When you spend a few hours hanging with Pat Musi at his engine shop, Pat Musi Racing Engines, in Mooresville, NC, it’s never enough to see just one engine he has being built – you have to see a few! Thankfully, Pat is more than happy to show you engine after engine.
If you’re familiar with Musi’s engine expertise, then you’re well aware he’s a big nitrous guy. It was fitting that we got to hear the details of this 632 cid big block Chevy nitrous engine during our visit. The engine combination has become one of Musi’s staple engine packages.
“This is really an Edelbrock deal,” Musi says. “It’s an Edelbrock manifold and heads. They’re all ported here in-house on our Centroid in the Race Center. These motors are for an entry level guy or grudge racer, and we plan to have these ready on the shelf.”
The 632 big block can come in either an aluminum block version or a steel block version, depending on your budget, and Musi Racing Engines ensures quality components make it into the entire build.
“These engines have all the normal components that we typically use,” he says. “Edelbrock’s Rick Roberts and I developed this 12-degree head a long time ago, and we’re constantly tweaking it, but it’s reliable. We also have the Edelbrock manifold and Jesel valvetrain and belt drive. This engine will go 150 runs before it even needs to be looked at. We haven’t had any failures. It’s a tried and proven piece.
“The valvetrain doesn’t move. Danny [Jesel] and I corrected all the stuff that’s been wrong with the Big Chief-style head. We put three valve cover bolts on and a lot of little, subtle things that change because the rockers were always running into the valve cover bolts and where the rocker bar is had to change – a lot went into this whole build. It’s really for a guy who wants an entry level engine and doesn’t want all the maintenance. Bolt it in and go racing.”
Aside from the heads, manifold and some of the valvetrain, the 632 big block also features a stout rotating assembly.
“It’s a GRP rod and Diamond pistons,” he says. “Due to the supply chain, we sometimes use a Wiseco or Gibtec piston. They’re all good parts. We go through so many parts we have to have a couple suppliers to keep up.”
As mentioned earlier, Musi loves a nitrous build, and this 632 is no exception. Without the nitrous, on a single 1700 APD carburetor, the big block Chevy makes 1,250 horsepower all day long. With a tune up for one stage of nitrous, the engine makes 1,650 horsepower. And, on two stages of nitrous, it’ll get close to 2,000 horsepower.
“You could run it 150 runs at 1,650 horsepower and never have to worry about rings or damage – just follow our instructions and away you go,” Musi says. “It’s a turnkey deal.”
Engine of the Week is sponsored by PennGrade1, Elring – Das Original and NPW Companies. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected].