| Description | Date | Identifier | |
| Graph showing the power output of a 20-HP engine with different exhaust system configurations. | 1st May 1926 | Box 6 \ 7 07-page012 | |
| Graph showing the power output of a 20 HP engine with increased compression ratios. | 15th Jul 1924 | Box 6 \ 7 07-page013 | |
| Blueprint of an experimental 20 horsepower exhaust manifold. | 16th Oct 1926 | Box 6 \ 7 07-page014 | |
| Preparation of a 20 HP car for a 10,000 miles test in France and a request for exhaust system modifications. | 6th Jun 1926 | Box 6 \ 7 07-page015 | |
| Delay in starting the design for the revised 20HP exhaust system. | 22th Jun 1924 | Box 6 \ 7 07-page016 | |
| Requesting an estimate on expected power increases from an engine after specific modifications. | 1st Nov 1926 | Box 6 \ 7 07-page017 | |
| The repeated breakage of the exhaust pipe and bracket on the 20 HP model. | 23th May 1927 | Box 6 \ 7 07-page018 | |
| Proposal to improve road clearance on Phantom and 20 HP models by modifying the exhaust pipe and rear petrol tank sump. | 9th Jul 1927 | Box 6 \ 7 07-page019 | |
| Modifications to increase the power output of the 20 HP engine K5771. | 1st Sep 1927 | Box 6 \ 7 07-page020 | |
| Comparison between an experimental engine and the standard production 20 HP model, detailing increased power and effects on petrol consumption. | 21th Jul 1927 | Box 6 \ 7 07-page021 | |
| Performance graph comparing the power output and fuel consumption of a standard 20 HP engine against an experimental engine. | 21th Jul 1927 | Box 6 \ 7 07-page022 | |
| Blueprint of the exhaust and induction manifold arrangement and timing diagram for an experimental Goshawk engine. | 7th Sep 1927 | Box 6 \ 7 07-page023 | |
| Test report comparing three new exhaust manifolds against the standard for a 20 HP engine. | 17th Jan 1928 | Box 6 \ 7 07-page024 | |
| Analysis of different exhaust manifold designs regarding power loss and gas flow dynamics. | 17th Jan 1928 | Box 6 \ 7 07-page025 | |
| Recommendation to increase the internal pipe diameter on an experimental manifold. | 17th Jan 1928 | Box 6 \ 7 07-page026 | |
| Graph comparing the performance of various experimental exhaust manifolds on a 20 HP engine. | 21th Jan 1928 | Box 6 \ 7 07-page027 | |
| Design for the Super Sports 20 HP exhaust manifolds and pipe. | 21th Jan 1928 | Box 6 \ 7 07-page028 | |
| The performance testing of various exhaust manifolds for a 20 HP engine. | 1st Feb 1928 | Box 6 \ 7 07-page029 | |
| Recommendation to produce a new low power loss manifold (Sch. 934) for the 20 HP chassis. | 24th Nov 1927 | Box 6 \ 7 07-page030 | |
| Performance graph comparing various experimental exhaust manifolds on a 20 HP engine. | 24th Nov 1927 | Box 6 \ 7 07-page031 | |
| Blueprint showing three different designs for 20 HP exhaust manifolds. | 15th Dec 1923 | Box 6 \ 7 07-page032 | |
| Potential engine improvements, referencing a Phantom scheme on the 20 HP model. | 28th Feb 1928 | Box 6 \ 7 07-page033 | |
| Proposed sheetmetal bracket to support an exhaust system silencer on an X-shaped cross member. | 3rd Jul 1928 | Box 6 \ 7 07-page034 | |
| Design modifications for the India 3 cylinder block regarding the water pipe flange and exhaust jacket connection. | 13th Jul 1928 | Box 6 \ 7 07-page035 | |
| Induction pipe for the India 3 model, detailing adaptations for various carburettors. | 4th Jul 1928 | Box 6 \ 7 07-page036 | |
| Meeting request to discuss preventing firing in the silencer for a 20HP car, chassis GRJ-23. | 19th Jul 1925 | Box 6 \ 7 07-page037 | |
| Drawings for exhaust pipes for India, specifically the design of branch pipes to avoid compound bends. | 28th Jul 1928 | Box 6 \ 7 07-page038 | |
| The testing of cross web pistons and the gas-tightness of pinned rings. | 9th Sep 1928 | Box 6 \ 7 07-page039 | |
| Extract from a personal report regarding a cracked exhaust manifold and the failure of aluminium treatment on car 14-G-4. | 10th Jan 1929 | Box 6 \ 7 07-page040 | |
| Design of 'SS' and 20 HP car exhausts to improve sound quieting. | 17th Jan 1929 | Box 6 \ 7 07-page041 | |
| Technical memo about exhaust blows on the 20 HP Chassis caused by back pressure. | 24th Jan 1929 | Box 6 \ 7 07-page042 | |
| Standardisation of using Staybright steel for the exhaust snout to prevent rusting. | 12th Feb 1929 | Box 6 \ 7 07-page043 | |
| Details for fitting a new part to the 40/50 HP and 20 HP chassis, including test dates and costs. | 1st Mar 1929 | Box 6 \ 7 07-page044 | |
| Exhaust boom issue on a 20 HP car and proposing a new exhaust system. | 1st Mar 1929 | Box 6 \ 7 07-page045 | |
| 20 HP manifold and silencer system, questioning the source of increased noise. | 1st Apr 1929 | Box 6 \ 7 07-page046 | |
| Problem with the 20 HP exhaust system and the proposed solution of a front expansion box. | 9th Apr 1929 | Box 6 \ 7 07-page047 | |
| The stages of improvements for the 20HP model, using codenames like 'India', 'China', and 'Japan' to track changes to the chassis, bore, and engine mounting. | 14th May 1929 | Box 6 \ 7 07-page048 | |
| Modifications to an exhaust system and analysing frame stiffness in relation to radiator movement and engine weight. | 27th May 1929 | Box 6 \ 7 07-page049 | |
| Advantages and disadvantages of thermostatically controlled radiator shutters as an alternative to hand control. | 27th May 1929 | Box 6 \ 7 07-page050 | |
| Review and critique of a 20 HP Cabriolet De Ville with a Blue Hooper Body, comparing it unfavourably to American cars. | 29th May 1929 | Box 6 \ 7 07-page051 | |
| Recommendation to increase clearance in the stud holes for the 20 HP exhaust manifold following breakage due to restricted movement. | 17th Jun 1929 | Box 6 \ 7 07-page052 | |
| Mr. Royce's decision to use new Crown Steel for exhaust valves and a high-conductivity alloy for valve guides. | 30th Jul 1930 | Box 6 \ 7 07-page053 | |
| New exhaust fittings for the 20HP chassis, detailing a revised nozzle to eliminate whistling. | 26th Sep 1929 | Box 6 \ 7 07-page054 | |
| Outlining an experimental plan for engine 'hot spots' and a development program for a 20 HP engine. | 16th Oct 1929 | Box 6 \ 7 07-page055 | |
| List of action points for engine component testing and modifications, specifically for inlet manifolds and cylinder blocks. | 8th Nov 1929 | Box 6 \ 7 07-page056 | |
| Checked print for an exhaust pipe for a 30HP chassis. | 8th Nov 1929 | Box 6 \ 7 07-page057 | |
| Sending an inlet and exhaust manifold and a cylinder head for the improved 'China' project. | 29th Nov 1949 | Box 6 \ 7 07-page058 | |
| Progress on engine and axle development projects codenamed 'China' and 'Japan'. | 11th Nov 1929 | Box 6 \ 7 07-page059 | |
| Alternative schemes for the front expansion box of the China exhaust system. | 15th Nov 1929 | Box 6 \ 7 07-page060 | |
| Dispatch of drawing LeC. 2762 for an exhaust pipe related to modifications for China. | 18th Nov 1929 | Box 6 \ 7 07-page061 | |
| Standardisation of chassis parts, specifically Firth's Crown Steel car engine exhaust valves. | 23th Aug 1929 | Box 6 \ 7 07-page062 | |
| Design committee report discussing 'F' type crankshafts, the Schneider Trophy, exhausts, and battery charging. | 13th Mar 1930 | Box 6 \ 7 07-page063 | |
| Two failures, a hypoid axle and the exhaust system, during a 10,000-mile test in France. | 14th Mar 1930 | Box 6 \ 7 07-page064 | |
| Component failures, agreed modifications, and arrangements for extended testing in France. | 14th Mar 1929 | Box 6 \ 7 07-page065 | |
| Recommendation to delete drain holes in silencers as they are a source of exhaust noise. | 19th Mar 1930 | Box 6 \ 7 07-page066 | |
| The failure of an exhaust valve on a 20 HP car and a request for steel analysis. | 22th Mar 1930 | Box 6 \ 7 07-page067 | |
| Covering letter for a correspondence from Halford, designer of a 16-cylinder air-cooled engine, concerning a silencer. | 26th Mar 1930 | Box 6 \ 7 07-page068 | |
| Request to manufacture a replacement sliding joint for a 20 HP silencer in two different bronze alloys due to a failure. | 26th Mar 1930 | Box 6 \ 7 07-page069 | |
| Vortex Silencers, sending a drawing of a 20 HP rear expansion chamber for testing. | 27th Mar 1930 | Box 6 \ 7 07-page070 | |
| Troubles with the 20/25 HP chassis exhaust system and potential solutions. | 27th Mar 1930 | Box 6 \ 7 07-page071 | |
| Confirming a blueprint for a Vortex Silencer has been sent to Major Halford to manufacture a test unit. | 29th Mar 1930 | Box 6 \ 7 07-page072 | |
| Nineteenth design committee report on a 10,000-mile test, discussing modifications and issues with exhaust pipes, valves, and rear axle. | 1st Apr 1938 | Box 6 \ 7 07-page073 | |
| Urgent request to prepare a complete set of 20 HP exhaust system pieces for production. | 4th Apr 1930 | Box 6 \ 7 07-page074 | |
| Change of material to S.L.V. steel for exhaust valves on 20 HP and 40/50 HP chassis. | 4th Apr 1930 | Box 6 \ 7 07-page075 | |
| Components and recommended modifications for the 20 HP exhaust system. | 3rd Apr 1930 | Box 6 \ 7 07-page076 | |
| Request for a Bijur pump, a front expansion box, and friction shock absorbers required for testing. | 7th Apr 1930 | Box 6 \ 7 07-page077 | |
| Directive to revert to S.L.V. specification No. 238.A for exhaust valves on 20/25 HP and 40/50 HP chassis. | 7th Apr 1930 | Box 6 \ 7 07-page078 | |
| Outlining the reversion to S.L.V. steel for exhaust valves, the associated scrap costs, and implementation timeline. | 8th Apr 1930 | Box 6 \ 7 07-page079 | |
| Suggestion to modify the longitudinal stay for the 20/25 HP chassis exhaust silencer. | 2nd Apr 1930 | Box 6 \ 7 07-page080 | |
| Request to prepare parts to modify the 20 HP car exhaust and clutch systems. | 24th Apr 1930 | Box 6 \ 7 07-page081 | |
| Cover memo from 'Wor' to 'Hs/Rm' forwarding an attached memo from 'Sg' for investigation. | 6th May 1930 | Box 6 \ 7 07-page082 | |
| Poor rear seat comfort and exhaust spitting on a 20/25 HP model. | 26th Jun 1930 | Box 6 \ 7 07-page083 | |
| Criticisms of the 20 HP car's ride and exhaust spitting, with proposed solutions and comparisons to other models. | 7th May 1930 | Box 6 \ 7 07-page084 | |
| Engine performance issues like 'spitting in the silencer', comparing with American and Experimental cars. | 21th May 1930 | Box 6 \ 7 07-page085 | |
| Issues and required improvements for body mounting and coachbuilding. | 21th May 1930 | Box 6 \ 7 07-page086 | |
| Report discussing chassis and body-related noise, vibration, and booming issues. | 1st May 1930 | Box 6 \ 7 07-page087 | |
| Standardisation report for exhaust valves E.53158, replacing a failed part following tests. | 16th Apr 1930 | Box 6 \ 7 07-page088 | |
| Carburettor and camshaft comparison tests performed on the 'Japan' engine. | 21th Aug 1930 | Box 6 \ 7 07-page089 | |
| Engine tests comparing riser pipes, bore diameters, and choke sizes to improve performance. | 24th Aug 1926 | Box 6 \ 7 07-page090 | |
| Report comparing engine performance with different camshaft configurations. | 23th May 1931 | Box 6 \ 7 07-page091 | |
| Summary of experiment results on the 'Japan' engine, focusing on twin carburetters and a long duration camshaft. | 23th Aug 1931 | Box 6 \ 7 07-page092 | |
| Table of actual valve timing data taken on an engine with .020 tappet clearance, showing results from twin carburetor tests. | 10th Jan 1932 | Box 6 \ 7 07-page093 | |
| Performance comparison graph of large and small bore induction manifolds using twin Zenith carburettors on a 'Japan' engine. | 11th Feb 1937 | Box 6 \ 7 07-page094 | |
| Performance graph comparing different camshafts on an engine codenamed 'Japan'. | 11th Feb 1937 | Box 6 \ 7 07-page095 | |
| Performance graph comparing twin Zenith carburetters against standard chassis carburetters on the 'Japan' engine model. | 29th Jul 1930 | Box 6 \ 7 07-page096 | |
| Blueprint detailing the arrangement of a twin Zenith carburettor and induction pipe on a Japan engine. | 28th May 1920 | Box 6 \ 7 07-page097 | |
| Standardisation of chassis parts, specifically the exhaust system E.55578. | 23th Apr 1930 | Box 6 \ 7 07-page098 | |
| Material and design of exhaust valves for car and aero engines. | 13th Aug 1930 | Box 6 \ 7 07-page099 | |
| Requesting to be kept informed of the results regarding exhaust valves for car and aero engines. | 2nd Sep 1930 | Box 6 \ 7 07-page100 | |
| Stating a reluctance to alter exhaust valves following previous issues with Austenitic Steel. | 9th Mar 1930 | Box 6 \ 7 07-page101 | |
| Outlining three design schemes for the revision of the 25HP 'Japan' engine. | 11th Nov 1930 | Box 6 \ 7 07-page102 | |
| Causes and potential cures for 'spitting in the silencer'. | 20th Nov 1930 | Box 6 \ 7 07-page103 | |
| The effects of fitting a smaller low-speed choke tube to a carburetter to correct spitting. | 20th Nov 1930 | Box 6 \ 7 07-page104 | |
| Tests carried out to investigate and resolve engine spitting issues on car 22-EX. | 20th Nov 1930 | Box 6 \ 7 07-page105 | |
| Failure of a 25HP exhaust manifold after 3000 miles and proposing potential solutions. | 1st Jan 1931 | Box 6 \ 7 07-page106 | |
| Causes of exhaust manifold failures and proposed solutions. | 26th Feb 1931 | Box 6 \ 7 07-page107 | |
| Manifold design issues and potential improvements for the P. 2 model. | 24th Mar 1931 | Box 6 \ 7 07-page108 | |
| Development of exhaust manifolds with cooling ribs for various car models. | 24th Mar 1931 | Box 6 \ 7 07-page109 | |
| Prints of exhaust manifold modifications for 20 & 25HP chassis. | 2nd Apr 1931 | Box 6 \ 7 07-page110 | |
| Design improvements for a 25HP exhaust pipe nozzle. | 9th Apr 1931 | Box 6 \ 7 07-page111 | |
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