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MRM Chassis #002: Completed Spring 2009
MRM-Built Fuel Injected Ford 306
240 RWHP, 276 Ft.Lbs. Torque
Specifications:
Chassis: 1990 Mazda Miata, 87,000 original underpowered miles, 600 miles since the conversion.
Engine Lower: 1991 Mustang HO X-block, bored .030 over resulting in 306 cubic inches of displacement. Blueprinted and balanced by Thomas McCully. Stock 1992 Mustang cam shaft.
Cylinder Heads: GT-40 iron
heads pulled from a 1996 Mercury Mountaineer. Blueprinted, worked and shaved by Thomas McCully. Valve springs upgraded to dual-spring Comp Cams springs. Stock 1.6 steel rockers.
Upper/lower intake: GT-40 style pulled from a 1995 Ford Explorer. Drilled and tapped to accept a Mustang ACT sensor in intake runner #5 and a Mazda Miata fan switch in it's thermostat housing. Upper and lower shaved to remove 3/8 inch of total height.
Throttle/EGR spacer: Throttle is a 65mm Ford Explorer unit with a modified throttle lever adapter. EGR spacer is an original Mustang 60mm unit, bored out to 65mm to match the throttle.
Fuel Delivery: Stock Miata fuel pump feeding a set of BBK aluminum fuel rails that have been modified to accept AN-type fittings. Custom AM-6 stainless braided crossover and connections to Miata hard lines. Complete 1991 Mustang evaporative system. Upgraded "Design III" Bosch 19lb injectors. Mustang OEM fuel pressure regulator mounted to a custom block.
Emission Controls: Full 1991 Mustang 5.0 EGR system, Mustang Evaporative system, Dual Magnaflow hi-flow cats, custom 72mm Mass air sensor tube using 1996 Explorer meter and a 1996 Thunderbird Air Tube.
Cooling: Stock Mustang water pump, custom Sultana racing aluminum radiator, dual "pusher" fans triggered via the or
iginal Miata fan thermo switch.
Suspension: The original Miata spring/strut/tophat units were removed and replaced with a custom-tuned adjustable coil-over set-up from Fat Cat Motorsports. The new setup utilizes new Bilstien HD struts that have been custom valved to be able to control a set of 2.5-inch diameter race springs (500lbs-front, 325lbs-rear). The bumpstops and tophats were replaced with units that incorporate the use of micro-cellular polyurethane as opposed to the original factory rubber. The new tophats also incorporate newer, Miata "NB" (1999-2005) suspension geometry to allow for greater strut travel. A Racing Beat 7/8 inch swaybar was added to the front, the rear swaybar was deleted.
Braking: The original 1990-'93 sized Miata brakes were replaced with the larger 1994-1998 type. This included replacing all 4 rotors with larger diameter ones as well as replacing the front calipers with larger units. The pads are Axxis ultimates.
Transmission: Borg-Warner World Class T-5, custom "red" speedometer gear
Driveshaft: Custom 30.5 inch steel driveshaft
Roll Bar: SCCA-rated 4-point roll bar from Hard Dog Fabrication
Interior/Top: 2005 Black Leather Miata seats, "NB" (1999-2005) Miata Sunfast clothtop with glass window from Robbin's Tops
Wheels/Tires: Original 14X5.5 inch "daisy" wheels removed and replaced with 15X8 inch "6UL" wheels from 949 Ra
cing. Tires are 225/50-15 Hankook Ventus RS-2's
Differential/Axles/Hubs: Ford 7.5 inch IRS differential from a 1995 Ford Thunderbird. 3.27 Gears with factory limited-slip. Half shafts are Ford Thunderbird units with custom axles from Monster Miata. Hubs are stock Miata units rebroached to accept the Ford 28-spline pattern. Differential is held in place with a custom torque plate welded to the front of the rear subframe and urithane bushings
Body Additions/Chassis Strengthening: Carbon Fiber front air dam (lip spoiler) from Rat's Back Fabrication, Mazda factory mud guards, "Home Depot" rear air dam, fully reundercoated, custom stainless steel frame rail stiffeners, custom transmission crossmember from Monster Miata, underside of hood modified and repainted
Exhaust/Headers: Full custom true-dual system built by Kevin of Meineke of Doylestown, PA. The sytem utilizes 2.25 diameter tubing from front to back and incorporates two Magnaflow cats, dual Borla Pro XP mufflers and dual custom resonators and ends with two custom stainless steel tips. The headers are custom thermal-coated units from Monster Miata.
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The Results:
Table of Contents:
Page 1: Specifications, Dyno Data, Planned Upgrades
Page 2: Differential Preparation, Rear Bushings, Engine Detailing, Custom 65mm Intake Parts
Page 3: Modifying a 1991 Ford Mustang Harness to work in a 1990-93 Mazda Miata Conversion
Page 4: Engine Removal, Front and Rear Subframe Removal, Front and Rear Subframe Modification, Engine Bay Modification
Page 5: Wiring Harness Installation and Finishing, Fuel/Brake line modification and Heat Shielding
Page 6: Creating a Custom AC system using the existing components, Modification of the Factory Air Ducting to work with the Monster Miata Kit, Front Subframe reinstallation
Page 7: Installing an engine from above, Using Mazda oil and water senders in a Ford block, mounting a Mazda PS pump on a Ford 5.0, relocating the coolant overflow bottle
Page 8: Design 3 injectors, BBK aluminum fuel rails, braided stainless fuel lines
Page 9: Ford ECU connections
Page 10: Spark plug differences, intake tube modification, throttle cable modification, sway bar bushing modification
Page 11: Brake Upgrades, Rear Half Shafts, Hood Goes On, Initial Start-up
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Build number 3 will be a white 1990 found in New Jersey. Presently I'm building it as my daily driver and demo vehicle but if anyone comes to me with the right amount of cash in the end I can always build another...
Here's the car before the build:
