SR360 Stand-Alone ECU: A Calibrated Upgrade for Mercury Racing 4.6L V8 Outboard Engines
The SR360 stand-alone Engine Control Unit (ECU) is a performance-calibrated replacement controller for select Mercury Racing 4.6L V8 outboards.
 
Developed by Speedmaster Marine and distributed through Buckshot Racing #77, SR360 is built for owners who want a wider, harder-pulling powerband, faster throttle response, and a higher operating ceiling, while keeping OEM-style sensor integration and protective engine logic on supported applications.
 
SR360 installs in the factory ECU/PCM location and interfaces with the existing sensor network and monitoring routines. The performance gain comes from control under load: SR360 refines fuel strategy, ignition mapping, and Mercury drive-by-wire throttle mapping so the engine delivers consistent torque and clean pull across the range, not just at a momentary peak.
 
Compatibility (Factory PCM Families)
 
SR360 is a direct replacement for designated Mercury Racing 4.6L V8 controller families including 8M0207597 (PCM 250R Mech CMS), 8M0207608 (PCM 300R V8 Mech CMS), 8M0207602 (PCM 300R DTS CMS), plus select APX 250 / APX 360 controller configurations that are not publicly retailed. Every SR360 is configured to the engine by serial number to match the correct rigging, throttle system, and controller family.
 
PCM / ECU Calibration (Flash) Upgraded
 
SR360 recalibrates combustion and torque delivery for real marine duty cycles. Fueling is revised for stability through sustained load and throttle transitions, ignition is optimized to strengthen midrange torque while staying controlled as RPM climbs, and drive-by-wire mapping is sharpened to reduce “soft” zones.
 
Motor Model Coverage
 
250R (8M0207597 - PCM 250R Mech CMS): SR360 is designed to pull harder through the midrange and carry load into the upper RPM range with a 7000 RPM limiter. Target: 320 HP @ 6500 RPM; 342 lb-ft @ 4450 RPM. Optional 80 mm throttle-body upgrade on qualifying builds supports up to 355 HP.
 
300R (8M0207608 - PCM 300R V8 Mech CMS / 8M0207602 - PCM 300R DTS CMS): SR360 broadens the usable powerband and improves response and midrange delivery for heavy hulls and acceleration-focused setups. Target: 360 HP @ 6500 RPM; 342 lb-ft @ 4450 RPM; 7000 RPM limiter.
 
250 APX (OEM PCM available to UIM/APBA/IHRA racers only): SR360 targets repeatable torque under sustained race load while maintaining APX rigging compatibility. Target: 320 HP @ 6500 RPM; 342 lb-ft @ 4450 RPM; 7000 RPM limiter. Optional 80 mm throttle-body upgrade on qualifying builds supports up to 355 HP.
 
360 APX (OEM PCM available to UIM/APBA/IHRA racers only): SR360 emphasizes consistent pull and drivability for tunnel-boat/race duty cycles with repeated throttle events. Target: 360 HP @ 6500 RPM; 342 lb-ft @ 4450 RPM; 7000 RPM limiter. 370+ HP option available on qualifying applications.
 
Fuel Requirement
 
Premium fuel is mandatory. SR360 requires 93-octane to maintain detonation margin and stability under sustained marine load.
 
Marine-Ready Electronics and Kit Contents
 
SR360 electronics are IP67-rated for water/dust-resistance. The kit includes (1) SR360 ECU, (2) SR360 jumper harness, (3) DCMD and igniter modules, (4) USB data cable for ECU access/diagnostics, (5) full instructions. 
 
Installation, Use, and Support
 
The SR360 swap requires correct access, routing, and reassembly for a required professional installation. SR360 is intended for closed-course, sanctioned competition/performance use; installing a non-OEM ECU can void the manufacturer's warranty and may be noncompliant with local regulations.
 
Ordering and Technical Support
 
Each SR360 is configured by engine serial number. Typically delivered in 2-weeks from order date. Contact Mike Hill: +1-714-697-1716 | mike@buckshotracing77.com