cc rating after recon

[Xtian]

Does any one know what my cc rating is after a rebore?
I have a 1275GT mini, so it was 1275cc it has since been bored by 20 thou. What is my new cc rating?
I hope someone can help me here.

 

[pgarner]

what was the original bore and stroke ?
cant say its going to be that much mor

 

[Xtian]

The 1275cc A series bore and stroke are as follows; 70.61 mm × 81.30 mm, (2.78 in × 3.2 in)

 

[stamford]

My calcs give that as 1273.42cc for a 20 thou overbore whereas the original bore would give the engine size of 1255.23cc. I would say a typical manufacturer upping their sizes as they do this all the time even when it comes to bhp figures!

 

[Xtian]

Thanks heaps for the response.
I knew it wouldn't be much, but was expecting it to be closer to the 1300 mark, at least over the 1275 anyway.
Thanks again, I'll let you know what I find out from the recon guys.

 

[obi_waynne]

Which pistons are your fitting and are you sticking with the stock crank? These things can also have a bearing on the cc.

 

[stamford]

I worked it out from the bore and stroke dimensions given and then re-adjusted the figures for the 20 thou. If going to Cooper internals and 60 thou then you get into bigger territory, 1293 up to 1340 for various combinations etc. I'd need to access my old David Vizard bible for the permutations etc. It's been several years since I have tinkered with the good old 'A' series.

 

[Xtian]

Sticking with the standard crank, pistons stepped up to next size to fit 20 thou rebore. Will get back to you on precise size.
Should be firing the little beast up in the next couple of days, Then all she needs is a warrant, and rego to make her legal.

 

[stamford]

When racing production class Mini's we were allowed a 0.060" overbore and skimmed heads, can't remember how much but was near the limits before hitting the waterway if I recall! Used to blow the odd head gasket now and then!