Doubling the power of any standard engine is possible (unless it'a already an all out race engine) but probably not an easy task, not to mention reliability.
I don't think of mini engines in terms of bragging but driving. You can get 50hp atws from a 988, 1100 or a 1275 (not sure about 850s no proof that I've seen yet). 1275 being thrown together, 1100 being worked nicely, 998 being heavily worked.
For the 1100 to beat the 1275 is bragging rights. I had a 998 equal my 1275s performance at the last dyno day that attended. I was very impressed by the 998, but it's a race engine my 1275 was put together with random twin carbies (now known to be 998 cooper manifold, 997 cooper carbies) and extractors that came with the car.
My engine would have produced approx 70hp at the fly. Should make 76-78, but due to my lack of knowledge and lack of tuning skills only made 70hp at the fly.
However a highly worked, race prepared 998 made 50hp atws (now doing 58hp atws, I last heard after rebuild). Which to me says heavily working a 988 or 1100 is for class puproses, you'll be more competative, but since I don't care about class I went down 1275 route then supercharger (was aiming for 80hp atws but fell short a bit, when I have more money and time I'll go back and look for the remaining hp, buyt doesn't bother me at the moment), which means there really no class for it anymore, but under 2 litre probably, which it is totally useless in. But my car is a road car, not a race car, and next year might be an occasional uncompetative track car.
What I'm getting at is that you should aim for what you want, for the correct reason. Do you want to race the car? If so, to race against who? Other mini's? If other mini's the 1100 is probably the way to go, but expect big money investments and definitely disc brakes for safety! Or do you just want a nice warm road motor with approx 70hp atws? If that's the truth then I'd recommend a warm 1275 properly set up and tuned (also with discs of course). If you want to beat big motors, for bragging rights then go the 1100. It's up to you.
Ok, I'm done...
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1964 Morris 850, 1330 Supercharged - 81.8hp atws.
1975 Leyland Mini S 1100S powered - Nice and reliable.
1977 Leyland Mini LS - Project LS-T
Plus I've heard that 1100's are alot smoother engine...
) was that it kept my car from going through regency. Too much of a PITA.
8)
) can be tamed down to be drivable street motor ( look at the compression todays factory engines run ).
