The first thing to think about is that this engine conversion was dreamed up long before the introduction of the 1300 A series engine, even the Cooper S was just a twinkle in John Coopers eye. The only large bore cylinder blocks available were the BMC Formula Junior items available to a "select few" who were in the know and at vast expense! Therefore when Speedwell offered this conversion it became a fairly popular way of getting a 70 bhp+ Mini, something almost unimaginable in 1962!

There was however one BIG problem from the outset!

SPORTS CAR (Dec 1962)

"Even though the test included a lot of high speed driving, the oil consumption worked out at 200 miles a pint"

AUTOCAR (Dec 1963)

"Almost incredible as it may sound, the overall petrol consumption over a 500 mile test was 32.2mpg. Against this one must offset a total of 9 pints of oil in the same period".

CARS ILLUSTRATED (Dec 1964)

"Oil consumption is heavy . . . . . we found it necessary to add a pint of oil to the sump at only 75 mile intervals".

The more astute of you will be starting to notice a pattern emerging! That's right these Speedwell engines used oil like it was going out of fashion!

The combination of a very thin bore wall and the clearances needed for the forged pistons made these engines portable smoke machines. In the 60's this was not a problem, after all emission testing and pollution laws were nothing more than a bad dream. Speedwell did however try to cure this problem, they began to fit their own liners to beef the bores up a bit, this increased the price of the engine, but did very little to reduce their thirst!

By 1964 Cooper 'S' blocks and engines were freely available which consigning this particular conversion to the history books.

Right, Speedwell blocks and pistons are a non starter, but,

I want to build a replica 1152 and I don't care about the cost.

There are two ways that this can be achieved;

You can contact Carl Schmidt in Germany and order a set of 67mm pistons, find a good 997 Cooper block, get it bored, have some liners made, have them fitted, fit the forged pistons made to the original specification to your special order and end up with a horrible smoking engine that is an exact replica of a Speedwell 1152.

You can do this;

Forget about massive overbore in small bore blocks and set your sights a little more realistically. Use a Pre A+ 1100 engine as the basis for your new motor, these are both cheap and available in excellent condition from a whole range of sources. Obtain a good quality set of +60thou 1100 pistons, although these don't grow on trees there are ready sources at a very reasonable cost, if you can't find any, contact me!

Build a nice sensible motor using these basic components, ensure a good quality centre main strap is fitted and pay very careful attention to all machine tolerances, and balance. Coincidentally the capacity of this new motor is 1148cc, quite close to the original, I am sure you will agree!

The rest of the spec is more or less up to you, but if you stick to using "Speedwell" parts you will end up with an engine that to all intents and purposes looks exactly like an 1152, gives approximately 70 - 75 bhp at the flywheel @ somewhere in the region of 6,250rpm and has considerably more torque than the Speedwell original.

I know of at least 3 "Genuine Speedwell" cars that have had their engines rebuilt in this way, and of course it is up to you whether you let on or not!