5.0 Mustang & Super FordsHow To Engine
Half-Price Hardware: How To Build A Budget 347 Stroker Motor
How to build a fun-time 347 for about half the price of an all-out race engine
Horse Sense: The newest part on thisbudget engine is the Funnel Web intake manifold from the Parker Company.Probe/Coast hasn't run this intake, nor have we, so it'll be fun to seehow it does on the dyno next month.
Some magazines make a living screaming headlines about JunkyardWarriors--we're not one of them. Like everyone else who's been oncearound the high-performance block, we realize there is no such thing aspocket-change racing or even sterling street performance. Speed costsmoney, and that's that.
The trick to real-world budget performance is learning what you can livewithout while getting your speed fix. For example, the goal here is tobuild 500 hp from a small-block Ford and not go totally broke in theprocess. By not going broke, we have to swallow once, take a deepbreath, and admit it still takes $7,733.06 to build a turnkey 500hpengine, and for that we aren't going to get everything. We'll have togive up the last word in durability--no bulletproof aftermarketblocks--and there is little budget for extensive hand-porting orexpensive systems. Such an engine will have to be built fromoff-the-shelf pieces, and nothing exotic at that. And while six or sevengrand is still a pile of money, it's a long way from the $13,000 to$14,000 it takes to assemble a full-on forged and Dart-blocked raceengine these days.
Probe and CHP
Don't worry if you're a bit confused by the relationship between ProbeIndustries and Coast High Performance. The two companies are closelyaligned and share much of the same physical plant, but Probe is themanufacturing company and Coast is the sales side of the organization.So, if you want to purchase an engine, call Coast High Performance andbuy one of theirs, and understand it will have Probe pistons inside it.Got it?
For our purposes we'll run the engine carbureted on the dyno to see howclose we came to our power goal. Carburetion is less expensive than fuelinjection, unless, of course, you already have a tunable fuel-injectionsystem you can modify to work at high rpm. That means a possible slightloss of driveability, definitely less fuel economy, and no hope on theemissions front.
All these parameters lead us to what the typical bracket racer wouldrecognize as a good budget build. The first step to power isdisplacement--there is no replacement for displacement--and the bestbang for the cubic-inch buck is, of course, a 347.
The next step is to pack as much air as practical into the cylinders,meaning a high-flow cylinder head and a really big cam, then squeezingit hard via elevated cylinder pressure to get some work out of it. Todate, a turbocharger is the most efficient way to squeeze air, butthat--and all other forms of supercharging--is off (budget) limits.Instead, we'll do it the old-fashioned way, with a generous dollop ofcompression.
What we've spec'd out is a 347 stroker packing a big, mechanicalcamshaft, decent heads, and a free-flowing intake manifold andcarburetor combination. That's just the sort of thing Probe is used toputting together for its bracket customers, and we followed along asthey demonstrated how they would put together a budget 347. This monthwe're showing the parts and highlights of how they went together; nextmonth we'll strap the engine to one of Westech's dynos to see how thepower comes out.
A final word on trading dollars for performance: This engine shouldparty hearty, but it will feature a choppy idle, thirst for premiumgasoline at the least, won't last 100,000 miles--and don't even thinkabout emissions. But it will scoot, and for a Saturday-night shaker,bracket or other fun machine, it should provide a grin made all thelarger because all that speed didn't cost so much.