Turbocharged Six Cylinder Ford Mustang

Last month, we showed you Classic Inlines' approach to building a solid, streetable, race-ready Mustang platform for not a V-8, but a hot six-cylinder. Mike Winterboer of Classic Inlines decided to approach Mustang building as differently as he does inline six-cylinder powerplants.

This month, we're in Will and Kelly McLearran's race shop in Tucson, Arizona, to build a 273ci tall-deck Ford inline-six for Mike Winterboer's '69 Mustang SportsRoof.

Because six-cylinder buffs don't enjoy the same wealth of performance parts as those of us with small-blocks, it becomes much like building a V-8 in the old days. If you're building a hot six, you have to improvise-make the most of what you have, beat the bushes for parts, and build durability into your engine in order to keep it together. This isn't done by way of a stroker kit with a steel crank, and it isn't always possible to do it with brute H-beam rods either.

If you think building a six is cheaper than building a small- or big-block V-8, think again. Six-cylinder engines call for specialized parts, and your desire for big power may overwhelm your budget. Build a six because you like six-cylinder engines, not because you're looking to save money. This is all about the desire to be different.

This is the Turbo 273 six's stroker kit from McLearran Racing. The lightened nodular-iron crankshaft has been massaged to perfection, including distressing, improving radiuses, and chamfering oil holes. The entire assembly, including oversize, custom-forged JE Pistons, has been dynamically balanced. These are stock Ford rods that have been shot-peened and fitted with ARP bolts.

This is the new Classic Inlines aluminum cylinder head for small Ford-sixes. Because it's based on the Australian 250-2V aluminum head and fitted with Ford hardware, it's an easy swap for anyone doing an afternoon home-garage conversion. This will save you a lot of money because the cost of custom valvetrain parts is eliminated.

Mike Winterboer's primary goals with the Classic Inlines aluminum head were to reduce total ignition timing while improving airflow. He achieved these goals with a high-swirl chamber that yields exceptional quench and fuel distribution. High-velocity intake ports yield improved torque. A fresh approach to exhaust ports means better scavenging. In dyno testing, Winterboer has witnessed outstanding performance across the powerband. Of course, much depends on camshaft and induction selection.

But First, A Ford-Six Primer
Ford's lightweight, gray-wall, cast-iron six-cylinder engine first appeared in the '60 Falcon. It was a rugged, lightweight, fiercely dependable inline six-cylinder engine fitted with a Holley one-barrel, glass-bowl carburetor. Ford designed this engine with budget in mind. It was cheap to make and even cheaper to operate.

Manufactured in the Dearborn Engine Plant, where Ford also built FE-series big-blocks, the little Ford six was rather anemic at 144 ci and 90 hp. In 1961, Ford increased stroke, bringing displacement to 170 ci and horsepower to 101. In 1964, bore and stroke were increased again to achieve 200 ci.

At first, the 200 six had four main bearings, just like the 144 and 170. For 1965, Ford changed this engine's architecture, increasing the number of main bearings to seven for rigidity and smoothness. The seven-main-bearing block is easily identified by five freeze plugs on the right side instead of three with the 144/170/200ci four-main-bearing blocks. The seven-main-bearing block is always the best choice for performance applications.

For 1969, Ford increased block deck height by approximately 2 inches and stroke by 0.784 inch to get 250 ci from the hardy Ford six. Although Ford had fuel economy and improved torque in mind for this engine, it didn't achieve fuel economy. A 302ci small-block V-8 gets better fuel economy than the 250. But if you're read-ing this article seeking performance, you're not concerned with fuel economy.

The 250ci six has features that make it different from the 144/ 170/200. Aside from a taller, wider block, five freeze plugs, and a deeper pan, the 250 also has a four-bolt water pump and a small-block bellhousing bolt pattern. Mustangs and other Ford compacts equipped with the 250ci six have an 8-inch removable carrier differential instead of the smaller 7 1/4-inch integral carrier rearend with four-lug wheels.

Another issue facing the six-performance enthusiast is mechan-ical versus hydraulic lifters. This calls for two different types of rocker-arm shaft assemblies, along with the corresponding pushrods. Hydrau-lic lifters call for nonadjustable rocker arms and round-tip pushrods. Mechanical cams call for adjustable rocker arms and cup-style pushrods. What's more, you can't install hydraulic lifters in an early Ford-six block with mechanical lifters. The necessary oil galleys to feed the hydraulic lifters aren't there in the early four-main-bearing blocks.

Building a six calls for the same attention to detail needed with V-8s. Cylinder blocks should be sonic-checked before any machine work, especially if you're going to boost the mix with a turbocharger or supercharger.

When you're building a hot Ford six, camshaft/valvetrain package deals aren't always available. Winterboer ordered his valve action la carte. This is an aggressive Clay Smith flat-tappet mechanical camshaft with 112-degree lobe centers. Clevite provided the dual-roller timing set. JP Performance was working on a similar timing set at press time. We'd like to see roller-tappet technology for these engines. According to Winterboer, they're working on this idea. Yella Terra 1.6:1 roller rockers, available from Classic Inlines, improve lift and reduce friction. Chrome-moly pushrods come from Rocker Arm Specialties.

Take a look at this induction system for the Classic Inlines 273ci turbo-six, and check out this six-barrel fuel-injection throttle package for the Classic Inlines aluminum head. Will McLearran custom fabricated the chrome-plated turbo plenum, which is expected to be available soon from Classic Inlines.

Power in the Hands... It has often been said there's no replacement for displacement, which is as true with inline-sixes as it is with V-8s. Although we have bored and stroked Winterboer's tall-deck 250 to 273 ci, this is only the beginning of the power gains he hopes to achieve with his turbo-six SportsRoof. Winterboer makes a quantum leap with a Turbonetics T04E 58mm turbocharger and a massive 26x12x3-inch Yonaka intercooler with 2 1/2-inch inlet and outlet.

This is the roughed-in Yonaka intercooler. If you're planning for air conditioning, expect to run into fitment issues-otherwise, this piece fits nicely. As its name implies, an intercooler deeply cools the intake charge for great power gains. It passes the heated inlet air from the turbo through a heat exchanger in the front air stream of the car before it reaches the throttle body or carburetor.

Mustangs Plus shipped us a Griffin aluminum radiator designed specifically for 200/250ci Ford sixes. We strongly suggest a fan shroud to increase air velocity. When you size the fan correctly and install it properly, overheating isn't an issue.

Talk about a turn-key electronic engine-control system-FAST, a division of Comp Performance Group, makes this system for fours, sixes, and V-8s alike. The FAST Electronic Fuel Injection System is user-friendly. You don't need a dyno-tuning professional to get it running properly.