Borla CrateMuffler S-Type 2.5-Inch Offset Inlet to 2.5-Inch Center Outlet T-304 Stainless Steel Oval Muffler for Big Block Chevrolet (400851)
Unlock ultimate exhaust flow and aggressive acoustic tuning with the Borla CrateMuffler S-Type Performance Muffler. Masterfully engineered to meet the specific engine mapped acoustic requirements of Chevrolet big block configurations, this is the world's first muffler purpose built to optimize the sound and power of crate and custom built motors. This highly efficient specialty unit features a 2.5-inch offset inlet and 2.5-inch center outlet configuration optimized for stock output Chevy platforms. At its mechanical core, this premium performance muffler breaks away from restrictive traditional baffle layouts by incorporating Borla's cutting edge straight through internal geometry tailored for specific engine displacement resonance frequencies. This innovative layout features a high velocity perforation core that optimizes gas flow and exhaust velocity, generating an excellent scavenger effect. This advanced aerodynamic design maximizes peak horsepower, expands torque delivery, and completely eliminates backpressure bottlenecks for optimized performance configurations.
The structural engineering of the Borla 400851 addresses long term durability and installation problems beneath harsh track and street conditions through a 100% welded, heavy gauge setup. Enclosed in a compact 4.35-inch by 9.10-inch oval by 14-inch long barrel case with a total 19-inch overall footprint, this robust assembly delivers excellent space optimization when tucked into tight muscle car floors, classic truck frames, or street rod undercarriages. The specialized straight through body layout features an engine specific directional design, which utilizes a built in structural mounting bracket welded directly to the outlet end cap face for fast identification and rock solid exhaust hanging. This internal matrix is precision tuned to dramatically reduce or completely eliminate annoying cabin drone on the specified engine families while delivering Borla's iconic, aggressive S-Type sound level under full throttle. Built completely from CNC machined, aircraft quality, premium grade T-304 austenitic stainless steel, this heavy duty canister provides absolute maximum resistance against corrosion and thermal fatigue. Delivering bulletproof structural stability backed by Borla's legendary Million Mile warranty, this unit can also be combined with an optional add on resonator (part number 400938) if your build requires shifting to a more mellow Touring sound profile.
Straight Through Flow Dynamics & Engine Specific Tuning: Unlike basic factory replacements, universal multi chambered mufflers, or generic parts that choke velocity and create harsh drone frequencies, this CrateMuffler is acoustic mapped to the firing orders and pressure pulses of Chevy stock output big blocks. The offset to center routing geometry allows builders to slide right into original muscle car channels while using precise internal perforation matrices to break down high energy sound waves without placing a physical restriction in the path of the thermal gas exit.
Fabrication Installation Guideline Note: This high performance universal CrateMuffler is a highly specialized directional component that must be oriented correctly to function as engineered. The outlet side is clearly identified by a heavy duty factory mounting bracket welded directly onto the end cap casing. This model is built with smooth, unnotched attachment collars engineered explicitly for a permanent, clean weld on installation by a professional fabricator.
Features
- Engine Specific CrateMuffler Technology: Purpose built and acoustically mapped to deliver optimal flow dynamics and sound properties for custom V8 applications
- Acoustically Tuned for Chevy Big Blocks: Precision engineered for Chevrolet Big Block 396, 402, and 427 CID stock output engines
- Aggressive S-Type Sound Level: Engineered specifically to produce a deep, throaty exhaust note under acceleration while targeting and eliminating annoying cabin drone
- High Flow 2.5-Inch Core Velocity: Straight through internal geometry layout eliminates backpressure bottlenecks to maximize peak horsepower and torque delivery
- Directional Flow Identification: Features a heavy duty exhaust hanger mounting bracket welded directly to the outlet end cap for foolproof orientation
- Modular Acoustic Capability: Can be combined with an optional Borla resonator (Part # 400938) to adapt the sound profile into a more mellow Touring volume level
- Heavy Duty 100% Welded Body: Fully welded seams deliver maximum structural strength to resist extreme backfire pressures and track vibrations
- Constructed completely from premium grade T-304 austenitic stainless steel for permanent structural integrity and ultimate rust resistance over low grade 400 series hardware options
- Proudly Manufactured in the USA: Built in America using high precision CNC manufacturing processes to guarantee flawless fitment and elite race proven quality
Detailed Fitment Breakdown
Universal Application Parameters & Structural Boundaries:
This premium CrateMuffler performance S-Type muffler is explicitly optimized for custom hot rods, muscle cars, classic trucks, and restomod builds running the following powertrain parameters:
Target Engine Application Fitment:
- Chevrolet Big Block 396 CID Stock Output V8 Engines
- Chevrolet Big Block 402 CID Stock Output V8 Engines
- Chevrolet Big Block 427 CID Stock Output V8 Engines
- Ideally suited for crate engines and custom built motors within these specified family boundaries
Sizing, Connection & Dimensional Details:
Fits your project layout across these exact structural specifications:
- Inlet Connection Size: 2.50-Inch internal diameter offset port neck
- Outlet Connection Size: 2.50-Inch internal diameter center port neck (with integrated mounting bracket)
- Muffler Case Configuration: 4.35-Inch x 9.10-Inch muscle car oval structural shape
- Muffler Case Body Length: 14.00 Inches of primary engine tuned sound suppression coverage
- Overall Muffler Total Length: 19.00 Inches from inlet tip to outlet tip boundary
- Internal Architecture Matrix: Directional straight through high flow performance configuration mapped for Chevrolet harmonic frequencies
- Material Grade Composition: Authentic T-304 Austenitic Stainless Steel with a natural mill finish
Important Application Notes:
* Premium Materials: Built entirely with authentic T-304 stainless steel to deliver superior rust resistance and durability over lower grade T-400 series or aluminized hardware choices.
* Directional Requirements: This is a directional flow component. Do not reverse mount this muffler; the end cap with the pre welded mounting bracket must always face the rear exit of the vehicle.
CA Residents: WARNING: Cancer and Reproductive Harm www.P65Warnings.ca.gov
