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Turbocharged Six Cylinder Ford Mustang - Inline Is Real Fine
McLearran Racing And Classic Inlines Build A Turbocharged, Intercooled, Six-Cylinder Powerhouse
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.
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.
|144 ci||90 at 4,200 rpm||138 at 2,200 rpm||3.500 inches||2.500 inches||'60-'64|
|170 ci||105 at 4,400 rpm||158 at 2,400 rpm||3.500 inches||2.940 inches||'61-'72|
|200 ci||120 at 4,400 rpm|
|190 at 2,400 rpm|
|3.680 inches||3.126 inches||'64|
|85 at 3,600 rpm |
|154 at 1,600 rpm|
|250 ci||155 at 4,400 rpm |
|240 at 1,600 rpm |
|3.680 inches||3.910 inches||'69-'84|
|99 at 3,600 rpm |
|184 at 1,600 rpm |