Silly question time

Looking at people's signature blocks I have noticed that engine capacity varies from the standard engine a car orignally fitted with a 1098 has become a 1132, 1144 or 1152. And a 1275 becomes a 1310 or 1380 once modified

Hows is this determined?

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1/2 the Diameter of the pistons including overbores if any

square this number then multiply it by 3.14 (pi) (area of the circle that is the bore of piston)

now times this by the the stroke of the engine

and then times this by four cause you have four pistons

This is as far as I know how it goes.
Correct me if I am wrong as far as I know it doesn't take into account combustion chamber size

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Roads need more corners
A Deluxe(CG13DE), 2 Clubbies(998 and 1275) and 2 Morris 1100Ss

Thanks Fuzzy but I think I'm more confussed now that before suddenly it sounds like a bad maths question.

Is there a easier way like 1275 +.020" (1293), +.040" (1310), +.060" (1330), or +.115" (1380)

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Yes I guess so but I don't know them so I can't say best ask Kev

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Roads need more corners
A Deluxe(CG13DE), 2 Clubbies(998 and 1275) and 2 Morris 1100Ss

Wrong Kevin, but you're spot on with the 1275cc overbore capacities there. Answered your own question in fact.
KB

1275 can become 1430 too...

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Jonathan
http://photobucket.com/albums/y64/FatMaserati/

as this is being discussed here might as well ask here... whats an 1100 +40 thou

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No longer Ms Westwoods mini outside her original kings road shop

yes but we were talking about overbores, not stroking as well.
For that you'll have to use the formula the fuzzy haired one gave us.
KB

OK using that formula and the bore size Kev gave in the other thread ( 65.6mm )and a 1100 stroke being 83.82mm

Ok so convert to cm 6.56 cm bore and 8.382 cm stroke

(6.56 / 2 ) ^ 2 * 3.14 = 33.79 square cm (X^2 means squared)

33.79 * 83.82 = 283.22778

283.22778 * 4 = 1132.9

1133 approximately

now lets see if Kev tells me if my calculation is right in practice

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Roads need more corners
A Deluxe(CG13DE), 2 Clubbies(998 and 1275) and 2 Morris 1100Ss

to work out any piston engine`s capacity--->

pie x r squared--- is the formula to work out the area of a circle (pie being 3.1412,,, & r being the radius of the cyl)

then times that by the length of the stroke of the crankshaft

Then times that by however many cyls there are

easy-peasy

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

That's what I said Did I get it right

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Roads need more corners
A Deluxe(CG13DE), 2 Clubbies(998 and 1275) and 2 Morris 1100Ss

thats a big thanks from me peoples

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No longer Ms Westwoods mini outside her original kings road shop

Yes an 1100 bored to +.040" is an 1132. +.060" gives 1152.
Next stop is 68.0mm (Imp pistons) for 1220cc approx. For what a decent set of UK Imp pistons is worth now, you could buy a 1275...

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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.

thanks again doc the previous owner said the motor had been rebuilt twice the most recent not that long ago mileage wise... motor looks good and everything else he said has checked out so far... (he was a good bloke) so i wont be touching the bore, only pulled it open to make sure things looked right. centre oil pickup is the only job im intending to do to the innards at this stage.

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No longer Ms Westwoods mini outside her original kings road shop

Thanks for everyone's input.

I just had my engine and gearbox rebuilt and during the process I was informed that my 1098 has been bored to +.040 and I wanted to know how to recalculate the capacity.

I am now looking forward to the next dyno day so I can see how much power I have gained as I had the diff changed, a road/rally cam fitted and I was already running twin SU and extractors.

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