John Hennessey, owner and founder of Hennessey Performance Engineering, says that the Ford GT is one domestic car that he would never put a big supercharged V8 in.

As a brand, Hennessey has made a name for itself by doing some pretty insane stuff. Insane like taking a Ford Raptor, giving it an extra axle, and then pumping its engine to produce 600+ horsepower. They call it the VelociRaptor 6x6, and it’s an absolute beast of a pickup.

Or maybe you prefer the insane HPE1200 Jeep Trackhawk upgrade that gives the 6.2-L supercharged V8 under the hood a colossal 1,200 horses?

Engine swaps and upgrades are Hennessey’s bread and butter, but they typically only happen to big, domestic vehicles. The key thing here is those big domestics have a lot of wiggle room under the hood. There’s space to actually fit something like a supercharged V8 in a Jeep Grand Cherokee, but under the hood of a rear-engined supercar? Not so much.

And that’s why Hennessey adamantly refuses to swap the Ford GT’s twin-turbo V6 for a larger V8. In his "qualified opinion", a big V8 just wouldn’t fit.

Hennessey spoke to Motor Authority where he finally dished about the reasons for keeping the GT just the way it is. He personally owns a Ford GT and has tested it on his personal test track shortly after taking delivery. On Hennessey’s website, he wrote: “It does not happen often, but some cars are not meant to modified. In our humble opinion, the new Ford GT is one of those cars.”

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Motor Authority clarifies that, writing, "Ford simply didn't leave enough room for Hennessey to squeeze a V8 such as a blown 5.0-liter or 5.2-liter unit from Ford's parts bin without destroying its distinctive styling, Hennessey said."

That’s really not surprising. The GT is built in the tradition of a modern supercar, where the car itself is mostly built around the engine. In the case of the GT, it’s a 3.5-L twin-turbo V6. Since everything about the GT is built around the engine, changing the engine would require so many fundamental changes to the car that it would be cost prohibitive to perform a swap.

"If a customer came to me with a bag of a million dollars and said, "Would you put a V-8 in the back of my Ford GT?' I won’t do it," Hennessey said.

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