Pictures: Jeff Jost

Car guys and boat guys may be different breeds of performance enthusiasts, but both share a passion for powerful engines. As it turns out, many of the same engines we gearheads find in our cars can also be modified for marine duty. Which means that if you’re a crafty and enterprising individual, you can stuff just about any engine into a boat… including an LSx motor.

That’s what Jeff Jost, a man who is no stranger to strange engine swaps did – after he found the old 454 BBC in his jetboat lacking enough oomph (and it blew up), he did what was only natural; swap in a modern LSx motor. He detailed his swap over at LS1tech.com.

In this case, the motor was an LQ4 6.0 liter truck motor. Jeff, an R&D engineer for Caterpillar, keeps himself busy by swapping LSx engines into a variety of vehicles. His own current stable includes a turbocharged 1969 C-10 pickup that was a father-son project, and he is in the middle of helping his brother install another LQ4 into his ’88 Monte Carlo.

And then there is the jet boat.

Getting the tired old 454 out of the boat was easy. Swapping in the LQ4? Not so much. “The most difficult part was the exhaust manifolds,” says Jeff. “They are Ford 351 units, and are almost like finding unicorns. I had to re-drill the stock 317 heads, and had to weld in the exhaust primaries on the manifolds a bit to close up a gap that would have allowed exhaust to escape. The second most difficult part was finding a pump drive coupler to bolt to the back of the LS. I was able to find one at a place in Oregon that custom machines them, and the goofy M11 bolts.”

However, now that the swap is all said and done, Jeff put up video proof that this new LSx-powered jet boat really hauls ass. It also gets better gas mileage, though Jeff is one of those guys for whom enough is never enough. “I want to go faster, so there is a good chance I will turbocharge it next summer.” We certainly hope he does.