5.0 Revival
Slide Show
Part Four: 347 Cubic Inches, Lots of Power
Three hundred eleven horsepower. Three hundred forty-six foot-pounds of torque. That’s how much power a 347 cubic inch stroker motor put to the rear wheels of our 1995 Mustang GT, dubbed 5.0 Revival.
In case you were wondering, the big motor was our ultimate goal when we dove into this project. Those nifty “Summit 347” badges on the fenders? We had ’em made before we turned the first wrench. Now that’s planning ahead.
Because not everyone can get into a stroker motor all at once—or even want to go beyond hopping up a standard five-oh engine—we did 5.0 Revival in stages. Check them out:
• Stage One
• Stage Two
• Stage Three
A Bigger Pump
Now that you’re up to speed, let’s get into our Mustang’s upgraded pump. A 347 is simply a 302/5.0L block bored .030 inch over and fitted with a 3.400 inch stroke crankshaft and 5.4 inch long connecting rods. Anything that bolts to a five liter will work on a 347, so you can swap over all your old hop-up parts. Now you just have 45 extra cubic inches of air pump to play with.
Getting those extra cubes is simple, thanks to the proliferation of 347 stroker kits available from a number of suppliers. We stuck to our vision of using as many Summit- and Trick Flow-brand products as possible by using a Summit Engine Shop 347 Rotating Kit. This is a premium-quality kit that includes the following parts:
• Forged 4340 steel, 3.400 inch stroke crankshaft
• Forged 4340 steel, 5.4 inch long H-beam connecting rods
• Forged aluminum pistons with D-shaped dish, 10.4:1 compression ratio with 61cc
combustion chambers
• Piston ring set with moly-faced top rings
• Main and rod bearings
• High-volume oil pump
The Summit Engine Shop kit is designed for externally balanced engines with 28.2 ounce imbalance and a two-piece rear main seal—essentially 302s from 1968 through 1982. In its infinite wisdom, though, Ford made it easy to change rear main seals and imbalances on small blocks. By swapping the later 50 ounce imbalance flexplate and harmonic damper for the early pieces and using the old style rear seal, you can use the Summit Engine Shop assembly in 1983 and later 5.0s. That’s exactly what we did with our ’95.
Since we wanted to build a 347 all along, we planned our bolt-ons accordingly. Our Trick Flow top end components—Twisted Wedge Street aluminum cylinder heads, Track Max roller cam, Track Heat EFI intake manifold, and 1.6 ratio roller rockers—are more than capable of feeding the extra cubic inches. The exhaust system (Summit shorty headers, off-road H-pipe, and cat-back system) is equally capable of getting rid of spent exhaust gas without restricting engine breathing. Even the new Summit suspension bits (1 1/2 inch lowering springs and rear control arm kit) were chosen with an eye to putting as much of our 347’s power to the pavement as possible.
Short Block by Fox Lake
While any good shop can handle the machine and assembly work required to build a 347 short block, we entrusted ours to one of the best in the business. Fox Lake Power Products has a stellar reputation in Ford drag racing circles for its cylinder head porting and development work. Owner Ron Robart, Cory Roth, Jim Tomassetti, and Tim Stockwell perform magic on stock and aftermarket heads using modern CNC and traditional hand porting techniques. It was Fox Lake magic done on a set of 4.6L 3-Valve heads that helped Steve Matusek shatter both ends of the Pro 5.0 record with a 6.54/215 mph pass at the 2007 NMRA World Finals.
Fox Lake is also in the engine building business, offering assembled pushrod and modular Ford short blocks as well as complete engines from stock rebuilds to stroked ‘n supercharged race bruisers. Cory Roth was assigned to our 347; he did the whole shebang for us, from boring and align-honing the block to gapping piston rings and final assembly. We didn’t get any special treatment, either—Fox Lake usually assigns an engine job to a single builder who handles it from start to finish.
Back to Big Shot
Once Fox Lake was done with the short block, we trucked it over to Big Shot Dyno and Performance for final assembly. While Big Shot makes its daily bread dynoing and tuning cars, it can also handle engine and parts installation too. Owner Keith Wenzel transferred all of the Summit and Trick Flow goodies to the new short block, installed the motor in the car, and whomped the heck out of it on Big Shot’s Dynojet chassis dyno.
Dyno Results
And what did we have after all of this building and whomping? A very respectable 311 peak rear-wheel horsepower at 5,400 rpm and 346 foot-pounds of rear-wheel torque at 4,100 rpm, that’s what. Using a 17 percent drivetrain loss factor (an accepted percentage for a manual transmission), that calculates to almost 364 horsepower and darn near 405 foot-pounds of torque (404.87). Just as important on a street car like our GT is the torque curve; it never dropped below 300 foot-pounds from about 2,600 rpm to 5,500 rpm. That is some pretty serious twist available right in the meat of a street engine’s rpm band.
What's Next
The Mustang is pretty much a done deal at this point. We’ll be using it as a display vehicle at various shows at Summit Racing (like Super Summit XVI, hint-hint); the GT might even go along with the Summit Racing display rig to some NHRA national events. So, it’s more of a What We Want rather than a What’s Next. For example, the Mustang is saddled with the factory 3.23 rear axle gear. While the car moves along nicely once you get into the powerband, a 3.73 cog will really make it run like jack the bear.
So, are we happy with 5.0 Revival? What’s not to be happy with—the Mustang goes fast, stops straight, and looks and sounds awesome. What’s more, we gave some love to a car that seems to have gotten lost in the Mustang shuffle. Maybe best of all, the GT is a real-world buildup, something most anyone with average mechanical skill can duplicate on a reasonable budget. And that makes us feel warm all over.
