Re: The Story of the A Series Engine - MG Car Club

Harry Hurst

Interesting discussion here on the advantages of low-end torque , especially with the addition of the Ford v Ferrari aspect. this reminds me of what Jim Hall told me about how the idea of the "automatic" transmission in the Chaparral came up when I was doing my book on the 1965 Sebring:

"We had introduced the automatic in the first part of 1964, at Laguna Seca in the USRRC. The story of the automatic is really interesting. My first Chaparral 2 had a 300 cid Chevy with a Colotti transmission and Hap’s had a lightweight 215 cid Olds aluminum V-8. When Hap drove mine, he said, 'Why do you even need a transmission? It’ll spin the wheels in whatever gear you’re in.'

So we got to messing around to make some type of an automatic transmission. About that time we started a testing agreement with Chevy R&D. The guy that ran it, Frank Winchell, was a transmission engineer and when he saw what we were doing, he said, 'Let me take a look at that.'

Later, he brought down a car for us to test that had a transaxle with a torque converter in it. We tested that car a good deal and found it to be quite acceptable. Initially it was a single-speed, and I didn’t feel it had quite enough torque on the bottom end. So it evolved from a single- to a two-speed and eventually to a three-speed with a torque converter. We then added a lockup clutch to the torque converter so it didn’t lose any efficiency. It worked great, just like Hap said it would."

The reality was that the "automatic" was really  manual gearbox without a clutch because it had the torque converter. Shifting was done manually by matching revs.

Harry Hurst
610-725-9600 Cell

January - May 1
1217 Timberbrooke Dr., Palm Harbor, FL 34684

May 1 - December
2138 Lombard St., 4A, Philadelphia, PA 19146


On 7/26/20 9:52 AM, Gregory Simms wrote:
289 vs 427,and wind drag. Ie. GT 40 was 40 inch height. Too high among other wind issues

On Sun, Jul 26, 2020, 8:43 AM Steve Perlman <sperlman63@...> wrote:
Wasn't long stroke versus big bore essentially the battle of Ford versus Ferrari? 

On Sat, Jul 25, 2020, 12:03 PM Kevin McLemore <kmclemore@...> wrote:
Yep, it's the battle between low-end torque and top-end power. Long stroke (under-square) engines are good at delivering low-end torque, which the average driver appreciates for daily driving - it gives good performance off the line and plenty of pulling power for hills without downshifting, hence why they were used a lot on consumer vehicles (and tractors, too, for that matter!).  

The Brits have a long history of doing unnatural acts to avoid taxes.  Three-wheeled cars like the Reliant, Morgan and Bond are a good example - they were made so that the 'car' could be taxed as a motorcycle. Similarly, cars were delivered as 'kits', like Lotus, Turner, Fairthorpe, etc., because they were taxed differently than a fully assembled car.  This even extended to houses, since taxation at one time was based on how many square feet of roof you had... so folks would remove the roof if they weren't going to use a house for a long period of time!


From: <> on behalf of Roger Searle via <>
Sent: Saturday, July 25, 2020 7:55 AM
To: <>
Subject: Re: [PhillyMGClub] The Story of the A Series Engine - MG Car Club
Engine Fun Facts.

I've noticed that engines often have bores and strokes that are almost equal "square" to achieve the desired displacement.  Reading this article I saw that the A engine had a bore of 57.92mm and a stroke of 76.20mm and is "under square" (i.e. long-stroke).  This reminded me that the British Govt. sometimes taxed cars on the engine bore.  So it is said some manufacturers increased the stroke to avoid some tax.

Doing a little research I learned:  "Under-square" (long-stroke engines) are used a lot today because it increases efficiency .  "Over-square" (short-stroke) engines are used in racing because it increases power.  (

Roger Searle
1978 MGB Roadster - original owner
1971 MGB GT - really cool with new AC system - see article in upcoming Nuffield News

-----Original Message-----
From: Roger Williams <rogerotto@...>
Sent: Fri, Jul 24, 2020 10:55 pm
Subject: [PhillyMGClub] The Story of the A Series Engine - MG Car Club

Hello All!

Here is an interesting article which my Mini and your MGs have in common.

The site is the MG Car Club in England which is also interesting.

Happy reading and exploring.

Roger Williams
‘66 Austin Cooper S

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