Bosal Headers vs Stock Manifolds Dyno Data - Torque & HP Comparison Chart
Bosal Headers article (p.4 of 6) torque-comparison graph and HP/TQ table: stock manifolds vs Brospeed/Bosal headers across 2000-7000 RPM; Bosal headers add a few HP/lb-ft (e.g. 125 vs 119 hp at 65 mph).
This is page 4 of a 6-page printout (dated 10/27/2001, from http://www.mtco.com/~westcj/Brian/bosal.htm) comparing exhaust header performance on a dynamometer. It is titled 'Bosal Headers' with a section heading 'Stock vs. Brospeed vs. Hotshot Tq Dyno Data.' A line chart plots corrected torque (lb-ft) against engine RPM (2000-7000) for three configurations: 'Dev '94, Hotshot I,' 'Brian '95, Stock Manifold,' and 'Brian '95, Brospeeds.' Torque peaks around 120-127 lb-ft near 5000 RPM and falls off toward 7000 RPM. Below the chart is a table listing vehicle speed (30-85 MPH), engine RPM (2466-6986), and horsepower and torque figures for stock manifolds versus Bosal headers at each point. The Bosal headers show consistent gains, e.g., at 60 MPH/4932 RPM stock produces 116 HP/124 lb-ft vs. 120 HP/128 lb-ft with the headers, and at 85 MPH/6986 RPM stock produces 99 HP/75 lb-ft vs. 109 HP/82 lb-ft. Handwritten notes next to each RPM value mark the HP and TQ gains (1-10 HP, 2-8 lb-ft). A partially legible footer heading references 'Absolute and percent gains in HP (Brospeed headers versus stock manifolds).' A reader learns the measured HP/torque improvement from aftermarket headers across the RPM range.
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Frequently asked questions
- How much horsepower do Bosal headers gain over stock manifolds in this dyno test?
- Gains range from about 1 HP at 30 MPH (2466 RPM) up to 10 HP at 85 MPH (6986 RPM); e.g., at 65 MPH/5342 RPM stock made 119 HP vs. 125 HP with Bosal headers.
- What torque gains do the Bosal headers show in the table?
- Torque gains range from 2 to 8 lb-ft, e.g., 121 vs. 127 lb-ft at 45 MPH/3699 RPM and 90 vs. 98 lb-ft at 75 MPH/6164 RPM.
- What setups are compared in the torque comparison chart?
- Three configurations: 'Dev '94, Hotshot I,' 'Brian '95, Stock Manifold,' and 'Brian '95, Brospeeds,' plotted as corrected torque (lb-ft) vs. RPM from 2000 to 7000.
- What is the peak horsepower shown with Bosal headers in the table?
- The highest HP listed for Bosal headers is 125 HP at 65 MPH (5342 RPM); stock manifolds peaked at 119 HP at the same point.
- Where did this dyno data come from and when was it printed?
- The page footer shows the source URL http://www.mtco.com/~westcj/Brian/bosal.htm and a print date of 10/27/2001.
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