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Date: Tue, 03 Mar 1998 22:06:18 +0000 From: Rick May To mini-list@autox.team.net Subject: MINI TECH: Rebores |
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Most people are boring and just go for 1380. A 1380 generally gives
about 15bhp more than a 1275 in the same state of tune.
If your not bothered about the fact that when your engine is knackered, you'll need a new block, then go for 1400cc. This is 74.0mm bore. 1380 is 73.5mm bore. You can go upto 1426cc by boring to 74.7mm, but don't because the walls are too thin. 1400cc is reliable, 100000+ miles. If you still want bigger, stroke it. This is how you get 1596cc, but don't go that far as it won't rev. The optimum engine size for power is 1480cc. This is 74mm bore with 86mm stroke. They are reliable but pricey. Stroking to give an extra 50cc is more effective than boring. You get masses of torque, making the car very drivable. Rick |
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Date: Sun, 8 Mar 1998 14:20:59 -0700 (MST) From: Robert Kroll To: mini-list@autox.team.net Subject: MINI TECH: Rebores |
99% of all Mini engines are very under square, the only square or
over square were the 970S & 1071S, the 850s the closest otherwise.
In modern terms undersquare engines are likely to be 125% or higher.
bore/stroke
850 92%
997 77%
998 85%
970 114%
1071 103%
1100 77%
1275 87%
1380 90% 73.5mm bore
1400 91% 74mm bore
1430 87% no worse than a stock 1275
1445 88%
As far as costs go, the major additional cost is the rods, admittedly
a sizable chunk in the US, if using S or 1275 Midget rods. As this
would be a lower rpm engine (7K?), reworked 998 rods might be usable
(A+?).
Bob |