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RR Merlin Power Enhancements

The 1962-65 Miss Bardahl set the standard for Unlimited Hydroplane racing for years to come. This is especially true in regards to horsepower increases from the teams' Rolls-Royce Merlin Engines. The Miss Bardahl team was the first (along with the Miss Exide) to introduce Nitrous-Oxide Injection into motor sports racing. NOx is now common in almost all forms of motor racing as a known power improvement.

The Miss Bardahl team also introduced Water-Alcohol Injection (although the Miss Thriftway team had previously used primitive water injection), used to suppress detonation at high power settings. The combination of these two systems (along with many structural modifications) allowed for well over 3,000 HP and set the trend for years to come in boat racing. Truly, one of the team's secret weapons was technical innovation.

The basis for these systems came from the University of Washington's Engineering Library. Crew member Dixon Smith was a UW Physics major at that time. His research led him to NACA (National Advisory Committee for Aeronautics - predecessor to NASA) reports written during WWII regarding performance increases for airplane engines.

The research paper, "The Engine that Saved the Free World: A History of the Rolls-Royce Merlin" discusses these developments in detail (starting on pg 55), including the testing completed on an instrumented engine.

Below are the reports which, along with the ingenuity and perseverance of Mr. Smith and the Bardahl team, allowed them to achieve the next level in performance.  All reports are from the NACA/NASA Technical Report Server:  http://naca.larc.nasa.gov/

Water-Alcohol Injection for Detonation Suppression/Anti-Detonation Injection (ADI):

Rpt. #812 - Knock Limited Performance of Several Internal Coolants (pdf)

Rpt. E5H12 - Water Alcohol Injection and Spark Advance (pdf)

Nitrous Oxide Injection:

Rpt. E5F26 - Nitrous Oxide Supercharging of an Aircraft Engine Cylinder (pdf)

Miss Bardahl's Laughing Gas by Dixon Smith (.pdf)

Turbo-Compounding of an Aircraft Engine:

#1602 Calculations of a 12-Cylinder Liquid Cooled Engine with Exhaust-Gas Turbine Geared to Crankshaft (pdf)

Above is a technical report detailing Turbo-compounding of an aircraft engine. Briefly, turbo-compounding refers to attaching a turbine wheel directly to the crankshaft of an engine and blowing the exhaust gas past it; thus recovering the exhaust energy directly back into the crankshaft. This differs from a turbo-charger, where the exhaust energy is used to pressurize the intake via a turbine-compressor assembly.

Turbo-compounding was developed in the latter stages of WWII, and represents the transition from reciprocating engines to turbine engines. In utilizing turbo-supercharging and early turbine technology, every last bit of power was being "squeezed" out of these later-era piston engines. Turbo-compounding was successfully used on several large radial engines, including the R-4350 and R-2800, in the late 1940's and early 1950's.

As far as a racing application, Dixon Smith and Dwight Thorn at one point were in the early stages of developing a system for a Merlin. Dixon completed the preliminary engineering calculations and specified a GE Type "B" turbo-supercharger turbine wheel to be used as the power recovery turbine. After the turbo-supercharger was purchased, momentum (and funding) for the project diminished. The turbo-supercharger is still in the possession of Dixon and Dwight; however the detailed engineering needed to adapt the turbo-compound concept to the Merlin has yet to be completed.

Below is a picture of the NACA development engine; a turbo-compounded Allison V-1710. (www.enginehistory.org)

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