Graham McCann is mostly right, the best source for rover v8 info is a
pair of books written by a gent called Paul Hardcastle - one on its
history the other on its tuning.
To summarise the versions available:-
There have been numerous detail design changes like crank oilseals,
waterpump, etc. but the major performance related items have been as
follows in the UK:-
>From introduction to 1976 the Rover cars version had 10.5:1
At the same time Land Rover had a version with 8.25:1 compression.
In 1976 Rover cars lowered the compression to 9.35:1, but to
compensate they increased the valve sizes.
In 1984 Rover cars used 9.75:1 compression on the SD1 Vitesse. They
also made the inlet valves flow slightly better. the last Rover cars
specified v8 was made in 1987 when the SD1 was phased out.
During this time Land Rover used all of the compression ratios for
different models, with the post 1976 valve sizes.
In about 1989 Land Rover introduced a 3.9 litre engine, all they did
was increase the bore size!
Finally in 1995 they introduced an updated version of the engine in 4
and 4.6 litre forms. This new engine has slightly redesigned cylinder
heads (bigger ports), a new oil pump drive and cross bolted main
To the best of my knowledge, until 1995 and the 4.6, the engine has
ALWAYS used the camshaft profiles. They have been advanced or
retarded by 2 degrees in some engines.
Compression changes have been achieved by changing the pistons.
The differing power outputs quoted depend very much on the inlet and
exhaust systems used, and it would appear that the engine works
better on fuel injection - but this could all be due to inlet
Also there have been law changes that control how the manufacturer
measures the power outputs and quotes the results in advertising.
For those that are interested my BGT V8 runs a Land Rover low
compresion engine on original type inlet and tubular exhausts to give
about 175 bhp @ 4400 and 220 lb/ft @ 3000 (flywheel figures)
Date: 09-Apr-1996 10:22am
From: Dave Brooke
Tel No: 01923 664574
Subject: Re: Rover V8 conversion