Manifold Mystery Tour – Dodge Exhaust Manifolds on Trial – Slant Six

The Slant Six Was a Legend of Efficiency and Durability: What Happens When We Add a Bigger Carburetor and Cast Headers?

So far in the Manifold Mystery Tour exhaust manifold vs. header dyno comparison series, we’ve examined the impact of exhaust headers on a 392 Chrysler HEMI®, 426 Street HEMI and 340 Six Pack. But what about the millions of Slant Sixes that powered the Darts, Challengers, Chargers and Coronets on the lower side of the performance curve, is there hope for added scoot? You bet!

Even though it’s been nearly three decades since the last Slant Six-powered Dodge rolled off the line, restorers, hot rodders and tinkerers still embrace the so-called “leaning tower of power” for its nifty looks and low cost. Rebuildable core engines can be purchased for next to nothing and there’s a ton of aftermarket support, so, why not?

About the “leaning tower” part, the Slant Six gets its name from the way its designers decided to set the engine block over at a 30-degree angle from vertical. By laying the engine over to the right-hand side of the engine bay (that’s the passenger side in the left-hand-steer cars we’ve got here in America), several benefits were achieved. None of them were accidental.

First, the overall height of the as-installed engine was reduced several inches. This allowed body designers to use lower, sleeker cowl and hood surfaces. The extra distance between the cylinder head and the left-hand side of the engine compartment added room for much more efficient intake and exhaust plumbing.

And finally, the 30-degree slant made extra room for the water pump to move from its traditional location – at the nose of the engine block – to a more compact location at the leading end of the left-hand side. This reduced engine length by critical inches, all the better to fit thicker radiators for improved cooling.

Introduced in 1960 with 170 or 225 cubic inches, early marketing materials referred to the new engine as the “30-D Economy Six”, the numeric nomenclature number being a reference to the 30-degree slant of the block. Though a catchy name, consumers quickly called it what it is, the Slant Six. In this article, lets watch as Donnie Wood and the team at R.A.D. Auto Machine (Ludlow, MA 413/583-4414) grab an extra 32 horsepower and 22.8 lb.-ft. of torque by switching carburetors and exhaust manifolds.

 

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