What's It Like Testing Mercury Racing's 750-HP Small Block Crate Motor?

Here's a hint: Pretty [expletive deleted] fun. 

When it comes to crate motors worth dropping into road-going speed machines, Mercury Marine likely isn't the first name that comes to mind. (A fact which likely has quite a bit to do with the word "Marine" in there.) But in spite of its aquatic roots, the company has a bit of history building sweet engines for high-performance cars. It was Mercury Marine, after all, that handled assembly of the Lotus-designed DOHC V8 that hid beneath the C4-generation Chevrolet Corvette ZR-1's hood.

In recent years, the company has begin making more of a point of showing off how nicely the assorted wares produced under its Mercury Racing brand work in an automotive context. Back in 2015, the company modified a twin-turbocharged 9.0-liter V8 for duty in SpeedKore Performance's carbon fiber-bodied '71 Dodge Charger known as "Tantrum." In that SEMA-spec muscle car, Mercury's motor cranked out a seismic 1,650 horsepower

Cut to the present day, however, and the company has launched its latest foray into crate engines specifically designed for automotive use. It's a little more tame than the Bugatti-beating engine crammed into the Tantrum...it's hardly a wimp. 

The Mercury Racing SB4 is a 7.0-liter four-valve-per-cylinder small block engine based on the beloved LS7 V8 found in the C6-generation Corvette Z06 and the former Camaro Z/28. The LS's in-block cam and pushrods get the old heave-ho, replaced with Mercury Racing's own dual-overhead-cam valve train. Thanks to engineers careful handiwork, the SB4 revs to 7,500 rpm and cranks out a stunning 750 horsepower—about 50 percent more than the engine it came from. 

Mercury Racing

The Mercury Racing SB4 small block. 

In order to help get the word out about the new Corvette-based engine, Mercury invited The Drive out to the company's Wisconsin headquarters (or, to be more accurate, a closed-off airstrip nearby) so we could have a chance to open the taps on the SB4. And since bench-racing an engine is only fun for nerds, the company gave us a chance to test it out by driving an Ultima GTR—a mid-engined track machine that weighs roughly as much as a Mazda Miata—equipped with the manic small block between its axles.

What was it like? Well, hit play and find out.