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The New Caterpillar C8.7

Strange Bedfellows

Some Engine builders are finding they need to partner up if they’re going to meet stringent new emissions regulations.

When I heard from Caterpillar that it would display its new pod drive with its newest engine, the C8.7, at the 2013 Ft. Lauderdale International Boat Show, I was intrigued. Both had been out for nearly a year, although I’d yet to see one or hear of one being installed. I remember thinking, well, I guess CAT’s  finally found a home for its new engine. That alone made it worth covering, which I did in a recent column (Power & Propulsion, November 2013 ➤) that filled you in on new engine-related products for 2014.

The C8.7 was intriguing. It seemed to come out of nowhere and then, for a year, go nowhere. So this most recent information motivated me to do a little digging. I quickly discovered that the engine was not only not derived from another Caterpillar marine engine; it wasn’t derived from any Caterpillar engine. That certainly explained its unique (for CAT anyway) technology. The C8.7 combines a second-generation common-rail fuel system, a belt-driven supercharger, and a turbocharger to generate 650 metric horsepower at 2300 rpm while meeting EPA’s Tier 3 emissions regulations. Both the turbo and supercharger are operational from idle, but the turbo doesn’t produce significant boost until the engine is around 1200 rpm (the threshold is adjustable). Being mechanically driven, the supercharger produces boost whenever the engine is running. Once the turbo makes positive pressure, an electromagnetic clutch automatically disengages the supercharger to prevent overboost. The result is very fast torque rise—and it is torque that puts a boat on plane.

Caterpillar C8.7Something else unusual is that CAT is apparently offering the C8.7 only mated to its Three60 Pod 650 drive system, not as a straight inboard. The allure of the pod is obvious, but it’s hard to imagine why CAT wouldn’t amortize development costs by offering it also as an inboard. 

Then there was nomenclature: What’s with the decimal point? For all other CAT engines, the integer following “C” signifies total displacement in liters, rounded to the nearest whole. So, for example, while the C12 displaces 12 liters, the C15 displaces 14.6 liters, not 15 liters, and it is not designated the C14.6. 

Obviously the best place to sort this out would be on the CAT Marine Web site: www.marine.cat.com. But guess what? The C8.7 isn’t listed—or at least wasn’t at press time. Since according to CAT the engine was developed “in tandem with Fiat Powertrain Technologies (FPT),” I tried searching Fiat’s Web site, and that of IVECO, the Fiat subsidiary that makes diesel engines and such. Nothing.

Finally I tried typing “C8.7 marine diesel engine” into Google. Among the results I got a CAT press release dated February 2013 announcing the C8.7 and including this quote from David Shannon, Caterpillar Marine Power Systems marine pleasurecraft global sales manager: “The C8.7 … will replace the 575-metric-horsepower C9 with a common-rail fuel system and a new air-management system, allowing us to produce 650 metric horsepower from a smaller and lighter package.” With more digging I discovered that apparently CAT chose not to invest in the upgrades required for the C9 to meet Tier 3, even though it needed to be in that market segment. 

So instead it partnered with Fiat, which is widely credited with developing the common-rail fuel system, to adapt a model from Fiat’s Cursor engine line. That would reduce development costs, but of course, CAT didn’t get it for free: It can offer the engine in only one recreational rating that meets Tier 3 and cannot sell commercial variants. But why offer the C8.7 only with CAT’s pod? According to one source, finding the right engine to power this pod—while meeting Tier 3—was the primary reason CAT went looking for a partner in the first place. Apparently the company is betting big on big pods. 

The expense of meeting Tier 3 also killed a C12 upgrade. Again, CAT and Fiat partnered on a compliant replacement called the C12.9 (ah, the decimal explained!), which uses Fiat’s second-generation common-rail technology and, in the 1,000-horsepower version, its supercharger-turbocharger combo, to meet the emissions limits. 

And if all this isn’t complex enough, let’s throw one more name into the mix: Volvo Penta. The company introduced a supercharger-cum-turbocharger diesel engine way back in 1991. But common-rail injection was only a dream at the time, and anyway the idea was faster planing, not lower emissions. Volvo’s KAMD42 really has little in common with the new C8.7.

So this is what the future most likely will hold: big pods and clean diesels that have been developed by multiple partners to minimize costs. The only question is how boaters are going to feel about having a yacht powered by Fiat.

This article originally appeared in the February 2014 issue of Power & Motoryacht magazine.

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