Strokers Wild: Part 4

The Giant Ford DynoFest
Strokers Wild Part 4

Three hopped-up Ford motors. 960 cubic inches. Hundreds of horsepower. Enough torque to pull down small office buildings.

Gives you goosebumps, doesn't it?

After building our Stroker's Wild series of Ford stroker engines -- a 347 cubic inch 5.0L, a 393 cubic inch 351 Windsor, and a 520 cubic inch 460 -- the time had come to strap them to Trick Flow Specialties' Superflow dynamometer and start whomping on 'em. We were either going to make some big numbers, or we were going to blow stuff up trying.

Fortunately, nothing broke, nothing went wrong, and the dyno printouts proved what we knew all along -- there's big power in stroker motors. In our case, a lot of that has to do with the careful parts selection and engine assembly done by the folks at Summit Racing (thanks guys!).

OK, enough with the blabbering and backslapping. Let's see how much power these Fords made.

The 347 was the first engine we built. Based on a new Summit 5.0L block, the 347 has a Summit cast stroker crank (3.400 in. stroke) and H-beam steel rods, plus a bunch of parts from Trick Flow: 10:1 forged pistons, Track Heat hydraulic roller cam (224/232 degrees duration @ .050, .542/.563 inches of lift), and a set of Twisted Wedge aluminum heads.

Since the majority of 347s end up in EFI Mustangs, we tried to duplicate that type of engine for the dyno test. We topped the motor with a Trick Flow R-Series EFI intake manifold, a fuel system consisting of stock Ford rails, 24 lb/hr. fuel injectors, an Accel adjustable regulator, and an MSD distributor with a 6AL ignition box. Exhaust consisted of Dynotech equal length headers with 1 5/8 in. primaries and dual 2 1/2 in. pipes with Flowmaster mufflers.

After a lot of experimenting with throttle bodies, fuel injectors, and ECUs (about 50 runs worth!), the dyno masters at Trick Flow settled on a BBK 70 mm throttle body, the 24 pound injectors, and a Ford EEC IV computer. Total timing was set at 34 degrees.

With this combo, the 347 proved to be a stout little motor -- almost 403 horsepower at 5,700 rpm and 395 foot-pounds of torque at 4,500 rpm. When you look at the dyno results chart, you'll notice how fat that torque curve is, especially from 3,500 rpm on up. That's the beauty of stroker motors, eh?

Further up the small block scale is the 393. Windsors are becoming -- heck, they already are -- a very popular swap with the Mustang crowd. It's kind of a no-brainer. For a few bucks more than a five-oh, the 351W gives you extra torque-creating cubic inches...and a stroked 351W gives you even more.

The key to the 393 is the crank. Summit now has a 3.850 in. cast stroker crank designed to build a 393 with a .030 overbored block, stock length 351W rods, and stock-type 302 pistons. Our 393 features that crank plus Summit H-beam rods, Trick Flow 10:1 forged pistons, a Crane .574/.595 in. lift roller cam with a Crane roller lifter retrofit kit (required for the 1979-vintage non-roller block), and Trick Flow R-Series cylinder heads.

Instead of going fuel-injected, we did the carburetion thing. Since the 393 is a veritable torque factory, we used an Edelbrock Victor Jr. 351W intake manifold to build some horsepower up top without losing low-end power. We originally planned to use the 750 Holley double pumper carburetor we featured in the 393 buildup article, but on the advice of the Trick Flow staff, switched to a 750 cfm Demon double pumper for the dyno tests.

After fiddling with timing (the 393 decided it liked 36 degrees total advance) and carb jetting (73s primary and secondary), and adding a 1 in. open spacer to help further boost the top end, we settled into making big power.

In the buildup article, we stated that the engine should make 500 horsepower naturally aspirated -- and even more with the 150 horsepower NOS nitrous kit we wanted to use. While the nitrous deal didn't happen in time for this article, we beat the 500 figure with 529 horsepower at 6,500 rpm. And there was all that lovely torque, peaking at 472 foot-pounds at 5,000 rpm. This power was not gained at the expense of low rpm torque -- not with 377 ft.-lbs. of it available at three grand. Think about this beastlike 393 between the fenders of a five-speed Fox body!

Now we swing the cubic inch needle way past 11 with Summit's 520 c.i.d. 460 big block. If you have the room, there just ain't no substitute for the natural torque production of a big block -- or the unnatural torque of a stroked big block.

To create the 520, Summit took a 1972 460 2-bolt block, bored it .030 over, then added one of their new 4.300 in. stroke cast cranks, 6.700 in. Trick Flow big Chevy connecting rods, and a set of custom Arias 12:1 compression flat top pistons. With this combo, no block clearancing or special bearings are required.

Rounding out the engine combo is a Crane .718 in. lift solid roller cam, Trick Flow A460 aluminum cylinder heads with a Crane valvetrain, Trick Flow A460 single plane intake manifold with a 1,150 cfm Holley Dominator (with #94 primary and secondary jets), and an MSD Pro-Billet distributor with an MSD crank trigger ignition. The Hedman Husler 2 1/4 in. primary headers we featured in the 520 buildup article were swapped for Hooker dyno headers with 2 1/8 in. primaries. Total timing was set at 34 degrees.

Since the 520 was built as a strip-oriented engine, we expected big numbers way up in the powerband. We were not disappointed: Horsepower peaked at 752 at 6,250 rpm, and torque hit 660 foot-pounds at 5,250 rpm. And in grand stroker tradition, torque production at the lower end was just as impressive, with 540 ft.-lbs. of the stuff available at 3,500 rpm. If you can't make a car go fast with that kind of moxie under your accelerator foot, you can't go fast.

There you have it -- three solid examples of the magic that can happen when you bore and stroke otherwise ordinary Blue Oval engines. With the popularity of stroker combinations growing by the hour, these engines are no longer exotic pieces built primarily for racing. Thanks to companies like Summit and Trick Flow, the parts required to build strokers are available -- and just as important, affordable. Now there really isn't any substitute for cubic inches!