Ford Racing's Boss 5.0 Engine Block

Performance 2V Build No. 2
MMR's TWO-Valve Street Thrasher Modular Mustang Racing is about two hours away from our offices, so we spent several hours poking around its shop for some more build ideas. Engine builder Alex Clochiatti outlined a cool build for us, which is a variant of the Street Mod 600 long-block the company sells as a crate engine on its website. This build starts with a new 4.6 block, a cast crank with forged rods and pistons, new PI heads, degreed PI cams, and ARP fasteners. This combination sells for $4,499.

Clochiatti's Street Thrasher recommendation swaps out the PI heads in the Street Mod long-block for a set of Trick Flow's new 2V cylinder heads. We ran a press release when TFS first released these things last year, but this was the first time we got to compare them with Ford's PI heads side by side. Note the different shape of the Trick Flow combustion chamber (left).
Clochiatti's Street Thrasher recommendation swaps out the PI heads in the Street Mod long-
When redesigning the heads, Trick Flow relocated the intake valves, arranging them in a way reminiscent of the original SOHC Cammer engine of the '60s The intake valve is the bottom one in the picture. The exhaust valve is in the stock location and angle.
When redesigning the heads, Trick Flow relocated the intake valves, arranging them in a wa
The new intake valve angle of the Trick Flow heads eliminates the piston-to-valve interference problems, now allowing guys to run cams with valve lift to 0.600 inch. It also improves airflow from the intake manifold to the valve. You can buy these heads from Summit Racing for $997.95 each, and Clochiatti and Modular Head Shop's McKinney both say that out of the box, the Trick Flow heads outflow any safely ported factory 2V heads. If there is a downside to all this extra airflow, it's that most naturally aspirated street engines may not be able to take advantage of it. The Trick Flow heads may be better suited to forced induction or stroker builds.
The new intake valve angle of the Trick Flow heads eliminates the piston-to-valve interfer

The other key element to the Street Thrasher combo is a stroker package. Dropping in a 3.75-inch stroke crank will get you the magical 5.0 liters, and MMR's stroker package includes a forged crank, forged H-beam rods, and forged pistons in the compression you choose. The assembly also includes bearings and has been balanced prior to shipping. Clochiatti said this bottom end will support up to 850 hp. In this photo are some of the piston and rod combinations for stock and long-stroke builds. So far everything we've mentioned for the 4.6 will also work for a 5.4 engine except the stroker package. Clochiatti said MMR does not recommend building a 5.4 stroker engine because the geometry creates too great a side load on the cylinders. If you want to add displacement to a 5.4 block, you're going to have to sleeve it.
The other key element to the Street Thrasher combo is a stroker package. Dropping in a 3.7
For the ultimate naturally aspirated 2V Street Thrasher, build the stroker motor using Ford Racing's Boss 5.0 block. Part number M-6010-BOSS50 is a cast-iron Windsor block with a 3.75-inch bore. With the stock 4.6 crank, it makes a 5L engine. Add the stroker package, though, and you've got an LS-killing 5.3 mod motor. You'll be getting up there in price, however, and our rough calculations put this combination at just north of $7,500. For that money, you could have had 32 valves instead of 16.
For the ultimate naturally aspirated 2V Street Thrasher, build the stroker motor using For