Eric English
August 2, 2012

Without a doubt, the mainstream approach to adding horsepower to a vintage Mustang invariably revolves around increased displacement. There may be a blower or nitrous shot that eventually augments, but a "bigger is better" mantra is ingrained in most of us with no hope of ever turning back. For example, unless limited by sanctioning body rules, does anyone really build a stock cube 289 anymore? How about that easy swap to the big brother 351, or while you're at it, why not a 408? Big-blocks anyone? While you could argue that the increasing frequency of high-tech mod motors bucks the mindset, the consistent theme of V-8 architecture and stroker cranks keep these choices well within a framework we're familiar with.

Completely out of the box is the idea of dropping displacement and cylinder count all in one fell swoop. Just imagine swapping out a 5-liter V-8 for a 3.8L V-6. Interested? How about downsizing from 200 cubes to just 140? Nope? Well, Brian Fitting said yes to this exact question when building the '66 coupe he'll give to his daughter someday, and he's not afraid to tell about it.

Now lest you think the choice was made as a move to keep power low for safety's sake, let's clarify what found its way under the hood. What Brian made work in this '66 may be a first for a first-gen Pony--an intercooled and turbocharged SVO 2.3-liter four-cylinder. The genesis for the project seems to have come through personal experience with a couple of mid-'80s 2.3-liter turbo Fords. A combination of good fuel economy, handling, and power left Brian wondering how a similar powertrain would perform in an early Mustang with 500 pounds less bulk. It's one thing to wonder, and quite another to actually find out, but Brian obviously pursued his curiosity to fruition.

Photo Gallery

View Photo Gallery

Of course, no enthusiastic hot rodder leaves well enough alone, and so this overhead cam four-banger sports an 0.020-inch overbore, and CP forged pistons that yield a boost-friendly 8.5:1 compression ratio. The ported cylinder head features 1.89-inch intake/1.59-inch exhaust valves, which are teamed with a Boport 1.0 camshaft and adjustable cam sprocket. Aside from the ATR header, that's about all there is to tell about the actual engine, other than the fact that Brian screwed it together on his own, and backed it with a '90 A4LD four-speed overdrive automatic. But with an SVO turbo, the nuts and bolts of the physical engine are only part of the story, and Brian is quick to thank everyone at who gave him help and encouragement along the way.

In this case, induction comes from a ported SVO intake and stock throttle body, while the turbo was upgraded to a T3/T4 unit teamed with a Spearco intercooler, Garrett wastegate, and two-stage BoostValve boost controller--allowing max boost to change from 10 psi to 25 psi at the flick of a dash-mounted switch. The whole affair gets its marching orders from a Brian Macy–tuned F.A.S.T. EFI system, and is reported to put down a healthy 300 horses at the rear wheels. Brian says this was with an ill torque converter and malfunctioning wastegate, so today's net may be even better.

The starting point for the whole project was a well-used '66 coupe--originally fitted with a Sprint package 200-inch inline six, and factory Pony interior. We were more than a little impressed to learn that Brian did all the work himself--including the replacement of the floorpans, the bodywork, paint, building the engine, exhaust, and removing the shock towers during installation of a Heidts independent front suspension. The latter was surely an upgrade, but Brian also says it was a necessity due to the width of the turbocharged 2.3's supporting hardware. The suspension upgrade includes rack-and-pinion steering and disc brakes, and was paired with a Heidts four-link rear suspension that hangs a 3.50-geared 9-inch fitted with FRPP discs. Rolling stock comes in the form of a set of price-friendly 16-inch '06 V-6 takeoff wheels, shod in Kumho rubber.