Max Heim wrote:
> ... [snip] ... I further admit I didn't have any data to base my
> comment on, I just assumed that since (non TC) A's have smaller
> engines and aren't much lighter that they couldn't be as quick as
> pre-smog B (also considering the historical evidence that
> disappointing performance of the 1622 was the reason for the
> development of the 1800).
Hmmm ... climbing up on my soap box.
I'm not familiar with your "historical evidence" ... I would have
to argue that the performance of the 1622 was/is far from
disappointing ...
Graham Robson writes:
" In the beginning, design went ahead with two engines in mind -
the 1,622cc ohv B-Series unit already slated for the MGA 1600 MkII,
and the existing 1,588cc Twin-Cam unit. Before long however, the
Twin-Cam engine was dropped altogether, and work was concentrated
on the pushrod design. The MGB, as everyone knows, has always been
built with 1,798cc engine, and although Abingdon knew of this unit's
existence when they stared work on the MGB, they originally
preferred to keep it in reserve for a later MGB development.
However, although the MGB's structure was efficiently laid out,
it soon became clear that it would result in a car slightly heavier
than the last of the MGAs, and that without another engine boost this
would mean a drop in performance. It was therefore decided to rush
through the bigger engine for the MGB, even though it would not be
used by any other BMC car until 1964, and then not in the same guise
or structural condition.
...[snip]...
Compared with the last of the MGAs - the 1600 MkII - there was a
measurable, if not sensational , performance boost. The MGB's maximum
speed was better by two or three miles an hour, the standing-start
quarter-mile was trimmed by a few tenths of a second, and the top-gear
performance was slightly better in spite of higher overall gearing.
of equal importance was the fact that fuel economy had suffered very
little, if at all, and even a small penalty depended on the way in
which the new car was driven."
Both the 1622 and the early "pre-smog" 1800 produce approximately
.053bhp(net)/cc. If the performance of the 1622 was/is
disappointing, it is surprising that it was considered for MGB, and
even more surprising that the 1800 fitted to the MGB didn't provide
a "sensational" increase in performance over the last of the MGAs.
Further ... the 1800 5-main engine was *not* developed due to the poor
performance of the 1800 3-main engine (at high revs, in excess of
red-line, the 3-main generates more "crank whip" which results in a
loss of power, and ultimately crank failure ... however, the reduced
internal drag of the 3-main engine gives a noticeable sharpness to
the throttle and the performance when compared to the 5-main) ... the
5-main was designed for a salon and fitted to the MGB as result of
rationalization efforts as the 1800 was fitted to other BMC cars in
1964.
Graham Robson writes:
" Original engines were Type 18G, but closed-circuit crankcase
breathing was introduced from Chassis No 31021 and the units became
Type 18 GA. When BMC introduced the front-wheel-drive Austin 1800
in the autumn of 1964 it had a five-bearing engine, and this cylinder
block was standardized on MGB's from Chassis No. 48766; these engines
were Type 18GB."
Roger Parker writes:
" I think that it is fair to say that the funding for the 5 bearing
engine came from the Austin 1800 programme. In that they wanted to
move into a more refined market sector and this needed a smoother
engine than the 3 bearing one. Also the fact that the new layout was
going to be transverse with the gearbox and engine sharing the same oil
(ah la Mini) would certainly have created far greater heat input into
the oil. They then probably created greater justification in saying
that they could then fit the unit to the MGBGT which was also in the
planning stages at that time."
... climbing down from the soap box.
Larry Unger
'61 1600 MkII
An MGB with a Twin-Cam engine ... now, that "could 'a been a contender".
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