The only Rolls-Royce ever supercharged and dry-sumped;
and the first owner-modified car not disavowed by the
Rolls-Royce company.
"Sheila" was bought new as a long wheel base chassis by Captain J. F. C. Kruse in October, 1925. He then commissioned Amherst Villiers (of world record-holder "Bluebird", "Villiers Vauxhall" and "Bentley Blower" fame) to supercharge and dry sump her. Amherst felt that traditional supercharging took too much power from the engine, so he designed a special four cylinder OHC 625cc, 8,000rpm and mounted it on the car's near side running board. Two spare wheels were placed on the opposite running board to balance the 200lb engine and blower. It "blew" itself as well as the main engine at 10lbs per square inch, which was very high for those days. The supercharger operated on the "Roots" principle; a form of gear pump employing two teeth per rotor. This was made by Amherst Villiers.
Amherst Villiers' engine was robust and built like a racing
machine with short stroke. The head and block were integral
with two valves per cylinder, actuated by an overhead cam. A
hefty counterbalanced crankshaft in a deep and rigid
crankcase helped to make the little engine as vibration free
as the main one. Aluminium was used wherever possible. It
was built like costume jewelry; totally elegant! It had its own
controls, primer and self starter on the dashboard (which,
incidentally, had 14 other gauges including an altimeter).
Other unique features were the exhaust, cooling and dry
sump systems which were shared with the main engine.
The main Rolls-Royce engine was redesigned with special camshaft, pistons and big ends to take the added pressures of the blower. It had a dry sump (still has today) and scavenger pump in the sump, pumping to a five gallon tank built into the chassis behind the gearbox. Special relief valves automatically kept 120 psi to the bearings and 90 psi to the valve gear and camshaft. The Rolls-Royce carburettor was extensively modified with a spring-loaded piston, which allowed the car to run on either its own system, or when the blower cut in, the piston was held down to allow the blower mixture into the carburettor.
The original open Barker body complimented the performance
with which Villiers had endowed the car.
The tail section of the body was opened by carriage keys, completely concealing the hood. When passengers were carried in the rear, they seated themselves and a tonneau section with a windscreen could be raised on hydraulic rams. The running boards opened on both sides to reveal a full range of Rolls-Royce tools set In green baize. The headlights are special "Carl Zeiss" designs, with glass mirror reflectors that can be changed to amber in fog, from the driver's seat.
Captain Kruse was understandably delighted when, after two years, Amherst Villiers delivered his very special Phantom 1 so delighted in fact, that he presented the Engineer with a straight-eight, 2litre Bugatti.
One of Sheila's chauffeurs, Reginald Powell, has fond memories of long trips in France and Germany
"but she weighed tons and with that weight, you couldn't expect too much in the way of acceleration. We used to get 12-14 miles to the gallon and with the 'blower' on, 7-8 miles per gallon".
The famous Tim Birkin took the big car around Brooklands at 108 mph. "More speed could have been attained if a high ratio Bentley 'diff' had been installed", Amherst personally told me. The "missing" engine and Blower are now in the hands of Amherst's daughter Janie. Maybe they will be united one of these days?
The original delivery invoice shows the following:
Chassis No: 31 HC 40/50 New Phantom"Sheila" was sold in 1998 and is now in the UK. The new owner has expressed interest in restoring her to her former glory, complete with original blower engine, which has been located, and a replica of the original tourer body. - Ed.
Engine No: AJ75.
Axle Ratio: 1 5x52
Tyres: Dunlop straight-sided cord. Front/Rear 33x5.
Date of Order: 17.9.'25. No: T75822W
Sale Price: £1850: - 2½ % rebate C/N 7533.
Date of Sale: 8.5.'25
Sold to Barker & Co. Ltd. 66-68 South Audley St., W1. - Capt J. F. C. Kruse
Chassis Price paid: £1655.4.6.;
Delivered on 22.10.25 to Barker by road ex L.H.
Invoice No: 27819/20.
Date: 15.10.25.