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Comments from Paddy's Engine Builder - 1380cc Engine - Torque Gain

From - Bill Gilcrease - Mincomp's Corner (May 1997)

No racing to talk about at the moment, so let me talk a bit about 1380cc motors.

Engine bayI am deluged with “what’s the deal with 1380s?” or “Why?” Well the answer starts out quite simply, “bigger is better,” referring to more cubic centimeters (CCs) or in big car terms cubic inches. The basic fact is that with all things equal except fore bore size a 1380 will have about 15 HP more than a 1275. But the real advantage is the torque gain. (Torque is what pins your head back of the seat when you accelerate.) Once, again, all other things being equal a 1380 can give up to 25ft. lbs. more torque than a 1275. The real significance to the increased torque is that it allows your beloved Mini to become a rather comfortable freeway cruiser by lowering the RPM that are required at any given speed.

Building a successful 1380 is not just as simple as boring it for the larger pistons. In most every instance I have found that a cam designed for the 1275 just does not work very well in a 1380. Now I can sit here and wait for miscellaneous hate mail/Faxes/phone calls about that statement or the next one I’m about to make. In 1991 or 1992 I had one motor on my dyno playing with this cam thing and in the end I came up with a spec. that turned that 1380 to life. Up to that point I must admit that I never could see what all the hype was about but after I was done with this project I was a believer, at least in the 1380’s I was building.


I guess the whole reason I got into writing about the 1380 camshaft thing was because I just finished up a job here at the shop that was a duplicate of several that I do over a year’s span. People call me or bring in their prize 1380 that they or someone else built for them stating “I expected a lot more.” Well I advised them on what I believe the fix to be, and why.


The bottom line here is that every time I have done this cam change the customer has left smiling because he has gotten what he originally expected, and quite often more than he hoped for!

Mincomps_corner_05XX97

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