From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparative table of compression ratios and maximum brake horsepower for various car models from 1927 to 1929.
| Identifier | ExFiles\Box 19\7\ Scan147 | |
| Date | 9th September 1932 guessed | |
| x790. (There is an average increase of 10 lbs. per sq.in. compression pressure in the last year for a given compression ratio due to better piping and valving etc. This also increases the tendency to knock.) COMPRESSION RATIOS 1927, 1928 and 1929 - MAX. BRAKE H.P. Make & Model. 1927 1928 1929 B.H.P. Comp.Ratio Stand. Op. B.H.P. Comp.Ratio Stand. Op. B.H.P. Comp.Ratio Stand. Op. Auburn 6.80 5.00 60-3200 5.05 65-3400 5.16 6.25 Auburn 8.90 62-3200 5.00 88-3200 5.15 93-3300 5.15 6.25 Auburn 120 90-3200 5.00 115.3300 120-3300 5.25 6.56 Black Hawk L 6 85-3200 5.25 5.50 Black Hawk L 8 90-3200 5.50 6.00 Buick 116 63-2800 4.79 63-2800 4.79 74-2800 4.3 4.80 Buick 121 77-2800 4.31 77-2800 4.30 91-2800 4.3 4.80 Buick 129 77-2800 4.31 77-2800 4.30 91-2800 4.3 4.80 Cadillac. 87-3000 4.75 90-3000 4.90 5.30 95-3000 5.3 4.8 Chandler 65 45-2600 45-2600 5.00 55-3000 5.0 Chandler Big 6 55-2100 63-2300 5.00 83-2600 5.0 Chandler 75 80-2600 80-3200 5.0 Chandler 85 80-3000 80-3000 5.00 95-3000 5.0 Chevrolet 26-2000 4.3 35-2200 4.50 5.1 46-2600 5.0 Chrysler 65 54-3000 4.9 5.00 6.00 65-3200 5.2 6.0 Chrysler 75 70-3000 4.8 75-3200 5.00 75-3200 5.0 6.0 Chrysler 80 92-3000 4.8 112-3000 6.00 4.75 112-3400 6.0 5.0 Cunningham 90-2400 4.26 106-2400 5.0 De Soto 55-3200 5.0 6.0 Dodge Bros. 6 40-2400 4.08 58-3000 5.18 5.54 Dodge Bros.Senior 60-2800 5.26 66-2800 5.55 Duesenburg 265-4500 5.20 Durant 4 36-2400 4.8 Durant 50 40-2400 4.79 43-2800 4.79 Durant 70 47-2800 5.40 52-2900 4.90 Elcar 75 4.9 52-2900 4.9 52-2900 4.9 Elcar 95,96 60-2900 4.9 70-2900 4.9 70-2900 4.9 Elcar 120 84-2900 4.9 84-2900 4.9 84-2900 4.9 Erskine 40-3200 5.0 40-3200 4.50 43-3000 4.87 5.30 | ||