From Wikipedia:
"The 3.5-litre V8 engine was bored out to 4,520 cc (4.5 litres) as to compensate for the loss of power following the changes in emission control regulations and due to lower fuel octane rating in the United States. The larger V8 engine was designated as M117 and had the same output figures as 3.5-litre V8 engine."An overhead cam fuelie V-8 was still reasonably exotic in that era.
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