I believe the "long stroke for tax purposes" story explains the *historical*
reasons for British engine design tendencies, but I seem to recall reading
once that this formula was abolished sometime in the 50s or 60s. If so, then
both of you are correct.
I might have a reference that explains this issue in more detail (if I can
find it)....
on 1/1/02 2:21 PM, Paul Root at proot@iaces.com wrote:
> Larry Hoy wrote:
>>
>> Kai, the C to C length of an MGB rod is 6.5", I think the twin cam is
>> the same (no math I looked it up in Haynes), the engine stroke is 3.5";
>> I think however, your barking up the wrong tree. The bore and stroke
>> was determined by taxes not engineering. There was a long and
>> convoluted tax formula that was applied to British engines. The end
>> result was the smaller the bore, the less taxes were paid for any given
>> displacement. That's why the British engines have a long stroke and
>> small bore.
>
> I got to disagree here. I'm just reading a book on MGBs and it said for
> manifacturing reasons, the stroke always stayed the same. They increased
> the B-series to 1798 by siamesing 1 to 2 and 3 to 4 (removing water
> jackets between the cylinders). Then they were working on siamesing all
> 4 cylinders and increasing to 2liter, but that got killed. It's
> interesting
> all the tragic mistakes BMC and BL made, the V4 and V6, the 2l B-series,
> the O-series, styling updates. All killed to save a bit short term
> money,
> thus killing the company.
>
> If they wanted to minimize taxes, they would have increased the stroke
> instead of the bore, if the tax angle were true. This company often
> destroyed prototype cars from companies outside the UK (Pininfarnia
> for instance) instead of having to pay the import duty. Which in the
> oppressive trade environment of the 70s and before were probably pretty
> steep.
>
> Paul.
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