Muscle Mustangs & Fast Fords
Modular Mustang Racing 850 Stroker Engine Build Part 1
Modular Mustang Racing Adds A Long-Swing Crank To Pump Up Project Silver Stealth Stang's Engine Displacement.
We settled on the MMR 850 stroker. While it may be a little overkill for a naturally aspirated engine, we wanted to get the bigger cubes, which requires a forged steel crank. There is an MMR 600 engine option, but then we would be saddled with only 281 ci, rather than the 300 ci that the MMR 850 provides. "The biggest hurdle to overcome with the Two-Valve modulars is their lack of displacement and head flow. This is where the MMR stoker engines and MMR-ported heads come into action," comments Lutton.
The company offers standard packages as well as custom builds, with sales representatives working with the customer to get an engine suitable for the application. Our pump gas and daily driver specifications were an easy task for the MMR crew. The block is a brand new casting, purchased from Ford Racing and machined specifically for this combination. MMR can modify your existing modular block if you don't want to spring for a new one. MMR also offers Ford Racing Boss and aluminum block options for an additional cost. The rotating assembly is straight forward, as MMR adds a forged steel stroker crank from KP Crankshafts (3.750-inches), steel rods from Manley (4340 steel rods with ARP bolts), and custom Manley forged pistons (built to MMR specs).
Other fancy components in the bottom end include an MMR/Ford Racing oil pump and MMR billet rear main seal. The billet rear main seal is made from 1/2-inch billet aluminum for strength and support. It also boasts a special gasket seal to ensure no leakage. The oil pump's body is CNC-machined with an O-ring groove for better seal. It also features valve work for better pressure and larger 15/16-inch pick up size for more oil delivery. The short-block is rated for 850 rwhp, but Lutton confidently said that we could push that number a bit if we decided to add a big, nasty shot of nitrous. Boost is also an option, but it would be tricky considering this engine was built as a naturally aspirated mill. The compression ratio in our engine is pegged at 11.2:1, so we couldn't run too much boost as it would require serious levels of meth injection and/or straight race fuel. The compression ratio is just right for 91-93-octane when rolling in naturally aspirated trim. Sealing the bottom end up is the job of a MMR oil pan, which holds 7 quarts of lubricating fluid.
Moving to the topside of the engine, the cylinder heads take center stage. The Two-Valve P.I. heads are new castings, once again from the Ford Racing catalog-not the junkyard. Intake and exhaust ports get worked over by a CNC machine and the castings flow 232 cfm and 194 cfm, respectively, at 0.500-inch lift. The MMR stainless steel valves are 1 mm larger than stock. Actuating the valves are Comp Cams XE270AH camshafts. These cams are designed to operate between 1,800 to 5,800 rpm. Comp suggests a minimum of 3.55 gears and a 2,000-rpm stall speed torque converter. Our car is equipped with a looser torque converter and 4.10 gears. The cams sport 234/238 degrees of duration at 0.050-inch lift. MMR uses Comp Beehive springs to keep control of the 0.550-lift on both the intake and exhaust lobes. MMR added a set of billet spacers on the backside of the camshafts. The MMR billet spacers are 80 percent lighter than stock, saving rotating weight but not compromising strength. The lighter weight helps the engine spin easier and quicker-leading to better performance.
We will be reusing the factory P.I. intake initially, but that might change down the road. We wanted to try a set of the new TFS Two-Valve cylinder heads, which boast some great features thanks to a clean-sheet design, meaning they are not ported OEM pieces. Unfortunately, TFS was feverishly ramping up production at press time and didn't have any production heads ready to test. Initial testing results point to very positive gains over ported stock heads. We plan on adding TFS heads and intake manifold to the MMR short-block down the road.