Riley 8/90 Adelphi. (1936-38)

The new 8/90 engine was launched at the 1935 motor show, sporting a new 6-light Adelphi body. The engine was essentially 2 Riley 9 blocks set at 90 degrees (hence 8/90). Despite rave reviews and a competitive price (£450) the 8/90 model failed to make money, and was often criticised for an inferior ride compared to the competition.

The chassis used was essentially that of the 8/90 Adelphi, itself a development of the 15/6 chassis. The body was, likewise, essentially the same as the Kestrel 15/6, albeit with a higher standard of trim. However, hindsight suggests that rushed development led to gremlins sneaking in and the cars were not as high class as the customers expected. That and the predictions of another war and economic uncertainty led to few orders.

The 8/90 recieved the Kestrel body in early 1936, but this was less popular selling only 2 compared to about 35 Adelphis. The Adelphi 8/90 itself was withdrawn officially at the end of 1937, although several cars were still in garages until late 1938. The project was killed to try and salvage Rileys finances, and although providing a temporary glimpse of hope was not enough.

Link: Blue Diamond's 8/90 Adelphi Blog

Chassis Types: 86A, 87A


V8cyl ohv
RAC rating 18.05hp
Bore 60.3 Stroke 95.2
Firing Order 1, 5, 4, 8, 6, 3, 7, 2
Capacity 2178 cc
80bhp at 4500rpm
Carburation 2 Zenith


4-speed Armstrong Siddeley Preselector Gearbox.
Top gear ratio 4.5:1
3rd g/r 6.71:1
2nd g/r 10.3:1
1st g/r 18.2:1
Reverse 20.33:1




Girling Mechanical Rod with wedge operated shoes.
(86A) 13" / (87A) 14" or 16" Drums


0-50mph 15.7secs
Standing Quarter Mile 23secs
Max speed 82mph
Fuel Consumption 17mpg


Wheelbase 9'4.5" / 9'8.5" (aprx 2950 / 3350mm)
Track 4'3" (aprx 1280mm)
Length 14'3.5" (aprx 4350mm)
Width 5'1.5" (aprx 1560mm)
Fuel Tank 11½ galls (aprx
Wheels (86A) Dunlop 3.25x18" centre lock wire
(87A) Magna wire 3.25x17" or 18"
Tyres 5.25x18
Weight 31cwt


£450 on launch
LWB £475