1987 MAZDA RX7


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Last Updated: 10/08/2000



20B FC3S PROJECT
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THE 20B FC3S PROJECT CAR

I'm Chito Solomon, from Northridge, a suburb of Los Angeles, California. This is a project I started five years ago – a 20B conversion of a 1987 second generation Rx7 (FC3S).I began this project when a close friend, Bebot Rodriguez, introduced me to rotary engines. Have you heard of a three rotor 20B engine? This is the only one built of its kind.

The original car was the usual left-hand drive. It was converted to right-hand drive (to look and drive like the model built in Japan) by using parts imported from Japan. The 20B was fitted with a Ford T5 transmission and Tilton’s twin-plate racing clutch (capable of 750ft/lbs torque). The 20B flywheel was replaced with the original Turbo II flywheel but using a 20B counterweight. The original Turbo II bell-housing and the original starter were used. The original engine cross-member was modified to accommodate the original 20B engine mounts. The drive shafts were modified to accommodate the Ford T5 transmission and the original Mazda rear-end.

Because the 20B is seven inches longer than the 13B Turbo II engine, the radiator was moved forward and replaced by a larger aluminum type with a cooling fan. The huge Spearco intercooler was also fitted in front. With these space-consuming modifications, the air-conditioning had to be removed and the front sway bar modified.

Due to the extremely complex layout of the sequential twin turbo and with no original EFI computer to run it, it was replaced by a single Garret T64 turbo. The original 20B in the Eunos Cosmo generated a stock 280HP to a maximum of 350-400HP with minor adjustments. Running a stock engine with a single T64 turbo produced 457HP on the wheels with 434 ft/lbs torque (see Jackson Racing Dynamometer Test Results). 550cc injectors were used on the primaries and 1100cc injectors on the secondaries. With these injectors, the 20B should have enough fuel for about 10-12 lbs boost with a little left over in injector capacity so it won't lean out. The exhaust is custom-made from stainless steel with a 3 ˝ " down-pipe to a 3 ˝" Borla stainless steel resonator branching into two 3" stainless steel pipes and two 3" Tri-Flow mufflers. It sounds great.

The Electromotive TEC1 engine management system was used with two sets of three coils, three spark plugs going into one set of coil (the other side is grounded). Two crank angle sensors were used 180 degrees apart, (leading and trailing). The TEC unit manages both ignition and fuel.

Additional modifications were the strut braces, coil covers all around with Tokico Illuminas, and front camber plates. Tri-Point racing body flares and spoilers were installed. Three-piece PanaSport wheels (16 x 10) with 265/45vr16 Kumhos were used.

ACKNOWLEDGEMENT

I would like to thank my good friends who helped me a lot with this project: Bebot Rodriguez, Alan Santos, Chito Cuison, Tony Santiago, Jun Arriola, Louie Depante and specially Fred Miranda, who actually wired, programmed the TEC unit, and made the car roadworthy.

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