Wes Duenkel
September 19, 2013

Is the V-6 in your Mustang ready for a rebuild? Does it need more oomph, but your wallet can’t handle a V-8 swap? Well, you’re in luck. The familiar adage, “there’s no replacement for displacement” certainly applies to the 3.8L V-6 found in 1994-2004 Mustangs. Increasing stroke and opening up the bore can add significant muscle, and using factory parts makes it easier on your wallet. We’ll show you how.

The centerpiece to this build is a factory-replacement 3.74-inch (95mm) stroke crankshaft found in 1997-2008 Ford trucks and minivans with a 4.2L V-6. We reused our 3.8L connecting rods, as they are the same between the 3.8L and 4.2L. The added stroke combined with stock-replacement 4.2L pistons sized for a 0.030-inch overbore yielded us 260 cubic-inches, or 4.3L. That’s only a third of a liter shy of the V-8s of the same era.

The rest of the parts from our 3.8L engine carried over, though we chose a slightly bigger bumpstick from Comp Cams to give us a fighting chance against our V-8 buddies.

Integral to any proper engine build is machine work from a competent engine machine shop. A critical step in the process was balancing the combination of flywheel, harmonic damper, and crankshaft. Follow along as Tommy's Auto Machine in Springfield, Tennessee helped us with this unique build.

Want to build your own big-inch V-6? Here’s what we used:
• Mustang 3.8L block
• 3.74-inch (95mm) stroke crankshaft from 1997-2008 Ford truck/minivan with 4.2L V-6
• 0.030-over pistons and matching rings
• 3.8L connecting rods (re-used, same for 3.8L/4.2L engines)
• flywheel from a 1998 Ford F-150 4.2L
• harmonic damper from a 1998 Ford F-150 4.2L • Comp Cams roller camshaft, P/N 44-702-9
• Comp Cams roller lifters, P/N 851-16
• Com Cams valve springs, P/N 26918-16
• new rod and crank bearings
• new oil pump
• new timing tensioner
• new gaskets

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