| Description | Date | Identifier | |
| Introduction of a modified, more economical exhaust system for the 20 HP 'V' Series chassis. | 7th May 1932 | Box 104 \ 2 scan0016 | |
| Agreeing to continue with the current exhaust system for the first 50 chassis of the 20 HP 'V' Series. | 10th May 1932 | Box 104 \ 2 scan0017 | |
| Outlining calculations and suggestions to eliminate an exhaust boom on a 25 HP model using a variable double resonance unit. | 30th May 1932 | Box 104 \ 2 scan0018 | |
| Design drawing and calculation sheet for a 25 HP silencer tuning chamber. | 2nd Jun 1932 | Box 104 \ 2 scan0019 | |
| Preliminary particulars of a modified exhaust system for the 20/25HP car, focusing on cost and weight reduction. | 2nd Jun 1932 | Box 104 \ 2 scan0020 | |
| Blueprint detailing the design and specifications for baffles in an experimental silencer. | 2nd Jun 1932 | Box 104 \ 2 scan0021 | |
| Further modifications to a silencer involving section lengths, baffles, and a Phantom II type swan neck. | 2nd Jun 1932 | Box 104 \ 2 scan0022 | |
| Blueprint showing the best tested arrangement for a 20/25 HP silencer. | 30th May 1932 | Box 104 \ 2 scan0023 | |
| The 20/25 HP car exhaust system, including an analysis and back pressure tests of a Cadillac silencer. | 2nd Jun 1932 | Box 104 \ 2 scan0024 | |
| Graph showing the results of exhaust silencer tests for the Phantom II engine. | 2nd Jun 1932 | Box 104 \ 2 scan0025 | |
| Testing resonance chambers on the J.III exhaust system pipe. | 6th Jun 1932 | Box 104 \ 2 scan0026 | |
| Blueprint detailing a dropped front section for a J III exhaust system with clearance specifications. | 7th Jun 1932 | Box 104 \ 2 scan0027 | |
| Recommending the purchase of additional exhaust silencer parts for the 20/25 HP 'V' Series chassis. | 7th Jun 1932 | Box 104 \ 2 scan0028 | |
| Proposal to standardise and test new resonance exhaust silencers on 25HP cars. | 27th Jun 1932 | Box 104 \ 2 scan0029 | |
| Typed letter regarding the logistics of fitting and testing new resonance exhaust silencers on a 20/25 HP trials car. | 29th Jun 1932 | Box 104 \ 2 scan0030 | |
| Development and testing of resonance exhaust silencers, referencing a car at Brooklands. | 30th Jun 1932 | Box 104 \ 2 scan0031 | |
| Short memo regarding the upcoming availability of GBT-24 for Resonance Exhaust Silencers. | 1st Jul 1932 | Box 104 \ 2 scan0032 | |
| Sending car GBT-24 to Derby for the fitting of a resonance exhaust silencer. | 5th Jul 1932 | Box 104 \ 2 scan0033 | |
| Blueprints for a resonant type silencer for the 20/25 HP Chassis. | 5th Jul 1932 | Box 104 \ 2 scan0034 | |
| Theory of resonance exhaust silencers, including formulas and experimental results. | 1st Jul 1932 | Box 104 \ 2 scan0035 | |
| Page discussing the principles of single and double resonance exhaust silencers. | 1st Jul 1932 | Box 104 \ 2 scan0036 | |
| Analysis of exhaust system noise, 'boom' periods, and silencer performance on various car models. | 1st Jul 1932 | Box 104 \ 2 scan0037 | |
| Results of experiments on the Phantom II and J.III models, focusing on silencer power loss and the necessity of the cutout feature. | 9th Jul 1932 | Box 104 \ 2 scan0038 | |
| Blueprint graph and equations for Double Resonance Response Curves by E.T. Paris. | 9th Jul 1932 | Box 104 \ 2 scan0039 | |
| Blueprint graph with calculations detailing silencer response and chamber frequency. | 1st Jan 1932 | Box 104 \ 2 scan0040 | |
| Blueprint detailing the internal structure of a Resonance Silencer. | 1st Jan 1932 | Box 104 \ 2 scan0041 | |
| Performance graph showing the results of 20/25 HP exhaust tests for a resonance silencer. | 14th Jun 1932 | Box 104 \ 2 scan0042 | |
| Performance graph for the 20/25 HP (China) unit plotting BHP, BMEP and exhaust back pressure against RPM. | 8th Jun 1932 | Box 104 \ 2 scan0043 | |
| Blueprint graph showing the results of 20/25 exhaust tests for a resonance silencer. | 17th Jul 1934 | Box 104 \ 2 scan0044 | |
| Sales trial for a resonance silencer, G.T.B.24. | 6th Jul 1932 | Box 104 \ 2 scan0045 | |
| The fitting of a new silencer to a car, noting issues with engine boom and suggesting brake attention. | 1st Jul 1932 | Box 104 \ 2 scan0046 | |
| Parts list for the Resonant Type Silencer on a 20/25 HP Chassis. | 8th Jul 1932 | Box 104 \ 2 scan0047 | |
| Continuation page of a parts list for an experimental modification, including a note about a superseded component. | 8th Jul 1932 | Box 104 \ 2 scan0048 | |
| Blueprints for the resonant type silencer for the 20/25 HP chassis. | 6th Jul 1932 | Box 104 \ 2 scan0049 | |
| Listing blueprints for the 20/25 HP chassis exhaust fittings and resonant type silencer. | 7th Jul 1932 | Box 104 \ 2 scan0050 | |
| Testing and performance of a resonance silencer on car GBT-24. | 11th Jul 1932 | Box 104 \ 2 scan0051 | |
| Performance and testing of an experimental silencer on car GBT.24. | 12th Jul 1932 | Box 104 \ 2 scan0052 | |
| Fitting and testing of a resonance type silencer. | 12th Jul 1932 | Box 104 \ 2 scan0053 | |
| Objectionable clicking feature in resonance silencers due to insufficient clearance in the baffles. | 25th Jul 1932 | Box 104 \ 2 scan0054 | |
| Design and performance of the Phantom II exhaust system and potential improvements. | 29th Jul 1932 | Box 104 \ 2 scan0055 | |
| Trying out a Silver Ghost component and gaining 7 BHP by deleting a pipe from the sliding joint. | 29th Jul 1932 | Box 104 \ 2 scan0056 | |
| Graph of performance data from resonance silencer exhaust tests on a Phantom II unit. | 2nd Aug 1932 | Box 104 \ 2 scan0057 | |
| Design change to the silencer supports for the 20/25 HP chassis. | 2nd Aug 1932 | Box 104 \ 2 scan0058 | |
| Buying 20 HP exhausts and the need to complete tests on a more economical modified resonant type. | 23th Aug 1932 | Box 104 \ 2 scan0059 | |
| Fitting a final 25 HP silencer and the upcoming issue of a Standardisation Sheet. | 24th Aug 1932 | Box 104 \ 2 scan0060 | |
| Improvements and requesting modifications to the 20/25HP Resonance Silencer for trial fittings on several cars. | 3rd Oct 1932 | Box 104 \ 2 scan0061 | |
| Blueprint detailing modifications to a resonance silencer for a 20/25 HP model. | 19th Oct 1932 | Box 104 \ 2 scan0062 | |
| The completed tests and final design for the resonance silencer on the 20/25 HP car. | 19th Oct 1932 | Box 104 \ 2 scan0063 | |
| Exhaust pipe and silencer performance, comparing different designs and proposing a new scheme for a trials car. | 19th Oct 1932 | Box 104 \ 2 scan0064 | |
| Drawing detailing modifications to Resonance Silencer E.58690 for the 20/25 HP model. | 19th Oct 1932 | Box 104 \ 2 scan0065 | |
| Graph plotting back pressure in inches of mercury against engine RPM for different silencer configurations. | 19th Oct 1932 | Box 104 \ 2 scan0066 | |
| Graph showing the effect of swan neck diameter on a 20/25 HP resonance silencer. | 19th Oct 1932 | Box 104 \ 2 scan0067 | |
| Graph plotting power loss for a 20/25 HP engine using an open exhaust, resonance silencer, and standard silencer. | 9th Nov 1932 | Box 104 \ 2 scan0068 | |
| Request from coachbuilder Park Ward about a lengthened exhaust pipe fitted to chassis 20-G-IV. | 9th Nov 1932 | Box 104 \ 2 scan0069 | |
| Confirming the lengthened exhaust pipe to the rear crossmember is now standard on the 20/25 HP chassis. | 10th Nov 1932 | Box 104 \ 2 scan0070 | |
| Standardisation sheet and modification details for the resonance silencer on 20/25 HP cars. | 14th Nov 1932 | Box 104 \ 2 scan0071 | |
| Investigation into an objectionable groaning noise from the silencer on 20/25 HP cars. | 17th Nov 1932 | Box 104 \ 2 scan0072 | |
| From 'Sg' to 'Hs' regarding feedback on a resonant exhaust's noise level. | 10th Nov 1932 | Box 104 \ 2 scan0073 | |
| Exhaust boom issue on the 20/25 model and the development of a new resonant silencer. | 18th Nov 1932 | Box 104 \ 2 scan0074 | |
| Requesting an exhaust system from the 'Bensport' car be fitted to car '19-G-IV'. | 13th Feb 1933 | Box 104 \ 2 scan0075 | |
| Oil dripping onto the silencer of a 25-HP Chassis, causing fumes and a potential fire risk. | 11th Mar 1933 | Box 104 \ 2 scan0076 | |
| Noise complaints regarding the non-resonant silencer on the 20/25HP model. | 13th Mar 1933 | Box 104 \ 2 scan0077 | |
| Technical memo discussing noise issues and clearance specifications for a 20/25 HP resonance silencer. | 14th Mar 1933 | Box 104 \ 2 scan0078 | |
| Standardisation of chassis parts, specifically a resonance silencer to reduce power loss. | 15th Nov 1932 | Box 104 \ 2 scan0079 | |
| Standardisation document for a new chassis part, detailing its first fitting, testing date, and associated costs. | 3rd Mar 1933 | Box 104 \ 2 scan0080 | |
| The worsening issue of 'spitting in the exhaust' on the 25-HP chassis. | 23th May 1933 | Box 104 \ 2 scan0081 | |
| Customer complaints of the 20/25 chassis 'spitting in exhaust on retard' defect. | 26th Aug 1933 | Box 104 \ 2 scan0082 | |
| Issue of spitting in the exhaust on the 25 HP chassis and the potential solution of fitting an S.U. carburetter. | 31th Aug 1933 | Box 104 \ 2 scan0083 | |
| Issues and potential improvements for exhaust systems, specifically concerning the Terraplane mounting. | 26th Apr 1934 | Box 104 \ 2 scan0084 | |
| The use of an adjustable exhaust nozzle on the 25 HP and Phantom chassis. | 7th May 1934 | Box 104 \ 2 scan0085 | |
| Instruction memo to produce a modified exhaust system front expansion box with a smaller diameter. | 13th Jul 1934 | Box 104 \ 2 scan0086 | |
| Letter to A.C. Sphinx Co. Ltd. regarding a drawing for a 20/25 Exhaust System. | 16th Jul 1934 | Box 104 \ 2 scan0087 | |
| Standardisation of parts documentation for an adjustable exhaust nozzle. | 27th Jun 1934 | Box 104 \ 2 scan0088 | |
| Cost estimate for extra jigs, tools, and equipment for the 'F.2' series. | 20th Jun 1934 | Box 104 \ 2 scan0089 | |
| Letter from AC-Sphinx Sparking Plug Co. Ltd. enclosing blueprints of exhaust silencer designs for Buick and Chevrolet. | 20th Jul 1934 | Box 104 \ 2 scan0090 | |
| Letter to A.C.-Sphinx Sparking Plug Co. Ltd. acknowledging receipt of blueprints and thanking Mr. Brown for his time. | 21th Jul 1934 | Box 104 \ 2 scan0091 | |
| Request to build an exhaust system with a sectional rear silencer for car 20-G-IV, referencing drawing Hs.1436. | 24th Jul 1934 | Box 104 \ 2 scan0092 | |
| Modifications to the 25 HP exhaust system as fitted to the 10,000 miles car. | 24th Jul 1934 | Box 104 \ 2 scan0093 | |
| New type of silencer from Huntington, Heberlein & Co. Ltd., and its potential for aero engine and car applications. | 19th Jul 1934 | Box 104 \ 2 scan0094 | |
| Letter from Huntington, Heberlein & Co. Ltd. requesting to test a new Swedish-developed engine silencer. | 17th Jul 1934 | Box 104 \ 2 scan0095 | |
| Letter acknowledging correspondence regarding a new silencer development for internal combustion engines. | 19th Jul 1934 | Box 104 \ 2 scan0096 | |
| Letter from Huntington, Heberlein & Co. Ltd. regarding a misunderstanding and enclosing a sketch of a silencer for testing. | 23th Jul 1934 | Box 104 \ 2 scan0097 | |
| Letter from Huntington, Heberlein & Co. Ltd. proposing to test a newly developed Swedish engine silencer. | 17th Jul 1934 | Box 104 \ 2 scan0098 | |
| Hand-drawn sketch with annotations for an exhaust pipe design on company letterhead. | 25th Jul 1934 | Box 104 \ 2 scan0099 | |
| Letter to Messrs. Huntington, Heberlein & Co.Ltd. regarding the preliminary testing of an exhaust silencer. | 25th Jul 1934 | Box 104 \ 2 scan0100 | |
| Letter from Huntington, Heberlein & Co. Ltd discussing the specifications and test results for a new engine silencer. | 26th Jul 1934 | Box 104 \ 2 scan0101 | |
| Page 2 of a letter from Huntington, Heberlein & Co., Ltd. regarding a new silencer design. | 26th Jul 1934 | Box 104 \ 2 scan0102 | |
| Letter providing specifications for a 25 HP exhaust system, including pipe diameter, engine displacement, and cruising RPM. | 30th Jul 1934 | Box 104 \ 2 scan0103 | |
| New, lighter and less costly silencer design developed with the A.C. Silencer Co. of America. | 30th Jul 1934 | Box 104 \ 2 scan0104 | |
| New drawing, LeC.4059, for a 25-HP flexible exhaust suspension, replacing the previously abandoned scheme LeC.3943. | 27th Jul 1934 | Box 104 \ 2 scan0105 | |
| Letter concerning the dispatch of a silencer and arranging an engineer's visit for testing. | 3rd Aug 1934 | Box 104 \ 2 scan0106 | |
| Letter from Huntington, Heberlein & Co. Ltd. clarifying the correct orientation of a silencer sent for testing. | 10th Aug 1934 | Box 104 \ 2 scan0107 | |
| Proposing a material change for 25-HP Exhaust Manifold Studs to overcome stretching. | 5th Sep 1934 | Box 104 \ 2 scan0108 | |
| Experimental modification to the 25-HP exhaust manifold to address a cracking issue. | 10th Sep 1934 | Box 104 \ 2 scan0109 | |
| Instruction to fit two 25 HP exhaust manifolds to chassis 20-G-IV and 21-G-IV. | 14th Sep 1934 | Box 104 \ 2 scan0110 | |
| Results of experiments on a 25 HP exhaust system to reduce noise. | 17th Sep 1934 | Box 104 \ 2 scan0111 | |
| Blueprint detailing modifications to a perforated pipe and a component described as a 'Top Hat'. | 14th Sep 1934 | Box 104 \ 2 scan0112 | |
| Comparative speed and performance tests between cars 18-G-IV and 20-G-IV at Brooklands track. | 19th Sep 1934 | Box 104 \ 2 scan0113 | |
| Experimental exhaust manifold with air cooling fins for the 25-HP model, referencing drawing LeC.4106. | 3rd Oct 1934 | Box 104 \ 2 scan0114 | |
| Letter from Huntington, Heberlein & Co. Ltd. inquiring about the test results for a previously sent silencer. | 10th Oct 1934 | Box 104 \ 2 scan0115 | |
| | | | |
