Scott, let me take a stab at this. I'm not sure about the design of the
old Bentley but this may explain the situation. Some old engines had
separate cylinder heads much like your motorcycle. I assume that the
author may be describing a plate that goes between the crankcase (lower
end) and the cylinder heads (upper end). This would keep the stroke the
same but when the piston was at top dead center there would be more free
cc's in the cylinder, therefore reducing the compression ratio. Make
sense?
Larry Hoy (MGB.Roadster@juno.com)
Denver, CO USA
1969 MGB Roadster
1987 Jaguar XJ6 Vanden Plas
===============================
On Sat, 1 Nov 1997 03:18:46 +0000 "Scott Gardner" <gardner@lwcomm.com>
writes:
>> Fellow Correspondents,
>>
>> A lucky find at what was probably one of the last Jumbles of the year
in
>> England was a pile of old "Automobile" magazines and a few "Motor
Sports".
>> I chanced upon an article by Bill Boddy on the Turbo charged Bentley
of
>> Jumbo Goddard. I remember that this monster was in the entrance foyer
of
>> the Donington racing car museum when it first opened. Where is it now,
I
>> wonder? I hope Mr Boddy does not mind my reproduction of his article.
>>
>> I leave the reader to come to his own conclusions as to the
appropriateness
>> of this conversion. Please bear in mind that the perpetrator is
Austrailian
>> (I believe). My prelidictions are well known.
>>
>> A TURBO-EXHAUST-SUPERCHARGED VINTAGE BENTLEY
>>
><<SNIP>>
>> graphitised alloy, the small-ends phosphor-bronze, The c.r. was
lowered to
>> approx. 6.5 to 1 by inserting a 7/16in. plate between cylinder block
and crankcase, which
>> also serves to stiffen the notoriously flexible crankcase of a vintage
Bentley.
>> <<SNIP>>
>> W.B.
>>
>>
>> Yours plagaristically, with all acknowledgements to William Boddy and
>> "Motor Sport" magazine,
>>
>> JH
>All in all, a very interesting description, but can anyone tell me
>how inserting a plate between the block and the crankcase lowers
>compression ratio? If the author meant "between the block and the
>cylinder head", this would make sense to me, but since he goes on to
>describe the plate's added benefit of stabilizing the crankshaft, I
>suspect this isn't the case. Can anybody enlighten me?
>Scott
>
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