Talk:Leyland Eight

A bit of original research
The Story of Veteran and Vintage Cars by Cyril Posthumus says that the Leyland Eight's engine had a 89 mm bore, a 140 mm stroke, and a displacement of 7967 cc.

Complete Catalogue of British Cars by David Culshaw & Peter Horrobin says that two engine sizes were available. Both had a 89 mm bore; the smaller had a 140 mm stroke and a displacement of 6920 cc, while the larger had a 146 mm stroke and a displacement of 7266 cc.

The sources agree on the linear dimensions but disagree greatly on the displacement.

I therefore decided to do some original research: converted the dimensions to centimetres, halved the bore, squared the result, then multiplied that result by pi to get the cross-sectional area of a cylinder in square centimetres, multiplied that by the stroke in cm to get the displacement of one cylinder in cubic centimetres, and finally multiplied that by the number of cylinders.

The result was approximately 6967.68 cc, close enough to a litre less than Posthumus's value that the first digit could be assumed to be a misprint were editors allowed to make that assumption. I can't fathom where Culshaw and Horrobin got 6920 cc from, although doing the same arithmetic for their bigger engine yields 7266.29 cc, which is almost exactly what Culshaw and Horrobin say it is.

Does anyone have any other sources for the size of the smaller engine that actually correspond with the bore and stroke given?

Sincerely, SamBlob (talk) 22:21, 5 January 2014 (UTC)


 * It's more like 6,937 & 7,252cc as over-precise numbers. The dimensions are (being Leyland) imperial, not metric: 3&frac12;" bore and either 5&frac12;" or 5&frac34;" stroke. Posthumus gives 7.3l in some coffee table books and Gaydon give 7.2l (and they do have the only survivor). AIUI, there was only the long stroke in production and the short stroke was more of a pre-production example than a customer option. Yet again, WP's back-conversions are less than helpful. Andy Dingley (talk) 00:16, 6 January 2014 (UTC)


 * Odd that both of the sources I found gave the values in millimetres and cubic centimetres rather than in inches and cubic inches, and that neither of them shows a displacement that related to the dimensions given. Then again, both were British and from the 1970s, so they might be examples of the political correctness and quality control of their time and place. Based on what you've said, I guess the short stroke was used on the version shown at Olympia and the long stroke was used on customer's cars. But that's just a guess; there's no hard evidence we can use. Sincerely, SamBlob (talk) 18:54, 7 January 2014 (UTC)


 * It's very common between the wars to have engines designed in inches, but then their capacity given to the public in litres, so as to be comparable to the European imports. Cubic inches were only used in the US and cc didn't appear until the '60s as the litre/cc conversion wasn't obvious to the UK marketplace. "Litres" might have been a measure of wine barrels or frog legs for all Captain Hastings knew, but he did know that the Grand Prix formula, Bugattis and Ballots were measured in them. Andy Dingley (talk) 20:49, 7 January 2014 (UTC)

There is an article in The Automobile magazine of May 2007 on the Leyland Eight and the author, Jonathan Wood, gives the 140mm stroke engine as 6967 cc and the 146 stroke one as 7266cc. Culshaw and Horrobin apparently put together their volume by researching brochures and press cuttings in the library at the National Motor Museum and errors, both in the original documents and in transcription have crept in. In the 2007 "A-Z of British Sports and Thoroughbred Motor Cars" by Nick Walker the bore/stroke figures are repeated but the capacity of the smaller engine is stated as 6968cc so some calculating might be going on rather than relying on original info which as stated above would almost certainly have used inches for the bore/stroke.

Incidentally, the car at Gaydon is not original but was assembled from spares in 1929. The number made is also not certain. According to The Automobile article, an enquiry to Leyland in the 1950s by Michael Sedgwick said they thought 15 had been made. But, when Parry Thomas left in 1922 he took a lot of parts with him including three chassis one of which migt have been built up to a car. Malcolma (talk) 11:04, 8 January 2014 (UTC)


 * The Gaydon car is original, but it's a Leyland-Thomas, not a Leyland. They're still badged as a "Leyland 8" because the famously penny-pinching Thomas said that there was no bloody point in making new badges if they weren't going to make it go any better (this is in one of Boddy's books on pre-war British sports cars). The Thomas-built cars I think all had sports bodywork rather than Leyland's rather dated-looking slab-sided tourer. They did have different carbs and ignition and the suspension was set up differently.
 * I've also heard it said that Leyland built the short stroke engine and Thomas built the long stroke - re-grinding the cranks to lengthen the stroke as much as would fit within the block. I've also heard that his was mostly done because he was re-drilling the cranks to provide better lubrication (actually using a drilled con rod to improve piston lubrication). As the rods thus had to be re-made, why not stroke it too? However I've heard this from two sources, one (more credible) saying that Thomas did this at Leyland, the other (in print somewhere) saying that it was a Thomas tweak for the tuned cars he assembled. Andy Dingley (talk) 11:53, 8 January 2014 (UTC)


 * There is an interesting letter currently for sale on eBay. I don't intend to buy it, especially at the extortionate price being asked, but the text as far as I can make out (some of the numbers are unclear) is as follows:


 * 7 January 1932


 * To: The National Automobile Chamber of Commerce, New York, U.S.A.


 * Dear Sirs,


 * In reply to your letter of the 1?th instant, we can confirm that the statement contained in “The Autocar” of October 15th 1920, page 545, to the effect that twin carburettors supply a mixture to the cylinders, is a mistake. On all Leyland “Eights”, with the exception of one especially designed for racing, a single carburettor was employed.


 * Yours faithfully,


 * Assistant General Manager


 * Malcolma (talk) 19:47, 9 January 2014 (UTC)


 * Interesting letter. I thought it was just generally known that the Leylands were single and the Thomas cars twins. Andy Dingley (talk) 21:58, 9 January 2014 (UTC)

Source
Does anyone have Hugh Tours' biog of Parry Thomas? It's probably the only really good source on the Leyland Eight. Forty quid mind, last time I looked. Andy Dingley (talk) 17:49, 8 January 2014 (UTC)