishing SoCal specialty shop to the next, picking up a reground crank here, chatting with a dry lakes veteran there, loading up a squared-up block there, and a recalibrated distributor from another source. With all the special jobs finished, the builder could then place the fresh block on the engine stand and start the fascinating process of measuring and assembly.

At present there are far more Harley Big Twin riders who might like a 40 percent torque increase than there are riders capable of building an engine reliably able to deliver that. That adds up to a nice little business, building and shipping out hi-po engines. In crates.

I saw the other side of this equation during my time at trackside in motorcycle racing. Through the ‘50s and into the ‘60s, Triumph, in the twin forms of Tricor and Jomo, offered a wide palette of speed parts (cams, big valves, high-compression pistons, etc.) from which a person with skills could assemble competitive racing engines or high-performance streetbikes. The necessary skills were everywhere, in the form of those who had worked in war plants 1941–45 and those with skills learned in the thousands of small job shops that then still existed. Use a micrometer? No prob. Operate a torque wrench? Every damn day!

Even when I fairly recently attended the Daytona TT, many of the builders I spoke with were small planets orbiting the US auto industry—many were tool and die people.

In the ‘80s I encountered people willing to tackle a crankshaft replacement on a club-racing RD350 Yamaha. One was a young man whose dad operated a fairly extensive machine shop. I walked past just as he rolled in from practice at Thompson, Connecticut.

“Crank just rattled out,” he said cheerfully. “No problem; I knew it was coming and I’ve got a fresh one in the van.”

Forty-five minutes later, here he came, warming up his bike with the new crank in place, all fasteners torqued and tab washers bent.

Another day I got an evening phone call. It was another club racer, wanting to know if I could give him and his partner some advice, since they’d decided their bike—also an RD—needed a fresh crank.

I said, “If you have the manual, you have most of what you need, and if you have questions or run into a snag, call me and we’ll sort it out.”

It took two weeks and a few calls; both men were employed so work took place evenings and weekends. But they stuck to it, getting familiar with how engine internals look, with what needs doing. I admired their spirit of adventure. “Let’s do this ourselves. We can do it.”

As time rolled on, the transition from two-stroke to four-stroke made engines more complicated and demanding to service. Want to put in the time measuring valve-to-piston clearance with high-lift cams, then setting up the pistons in the mill to fly-cut the necessary clearance? Meanwhile, the population of people with factory and machine-shop experience was dwindling. More of my club-race customers needed to have more and more done for them.

It was no accident that Supersport racing, which strictly limits engine modifications, quickly became more popular than the old 250 two-strokes that had trained so many fine riders in the later ‘60s, the ‘70s and the ‘80s. The skills needed to run a Supersport bike were less demanding, mostly limited to tune-up procedures with an occasional R&R cylinder head to “freshen up” the leak-down via valve reseating. Even tire changing became specialized. Garage photos from the later ‘70s and ‘80s showed long tire levers at the ready, but the tire companies began providing trackside mounting and balancing services. All a team had to do was send a warm body pushing a wheeled tire rack to the Michelin or Dunlop service tent, with instructions. No more pinching three tubes in a row. No more leaving a tire iron inside a tire. Professionals took over.

The idea of trackside people needing engine-building skills was becoming as strange as a do-it-yourself appendectomy.

Nights at tracks in the US and abroad had once resounded to the whine of die-grinders as new two-stroke cylinders were prepped to install. This was replaced by well-equipped four-stroke teams whose engines were never, ever apart at trackside (The dust! The filth!): They were professionally built in clean, well-lit, and well-equipped facilities, then put into sealed shipping caissons.

We used to dream of such things when we were DIY “cellar dwellers” with no money. We dreamed of ready-to-start engines in shipping caissons, up in the truck in serried ranks and rows as had become NASCAR practice (I don’t know about today, but Hendricks used to take 32 engines to Daytona). We also dreamed of rows of milling machines and lathes staffed with skilled machinists.

Harley-Davidson’s Screamin’ Eagle 135R Stage IV crate engine. Why is it called a crate engine? It comes in a crate! (Harley-Davidson/)

Even that was changing—replaced by “machining centers” that were loaded with palletized work-pieces by “stagers” (aka “warm bodies”). Machinist skills were in process of being canned into CNC programming. That meant fewer actual machinists and more “metal-removal specialists’' whose work was mainly programming. By 1990 it was considered wasteful to have a $70,000 machining center on the floor for a single shift. Many shops rented out a second shift to make sure the monthly payments couldn’t become a problem. Or they set up the jobs during the day and hit “run” as they clocked out at five.

Yet people still want and need such things as remanufactured engines and “crate engines” built for special purposes—engines like Harley-Davidson’s new Screamin’ Eagle 135R Stage IV. In both cases they are built by professionals, using capable modern facilities. The existence of such engines makes it possible for people, who have not devoted their lives to learning the necessary skills, to have the engines they need.

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