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.
For those who have been following our latest in-house project vehicle, the Silver Stealth Stang, we are well under way in taking an innocent '99 Mustang GT and turning it into a budget-minded street/strip stormer. Ken Miele, author of our Yo, Ken! column, picked up the high-mileage Stang for the reasonable sum of $5,800. It serves as a daily driver and the odometer shows over 160,000-miles and counting. As of today, though, we are well on our journey to reviving the Stang's health and performance.
After adding a better suspension system, we turned our focus to power and performance at the drag strip. Radical Racing added the usual assortment of intake and exhaust upgrades. The baseline output was 215 rwhp and 247 rwtq, with a 100 percent stock car. The intake and exhaust modifications upped output to 234 rwhp and 272 rwtq. That helped push the Stang to a best of 13.97 at 97.50 mph, with a set of 3.73 gears out back. We came back last issue and added 4.10 gears and an aluminum driveshaft, which effectively knocked Silver Stealth Stang down to a best of 13.62 at 99 mph. A looser torque converter was added, too, but unfortunately the winter months in New Jersey have prevented us from getting strip results. Long story short, we think the Stang can run 13.30s-if the Nitto 555s can hook up. The looser torque converter made a big difference in seat-of-the-pants feel, so we may have to get stickier tires for our next outing.
Our initial plan for this month's installment was to add a set of ported Two-Valve cylinder heads and some bumpy camshafts. Unfortunately, things didn't go as we hoped. It wasn't that we couldn't do the swap, it is just that Craig Radovich of Radical Racing (the shop handling the build) talked us out of the idea. Radovich warned us about continually chasing horsepower on such a high-mileage engine. Our 4.6L bullet was running fine in its current trim, but Radovich felt that at 160,000 miles the short-block was getting really tired. He said the car would pick up power at the wheels, but it wouldn't be optimal-eventually we would need to add a new short-block.
Turning higher rpm and increasing airflow certainly isn't the wisest thing with a overly tired engine. Essentially, we'd be wasting time and money adding a new induction system-the ring seal and bearings could be mostly worn out and if we have to replace the short-block later we'd have to do most of the work twice. We didn't do a leak down test, but odds are the cylinder seal isn't optimal. If adding heads and cams was out of the question, then turning to forced induction couldn't even be considered.
Our hopes and dreams of cracking into the 12s with the factory short-block vanished as we listened to reason. After all, who wants to spend money on parts and not get the full potential from the mods? That left us scrambling for a back-up plan. The quest for more power sent us west-and it wasn't to search for gold. Our mission was to link up with Modular Mustang Racing (MMR), a mail-order engine shop that focuses solely on modular engines (as per the company name). We boarded a flight and headed to Ventura, California, to discuss a street/strip Two-Valve combination for SSS. Since the car is a daily driver, MMR's Mark Lutton suggested one of the company's 300ci crate engines. "Our crate engine's ingredients make for a high revving, cam loping monster that most Two-Valve Mustang owners want," Lutton explains. "Power is increased dramatically throughout the powerband and the rev limit is raised to 6,700, in most applications. The Two-Valve crate engine we are building for the Silver Stealth Stang will put a stock supercharged '03-'04 Cobra to shame in a drag competition."
The engine is built using brand new parts and comes in many variations to suit mild street engines to twin-turbocharged strip stormers making well in excess of 1,200 hp. Our main goal has always been natural aspiration, primarily to keep the cost reasonable as well as simple.
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.
Lutton continued to inform us of the virtues of the MMR 850 engine. "These short-blocks love nitrous and the bottom end was built for the abuse. These engines on pump gas will make between 360 and 380 at the rear wheels and over 400 rwhp on a little bit of 100 octane." That is more than enough for Miele's street machine, and we estimate times on the drag strip to be in the low 12/high 11-second zone in drag trim (slicks and skinnies).
The engine is currently making its way across this great nation and to Radical Racing. Once there, we plan on getting the old engine out and the new one installed as quickly as possible. That way Miele can log some street miles and we can workout the kinks on Radical Racing's chassis dyno.