I have this 1990 Cooper S engine imported from England, rebored/rebuilt (the whole lot) to 1430cc. Any ideas what horsepower this thing would produce? I will do a few things to make it better, and eventually get a real evaluation, but I was just curious the ball-park figure.

It depends entirely on what else is done to it. Just boring/stroking a stock motor from 1275 to 1430 would only net you about 6 or 8 HP at most, and a bit more torque.

Ballpark- a road 1380S motor I rebuilt last Xmas made 110HP and 106 lb/ft torque at crank, on Russell Engineering's engine dyno.
It had a 286 cam, LCB, stage 3 head, 45DCOE Weber carb with 34mm chokes, and `offset bushed' Cooper S forged rockers.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Mine is a 1430 with extensively ported heads and larger valves, running twin 1"1/2 SUs with LCB exhaust. The cam is large, but unknown, and has been 'dialed back' by the previous owner. (I will get arround to sorting it one day!!)

Makes 85BHp at the Wheels at 5100Rpm

Hope this helps

Minimad

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You can take the boy out of the racer.........but not the racer out of the boy!