British Makes

"R.N. Robinson" realised it was Fri, 10 Feb 2006 15:58:23 -0000 and decided it was time to write:

Lovely. :-)

Mr Chapman will no doubt have taken the opportunity to prove that an Isetta doesn't need as many as three wheels most of the time.

Reminds me of an ad by a vintage tyre supplier that used to run in the The Autobile. It showed a picture of a Morgan Super Sport being thrown

*very* enthusiatically around a corner, with the caption 'economy tyre testing'.

How would the Hp tax encourage log thin cylinders?

"In 1921 the so-called "horsepower tax" was introduced based on the

1906 Royal Automobile Club (RAC) formula. The annual tax was =A31 (UK Pounds) per horsepower.

The calculation was partly based on the bore of an engine and thus caused American cars to be badly affected. A Ford Model T at 22.5hp paid =A323 (UK Pounds) instead of the previous Road Fund Licence of =A36

6s (=A36.30) (UK Pounds), whereas a Morris Cowley at 11.9hp paid just =A312 (UK Pounds).

This Tax continued until 1947 when it was replaced by a flat rate system. The narrow bore/long stroke engines it had encouraged now went out of fashion."

I grew up knowing that European cars favoured short stroke engines and had the ability to run on 2 or 3 star (as it later became known) but never really understood why.

And why all the fuss about phasing out Ethyl (as 5 star was once known.) Standard Oil and GM knew all about it's ill effects -as did the rest of the world very soon after:

Err, no. All the BMC engines - A, B and C Series remained under square. As did most other UK makers engines.

The first really over square mass production engine was the Ford 105E in '59.

Over square engines allow higher maximum revs since the piston speed is lower. In theory. And allow bigger valves therefore better breathing at high revs. However, they're not as popular in these days of multi valve engines.

The modern road car engine was essentially developed by BRM, working with Shell on combustion technology, for the 1.5 litre F1 of 1961/5 and refined in the 2 litre Tasman version of the V8. This technology was taken to Lotus Engineering by Tony Rudd, scaled up into a modular

2 litre 4-cyl; 3 litre V6 and 4 litre V8 and sold to the world's car companies on a consultancy basis. Pretty much everything we drive these days stems from here.

David Betts ( snipped-for-privacy@motorsport.org.uk) The Classic Car Gallery:

The calculation was partly based on the bore of an engine and thus caused American cars to be badly affected. A Ford Model T at 22.5hp paid £23 (UK Pounds) instead of the previous Road Fund Licence of £6

6s (£6.30) (UK Pounds), whereas a Morris Cowley at 11.9hp paid just £12 (UK Pounds).

This Tax continued until 1947 when it was replaced by a flat rate system. The narrow bore/long stroke engines it had encouraged now went out of fashion."

But not instantly. My 1952 Mayflower had a 63mm bore and 108mm stroke.

Jim

But that was essentially a pre-war engine?

It was the engine originally used in the Standard Flying 9, so pre-war design, if not actually pre-war manufacture.

Jim

And a remarkably sweet little unit.

But many engines designed after the war - the A, B and C series for example were also long stroke. The famous Jaguar XK series.

The effect of pool petrol, maybe? If all's that's available is low-octane stuff then long-stroke engines are more attractive. The other possibility is the desire to cater for the "stuff it in top at 20 and let it get on with it" approach (pace George Bishop, of course :)

I doubt you're going to design an engine specifically for pool petrol when expecting it to have a 25 year plus production run...

Well, BMW sixes of today are still long stroke and they seem to bring out a new one every few years.