| Description | Date | Identifier | |
| Notes on compression tests for different engine piston rings and cylinder configurations. | 24th Apr 1908 | Box 19 \ 7 Scan005 | |
| Letter to Mr. Royce regarding a proposal to increase the standard engine compression volume. | 21th Sep 1910 | Box 19 \ 7 Scan006 | |
| Telegram from Royce to Barrington with instructions to increase a clearance with a specified tolerance. | 22th Sep 1910 | Box 19 \ 7 Scan007 | |
| Engine vibration differences between the 1300 and 1400 series due to cylinder capacity measurement errors. | 27th Sep 1910 | Box 19 \ 7 Scan008 | |
| Proposal to modify engine volume to 27 cubic inches to improve smoothness, reduce crankshaft rattle and other issues. | 27th Sep 1910 | Box 19 \ 7 Scan009 | |
| Letter detailing the decision to cease increasing engine compression due to a list of resulting faults. | 1st Oct 1910 | Box 19 \ 7 Scan010 | |
| Letter discussing engine B.HP for the 1913 car, with handwritten notes comparing the hill-climbing performance of car '1601' to the 'Silver Phantom'. | 1st Oct 1910 | Box 19 \ 7 Scan011 | |
| List of high compression and long stroke engines prepared by the Repair Department. | 7th Oct 1910 | Box 19 \ 7 Scan012 | |
| Continued list of numerical references for High Compression engines. | 18th Aug 1910 | Box 19 \ 7 Scan013 | |
| List of high compression engine numbers that have had their compression lowered since leaving the works. | 18th Aug 1910 | Box 19 \ 7 Scan014 | |
| 'sweetness of running' in engines, focusing on balance and compression. | 22th Sep 1910 | Box 19 \ 7 Scan015 | |
| Engine vibration, compression standards, and cylinder correction methods. | 22th Sep 1910 | Box 19 \ 7 Scan016 | |
| Correcting engine batches sent out with too high compression. | 22th Sep 1910 | Box 19 \ 7 Scan017 | |
| Engine chirping issues and remedial actions taken on a 3-ring piston. | 19th Feb 1910 | Box 19 \ 7 Scan018 | |
| Power and compression test results for Chassis 1177 with specially high compression. | 6th Dec 1909 | Box 19 \ 7 Scan019 | |
| Compression test on a 1910 type standard engine using oil instead of a gauge. | 29th Jul 1909 | Box 19 \ 7 Scan020 | |
| Table showing compression test results at various engine speeds for a test engine. | 10th Aug 1909 | Box 19 \ 7 Scan021 | |
| List of compression values for various engine types and configurations. | 23th Jul 1920 | Box 19 \ 7 Scan022 | |
| Table of engine compression measurements at different speeds for chassis No. 935. | 23th Jul 1920 | Box 19 \ 7 Scan023 | |
| Modifications for Chassis 1719 (Bolton) and 1869 (Gjers) to achieve higher speeds. | 7th Sep 1911 | Box 19 \ 7 Scan024 | |
| Test results for engine explosion pressures for each of the six cylinders. | 5th Dec 1911 | Box 19 \ 7 Scan025 | |
| Comparing the weights of L-E engines versus standard engines. | 1st Oct 1913 | Box 19 \ 7 Scan026 | |
| Engine horsepower, compression ratios, and comparisons between engine 2704 and a 'Sluggard' engine. | 5th Mar 1914 | Box 19 \ 7 Scan027 | |
| Outlining design faults and suggested modifications for a specific chassis. | 6th Mar 1914 | Box 19 \ 7 Scan028 | |
| Urgent request for the clearance volume of an engine at 80 lbs. compression. | 14th Sep 1914 | Box 19 \ 7 Scan029 | |
| Note on the clearance volume of an engine with 80 lbs compression. | 16th Sep 1914 | Box 19 \ 7 Scan030 | |
| Clearance volume of an engine with 80 lbs compression. | 16th Sep 1914 | Box 19 \ 7 Scan031 | |
| Telegram from Elliott requesting a wired reply from Hives regarding a previous note on compression volume. | 17th Sep 1914 | Box 19 \ 7 Scan032 | |
| Confirmation of a telegram urging a reply to a note regarding 'compression volume'. | 17th Sep 1914 | Box 19 \ 7 Scan033 | |
| Horsepower tests with varying engine compression and carburettor setups. | 23th Feb 1915 | Box 19 \ 7 Scan034 | |
| Engine modifications involving compression, Zephyr pistons, and their effect on power and fuel consumption. | 23th Feb 1915 | Box 19 \ 7 Scan035 | |
| Graph of horsepower curves and fuel consumption differences at various engine compression levels. | 19th May 1915 | Box 19 \ 7 Scan036 | |
| Engine horsepower test to determine the effect of compression leakage on power output. | 19th May 1915 | Box 19 \ 7 Scan037 | |
| Engine performance, focusing on the effects of piston ring fitment, gas leakage, and friction on horsepower. | 1st May 1917 | Box 19 \ 7 Scan038 | |
| Page concluding that power loss from leakage is proportional to speed. | 4th Sep 1915 | Box 19 \ 7 Scan039 | |
| Engine horsepower tests, leakage, and proposed experiments on induction systems. | 21th May 1915 | Box 19 \ 7 Scan040 | |
| Possibility of 'ramming the induction' on an engine by coupling cylinders. | 3rd Nov 1910 | Box 19 \ 7 Scan041 | |
| Record of engine compression experiments conducted at various speeds on a chassis. | 3rd Nov 1910 | Box 19 \ 7 Scan042 | |
| Revisions and additions for the 'After the War Chassis', including a request for an American model. | 19th Sep 1917 | Box 19 \ 7 Scan043 | |
| List of technical recommendations regarding modifications to compression, shock absorbers, valves, wiring, and other vehicle components. | 19th Sep 1917 | Box 19 \ 7 Scan044 | |
| Updating chassis 49.GE and the proposal to build a new 'after the war' chassis model. | 19th Sep 1917 | Box 19 \ 7 Scan045 | |
| List of decisions regarding parts to be incorporated into the post-war chassis. | 19th Sep 1917 | Box 19 \ 7 Scan046 | |
| Page 2 of a numbered list detailing vehicle component specifications and modifications. | 9th May 1917 | Box 19 \ 7 Scan047 | |
| Use of aluminium pistons to increase the compression range on the 40/50 chassis. | 18th Feb 1919 | Box 19 \ 7 Scan048 | |
| Modifications to the carburetter and camshaft for the 7 CA engine. | 18th Feb 1919 | Box 19 \ 7 Scan049 | |
| Inconclusive results of comparative tests on engine horsepower, consumption, and varying compressions. | 13th Nov 1919 | Box 19 \ 7 Scan050 | |
| Peugeot and Duesenberg engine performance, focusing on compression and mean average pressure. | 18th May 1920 | Box 19 \ 7 Scan051 | |
| Engine horsepower characteristics over a range of speeds, with a comparison to Peugeot and Duesenberg. | 18th May 1920 | Box 19 \ 7 Scan052 | |
| Use of liners for chassis pistons. | 11th Jun 1920 | Box 19 \ 7 Scan053 | |
| Use of liners with pistons to achieve low compression and address engine vibrations. | 11th Jun 1920 | Box 19 \ 7 Scan054 | |
| Directive to abolish the liner used with low compression pistons and to create a new piston. | 16th Jun 1920 | Box 19 \ 7 Scan055 | |
| Use of a liner for packing between the cylinder and crankcase to modify engine compression. | 14th Jun 1920 | Box 19 \ 7 Scan056 | |
| Confirming experiments to determine relative and hill-climbing speeds of cars with high and low compression. | 20th Nov 1919 | Box 19 \ 7 Scan057 | |
| Conversion of low compression engines to medium compression for chassis. | 19th Jul 1921 | Box 19 \ 7 Scan058 | |
| Compression and axle gear ratios for the 40/50 model, distinguishing between open and closed cars. | 25th Jul 1922 | Box 19 \ 7 Scan059 | |
| Engine performance, crankshaft deflection, and the importance of reducing vehicle weight. | 20th Jul 1922 | Box 19 \ 7 Scan060 | |
| Complaints of vibrations on the 40/50 chassis and potential solutions. | 20th Jul 1922 | Box 19 \ 7 Scan061 | |
| Standardising cars with low compression and 14-tooth axles, balancing speed against vibration. | 25th Jul 1922 | Box 19 \ 7 Scan062 | |
| From B.J. to Hs. requesting clarification on engine compression values and percentage reductions. | 25th Jul 1922 | Box 19 \ 7 Scan063 | |
| From CJ to Hs. regarding the refusal to accept chassis with above-medium compression. | 27th Jul 1922 | Box 19 \ 7 Scan064 | |
| Request for a non-technical explanation of the advantages of different engine compression levels. | 29th Jul 1922 | Box 19 \ 7 Scan065 | |
| Chasing a reply to a previous query regarding engine compression. | 11th Aug 1922 | Box 19 \ 7 Scan066 | |
| Requesting results of petrol consumption tests at Brooklands for different axles and engine compressions. | 15th Sep 1922 | Box 19 \ 7 Scan067 | |
| Viability of a deeper radiator and larger fan for engine cooling, referencing conditions in Switzerland and India. | 9th Oct 1922 | Box 19 \ 7 Scan068 | |
| Cover letter forwarding a document from America regarding 'Harsh Engines'. | 21th Nov 1922 | Box 19 \ 7 Scan069 | |
| Letter from the American branch to the London office discussing high compression engine noise, ignition issues, and modifications. | 9th Nov 1922 | Box 19 \ 7 Scan070 | |
| Engine harshness, its causes in the induction system, and improvements from vaporizer pipes and compression changes. | 9th Nov 1922 | Box 19 \ 7 Scan071 | |
| Letter from an engineer concluding a discussion on the benefits of vaporizer pipes. | 1st Jan 1923 | Box 19 \ 7 Scan072 | |
| Piston design and compression ratio for the 'Hawk-Northcliffe' chassis. | 1st Jan 1923 | Box 19 \ 7 Scan073 | |
| The 5-Goshawk-11 car with Gwynne all-weather body, detailing its silent performance and discussing potential modifications. | 19th Jan 1923 | Box 19 \ 7 Scan074 | |
| Series of graphs comparing engine performance characteristics for high and low compression engines. | 5th Sep 1923 | Box 19 \ 7 Scan075 | |
| Table detailing specifications for car engines, including bore, stroke, displacement, clearance volume, and compression ratio. | 17th Oct 1923 | Box 19 \ 7 Scan076 | |
| Engine compression ratios and the effect of fuel quality in France on engine detonation. | 1st Feb 1924 | Box 19 \ 7 Scan077 | |
| Disadvantages of high compression ratios, such as detonation and vibration, and proposing double battery ignition. | 10th Mar 1924 | Box 19 \ 7 Scan078 | |
| Optimal cylinder compression capacity for the 40/50 engine, comparing Derby and Springfield practices. | 5th May 1924 | Box 19 \ 7 Scan079 | |
| Secret memo suggesting an increase in the compression ratio for the EAC engine to gain extra power. | 6th Oct 1924 | Box 19 \ 7 Scan080 | |
| Experiments with compression ratio and exhaust systems on a 20 HP engine. | 1st May 1926 | Box 19 \ 7 Scan081 | |
| Engine performance comparing different compression ratios, focusing on power output and detonation. | 1st May 1926 | Box 19 \ 7 Scan082 | |
| Testing a piston with a deep concave head to improve combustion turbulence and reduce detonation in a Phantom engine. | 1st May 1926 | Box 19 \ 7 Scan083 | |
| Power loss analysis due to various parts of the exhaust system. | 1st May 1926 | Box 19 \ 7 Scan084 | |
| Experiments with low loss manifolds and silencer systems to reduce back pressure. | 1st May 1926 | Box 19 \ 7 Scan085 | |
| Graph of power output against RPM for a 20-HP engine with various exhaust system configurations. | 1st May 1926 | Box 19 \ 7 Scan086 | |
| Graph of engine power output (B.HP) against engine speed (R.P.M.) for a 20 HP engine, comparing standard and increased compression ratios. | 1st May 1926 | Box 19 \ 7 Scan087 | |
| Blueprint for an experimental 20-HP exhaust manifold. | 1st May 1926 | Box 19 \ 7 Scan088 | |
| Modifications to the Lighter Phantom Engine, including changes to the crankcase, pistons, and connecting rods. | 7th Jun 1926 | Box 19 \ 7 Scan089 | |
| Car acceleration, comparing various models and the effect of axle and compression ratios. | 19th Nov 1926 | Box 19 \ 7 Scan090 | |
| Two acceleration graphs, one comparing a Rolls Royce Phantom to a Bentley, and the other comparing different axle ratios on a Phantom. | 16th Nov 1926 | Box 19 \ 7 Scan091 | |
| Blank document with a Print Room stamp from Derby. | 16th Nov 1926 | Box 19 \ 7 Scan092 | |
| Two graphs comparing vehicle acceleration performance, one for high vs low compression ratios and the other for the 20 HP vs 40/50 models. | 16th Nov 1926 | Box 19 \ 7 Scan093 | |
| Two graphs showing acceleration performance comparisons for standard and high compression 20 HP engines. | 18th Nov 1926 | Box 19 \ 7 Scan094 | |
| Blank page with a Print Room stamp. | 18th Nov 1926 | Box 19 \ 7 Scan095 | |
| Ricardo's latest paper on petrol engine development and its views on compression ratio and harshness. | 23th Feb 1927 | Box 19 \ 7 Scan096 | |
| Responding to Ricardo's remarks on high compression causing engine roughness and its effect on detonation. | 24th Feb 1927 | Box 19 \ 7 Scan097 | |
| Analysis of a Lorraine Dietrich engine to identify potential improvements for the 20 HP engine's power development. | 1st Apr 1927 | Box 19 \ 7 Scan098 | |
| Report page detailing comparative tests of larger diameter valves and Zenith carburettors against standard components. | 1st Apr 1927 | Box 19 \ 7 Scan099 | |
| Increased engine power with lower induction pipe depression and different carburetors. | 1st Apr 1927 | Box 19 \ 7 Scan100 | |
| Engine power increases achieved through modifications to valves and carburetters. | 1st Apr 1927 | Box 19 \ 7 Scan101 | |
| Report page comparing engine performance based on compression ratios, carburetters, valves, and ignition systems. | 1st Apr 1927 | Box 19 \ 7 Scan102 | |
| Summary of test conclusions for increasing the power of a 20 HP engine by modifying carburetors, valves, and compression ratio. | 1st Apr 1927 | Box 19 \ 7 Scan103 | |
| Proposal to test a 6/1 compression ratio on the 20 HP engine to match the specific output of the Lorraine engine. | 30th Mar 1927 | Box 19 \ 7 Scan104 | |
| | | | |
